Loading...
The URL can be used to link to this page
Your browser does not support the video tag.
Home
My WebLink
About
Cordova Power Supply Interim Feasibility Assessment Technical Data June 1982
CORDOVA POWER SUPPLY | INTERIM FEASIBILITY ASSESSMENT TECHNICAL DATA JUNE 1982 /\ Stone & Webster Engineering Corporation ALASKA POWER AUTHORITY CORDOVA POWER SUPPLY INTERIM FEASIBILITY ASSESSMENT * TECHNICAL DATA CORDOVA POWER SUPPLY INTERIM FEASIBILITY ANALYSIS SUPPLEMENTARY VOLUME - TECHNICAL DATA TABLE OF CONTENTS SUPPLEMENTARY TECHNICAL REPORTS CORDOVA - VALDEZ DC TRANSMISSION TIE LINE FEASIBILITY REPORT PREPARED BY ALCAT ENGINEERING, May 1, 1982 METEOROLOGICAL EVALUATION OF THE PROPOSED ALASKA TRANSMISSION LINE ROUTES PREPARED BY METEOROLOGY RESEARCH, INC., January 25, 1982 METEOROLOGICAL EVALUATION OF THE PROPOSED PALMER TO GLENNALLEN TRANSMISSION LINE ROUTE PREPARED BY METEOROLOGY RESEARCH, INC., April 23, 1982 SOUTHCENTRAL HYDROPOWER CORDOVA INTERIM, CORDOVA, ALASKA DRAFT COORDINATION ACT REPORT SUBMITTED TO ALASKA DISTRICT, U.S. ARMY, CORPS OF ENGINEERS, ANCHORAGE, ALASKA PREPARED BY WESTERN ALASKA ECOLOGICAL SERVICES FIELD OFFICE, U.S. FISH AND WILDLIFE SERVICE, ANCHORAGE, ALASKA, November 1980 VALDEZ INTERIM SOUTHCENTRAL RAILBELT STUDY, ALLISON LAKE HYDROPOWER PROJECT, ALASKA FINAL FISH AND WILDLIFE COORDINATION ACT REPORT SUBMITTED TO ALASKA DISTRICT, U.S. ARMY, CORPS OF ENGINEERS, ANCHORAGE, ALASKA PREPARED BY WESTERN ALASKA ECOLOGICAL SERVICES FIELD OFFICE, U.S. FISH AND WILDLIFE SERVICE, ANCHORAGE, ALASKA, May 1980 Southcentral Hydropower Cordova Interim Cordova, Alaska Draft Coordination Act Report Submitted to Alaska District U.S. Army Corps of Engineers Anchorage, Alaska Prepared by: Paul Hanna, Project Biologist Approved by: Robert Bowker, Field Supervisor Western Alaska Ecological Services Field Office U.S. Fish and Wildlife Service Anchorage, Alaska November 1980 SSS Table of Contents Page ) Tmt roducts Orverereierciciersicicicleloic.cicioieivieie-0]o cioivicio-cielsicicleie cleicicieisiersicicicislon/, Project Description. ..cccccccccccccccccccccccvccccccoccccscs | Crater Lake... .ccccccccccccccccccccccccccccces eloretotoreretatelaroral/ Humpback Creek.....cccccccccccccccccscccccsccccccscccccccs | Powe ral Cre @k stoeiorclotelore'o cioieicioio (cicie\cieleleleletereloicleleleioieioteloreloieloicforclelersia Description of RESOUTCES....cceerecccccccccccccccceccccsceee ll Cordova Vicinity. ..cccccccccccccccccccccccccccccccoscscceelO Cematexs Talee ojoiciic v's o1o'c oie inileloicleiciciolc oie cieicreia sisla\olelololeloloteloreleloleio et L. Humpback Creek. .....ccccccccccccccccccccccsccccccccccscse eld POWOr CROOK o1c cicero cicccicccicice cols cleicielviwisisisiciaisicivicic «ice cinciciseicieisetU Major Potential TEBACES oiciciercic cicieieisin eelelercivicisisicic cicielcleiciciceieiccicie 40 Grater: Lake ciccicclcio:ciers ciciciclaicreloiciclole-c1elclcio(cinielolarsloieloleieisiejelorcinisinie 40) Hummback Cra@ko:o.c.00 oleic cclee 0.0 6:10 o.cie wicicincivieiec’s qelvwinisineiciciooel? GWE CHO Ok a aioc ioreialac ais ciniaicic cre crcieie nite sinisieia(cialeic-citicie sive lsloleicio tt Dilwetim elon seforcicieiciciciaiclaisioloicleleselerele cieieieielsreleieinioicieieie[elsieleicie/s cleleincios . Grater EARGlscicicc cicleleicisicieici ciclo cle oleleiore (oi e.creloisioleloleicicinlcieleiviv cicisicic > “ Humpback Creek....cccccccccccccccccccccccccccccsscssccses cl Web CLOOK icicisivic viciciccicic'claie aisle vinis oleic civics cisivicicivivicie sie viciciclcio I> RBCOMMONGETLONG « 0.6 oc ccccccccccccccsoceccectceconccccreccecedO CHOCOE Lake oicicieicicieielelowlslvie eicloioaisicisicincivicic sleic olclo win oeisieicieslerlc JO Humpback Creek....cccccccccccccccccccccccccccccccces ce sees50 Pawel CLEEK ciciccecic sicic vais viele ole oie cicinicioialcicislolsioiele sie oislelcicicie siviccieD? Literature Cited cciccic.cviccccic cccccic.c os ccsiee celcisccccciciccccceced® Appendices...cccccccccccccccccccccoccecesscsccscsseccceseesed 2 Table Table Table Table Table Table Table Table Table Table 9. 10. List of Tables Page Pink salmon escapement counts, Humpback Creek, 1960-79. cccccccccccccccccccccccccccccccccccscccccels Power Creek water temperatures from March 27 to September 1, 1980. .ccccccccccccccccccccccccccccccecd Spawning depth - water velocity criteria for salmonid fishes found in Power Creek.......220002228 Summary of trapping results on Power Creek using minnow traps, March 27 and 28, 1980........eeeeee035 Summary of trapping results on Power Creek using minnow traps, April 18-20, 1980.......ceeceeee eee e355 Summary of trapping results on Power Creek using minnow traps, June 4-7, 1980.....cccecececececeeee36 Summary of trapping results on Power Creek using fyke nets, June: 4-7, 1980. ..ccccccccccccccccccscce ds Summary of fish captured on Power Creek using minnow traps and fyke nets, June 4-7, 1980........37 Summary of fish captured on Power Creek during spring and summer, 1980......cccccccccccccccccesee to Percent of time streamflow exceeds minimum allowable flow for turbine operation on Power Creek (run-of-the-river) ....ccccecccccccccccccceee cl Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure 9. 10. ll. 12. 13. 14, 15. 16. 17. 18. List of Figures Page Cordova location and vicinity map........sseeeeee 8 Potential hydropower sites near Cordova.......... 9 Crater Lake with Eyak Mountain in the background - Tune 6, 198D..cccccccccccccccccccccccccccccccccselZ Distribution of mountain goats north and. Cast OF COTKOVA. ccccccccccccccccccccccccccccccscels Humpback Creek looking upstream towards the head of the drainage.....ccccccccccccccccccccsceeld Humpback Creek delta jutting out into Orca Tnlet.cccccecsccccccccccccccceccccccccescoccceeoeelLO Humpback Creek delta above the normal high tide Line. ..ccsccccccccccccccccccccccccccccccccsc lO Uppermost man-made dam on Humpback Creek, June 6, 1980. .crccccccccccccccccccccccccccccccccccccscl& Log crib dam on Humpback Creek constructed for power generation in the early 1900's. June 6, 1980. .ccccccccccccccccccccccccccccccccccccccccccel& Upper end of the Power Creek drainage............21 Ohman Falls on Power Creek... .cccccpecccccccseecl Power Creek delta looking west towards Eyak LAK S 6's. crsce: s0.sitre 6 00's-0:cic. 6 sin eis.c'c'njsie 06:0 6 6 66-0 bos 40sieieele Power Creek prior to entering steep canyon area. Massive landslide responsible for creating Ohman Falls enters from the right.......cceeeeee 222 Potential salmon spawning habitat in the mainstem of Power Creek, April 19, 1980. Average daily stream. flow: 62 | CES. )sc.5.2.. 0:0 oleic o1c1e-sie1e' ci esinie ee ao Potential spawning area depicted in Figure 13, June 5, 1980. Average daily streamflow 630 CES. ccccccccccccccccccccccccccccccccccccceceeld Outlet of only significant tributary to Power Creek within the project area, June 5, 1980......31 Photo identical to Figure 15 taken on March 27, 1980. ccceccecceccccnceccscccecccccccesccecsecte Salmon spawning area, tributary to Power Figure Figure Figure Figure Figure 19, 20. 21. 22. 23. Salmon spawning area, tributary to Power Creeks ee sacianieceieleleleieicicis oiciersleieielolercleiecleieieisicisieine 32 Salmon spawning area, tributary to Power Cre EK c.o-c 0 o0rc.00.0 c.ccc05 cc cel csevcsiccccccsccsoesseceedS Evidence of spawning salmon scattered along the bank by bears the previous VERT »\-0\o clove siefeleloislelcxe'ce 5S Length — frequency graph of Dolly Varden trapped on Power Creek June 4-7, 1980.....cceceeeeee eee o42 Extensive wetland area above Ohman Falls created by groundwater flow and beaver dams..ccccccccccee 4h » Appendices Page Appendix I. Scientific names of vegetation, mammals, birds fish, and marine invertebrates appearing in Tee CORE elcticle wialerneloleialoloinietersicielereleloleicicioieieierciele eieieicicleis IS Appendix II. Drawings of Power Creek depicting the major physical and biological characteristices fron the USGS gauging station to 0.3 miles above the end of the Power Creek road....eeeeeeeeece eee es 062 “y INTRODUCTION Cordova is located on the southcentral coast of Alaska, approximately 160 miles southeast of Anchorage (Figure 1). The town is situated on Orca Inlet near the eastern entrance to Prince William Sound. The population of the area is small and at present has a fishing and fish-processing based economy. Due to the great distance from readily available sources of power, Cordova has developed its own means of producing electricity - diesel generation. Currently Cordova is faced with the problems of burning an expensive, non-renewable fossil fuel as its sole source of power. The purpose of the Corps of Fngineers (CE) investigation is to evaluate potential hydroelectric power sites near Cordova to see if the town can ultimately replace all or some of its diesel generators. A Reconnaissance Report submitted to the CE in September 1979 by CHAM Hill concluded that hydropower development in the immediate area of Cordova was a feasible alternative to diesel generation. Three areas were identified for further study: Crater Lake, Humpback Creek, and Power Creek. Biological investi- gations associated with the project areas were conducted by U.S. Fish and Wildlife Service (FWS) and CE biologists on March 27 and 28, April 18-20, June 4<3, and October 2, 1980. PROJECT DESCRIPTION The three potential sites identified include a lake tap (Crater Lake) and two run-of-the-river developments (Humpback Creek and Power Creek). At this time, design plans are not available. Due to low flows and ice problems, hydroelectric generation for Crater Lake and Humpback Creek would only occur from May through October. Power Creek has the potential for year round generation. Crater Lake — This site is located approximately 2.75 miles northeast of Cordova (Figure 2). It would affect lands belonging to the Eyak Native Corporation and state-owned land withdrawn by Cordova. Development would consist of a lake tap utilizing a concrete diversion dam 5 feet high and 15 feet long and a 4,800=—foot penstock of 18-inch pipe leading to a powerhouse on Orca Inlet. The rated capacity of this project would be 458 Kilowatts (Kw) and would not meet Cordova's present _ demand of 3,150 Kw. Humpback Creek — This site is located 6 miles northeast of Cordova (Figure 2). It would affect lands belonging to the Eyak Native Corporation and the Chugach National Forest. Development would consist of a run-of-the-river project utilizing a “concrete diversion dam 5 feet high and 30 feet long, a 6,625-foot flume and a 700-foot penstock of 30-inch pipe leading to a powerhouse approximately 0.75 miles from Orca Inlet. The rated capacity of this project would be 1,010 Kw and would not meet Cordova's present peak demand either. Power Creek = The project area is located 8 miles northeast of Cordova (Figure 2). It would affect lands belonging to the Chugach National Forest. The Reconnaissance Report indicates that this site is the most feasible for power generation (CH.M Hill, 1979). Development would consist of a run-of-the-river project utilizing a l0=-foot concrete diversion dam near mile 3.2 on Power Creek with a tunnel pipeline and vregure “xs Se a * goedeT Cay CO deonng fOM “Po {Abakone det aN yen Giennallen ‘AN Teale — dren Giver Chen seeds. | C, atytoeyyt Tow ye i ou ghs po | feet teat be: SRE « SCHnAOt AY : . 37, ay Ihde f. J Weeimatan, rey) © Swot er Bite} Beak | Game Cara 1214+ Naked | Read Had 0h . : p PRIixSE WILLIAM toe oldotna Pax ee fo Sent NHiepand fonsky x | Ae) en eas f we SOUP IO Poe NSULA,(Sohce™™” 2) WWATIONALS nf Pau! é KENAL daeeasol Vo Se fs DuyLled abepea » ~4! ¢ w fia Gain’ an ev es wy v7 %.7 20, \Wustumens 7-9. , wh Yn we "hh : v4 ‘ J rp “ace Kasilol f ‘, wy jh Mi £95 . cry z 4 avene}—*-# ‘ oC 7! =Y ‘ i via oS, sé . J Ba 2 Mon ue | s, G Ro) aR Es genes 2 Montague | . i Ce. ! ay POPES ¢ cy Z- & Ngee 4 men ba 2 ache t¥e . 5 Middiston \jor 0-7 Fhecrung Spd’, Lo DL Pugrbae 93 “_- diversion dam -———= flume - oe —— —penstock seers + transmission line us power house a N ! BEST COPY: a ) penstock leading to a powerhouse approximately 0.5 to 0.75 miles fron Fyak Lake. The rated capacity of the project would be 5,000 Kw and essentially meet Cordova's demands through the year 2C00. DESCRIPTION OF RESOURCES Cordova Yicinity - The fish and wildlife resources present in the vicinity of Cordova are representative of aquatic species found in Prince William Sound and terrestrial species associated with the coastal western hemlock= Sitka spruce forest. Scientific names of vegetation, mammals, birds, fish, and marine invertebrates appearing in the text are listed in Appendix I. The Chugach Mountains surround the commmity, confining it to a narrow band along the edge of Orca Inlet. Rugged east trending ridges and massive mountain peaks are separated by a network of narrow valleys and passes. The area has been heavily glaciated and vast icefields and glaciers persist throughout. The coast is cut by many fiords anc the ridges may extend into the sea as islands. Streams are short, swift, and mostly glacial. The climate is controlled largely by the mountain barriers and the Gulf of Alaska. Annual precipitation increases gradually from west to east. Heavy snowfall and frequent rain push average precipitation levels to over 100 inches 4 year in coastal areas. The moderate climate and high precipitation produces forests of Sitka spruce and vestern Loy hemlock. Dense alder patches occur near timberline and on steep exposures. Timberline is rather low, often around 1,500 feet, but sometimes as low as the shoreline. A heavy undergrowth of devilsclub, ferns, nosses, grasses, and brush is common. Cordova lies just west of the Copper River Delta. This area produces more ducks per square mile than most known habitats in Alaska. It is also an important stop for migrating geese, swans, cranes, and a ayriad of shorebirds. Several species of marine mammals occur within the Cordova area. However, only harbor seals, sea otters, and an occasional Dall porpoise are documentec as utilizing nearshore waters. Typical terrestrial marmals represented around Cordova include, but are not limited to the following: Sitka black-tailed deer, brown bear, black bear, mountain goat, porcupine, marten, river otter, short-tailed weasel, mink, beaver, and red squirrel. Northern bald eagles are common residents. The entire Cordova area contains a high density nesting population. Eagles nest in spruce or hemlock trees at or near the water's edge. Concentrations are found on salmon spawning streams during the summer and fall. Local waters are lucrative seafood-producing areas roted for fish and ™ shellfish. The anadromous fish populations are dominated by five species of Pacific salmon, Salmon used for both commercial and recreational purposes throughout the resion include pink, sockeye, chum, coho, anc chinook, Other fish in the Cordova region of economic value are herring, halibut, and flouncer. Dungeness, king, and tanner crabs as well as scallops and shrimp are found within the region. Razor, butter, horse, and surf clams as well as cockles are harvested locally; however, only scene clama are harvested commercially. Based on the best information currently available, no threatened or endangered species as listed by the U.S. Department of the Interior (1979) for which the FWS has responsibility are known to occur in the Cordova area. Protection of threatened or endangered marine mammals is the responsibility of the National Marine Fisheries Service (NMFS). The CE may wish to contact the NMFS to determine the presence of these species near Cordova. Crater Lake = Crater Lake is a clear, alpine lake situated in steep, mountainous terrain between Orca Inlet and Eyak Lake (Figure 3). It has a surface area of approximately 25 acres, a maximum depth of 61 feet, and drains about 0.3 square miles. The lake lies at approximately 1,600 feet elevation and is accessible by trail from the Eyak Lake road. The Recon- naissance Report (CHAM Hill, 1979) indicates that Crater Lake has no Matural outlet. Howéver, on June 6, 1980, water was observed spilling from the lake. Presumably the flow is intermittent and the result of snowmelt. Vegetation The vegetation around Crater Lake is characteristic of alpine tundra. Much of this type consists of barren rocks, but interspersed between the bare rocks and rubble are many mat forming herbs, such as moss campion and mountain avens. Common shrubs are the low growing cassiopes, nountain heath, Labrador tea, and alpine azalea. Fish According to Mike McCurdy (1979), a fishery biologist with the Alaska Department of Fish and Game (ADF&G), there were no native fish species in Crater Lake prior to planting rainbow trout. The first stocking program was initiated by the FWS prior to Alaska statehood. Presently, the ADF&G stocks the lake every 3 to 4 years with rainbows. The lake provides good fishing for those local residents willing to hike uphill for several miles. No creel census data are collected, so catch and growth rates are unknown. It is believed that there is some limited natural reproduction in the lake (McCurdy, 1979). The outlet to Crater Lake flows northwest into Orca Inlet adjacent to the Orca cannery. The ADF&G includes the Crater Lake outlet in their index of pink salmon spawning streams but does not usually survey it during annual escapement counts (Pirtle, 1977). Escapement information is limited to 1977 and 1979 when 200 fish were counted each year (Mike McCurdy, ADF&G, pers. comm.). Mike McCurdy (pers. comm.) believes that the small area where the lake outlet water enters Orca Inlet is only used during odd years when pink salmon runs are normally highest in Prince William Sound. These fish may be strays that have been forced to leave overcrowded spawning areas nearby. The data presented in Table 1 tend to support McCurdy's opinion. Table 1 contains escapement counts for pink salmon in Humpback Creek a short distance to the northeast. Both 1977 and 1979 were near record runs in that drainage. Marmals The ADF&G (1973) indicates that mountain goats are found in the steep terrain northwest of Eyak Mountain. This area includes the small Crater Take haein (Fienre 4). No estimate of the number of coats near Crater -12- Figure 3. Crater Lake with Eyak Mountain in the background - June 6, 1980. BEST COPY AVAITABLE | | ie Observation 4/1 hs ef Mae Jeong Spaty Source: Julius Reynolds, C3 SAREE Y = Pale ac AS ey / , NS Se, : (WO Smut bike Evens, \ YY { ( a BEST COPY AVAILABLE Y Juea Alaska Deparctzent of Fish and Game, Cordova SS KO, -€T- a population near Cordova has been reduced by hunting pressure due to the proximity of town. Slack bears are common and may be found in the Crater Lake vicinity during the spring and summer. Sitka black-tailed deer are also common during the summer and fall. On June 6, 1980, a short helicop— ter flight was taken to view Crater Lake and the surrounding area (Figure 3). The lake was still 95 percent covered with snow and ice and no landing was attempted. Mountain goat tracks were observed at the lake near the eastern shoreline. Several sets of bear tracks were also observed paralleling the ridge top. Humpback -Creek — Humpback Creek is a short, steep, coastal stream typical of the Prince William Sound area (Figure 5). It flows generally in a westerly direction before entering Orca Inlet. Presently, there is no Toad access. The watershed drains 2.6 square miles, and the mean annual flow is 25 cubic feet per second (cfs). The stream tends to freeze over in the winter and flows virtually cease (CHAM Hill, 1979). Humpback Creek provides considerable stream and intertidal spawning for pink salmon on the lower 0.5 miles of the drainage. A steep canyon area and a series of old log dams precludes any further upstream movement of fish. Vegetation The primary vegetative type in the project area is a coastal western hemlock=Sitka spruce forest. A narrow band of riparian species occupies the Humpback Creek floodplain and marine flora typical of Prince William Sound inhabit the terminus of the Humpback Creek delta where it enters Orca Inlet. The western hemlock-Sitka spruce vegetation type is well represented. Sitka spruce and western hemlock are the dominant members of the community. Blueberries, devilsclub, and several species of ericaceous shrubs make up the understory. Because of the high rainfall and resulting high humidity, mosses grow in great profusion on the ground, on fallen logs, and on the lower branches of trees, as well as in forest openings. Alders and willows occupy a narrow band along the stream channel primarily near the mouth and above the canyon area. The creek has formed a small gravel delta into Orca Inlet. (Figures 6 and 7). A portion of the delta is being colonized by willows, grasses, and forbs. The rest is barren. The intertidal and subtidal areas off the delta appear to be quite pro=- ductive in terms of marine flora. Rockweed, sea lettuce, wrack, and a species of red algae are all abundant. Fish Prince William Sound pink salmon stocks are particularly adapted to heavy use of the intertidal zone and Humpback Creek is no exception. Pink runs typically display an even-odd year cyclicity and those stocks returning to Humpback Creek tend to dominate on odd years (ADF&G, 1978a). Spawning activity usually takes place from late July to early August. TUscapenent counts conducted by the ADF&G are shown in Table l. Dolly Varden are found in lower Humpback Creek and are probably seasonally attracted following migrating pink salmon. Sport fishing effort for pinks and Dolly Varden is low (Pete Fridgen, ADF&G, Cordova, pers. comm.). =15< Figure 5. Humpback Creek looking upstream towards the head of the drainage. BEST COPY*AVAILABLE -16- cla eee Kat iy Figure 6. Humpback Creek delta jutting out into Orca Inlet. Figure 7. Humpback Creek delta above the normal high tide line. BEST COPY “AVAILABLE Te eee la eererepamnemmtelail tee area atau Dad ae 1. Pink salmon escapement counts, Humpback Creek, 1960-79. Year No. Year No. 1960 2,390 1970 “340 1961 16,010 1971 8,230 1962 7,200 1972 1,740 1963 9,360 1973 2,510 1964 3,560 1974 70 | 1965 1,200 1975 6,800 1966 310 1976 340 1967 420 1977 13,920 1968 550 1978 360 1969 4,730 1979 11,940 Source: Mike McCurdy, Alaska Department of Fish and Game, Cordova. l mile before it enters Orca Inlet. The canyon area is estimated to be between 0.5 to 0.75 miles long. A series of three old log dams, constructed for power generation in the early 1900's, are situated approximately 0,25 miles apart beginning with where the creek first enters the canyon. The uppermost dam is abeut 12 feet high and is situated where the creek enters the canyon (Figure 8). Downstream about 0.25 miles in the steepest part of the canyon is another small dam about 10 to 12 feet high. About 0.25 miles below the second dam is a large dam about SC to 100 feet high —“""™Tigure 9). The big dam was constructed of log cribbing and is slowly péeteriorating. The ADF&G estimates that 50,000 to 60,000 cubic yards i ine (eu. yds.) of gravel is backed up behind the structure (Dick Nickerson, | ADF&G, Cordova, pers. comm.). During periods of high flow, gravel move— | ment over the big dam scours the lower creek channel cecreasing the survival of pink salmon eggs. | | As previously mentioned, Humpback Creek flows into a canyon approximately | The big dam does not block salmon migration. Natural velocity barriers occur downstream (Dick Wickerson, ADF&G, pers. comm.). However, if the dam collapses, a tremendous amount of gravel would be released and it could take several years for the creek to flush all the gravel out of the system. Pink salmon eggs in the lower end of the creek could be physically damaged or buried limiting the adult returns in future years until the lower end of the creek and the expanded delta area eventually stabilized. Information on the occurrence of fish species in Humpback Creek above the canyon area is not well documented. The ADF&G states that fish are probably absent (McCurdy, 1979; Pete Fridgen, ADF&G, pers. corm.). Information provided by CH, Hill (1979) indicates that winter flows in Humpback Creek can get as Iow as 2 cfs and have been known to cease. This makes the presence of a resident fish population highly unlikely. On June 6, 1989, biologists sampled upper Humpback Creek with minnow traps and traditional sport fishing gear. “No fish were captured. The creek was visually estimated to be flowing over 150 cfs. Abundant stream mbank cover and a favorable pool-riffle ratio would aake the upper stretch >: good Dolly Varden stream if the winter flows did not disappear. Mamnals Game species present in “Yumpback Creek include Sitka black-tailed deer, brown bear, black bear, and mountain goat. ‘Mountain goats are usually i tot 44 seb attetan eho mer miveed. inaceessible Figure 9. Log crib dam on Humpback Creek constructed for power terrain. On June 6, no goats were observed in Humpback Creek during a brief helicopter flight although suitable habitat is available (Figure 4). Reynolds (1930) estimates no more than 20 goats are found in the Humpback Creek and Power Creek drainages at any one time. Goats use the ridges overlooking Humpback Creek but their distribution varies greatly by season. For purposes of this report, goat habitat in Humpback Creek is considered to be above the 500-foot contour line (Reynolds, 1980). Black bear prefer forested habitat but are commonly seen foraging in open meadows, tidal flats, brush fields, and alpine areas. Although no black bear were seen during field investigations, Humpback Creek contains excellent bear habitat. No critical denning habitat for black bear has been identified in the Humpback Creek drainage (ADF&G, 1973; Reynolds, 1980). The ADF&G (1973) has documented that the salmon spawning area on lower Humpback Creek contains seasonal concentrations of brown bear attracted by the readily available food source. Clumps of brown bear hair were found in the brush near the uppermost dam during field investigations on June 6. Skeletal remains of pink salmon were found scattered on the bank along the spawning reach. Biologists assumed that the fish remains were evidence of brown bear use during the 1979 spawning season. No critical denning habitat has been identified for brown bear in Humpback Creek by the ADF&G (1973). Reynolds (1980) estimates there are probably six brown bear using the drainage. Biologists encountered frequent evidence of Sitka black-tailed deer while traversing the area from above the canyon to the delta. Deer tracks were present in the sand along the creek above the canyon area and on the delta. Numerous tracks and pellet groups were observed around small bogs in the forest parallel to the creek. During the winter, deep sncws force deer down to the beach fringe throughout Prince William Sound and when populations are high, almost all these fringe areas can become critical winter range. According to the ADF&G (1973), mainland deer populations in Prince William Sound are low and the eastern shore of Orca Inlet is not considered to be an important winter range. Even though direct documentation is lacking, there is enough evidence of deer in Humpback Creek to suggest that portions of the beach fringe on the eastern shore of Orca Inlet, including the Humpback Creek delta, may be winter range for a few animals. Birds The Humpback Creek delta provides feeding and nesting habitat for water- fowl and shorebirds. Twenty Canada geese were observed on the delta on June 6. Close investigation revealed that the geese were feeding on succulent forbs growing on the higher, dry areas of the delta where permanent vegetation has become established. There was no evidence of goose nesting. Several species of shorebirds nest on the delta although not in great numbers. Species that were displaying protective behavior indicating that they had nests nearby were: two pairs of spotted sand— pipers, two pairs of semipalmated plovers, and one pair of black oyster- catchers. Other birds observed in the area were glaucous-winged gulls, mew gulls, black-legged kittiwakes, ravens, scoters, water pipits, harle- quins, northern bald eagles, and savannah sparrows. Creek. During field investigations, biologists used a helicopter to search the shores of Orca Inlet for several miles in either direction from the mouth of Humpback Creek and the lower 5 miles of Humpback Creek looking for bald eagle nests. None were located in spite of the fact that a dozen adult birds were seen in the area. Marine Biota Besides the abundance of seaweed, the intertidal and subtidal habitats off the delta appear to be productive in terms of marine organisms also. Profuse amounts of barmacles cover all the exposed rocks and cobble. Mollusk shells windrowed by the surf are abundant - mussels, horse, butter, and littleneck clams, and cockles. In addition, four sea otters were observed feeding a short distance offshore. Power Creek ~ Power Creek begins at a small glacier in the Chugach Moun tains at a point about 13 miles northeast of Cordova (Figure 10). It flows southwesterly for a distance of approximately 7 miles and enters Eyak Lake near Mile 6 on the road leading from Cordova. Miller (1951) investigated the geology of a proposed dam and reservoir on Power Creek for the U.S. Geological Survey (USGS) and gave the following description of the creek. In the upper 2.5 miles of the drainage, Power Creek flows in a shallow canyon cut in unconsolidated glacial and alluvial deposits. For the next 2.5 miles the creek meanders from one side of the valley to the other on a floodplain of unconsolidated mud, sand, and gravel, from 0.25 miles to 0.5 miles in width. At a point about 2 miles from Eyak Lake the creek swings to the southeast side of the valley and vertically drops 52 feet at Ohman Falls before continuing through a steep walled canyon 200 to 450 feet deep cut in part in bedrock (Figure 11). Less than 0.5 miles from Eyak Lake the creek emerges from the canyon and has formed a delta by filling in the northeast arm of the lake (Figure 12). The valley walls on both sides of the creek basin are steep, rising abruptly from 2,000 to 4,000 feet. The valley of Power Creek exhibits the U-shaped profile and flat floor that is typical of glacially-scoured and partially refilled valleys in the region, except for the lower 2 miles. In this stretch the even fall of the valley is interrupted by a broad, fanlike ridge that extends nearly across the valley from the northwest side. This feature is respon—- sible for the creation of Ohman Falls and the steep canyon in the lower portion of the drainage. Miller (1951) concluded that the fanlike ridge was actually a massive landslide that came from the northwest valley wall partially filling the glaciated valley and forcing Power Creek to cut through a bedrock spur along the southeast side of the valley (Figure 13). That portion of Power Creek between Ohman Falls and the delta is charac- terized by a relatively straight, stable channel. The only areas of obvious erosion of the streambank are found just below Chman Falls where several active slides are contributing sediment. The steep canyon area is lined with bedrock and large boulders providing long-term stability. Where the canyon widens out prior to entering the delta, the stream also widens. Sitka alder, other shrubs species, and conifers are well esta= blished along this reach and even during extreme high flows protect the streambank from significant erosion. The creek gently meanders and does ce a 22- PE Mays ee . Figure 12. Power Creck delta looking west towards Eyak Lake. Figure 13. Power Creek prior to entering steep canyon area. Massive landslide responsible for creating Ohman Falls enters from rhe riehr. NEE traight, narrow canyon through which the creek flows, no significant Naciwacer ponds or sloughs are present; no islands or extensive deep \ pools have been formed; few log jams accumulate; and only one significant tributary enters the main stream. Several seeps and small springs occur but they do not appear to contribute significantly to the average annual flow. The extent of groundwater discharge into the creek is unknown. However, the CE plans to gather the data to estimate what the groundwater contribution is (Tom Murdock, CE, pers. comm.). Power Creek has a high runoff, but is unevenly distributed throughout the year and is related directly to climatic conditions. During the winter months when most of the precipitation comes as snow, the streamflow is low. Due to the rugged topography of the basin, much of which is barren, there is very little ground or bank storage (Johnson, 1949). There are no lakes in the basin to provide natural storage. The snow accumulation during the winter months, however, serves as a natural reservoir, releasing the water with the warmer temperatures of early summer (Johnson, 1949). Daily variations in flow are also directly related to rainfall. Because of the historic interest shown in developing a hydro project on Power Creek, the USGS installed a gauging station in 1947 to record flows. The gauge has been maintained continuously from that date and flow records are published annually in the USGS Water Data Reports for Alaska. OY Baseline data on water temperatures for Power Creek have not been ¥ adequately collected in the past. Consequently, the CE installed a Peabody=Ryan thermograph on March 27, 1980, about 100 yards upstream from the USGS gauge. Table 2 contains daily highs and lows recorded from March 27 to September 1. Vegetation The major vegetative type in the project vicinity is a coastal western hemlock=Sitka spruce forest. ‘lestern hemlock and Sitka spruce are the dominant species. Other tree species include a few balsam poplar. The understory environment of the forest is composed primarily of blueberry, devilsclub, and bunchberry. Copious growths of mosses and lichens cover the forest floor, downed logs, and the lower branches of trees. A thin fringe of Sitka alder borders the edge of Power Creek and separates the stream bank from the forest. Occasional black cottonwood trees occupy the floodplain and the delta area where Power Creek enters Eyak Lake. Aquatic vegetation of the streambed is composed predominantly of a filamentous brown algae. Mosses cover all the exposed rocks in the stream and within the limits of normal high water. Fish ”» Coho Salmon The most important fishery resource in Power Creek is coho salmon. The annual coho run into the Lyak Lake system is estimated at 3,000 to 12,000 fish (McCurdy, 1979). Available information indicates that the great majority of cohos entering Eyak Lake migrate up Power Creek and the run Table 2. Power Creek Water Tenpevatutee! From March 27 to September 1, 1980, (half day) 5 OS ES OO OO SO iO) O10) Oo So. Noo I AMANMAANNAMNANMNMMIAMNMNMNMNMAMINYNMNYNSTATONSTTITOM lst st B HMnaqgaageOnononnagesoennoooqgooeonaco oon tH ee ee Be ae OF FX | ee ee . ee td FOPTHIHNSENNHHHENIAOHEHNHHNHOHAH ST SH no”m Ele ee Al: ANON tNOR DWHO-4 oe SS) See aos whan oe ANOS & anyon ? Hy aaddad HIGH OSS anaad DATE Mar > u et ANNFANORDNOANMNFTNHONDAMNOANMSN DO S8n S59 ANNNAN AN PoP MY SPONGY eh ee) A 8 SP OOO OM O'S . ee @¢ © © © © © 6 eee @ © © © 6 ee HABANA ANNANMOSCCOHANNANNHANAM AMI GOW BHO 4.0 O 06. O 8G OS 4) oS 8 OM) Oi Quy ¢ e oeeee eeee ° eee AKIAAMNEMAENNMHOAANAMANMAMAAAMM OH 29 30 att C, emperatures in degrees Centigrade Recording tape changed, new battery installed l/ All t ry Table 2 (continued). - ° e eee e 8 6 © © © ee 6.6 8.6. 0. 048 ©. 4. 6 oe e@ toe Gunns nnnnunnnny VOTH AHAKH HHH AA Low | So NY OM) CSO. O CO SO OD OC 5 DD CON WEN CC 1D.) Ce . ° e e430 # 6 oe ° oe . eeee ° OOWSSODBOOCHONOHNHOCHONS ONSMHDOBDDOONRDORODOUWKDOOR BIGCH | HoQagoneqoneonHnageoes OD I OO OS Oe ey Oe ust oo DATE July 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Au 13 20 ANONTNOKN DADAMS MN ad tt ot re) AAO SINSFIHNENEEEMNGEENEE TE ETINS Esse Hnessane . ° e ° ° ° e ee RAK SER OEE HNO FEHSTHOCHHNHHHHNG RONODHNONHONMNNWY HIGR | eoneneannnesanneennnnengcey MOYO 874) Ow) CO DATE July June 4 5 6 7 8 9 10 ll 2% i3 14 15 16 17 18 19 20 25 az 23 4 25 26 27 3 29 30 AINOMNANORDHOAN seit Table 2 (continued). LOW HICH DATE 3 eoeonneeeansas ° e re) vues nnNnnnn wy ti 9 enengnesnysess S e or CRSCKRKOBONGSO wo Ls] v 4 4 § md ¥ t4 a aaa aAwtnNon ano ae a N NANANNAIOY —————— is estimated at 7,000 to 9,000 (Pete Fridgen, ADF&G, pers. corm.). -These estimates are based on the opinions of ADF&C personnel stationed at Cordova as actual escapement counts are not available for cohos. High flows and turbid water conditions during the peak spawning period usually prevent counting spawning adults. Spawning fish cannot use the entire Power Creek watershed due to Ohman Falls. Only the lower 2.5 miles of the drainage is available. The ADF&G also estimates that nearly half of the annual coho escapement utilizes the creek above the USGS gauging station (McCurdy, 1979). This involves about 3,500 to 4,500 fish. The remainder of the run spawns below the USGS gauge downstream to Eyak Lake. Spawning takes place from late August to early December, usually during periods of peak high water (McCurdy, 1979). Although spawning may occur in main channels cf large rivers, locations at the head of riffles in shallow tributaries or narrow side channels are preferred. Optinun substrate composition is small-medium gravel. However, ccho are extremely adaptable and will tolerate up to 10 percent md. Optimum stream discharge is 3.4 cfs (ADF&G, 1978a). Table 3 contains sone reported spawning depth-water velocity criteria for coho from the literature. Information on the location of coho spawning areas in Power Creek was inadequate to determine what impacts would result from a small hydro project, so field investigations were initiated by FWS and CE biologists during the spring and summer of 1930 to find and map sites in Power Creek that were potential coho spawning areas. From April 1ld-20, during low flows, the streambed was walked from the USGS gauge to approximately 0.5 miles below Ohman Falls. Using a hand held compass and a range finder, a rough habitat map of Power Creek was drawn on graph paper to a scale of 1" = 60° (See Appendix II). Major characteristics of the substrate, streambank, stream channel, and potential coho salmon spawning areas were described. Biologists were unable to survey the stream all the way to Ohman Falls as the last 0.5 mile was in an active avalanche zone and was completely buried by snow slides up to 30 feet deep. In addition, biolo— gists walked the lower portion of Power Creek from the USCS gauge downstrean to the beginning of the Power Creek delta. Because of the snow depths (3-4 feet on the level) only the mainstem of Power Creek was surveyed in April. On June 4, 5, and 3 investigators returned to inspect the 0.5 mile stretch below Ohman Falls and to insure that no areas adjacent to the mainstem had been missed. Consequently, one small tributary was discovered (Appendix II, p. 2). Results of the spawning ground surveys indicate that the bulk of the potential coho salmon spawning areas in Power Creek are located below the USCS gauge. This area was judged to be outside of the project influence. However, potential spawning areas were located within 0.5 mile upstream from the gauge (Appendix II pp. 1-5). This potential spawning habitat terminates just below the end of the Power Creek road. Areas were judged to be potential spawning habitat by comparing physical characteristics with areas of known coho spawning elsewhere. Such physical parameters as substrate composition, stream velocity, and stream depth were considered among the primary factors. The most extensive potential habitat in the : fom --- = Meant ahawa the cance is shown in Appendix II, pp. 3 5 ble 3. Spawning depth-water velocity criteria for Salmonid fishes found in Power Creek. >pecies Depth Velocity Reference (meters) (feet) (en/sec) (ft/sec) tho 1,021.25 1.2=1.3 Chambers et al., i955 who 0.3=1.90 0.5=3.0 Sams & Pearson, 1963 Coho b 0.6 1.0=3.0 Thompson, 1972 ho 15 21-70 Smith, 1973 pees erg eS fae aie lela ares tienen ahammar Sockeye 1.01.5 Lae i Chambers et al., 1955 ockeye - 1.75=1.8 Clay, 1961 Cutthroat - 1.0=3.0 Hooper, 1973 atthroat 0.2=1.5 0.35=2.37 Hunter, 1973 Dolly Varcen 0.7=1.4 1.13=2.15 kunter, 1373 y ‘pieasured at 0.4 £t. above streambed. Minimum vource: Stalnaker and Arnette (1976). =29> Figure 14. Potentiai salmon spawning habitat in the mainstem of Power Creek, April 19, 1980. Average daily stream flow 61 cfs. Were ee Figure 15. Potential spawning area depicted in Figure 14, June 5, 1980. Average daily stream flow 630 cfs. Se 4ecreases, water velocity slows down, and sand and gravel are deposited. | “ging material is a mixture of fine sand, small gravel, and medium i g gl with less than 1 percent large rock. Depths varied from less than 1 __iJet to slightly over 2 feet. No water velocity measurements were aken. Average daily streamflows from April 18-20 recorded at the USGS pjauge were 63, 61, and 61 cfs respectively and were sufficient to cover 100 percent of the potential spawning areas in the mainstem (Figure 14). Ither sections of Power Creek contain what were considered to be limited i spawning habitat due to unsuitable substrate, deep water, or the areas were too small to hold more than a few redds (Appendix II pp. 1, 4, 5, and 7).. The remainder of Power Creek above the end of the road was not considered to be important to coho spawning as the potential habitat is either absent in most stretches or very limited. On June 8, approximately 20 percent of the 0.5 mile section below Ohman Falls was still covered by avalanche slides and biologists were once again unable to view the entire streambed. Since the sections of stream that were open just above and below the slides were not suitable spawning habitat due to the stream gradient and the presence of many rocks and rapids, the sections flowing beneath the slides were presumed to be unsuitable as spawning habitat i also. | As previously mentioned, a small tributary was discovered on June 5 (Figures 16 and 17). Just upstream from the USGS gauge on the outside of a.90° bend in the creek a small tributary enters Power Creek (Appendix ~“) >. 2). The tributary contains clear water and is not milky like i begin rv Creek is during high flows. The origin of the water is a series of ' seeps and groundwater springs coming out of the mountain. It was visually estimated to be flowing less than 10 cfs. The entire tributary contains spawning habitat (Figures 18-20). Salmon bones were scattered along the banks where bears had evidently carried adults to feed on the previous year (Figure 21). This area is shielded from the main stream by spruce trees and a thick stand of alder. During the winter it is blanketed by 4 to 6 feet of snow. Additional verification of spawning areas should be made by viewing adults later during the spawning period. On October 2, 1980, biologists were able to partially verify spawning areas by direct observation. Four pairs of cohos were observed spawning along the bank of Power Creek about 300 yards below the USGS gauge. digh flows and murky water prevented investigators from adequately surveying the main stream. Despite the turbid flows, biologists were of the opinion that the coho run had only recently begun and that one additional trip in uid-November 1930 would be necessary. Field work during spring and summer 1980 also involved determining if coho salmon juveniles were over-wintering in Power Creek and if the : presence of coho spawning areas could be further identified by trapping emergent fry. . ; “Prono eggs in the gravel develop slowly during the cold winter months, hatching in about 6 to 3 weeks (ADF&G, 1978a). The sac-fry remain in the gravel and utilize the yolk material until emerging 2 to 3 weeks later Clay-June). Upon emergence, the fry school in shallow areas along the shores of the stream. These schools break up rather quickly as fry establish territories. The fry defend these territories from other =37— Figure 16. Outlet of only significant tributary to Power Creek within the project area, June 5, 1980. Figure 17. Photo identical co Figure 15 taken on March 27, 1980. BEST_COPY_AVAILABLE Salmon spawning area, tributary to Power Creek. Figure 19. BEST.COPY“AY AILABLE Figure 20. Salmon spawning area, tributary to Power Creek. Figure 21. Evidence of spawning salmon scattered along the banks by bears the previous year. BEST COPY AVAILABLE juvenile coho with aggressive displays. This territory is usually along the shoreline or behind a log or boulder. From such a locaticn the young fish do not have to fight the current, and can dart out to feed on surface insects or drifting insect larvae. Juvenile coho grow rapidly during the early summer months, and spend the winter in deeper pool areas of spring= fed side ponds. Cohos also rear in ponds or lakes, where they feed along shoreline areas. The possibility of coho salmon juveniles rearing in Power Creek over the winter period was discussed with fishery biologists from the ADF&G and the Chugach National Forest. The general consensus was that Power Creek was probably not an over-wintering area even though there were no data to support such a conclusion (Pete Fridgen, ADF&G; Ken Holbrook, Chugach National Forest, Cordova, pers. comm.). Pete Fridgem (pers. comm.) felt that Eyak Lake is such a productive environment that cohos most likely migrate out of Power Creek into the lake after emergence and would have no reason to return prior to outmigrating as smolts to the sea. Further=- more, rearing habitat in Power Creek above the USGS gauge preferred by cohos was felt to be limited. Sloughs, backwater channels, and spring-fed ponds are generally absent. In order to verify Fridgen'’s opinion, baited minnow traps were placed in a variety of stream habitat available to fish over-wintering in Power Creek. (Trap locations are all identified on the habitat caps in Appendix II.) Approximately 0.5 mile of the stream was sampled on viarch 27 and 28, April 18, 19, and 20, and June 4, 5, 6, and 7. The results of the trapping effort can be seen in Tables 4=9. No over-wintering juvenile cohe were captured. The results support Fridgen'’s opinion that Power Creek is not a rearing area for coho salmon. Coho salmon fry, newly-emerged from the gravel, were captured by using minnow traps and fyke nets from June 4-7 (Tables 6-3), Twenty one minnow traps and two fyke nets were set from the USGS gauge to just above the end of the Power Creek road (0.5 aile). Daily air temperatures reached 75° F causing the creek to rise rapidly from melting snow and assume a milky appearance from glacial flour. High flows hampered the trapping operation. One fyke net in the main channel of Power Creek was removed after one day due to rising water and one minnow trap was washed away. Several traps became plugged with debris and didn't fish effectively. Nevertheless, 33 newly emerged coho salmon fry were captured along with 119 juvenile Dolly Varden. Of the 33 newly emerged coho salmon fry captured, 30 of them were caught near the junction of the small tributary with Power Creek (Appendix II, pe 2). The majority of the fry were 25 mm in length. Visual obser- vations of the area indicate that the flow of the small tributary appears to be independent of Power Creek except during extremely high water. At very high flows, Power Creek would overflow its normal banks and inundate the area. Only three newly emerged coho fry were captured in the mainstem of Power Creek. Due to the warm air temperatures and resultant runoff, the creek Tose steadily making it impossible to use a fyke net in the main strear. Average daily flows recorded at the USGS gauge from June 4-8 ranged from a low of 455 cfs on June 4 to a high of 630 cfs on June 5 and 7. Any coho fry that vere emerging would immediately be swept downstream as the a Table 4. Summary of trapping results on Power Creek using minnow traps, March 27 and 28, 1980. f ) Trap 3/28 , LDV i 2 15DV 3 0 Total 1GDV Table 5. Summary of trapping results on Power Creek using minnow traps, April 13-20, 1980. Trap 4/13 4/26 4 ore 5 1Dv baw Dv 9 Total 2DV 0 *In addition, one dead DV was found washed up on the bank. **Trap 7 was placed outside of the project area in a deep hole where the Power Creek delta begins. J Table 6. Summary of trapping results on Power Creek using minnow trape, June 4—7, 1930. tra 6/4 6/5 6/7 A LDV Lost - B 3DY 4DV 4DV c 3DV Plugged 25V D 0 Plugged Plugged E lpv 3bV 1Dv* F 6 Go 6DV G ipv 4DV 2nV q 1 coho fry 0 z 5DV 4DV J 7DV 3DV K 8DV SDV L 4DV 3DV M 1pv 2DV, plugged Ny 2DV 2DV, 1 coho fry 9 1DV 4DV P 6 coho fry 7 coho fry Q 9 5DV i 4DV LDv* Ss 1pv* 1DV, 1 coho fry ee ae 3DV 2DV, plugged U 3DV SDV, plugged Subtotal 9DV 55DV 52DV 7 coho fry 9 coho fry -*l unidentified fry escaped Table 7. Summary of trapping results on Power Creck using fyke nets, June 4-7, 1980. Trap 6/4 6/5 6/7 1 0, pulled ~ = 2 2DV, 6 coho fry IDV, 11 coho fry Subtotal 0 2DV, 6 coho try ibV, 11 coho fry Table 3. Summary of fish captured on Power Creek using minnow traps and fyke nets, June 4-7, 1930. capture method aL 6/5 6/7 total Minnow traps 9DV SSDV 52DV 116bV 7 coho fry 9 coho fry 16 coho fry fyke nets o 2DV 1bV 3DV 6 coho fry 1l coho fry 17 coho fry Total 9DV 57DV 53BV 119DV 13 coho fry 20 coho fry 33 coho fry S Table 9. Summary of fish captured on Power Creek during spring and summer, 1980. Capture Method 3/28 4/19 4/20 6/4 6/5 6/7 Total Minnow traps 16DV 2DV 0 9DV 55DV 52DV 134DV 7 coho fry 9 coho fry 16 coho fry Fyke nets 0 2DV bv 3DV 6 coho fry 11 coho fry 17 coho fry Total 16DV 2DV 0 9DV 57DV 53DV 137DV 13 coho fry 20 coho fry 33 coho fry -8e- a 5 velocity and depth of the creek were such that biologists could not wade it safely. High water conditions biased the trapping results and contri- buted to the low number of coho fry captured in the mainstem. The potential salmon spawning habitat located during April was observed in June to compare conditions at low flows (April) with conditions at medium to high flows (June). The potential spawning areas were senerally unrecognizable. Depths ranged for 3 to 3.5 feet compared with 0.5 to 2 feet in April. Standing waves and swift water were present where slow, even flows were the rule in April. Sockeye Salmon McCurdy (1979) estimates 15,000 to 25,000 sockeye salmon enter the Eyak Lake system annually, but the percentage using Power Creek is unknown. Sockeye spawning takes place along the Eyak Lake shoreline and the lower end of Power Creek from late August to mid-October. The majority of sockeye that spawn in Power Creek do so in the braided channels in the lower delta. Optimum substrate composition is fine-medium gravel with no more than 1 percent of the gravel being 5.9 inches in diameter (ADF&G, 1978a). Table 3 contains some reported spawning depth-water velocity criteria for sockeye from the literature. Redd size generally averages 2.09 square yards (ADF&G, 1978a). According to the ADF&G, no sockeye are known to spawn above the USGS gauge (McCurdy, 1979). On October 2, 1980, investigators observed sockeye spawning in the mainstem of Power Creek from the USGS gauge downstream to the beginning of the delta, in the small tributary just above the gauge (Appendix II, p. 2; Figures 18-20), and in another small tributary located about 200 yards below the gauge. From the appearance of the fish, there seemed to be two fairly distinct runs. The small tributary above the gauge contained the remains of 50 sockeye that had been dead for quite some time. The live fish observed (365) were bright red and still actively spawning. In several places it appeared that completed redds were being excavated. In addition, 25 dead fish were strewn along the bank having been partially eaten by bears. This area was estimated to contain 1,253 square feet of spawning habitat and is the same area that most of the coho fry trapped in June came from. The small tributary downstream from the gauge is located across Power Creek from the road and enters the mainstem near the USGS cable car A-frame. Fifty-two live sockeye were enumerated. No dead fish were found. The spawning habitat was estimated to contain 600 square feet of suitable gravel. Sockeye observed in the mainstem of Power Creek below the USGS gauge were spawning solely within 6 feet of the bank on both sides of the creek. Although a considerable amount of spawning habitat exists in the mainsten, it was not being used. Stream velocities appeared to be too fast. Until Power Creek flows decrease substantially, biologists felt that the majority of gravel in the mainstem of Power Creek would be unavailable to spawning salmon (both sockeye and coho). Due to the murky water, the number of salron observed was undoubtedly low. In spite of the poor conditions, 107 live and 10 dead sockeye were counted. No sockeye juveniles or fry were captured during the spring and summer field work. Under normal conditions, sockeye eggs incubate for a period of 80 to 140 days. When the eggs hatch, sac-fry remain in the gravel for 3 to 5 weeks and emerge in early spring - April and May (ADF&G, 1978a). Sockeye spawning in lake inlets move downstream into the lake after emergence. In this case, it appears that sockeye emergence was missed by sampling the stream in mid-April and early June. Wo sockeye were captured in or near the small tributary above the gauge in spite of the fact adults were seen spawning there in October. Another explanation for the absence of sockeye fry in the minnow traps is trap bias. Sockeye fry are planktonic feeders and may not have been susceptible to the bait used — commercially prepared salmon egg clusters. Dolly Varden Power Creek contains a good population of Dolly Varden below Ohman Falls. The ADF&G indicates that the sport fishery, although readily available, is not utilized very much by local residents (Pete Fridgen, ADF&G, pers. comm.). No population estimates are available for Dolly Varden. Both anadromous and non—anadromous forms of Dolly Varden occur in the Prince William Sound area. The largest populations of sea=-run Dolly Varden are associated with productive salmon systems. Lake systems are of special importance as anadromous fish utilize freshwater lakes like Eyak Lake for over-wintering habitat. Spawning activity begins in September and in some systems extends as late as November (ADF&G, 1978b). Information on Dolly Varden spawning areas and peak spawning periods for Power Creek is not well known. According to the information available, Dolly Yarden have been seen spawning in lower Power Creek just before it enters the delta and Eyak Lake (Ken Holbrook, Chugach National Forest, pers. comm.). No Dolly Varden spawning areas were identified during field investigations. However, several large individuals were seen mingling with spawning sockeye in Qctober. Biologists assumed these fish were preying on sockeye eggs and were not spawners. Since Power Creek was still too high for Dolly Varden to spawn in the main stream, biologists felt that another trip to the area in mid-November would be necessary.. At that time Power Creek normally drops, the water clears up, and visual sightings of Dolly Varden spawning would be much easier. Dolly Varden eggs develop slowly in the cold water temperatures usually present during the incubation period. Hatching of the eggs occurs 4 to 5 months after fertilization, usually in March (ADF&G, 19738b). After hatching, young Dolly Varden obtain food from their yolk sac and usually do not emerge from the gravel until this food source is gone. According to the ADF&G (1978b), emergence occurs in April or May. Juvenile anadromous Dolly Varden rear in streams before beginning their first migration to the sea. During this rearing period their growth is slow, a fact which may be attributed to their somewhat inactive feeding habits. Young fish often remain on the stream bottom, hidden from view under stones and logs or in undercut areas along streambanks. Dolly Varden young seldom swim near the surface and appear to select most of their food from the stream bottom (ADF&G, 197Sb). SSS Power Creek appears to be an important rearing area for Dolly Varden. Trapping results during March, April, and June showed juvenile Dolly Varden to be abundant and evenly distributed throughout the stream reach from below the USGS gauge to above the end of the Power Creek road (over 9.5 mile). Eighty percent of all fish captured in Power Creek were juvenile Dolly Varden (Table 9). The data in Figure 22 taken from fish captured June 4-7 suggests several age classes of Dolly Varden were present. Lengths of Dolly Varden captured ranged from 35mm to 150mm and coincide with the age classes that represent the major portion of the rearing fish population - age groups 0, I, II, III, and IV. The largest individual caught (not included in Figure 22) was 200mm (3 inches) in length. This fish was taken in a fyke net at the junction of the small tributary with Power Creek. Due to the presence of emerging coho fry in this area, this fish may have been preying on small coho. . Cutthroat Trout The Eyak Lake system also contains sea run cutthroat trout. Very little is known of their distribution or abundance. The ADF&G states that they are found in Power Creek (Pete Fridgen, pers. comm.). Prince William Sound is the northern and westernmost extension of the cutthroat trout range in North America (ADF&G, 1978b). According to Xen Holbrook (pers. comm.), cutthroat can be caught in Eyak Lake right after the ice goes out. The fish are not large, weighing 0.5 to 2 pounds and 12-18 inches in length. Cutthroat spawn in small, clearwater, gravel-bottomed streams during April through early June, peaking in May (ADF&G, 1973b). The female digs one or more redds about 1 foot in diameter and 4-5 inches deep. The eggs are deposited in the redd, fertilized, and covered with 6-8 inches of gravel, Hatching usually occurs in 6 to 7 weeks, after which the sac-fry remain in the gravel several additional weeks. Spawning activity occurs primarily at night. After spawning, anadromous fish often survive to return to saltwater. Cutthroat rear several years in small tributaries before moving into larger streams, lakes, or migrating to the sea for the first time. Sloughs, side channels, deep pools, and beaver pond areas constitute important rearing areas. Overwintering at sea is uncommon, and in the fall, both mature and immature cutthroat return to freshwater to overwinter in lakes or streams with deep holding areas (ADF&G, 1978b). Cutthroat may or may not overwinter in the same system every year. In-migrations occur from April to November. The earliest in-migrants are mature spawners which enter from April to early July. Both immigration and emigration occur primarily in darkness. No evidence of cutthroat was found in Power Creek during Harch, April, or 5 June. to spawners or redds were observed. No juveniles or fry were y captured. If cutthroat are spawning in Power Creek, the population mst be small or they may be using the delta arca and not that section above the gauge. -42-~ ; fo) , | i - °o . ' . ie - ; ~~ i : ats Le : ' o ! | | ai at i a i ‘ «4 : : e i ' . | iiss ) ivi ‘ t i , vu ‘ a Paulin : Bie = sees ea Olea, Suc ee os s Poor p cbc) pee i. 9 ! , 0 : . — u — en ny oe o--0 ere emeee- © — = — - ——— : > : . > ; ! i fa ! a i ! { ° ' i E { a ! i ¢ ‘ wu 4 : Oo: nA. == i Sa SADR NEUADD PRN NEE T a oO ; eee: ! = \ n z Mn aerate ee tee 2 ~ ; >) : = | us 1 H & ; 91 vw +7! 96 eae v3 - - wn nt en / v5 ; : ue . “a : x : wu o ' wu t ‘ vo ! Me ‘ _ 9 eg te ce cae ga } ' a Figure 22. Length - 20. 32 . 30 25 e { JO YaAGNON © zl | igen ciate: mnielaetd es ® Other Fish Species Pink salmon runs into Eyak Lake are minimal as a result of uplifting by the 1964 earthquake. Pinks do not spawn in Power Creek (McCurdy, 1979). Eyak Lake also contains round whitefish and burbot (ALF&G, 1973b; Morrow, 1980). Both of these species are uncommon in the Prince William Sound area. Neither of them are found in Power Creek. Some ice fishing for burbot and Dolly Varden takes place on Eyak Lake in the winter. Upper Power Creek Above Ohman Falls the Power Creek drainage assumes a considerably different set of characteristics. The creek is a meandering stream with braided channels and lies in a wide, flat, U-shaped valley typical of glaciated watersheds. Steep mountains rise abruptly on both sides of the valley floor. The floodplain is extensive and in numerous places clear groundwater enters the main stream. Just above the falls, beaver have succeeded in backing up water creating large ponds and extensive bog areas (Figure 23). Because of Ohman Falls, anadromous fish are prevented from using the great majority of the Power Creek drainage. The ADF&G assumed that upper Power Creek contained a resident population of Dolly Varden but no cata were available to support their assumption (Pete Fridgen, pers. comm.). On June 5, investigators sampled about 1 mile of upper Power Creek including twe clear groundwater tributaries. The location of the sampling was in the general vicinity of CE Drill Site #1. The mainstem of Power Creek was flowing too fast to sample with a handheld seine. ‘Iwo baited minnow traps were set, one in the mainstem behind a small debris jam, and one at the junction of a clearwater tributary. Ho fish were captured in the minnow traps. Because the nain stream was cloudy from the glacial influence, it was difficuit to see any fish except in very shallow areas. Two small fish were observed that biologists assumed were Dolly Varden. The two groundwater tributaries were estimated to be flowing 20 to 25 cfs and were easy to sample with a handheld seine. Small fish 50 to 100mm long were frequently observed escaping the seine and only two were captured. 80th of them were Dolly Varden. In accition, one Dolly Varden was found dead along the bank. . The short period of time spent in upper Power Creek only verified that Dolly Varden are found in the upper portion of the drainage. No con= clusions can be drawn as to their abundance or general distribution at this time. Maumals Mountain goats are found in the higher elevations on both sides of Power Creek. A brief helicopter flight on June 5 above Drill Site #1 confirmed the presence of four goats. Reynolds (1930) estimates probably no mors than 20 coats are found in Power Creek and Humpback Creek at any one time. Goat habitat is usually restricted to the ridgetops and steep, rocky areas but Reynolds (198C) considers everthing above 5C0 feet in elevation to be mountain goat habitat (Figure 4). Moose do not occur in the Power Creek drainage (ADF&G, 1973). The closest moose range is due south and east of Power Creek in the Ibeck -44- Figure 23. Extensive wetland area above Ohman Falls created by groundwater flow and beaver dams. BEST COPY AVAILABLE Black bear are common near Cordova (ADF&C, 1973) and the Power Creek watershed contains excellent bear habitat. Cne large black bear was seen foraging on the open slopes east of Ohman Falls on June 5. As in the case of Mumpback Creek, the ADF&G (1973) has not identified any critical denning habitat in the Power Creek drainage. The ADF&G (1973) has documented that the lower Power Creek watershed harbors seasonal concentrations of brown bear. The bears are attracted by spawning salmon which serve as an important food source. Personnel of the Cordova offices of the ADF&G and Chugach National Forest indicate that local people tend to avoid the area vhen salmon are spawning duc to the abundance of brown bears (Pete Fridgen; Ken Molbrook, pers. comm.). Reynolds (1980) estimates 12-15 bears utilize Power Creck. CE personnel flying to Drill Site #1 observed a brown bear sow and a large cub several times just above Ohman Falls curing early June (Chuck Floyd, CE, pers. comm.). In addition, brown bear hair anc scats were found along the Power Creek trail below Ohman Falls by investigators on June 5. The remains of a freshly killed porcupine were located the sane day across Power Creek from the USCS gauge. Large paw prints in the snow indicated the predator was a brown bear. On October 2, numerous freshly eaten sockeye salmon and bear scats were observed along the small spawning tributary just above the USGS gauge. Sitka black-tailed deer are widely distributed throughout the Cordova area, Evidence of deer in Power Creek was minimal. ‘Two fresh pellet groups were seen on the Power Creek trail on June 5. The ADF&¢ (1973) states that the mainland deer pepulation is low and has not identified any winter range in the Power Creek drainage. Other mammals known to occupy habitats in Power Creek include: red squirrel, porcupine, hoary marmot, beaver, muskrat, and river otter. Birds The coniferous forest is the most extensive vegetative type in Power Creek near the project features. The majority of the bird species found there are forest dwelling passerines. These include, but are not limited to: Wilson's warbler, yellow warbler, winter wren, ruby and zgolcen-crovned kinglets, varied and hermit thrushes, American robin, downy woodpecker, Steller's jay, common raven, and several sparrows. The most common bird found along the Power Creek corridor was the dipper. Spruce grouse, northwestern crows, and several owls are also found in forested areas near Power Creek. Yetland habitats associated with the project include the Power Creek ~delta and a large series of beaver ponds and sloughs above Ohman Falls 7 The large network of beaver ponds has created suitable nesting habitat for some vaterfowl and shorebirds. At least one pair of whistling swans and several pairs of Canada geese were utilizing the pond areas for nesting. Other birds observed were: arctic tern, spotted sandpiper, varied thrush, and greater yellowlegs. “o survey of the wetlancs in the Power Creek delta was made hecause a small hydro project unstream was helieved to have ro impact on this area. Nesting habitat is available for ducks, geese, swans, and shorebirds but ne estimate of the nunber of birds nesting on the delta is available. nnd Aquatic habitat of Zyak Lake adjacent to the Power Creek delta is used by f ) several species of waterfowl for feeding and molting during the summer and early fall. Migrating ducks and geese also utilize the lake as a staging area prior to flying south. Species observed during spring and early summer include: whistling swan, Canada goose, mallard, zreen-—winged teal, common merganser, bufflehead, and pintail. Northern bald eagles are numerous throughout the lower end of Power Creek and all along the Zyak Lake shoreline. CGusey (1973) states that during the winter of 1969, 416 bald eagles were observed feeding on spawned-out salmon at Eyak Lake. Personnel from the ADF&G and Chugach National Forest could not document any active or historic eagle nest sites on Power Creek or the northern arm of Eyak Lake (McCurdy, 1979; Carvin Bucaria, wildlife biologist, Chugach National Forest, pers. comn.). Since suitable nesting habitat ia available, a helicopter survey was conducted on June 5 to thoroughly search for nests. The entire Power Creek drainage from Drill Site #1 to and including the delta and the shoreline of Eyak Lake within 2 miles of the mouth of Power Creek was surveyed. No bald eagle nests were located. MAJOR POTENTIAL IMPACTS At this point in the CZ's study, design plans for all three proposals are very preliminary. Therefore, reliable predictions of all adverse impacts are not fully possible at this time. Prior to submission of a Final & Coordination Act report, design plans and specifications of all project » features should be submitted to the FWS. Additional information necessary to complete our analysis is the exact location of all vroject features and locations of any necessary access roads and transmission line corridors. Crater Lake — The major potential impacts of the lake tap proposed for this project can basically be summed up in three categories: diversion dam construction, land clearing for the penstock, and cewatering the lake outlet. According to the CE, no road would be built into Crater Lake (Tom ilurdock, CE, pers. comm.). All construction materials would be flown in by helicopter. The exact dimensions of the diversion cam have not been deternined although the Reconnaissance Report suggests a concrete structure 5 feet hish and 15 feet long (CH, Hill, 1979). The exact location of the lake tap has not been establiShed either. The CE envisions water being drawn off very close to the present level of the lake and not from some point in deep water (Tom Murdock, CE, pers. comm.). The dimension of the pipe would be 18 inches and capable of carrying a maximun of 4 cfs. Environmental impacts from constructing a small concrete diversion would be minor. Some wildlife habitat would be covered up by the dam itself and permanently lost. Habitat adjacent to the present lakeshore would also be inundated by raising the level of the lake enouzh to draw off water. Mo estimate of the amount of habitat that weuld be inundated is ” available but it is not anticipated to Sse very great. Resident wilciife affected by these actions would probably be licited to small rodents. During construction of the dam and lake tap, human activity and noise associated with helicopter traffic vould undoubtedly disturb resident species of wildlife, such as mountain goats, black bear, Sitka black— Batt 2d Gane 2nd anenaeina Kiede Thie dtaturhance. however. would only be short-lived. Once construction is finished, disturbances from helicopter traffic and the presence of humans would return to pre= construction levels. No long-term adverse impacts to wildlife should result. In order for helicopters to land safely, some habitat may have to be disturbed for the construction of landing pads. These areas would prob— ably not revegetate well and may end up as long-term scars. The water level of the lake would not fluctuate dramatically, so the rainbow trout fishery in Crater Lake should be affected very little. The CE does not envision a large draw down primarily because the project would only be operable from May through October, the period of highest runoff (Tom Murdock, CE, pers. comm.). MeCurdy (1979) indicates there may be some natural fish reproduction in the lake. Any draw down in late summer could then expose eggs hatching along the lakeshore. The poten— tial loss of any natural reproduction is probably not significant. Even without the project the fishery is only kept viable by stocking hatchery rainbows every 3 to 4 years. In order to construct a 4,800=foot penstock of 18<inch pipe from Crater Lake to Orca Inlet, a swath of vegetation would have to be cleared through a dense Sitka spruce forest to the powerhouse near sea level. Because the terrain is so steep, the methods used to clear the vegetation and install the pipeline would have a direct bearing on the eventual impacts to the environment primarily from erosion. For example, hand clearing of trees and shrubs would have less detrimental impacts than the use of tracked vehicles. At this time, the CE has not determined the method of vegetation removal nor whether the pipe would be buried or elevated. Consequently, evaluation of the impacts of the penstock placement cannot be adequately assessed at this time. The end result of a cleared strip through the forest would be visible to boat traffic along Orca Inlet. To some people, this would be esthetically unpleasant. The powerhouse would be constructed near the Orca canneries adjacent to an existing transmission line from Cordova. Impacts from this action would be localized and may require removal of some vegetation and ground leveling. The diversion dam would eliminate the natural overflow of water out of Crater Lake during the months of May through October. Pink salmon periodically spawn in the outlet waters at the junction with Orca Inlet from late July to early August. The available spawning habitat is small but up to 200 fish have been observed using the area. Unless the tailrace water is returned to the outlet drainage prior to entering Orca Inlet, pink salmon spawning and the survival of eggs would most likely be severely reduced or eliminated entirely. One unquantifiable impact would be what effect the project has on people who are used to trout fishing at Crater Lake. The area is highly scenic and undisturbed. The dam, penstock, and disrupted vegetation would most likely decrease the quality of the outdoor experience for some people. This impact appears to be unavoidable. Humpback Creek - Impacts to the environment associated with this project include construction of a small diversion dam, partial dewatering of the ernek land ecloarino. and the nossihilitv of road construction. As in the case of Crater Lake, the actual impacts of constructing a small concrete diversion dam on upper Humpback Creek would be minor. The diversion would be built approximately 2 miles upstream from the mouth of the creek. The Reconnaissance Report indicates a 5<foot x 30-foot struc- ture would be adequate (CHM Hill, 1979). The location of the diversion ig well above the pink salmon spawning area and no fish passage facilities would be needed. A portion of the creek behind the diversion would be inundated. The exact size of the impoundment is unknown but it would not be very large. Some streambank vegetation would be drowned but the impacts are not considered to be significant. A flume 6,625 feet long and a 700-foot penstock would carry water from the diversion to a powerhouse about 0.25 to 0.5 mile from Orca Inlet. The diameter of the penstock would be 30 inches and capable of carrying a maximum flow of 40 cfs. ‘The proposed location of the powerhouse would be very close to the uppermost old log dam on Humpback Creek previously described (Figure 3). The water that is removed at the diversion would be returned to the creek above the spawning area. Therefore, no reduction in flow through the spawning gravel would occur. If the powerhouse were situated in the right place, this project could actually enhance the survival of pink salmon eggs and the fishery by returning water to Humpback Creek below the deteriorated log crib dam further downstream from the proposed powerhouse location (Figure 9). By cutting down the peak high flows and bypassing the large amount of gravel backed up behind the log crib dam (50,000 to 60,000 cubic yards), egg mortality from gravel scouring downstream should decrease. The project would only operate from May through October when flows in Humpback Creek are highest. Drawing 40 cfs out of the creek above the dam can only help cut dowm the amount of gravel moving down the strean. The Reconnaissance Report indicates that to ensure some water in the stream below the diversion, flows equal to twice that of the 7-day, 2-year low would be allowed to pass the structure at all times. This minimum flow was found to be 1.4 cfs (CHM Will). MeCurdy (1979) states that there are no fish above the log dams. In addition, sampling done in June 1980 failed to detect any fish in the stream. Adverse impacts of the reduction in flows would probably result in a decrease in the produc— tion of aquatic invertebrates in that section of the stream and possibly elimination of some passerine birds like the dipper. At this stage of the study, the CZ has not determined the extent or location of any road construction necessary for access to the powerhouse site, access to the point of diversion, or for construction of the trans— mission line. Therefore, the FWS cannot adequately assess the impacts of roads until further information is received. Generally, some adverse impacts of read building include, but are not limited to: removal of wildlife habitat, interception of ground water flow, increase in erosion, and allowing motorized vehicles access into areas previously inaccessible. ee Approximately 3.6 miles of 15 Kv transmission line would be constructed to tie into the present line from Cordova that ends at the Orca canneries. Potential impacts cannot be adequately described until a detailed route for the line has teen chosen and whether the line would be constructed by road or helicopter. Regardless of where the line is placed, erosion would result from land clearing activities. However, an acequate erosion control plan can minimize the amount of sediment or debris capable of entering the aquatic environnent. Transmission poles are often used by large raptors for perching and can be a source of mortality from electrocution if the lines are not properly spaced. It has been determined that grounding practices on distribution and transmission lines from 4 Kv through 69 Kv can be a substantial cause of raptor deaths (Raptor Research Foundation, 1975). Because of the density of bald eagles all along Orca Inlet, this is a definite concern. However, proper line construction can eliminate any mortality of eagles from electrocution. Visual impacts frem transmission lines and corridors can be significant. In wany instances, it is difficult or impossible to blend them into the background vegetation. In this case, a 15 Xv line does not require huge steel towers and by using wooden vcles and careful clearing techniques, this impact can be minimized. During construction of the project when a work force is present, bear- human encounters may result. The ADF&C (1973) has documented seasonal concentrations of brown bear drawn to lower Fumpback Creek to feed on spawning pink salmon. Spawning activity, and thus the presence of bears, would occur from early July to nid-September. This same time framework would most likely be the height of construction activity. Preventing a nuisance bear situation by disposing of all refuse and co feeding of bears would help reduce bear—human encounters. Power Creek = Ohman Falls is situated at mile 2.5 om Power Creek and blocks salron movement any further upstream. The Reconnaissance Report identifies a suitable site for a diversion dam above the falls, There- fere, no migration block would result, and no fish passage facilities would be required. Non=anadromous Dolly Varden are the only fish species that have heen identified in Power Creek above the falls. Some waterfowl and shorebirds nest in the wetland areas and ponds created by beaver adjacent to the proposed diversion site. The diversion would create no significant impoundment (CUM Hill, 1979) and consequently impact fish and wildlife species for only a short time during construction. A combination of pipeline and penstock would carry water from tne diver— sion to a powerhouse tentatively located near the present site of the USGS gauging station along the Power Creek road. Approximately 1.5 miles of Power Creek would then be partially dewatered. Almost the entire 1.5 miles provide rearing habitat for Dolly Varden and the 0.5 nile stretch above the eause contains spawning habitat for approximately 3,569 to 4,500 cohe salmon and possibly a few sockeye salmon. The amount of water left in the creek would have a direct bearing on whether Power Creek can continue to support populations of coho salzon and Dolly VYarcen to the magnitude it does now. The azraatest impact on coho salmon would occur during the winter and early spring ronths = Secember throush April. This is the period of natural low flows when civerting water would take a proportionally higher percentage of the stream. Coho eggs incubating in ‘spawning gravels could be exposed by removing water and result in consid= erable mortality from dehydration or exposure to freezing temperatures.. Table 10 contains a summary of the percent of the tine the natural stream Ge in Power Creek would exceed the minirun allowable flow necessary for gmall turbines rated at 1.25 megawatts (iv) to 10 iw. It is readily apparent that a 10 Mw turbine could not operate during the low flow sonths (December to April) and therefore cause no impact on coho egss in the gravel. owever, this would not give Cordova a year round source of hydropower. It is also apparent that a 1.25 iw turbine could conceivably take the entire streamflow during the extremely low flow months in any given year eliminating any survival of cohos above the powerhouse. Since four of the 1.25 Mw plants could he hooked up to provide 5 Mw of power curing high flows, this scenario is feasible from an engineering standpoint (Tom Murdock, CZ, pers. comm.). Direct observation by biologists, coupled with records from the USCS gauge, indicate that for the ronths of May through November, adequate flows would remain in Power Creek to allow coho fry to outmigrate to Lyak Lake and adult coho to ascend the creek and spawn despite the reduction in flow needed to run a 5 “fw plant. In fact, a reduction in flow during that time period may even be beneficial. The IWS did not locate any Dolly Varden spawning areas above the USGS gauge, but the presence of young-of-the-year (age Class 0) taken in ninnew traps during early June suggests that spawning does occur above the gauge. Impacts on Dolly Varden egzs incubating in the gravel would be similiar to those described for coho salmon. Removal of water during »™ critical low flow months would expose eggs to dehydration and freezing. Impacts on juventle Dolly Varden over-wintering in that portion of Power Creek that is dewatered would probably not te as severe. Juvenile fish (age classes 0 through IV) are distributed throughout the stream. The great majority of them were captured in pools which are preferred habitat. Reducing winter flows to zero would zost likely not dry up the entire stream as the deeper holes would still contain water and some groundwater would probably still surface in the streambed. However, competition for food would increase as the amount of available habitat decreases. In the absence of appreciable running water, the pools would freeze over and oxygen levels eventually decrease. Adverse impacts on coho salmon could be eliminated if the pewerhouse were located near the end of the Power Creek road. This site is above the potential spawning area. Adverse impacts on Dolly Varden could be mini- mized, but not eliminated, if the powerhouse were moved upstream. Dolly Varden juveniles probably over-—winter in Power Creek all the way to Ohman Falls. In addition, it is highly likely that Dolly Varden are spawning above the gauge also. The diversion and eventual return of water to Power Creek should not have any impact on Eyak Lake or on the stream below the selected powerhouse site. No change in water temperatures or levels of saturated gases would apes as there would be no large storage reservoir with this proposal. Zcouring of the stream channel below the powerhouse tailrace could be minimized by installing an ecnerzy dissipator. 2 Table 10. Percent of tire streamflow exceeds nininun allowable flow for turbine operation on Power Creek (run—of-the-river). ne eee U EEE EIEEE EERE 10 MW Stiw 2.20 1.25MW (Qnin=152_ cfs) (Qnin=76 cfs) (Gmins33 cfs) (Omin=l9 cfs) JAN 3 13 61 190 FEB 3 ll 47 93 HAR 2 z 31 87 APR 2 ll 47 94 MAY 57 76 93 100 JUN 99.7 100 100 100 JUL 100 100 100 100 <> AUG 1co : 1co 10¢ 1co SEP es 1c0 100 100 ocT 69 98 106 100° Nov 31 67 ico 100 DEC a 32 37 iu0 i Source: Tom Murdock, Corps of Engineers. | The FWS did not identify any other fish species using the mainstem of Power Creek above the USGS gauge. A minimum of 440 (365 live and 75 dead) sockeye salmon were utlizing the small tributary that enters Power Creek above the gauge. However, this stream appears to be independent of ey) Power Creek flows. The source of water is a series of springs and seeps and seems to be relatively constant. Biologists could discern little difference in flow between June and October although no measurements were taken. Removal of water from Power Creek upstream should have no effect on this tributary. For that reason, no adverse impacts are anticipated. It is highly likely that some sockeye are spatming in the mainstem of Power Creek within 0.5 mile above the gauge. However, spawning habitat next to the bank is limtted and stream velocities are such that during the peak of the sockeye run the preferred spawning habitat is unusable. The bulk of the spawning area above the gauge probably does not become available to salmon until the middle of November when streamflows decrease. Coincidentally, mid-November is when the bulk of the cohos are ready to spawn and the sockeye have already spawned and died. Available data indicates that anadromous cutthroat trout are present above the gauge. Since the FWS's sampling effort was not intensive, this species may have been missed. However, if the population of cutthroat was sufficiently large, sampling should have detected them. If cutthroat are spawning in Power Creek, the population must be small or they are spawning in the delta area. The ADF&G (1973) has documented concentrated brown bear use during the “a salmon spawning period on lower Power Creek. Any great reduction in the » coho run above the gauging station could eliminate a valuable food source for some of the big bears and force more of them to forage closer to Eyak Lake. This could result in a greater feeding density of individuals than the species is willing to tolerate. Younger bears would probably be chased off and have to forage closer to town increasing the likelihood of bear-human encounters that ultimately would result in more bears being killed in defense of life or property. Adverse impacts to other big game animals are not anticipated. Moose are not found in the Power Creek drainage. Sitka black-tailed deer are not abundant. Mountain goats, although present in the drainage, should be affected very little. Their narrow range of habitat preference during most of the year precludes use in much of the drainage except the steep, inaccessible rock cliffs and precipices. Reynolds (1980) indicates goat habitat does extend down to 500 feet. In the area of Ohman Falls and upper Power Creek the 500-foot contour comes right down to the valley floor (Figure 4). It is assumed that any downward migration of goats is seasonal and coincides with winter snowfall. Since any construction on the diversion dam or penstock is not likely to be done during the winter, no project related impacts on goats should occur if individual goats decide to winter in the rocks near Ohman Falls. Adverse impacts to smaller mammals and birds utilizing the coniferous forest habitats have not been quantified but are not expected to be significant. i) The transmission line corridor is depicted in the Reconnaissance Report 3 paralleling the Power Creek road all the way to Cordova. The report also recommends that the line be buried. Since bald eagles concentrate all along Eyak Lake during the salmon spawning season, a buried powerline Caen reer errr reer eee ee a a would eliminate any chance of electrocution and is preferable. Burying the line would also eliminate any visual impacts. TNowever, even if the line is elevated, electrocution can be eliminated by proper line spacing. DISCUSSTON Crater Lake — Our analysis of the potential adverse impacts of a lake tap hydro project at Crater Lake indicates that wildlife resources should not be significantly affected. Potential impacts to pink salmon spawning in the outlet waters of the lake adjacent to Orca Inlet could be eliminated by returning tailrace water above the spawning area. Short-term impacts to mountain goats, bear, and deer from construction activity at the lake would cause these species to avoid or temporarily abandon the area until the project is completed. Due to the short working season at the lake's elevation, setting time constraints to minimize impacts on wildlife is not realistic. However, if the diversion and lake tap can be completed during one work season (July through September), impacts from the presence of humans and construction noise should be minimal. Because no road would be built to the lake, helicop- ters would be necessary to transport all materials and workers to the site. In order to minimize detrimental impacts to game species from helicopters, the CZ should insure that contrators use the same access route to and from Crater Lake. We recommend that the ADF&G office in Cordova be consulted and a route chosen that would avoid known concen trations of big game, primarily mountain goats. The only fish in Crater Lake are rainbow trout. Raising the level of the lake and subsequently drawing it down to release water should have little impact on the trout population. There are some indications that limited reproduction takes place and drawing the lake down could expose eggs hatching along the shoreline. However, the ADF&G stocks the lake every 3 to 4 years with hatchery fish because the lake cannot support a naturally reproducing population. One unquantifiable impact would be what effect the project has on people who are used to fishing Crater Lake. The area is highly scenic and undisturbed. The diversion, penstock, and disrupted landscape would probably decrease the quality of the outdoor experience for some people. In order to minimize the visual impacts, any soil disturbances such as helicopter landing pads should be carefully planned to avoid leaving an unsightly scar that would not revegetate for many years. Organic soils excavated during construction should be stockpiled and spread over disturbed sites to encourage revegetation. Any equipment used to con—- struct the diversion should be operated only in the immediate vicinity of the project to prevent unnecessary damage to the fragile alpine vegetation. Waste construction materials should be cleaned up and removed after project completion. In order to build the penstock, a swath of timber would have to be removed from the vicinity of Crater Lake down the mountain side to the Proposed powerhouse location near the Orca canneries. Presently, the slope is covered with a dense stand of western hemlock and Sitka spruce. Impacts from this activity would result in the elimination of some wild- life habitat and, depending upon construction techniques, may impact pink salmon spawning in the outlet waters of Crater Lake adjacent to Orca Inlet. Impacts could be minimized by clearing trees and tall shrubs using hand tools instead of heavy equipment and positioning the penstock and powerhouse.a safe distance away from the small watershed that drains Crater Lake. The FWS will be able to provide the CE with a mininum acceptable distance after a site reconnaissance scheduled for wid-November 1980. The tailrace from the powerhouse should be constructed so that the water is returned to the small watershed draining Crater Lake prior to entering Orca Inlet. This would insure that pink salmon spawning habitat is not eliminated. Any swath cut through the timber would be visible to ferry and boat traffic on Orca Inlet. Careful clearing of trees and high brush using hand tools could minimize this visual impact. Humpback Creek - Should this proposal be selected, design plans and information pertaining to all project features including the exact location of all roads, stream crossings, and the location of the transmission line corridor should be supplied to the FWS. With the information available, adverse environmental impacts that have been identified to date do not appear to be significant. The project location is well above the pink salmon spawning area and no fish passage facilities would be required. No fish have been found in that portion of the creek that would be partially dewatered. Impacts from the impoundment behind the diversion dam are judged to be insignificant. tio bald eagle nests are located within 2 miles of the project area. No long-term impacts on big game animals have been identified. Our analysis of the proposed powerhouse location reveals that if the powerhouse were situated downstream from the deteriorated log crib dam, this project may enhance the survival of pink salmon eggs and the fishery. The tailrace from the powerhouse should return water to Humpback Creek below the log crib dam. Immediately below the dam would be preferable. This action would reduce flows over the dam by 40 cfs and help alleviate gravel scouring of spawning areas downstream. An energy dissipator should be installed to prevent scouring of the streambed where the tailrace discharge enters the creek. — In order to reduce the amount of land clearing, the transmission line should parallel any road that is built for access to the mouth of Hurp= back Creek. The line should be built to eliminate any possible chance of electrocution of large raptors. Transmission line construction should be governed by "Suggested Practices for Raptor Protection on Powerlines" (Raptor Research Foundation, 1975) and Bulletin 61-10 prepared by the Rural Electrification Administration, U.S. Department of Agriculture, dated March 9, 1979. Improper disposal of food-related garbage would attract bears and lead to bear-human encounters. This results in removal or destruction of offending bears. During construction, all food-related garbage should be placed in metal containers and removed from the site daily. At no time should construction crews be allowed to feed bears. Power Creek = The FWS has not received much nore information on this project than what is contained in the Reconnaissance Report. Therefore, any prediction of adverse impacts can only be done on the information available in that report. The Reconnaissance Report indicates that this site is the most feasible of the three proposals for power generation (CHM Hill, 1979). Our analysis of potential impacts.also points out that this project could be he vost detrimental in terms of adverse effects on fish, primarily coito almon and Dolly Varden. The diversion dam would be built above Chnan Falls, a natural barrier to fish migration. Therefore, no fish passage facilities are necessary. Nowever, a combination of pipeline and penstock would draw water from the creek and eventually return it appreximately 1.5 miles downstream. (This «5 mile stretch would be partially dewatered. Almost the entire 1.5 miles provide rearing habitat and suspected spawning habitat for Dolly Yarden and a 0.5 mile reach above the USGS gauge is spawning habitat for coho’ salmon and most likely a few sockeye salmon. The flow regine in Power Creek is such that removal of water would have the greatest impact on salmonid eggs in the gravel from December through April = the period of natural low flows. By utilizing a series of small turbines, it is possible to take all the surface water from the creek in the low flow months. ‘The end result would be the loss of any salmonid eggs incubating in the gravel in Power Creek above the powerhouse location. The ground=- water contribution to the stream between Ohman Falls and the gauge is unknown. Unless the CE can supply the information that sufficient ground= water remains during the low flow months to keep salmonid eggs alive, the PHYS cannot assume groundwater flow is a significant factor. \The potential loss in salmonid production could be eliminated one of two ways; (1) Develop monthly flow requirements for Power Creek necessary ~< Yor opticum salmon production and survival. This aiternative would _ "require additional field work and funding in order to develop recommended flows. Winter flows in Power Creek get low enough that it is anticipatad that the range of optimum flows would be very narrow and most likely coincide with natural flows. Being realistic, surplus water for power generation would probably not be available during the winter months. (2) Move the proposed powerhouse location upstream to the end of the Power Creek road. This alternative would require the CE to calculate the less in elevation from the USCS gauge to the enc of the Power Creek road and determine if the corresponding loss in head is small enough to sake this recommendation acceptable. Additional information is necessary to document coho salmon anc Dolly Varden spawning areas by visual observation of acults. A field trip is scheduled for mid-November 1930 to provide this information. Regardless of the powerhouse location, the tailrace should te constructed to prevent scouring of the streambed where discharge water returns to the ceresk. In addition, the discharge should re-enter the creek so it does not serve as an attraction to adult saimon returning to spawn. Land clearing activities and access roads for the senstock and pipeline would remove wildlife habitat amc may serve as a source of silt from ee: Fowever, until further information is received from the CE on he location of those structures and additional roads, we cannet comment on the potential impacts of those project features. The transmission line corridor should closely parallel the Power Creek road. This will minimize the amount of land clearing necessary and reduces the rial of arneian. A buried nsowerline would reauire very little eT a a a land clearing, eliminate any chance of electrocuting bald eagles, and &) create no visual impacts. For those reasons, it is preferred over an elevated line. An elevated line can be built to eliminate the electro- cution of eagles (Raptor Research Foundation, 1975; U.S. Department of Agriculture, 1979) but requires more land to ve cleared and creates a significant visual impact. Improper disposal of food-related garbage would attract bears and lead to bear—human encounters. This results in removal or destruction of offending bears. During construction, all food-related garbage should be placed in metal containers and removed from the site daily. At no time should construction crews be allowed to feed bears. RECOMMENDATIONS The following recommendations are provided to minimize the potential environmental impacts of constructing three small hydro projects near Cordova: Crater Lake 1. That the exact project design plans be provided to the FWS as soon as they are available; 2. that the CE.consult with the ADF&G office in Cordova to choose a a helicopter route to avoid traffic in the vicinity of known concen ” trations of mountain goats; 3. that any organic soils excavated during construction at the lake be stockpiled and spread over disturbed sites to encourage revegetation; \ 4. that any equipment used to construct the diversion or lake tap be operated only in the immediate vicinity to prevent unnecessary damage to alpine vegetation; 5. that all waste construction materials be cleaned up and removed after project completion; 6. that the penstock corridor be cleared of trees and shrubs by workers using hand tools; 7. that the FWS survey the Crater Lake outlet in nid-November to provide the CE with a recommendation as to how far the penstock and powerhouse should be located away from the stream to protect fishery resources; and 3. that the powerhouse tailrace return water to the small outlet stream draining Crater Lake prior to entering Orca Inlet. Humpback Creek 1. That the exact project design plans complete with all road locations, stream crossings, and transmission line corridor be supplied to the FWS as soon as they are available; 2. that the powerhouse be located immediately downstream from the deteriorated log crib dam in the lower stretch of the Humpback Creek ecanvon: 3. that an energy dissipator be installed to prevent the tailrace discharge from scouring the streambed; that the transmission line parallel any road constructed from the Orca canneries to the routh of Humpback Creek; that the transmission line be built to eliminate any possible chance of electrocution of large raptors (bald eagles); and that during construction, all food-related garbage be placed in metal containers and remeved from the site daily to prevent a nuisance bear situation. Power Creek 1. That the exact project design plans be supplied to the FWS as soon as they are available; 2. that the CE fund the FWS to determine conthly stream flow requirements for optimum salmonid production and survival or that the CE move the proposed powerhouse location upstream to the end of the Power Creek road ; 3 that the FWS make an additional stream survey in mid-November to help verify spawning areas for coho salmon and Dolly Varden; ay 4. that the tailrace be constructed to prevent scouring of the streanbed =a below the powerhouse; 5. that the tailrace discharse enter the creek in such a manner 30 as to avoid attracting adult salmon returning to spawn; 6, that during construction, all fveod=related garbage te placed in metal containers and removed from the site daily to prevent a nuisance bear situation; and 7. that the transmission line be buried parallel to the Power Creek toad from the powerhouse to the substation in Corcova. HANNA saw: fh:9/11/80 Diskette: CORDOV 0S:6:Job C 7 canner LITERATURE CITED f ) Alaska Department of Fish and Game. 1973. Alaska's Wildlife and Habitat. Edited by R. LeResche and R. Minman. 143 pp., 563 naps. . 1978a. Alaska's Fisheries Atlas, Volume I. Compiled by Re. MeLean and Xk. Delaney. 40 pp., 357 maps. . 1978b. Alaska's Fisheries Atlas, Volume II. Compiled by Re MeLean and X. Delaney. 43 pp., 269 maps. CHM Bill. 1979. Reconnaissance study of hydropower sites near City of Cordova, Alaska. Submitted to Alaska District, Corps of Engineers, Anchorage. Contract #DACW85~79-J-0019. 51 pp. Cusey, W. 1978. The Fish and Wildlife Resources of the Gulf of Alaska. Environmental Affairs, Shell Oil Co., Houston, Texas. 580 pp. Johnson, A. 1949. Preliminary report on water-power resources of Power Creek near Cordova, Alaska. U.S. Geological Survey, unpublished report. Tacoma, Washington. 37 pp. McCurdy, M. 1979. Letter, Mike McCurdy, Alaska Department of Fish and Game, Cordova, to U.S. Fish and ‘lildlife Service, Anchorage, 14 December 1979. — ) Miller, D. 1951. Geology at the site of a proposed dam and reservoir on Power Creek near Cordova, Alaska. U.S. Geological Survey Circular 136, 8 pp. Morrow, J. 1980. The Freshwater Fishes of Alaska, Alaska Northwest Publishing Company, Anchorage, Alaska. 243 pp. Pirtle, R. 1977. Historical pink and chum salmon estimated spawning escapements from Prince Willima Sound, Alaska streams, 1960-1975. Technical Data Report No. 35. Alaska Department of Fish and Game, Juneau. 332 pp. Raptor Research Foundation. 1975. Suggested practices for raptor protection on powerlines. Brigham Young University. Provo, Utah. 3 pp. and 16 plates. Reynolds, J. 1980. Letter, Julius Reynolds, Alaska Department of Fish and Game, Cordova, to the U.S. Fish and Wildlife Service, Anchorage, 29 September 1930. Stalnaker, C. and J. Arnette. 1976. Methodologies for the Determination of Stream Resource Flow Requirements: Am Assessment. Prepared for the U.S. Fish and Wildlife Service, Office of Bioloyical Services, Western Water Allocation by Utah State University. Logan, Utah. 9 199 pp. U.S. Department of Agriculture. 1979. Powerline contacts by eagles and other large birds. Rural Electrification Administration, Bulletin 61-10 (revised). ‘ashington, D.C. /7pp. T.S. Department of the Interior. 1979, List of endangered and threatened 5 “Y) Panes ) APPENDIX I. Scientific names of vegetation, mammals, birds, fish, and marine invertebrates appearing in the text. VEGETATION Common Name Western Hemlock Sitka Spruce Balsam Poplar Black Cottonwood Sitka Alder Devilsclub Blueberry Willow Mountain Heath Cassiope Labrador Tea Alpine Azalea Moss Campion Mountain Avens Bunchberry Rockweed Sea Lettuce Wrack MAMMALS Common Name Barbor Seal Sea Otter Dall Porpoise Mountain Goat Sitka Black=-tailed Deer Brown Bear Black Bear Porcupine Short-tailed Weasel Mink Marten Red Squirrel Roary Marmot Beaver Muskrat River Otter BIRDS Common Name Whistling Swan Canada Goose Mallard Scientific Name Tsuga heterophylla Picea sitchensis Populus balsamifera Populus trichocarpa Alnus sinuata Oplopanax horridus Vaccinium spp. Salix spp. Phyllodoce aleutica Cassiope spp. Ledum palustre Loiseleuria procumbens Silene acaulis Bryas integrifolia Cornus canadensis Fucus sp. Ulva sp. Laminaria sp. Scientific Name Phoca vitulina Enhydra lutris Phocoenoides dalli Oreamnos americanus Odocoileus henmionus sitkensis Ursus arctos Ursus americanus Erethizon dorsatun Mustela erminea ifustela vison Martes americana Tamiasciurus hudsonicus Marmota caligata Castor canadensis Ondatra zibethicus Lutra canadensis Scientific Name Olor columbianus Branta canadensis Anas platyrhynchos Pintail Green-winged Teal Buf flehead Harlequin Scoter Common Merganser Northern Bald Eagle Gyrfalcon Spruce Grouse Ptarmigan Black Oystercatcher Semipalmated Plover Spotted Sandpiper Greater Yellowlegs Glaucous-winged Gull Mew Gull Black-legged Kittiwake Arctic Tern Downy Woodpecker Steller’s Jay Common Raven Northwestern Crow Dipper Winter Wren American Robin Varied Thrush Hermit Thrush Golden=crowned Kinglet Ruby=crowned Kinglet Water Pipit Yellow Warbler Wilson's Warbler Savannah Sparrow FISH Common Mame Pink Salmon Sockeye Salmon Chum Salmon Coho Salmon Chinook Salmon Pacific Herring Pacific Halibut Rainbow Trout Dolly Varden Cutthroat Trout Burbot Round Whitefish MARINE INVERTEBRATES Common Name Barnacle | Anas acuta Anas creeca Bucephala aibeola Histrionicus nistrionicus Melanitta spp. Mergus merpanser Haliaeetus leucocephalus alascanus Falco rusticolus Canachites canadensis Lagopus spp. Haematopus bachmani Charadrius semipalmatus Actitis macularia Tringa melanoleuca Larus glaucescens Larus canus Rissa tridactyla Sterna paradisaea Picoides pubescens Cyanocitta stelleri Corvus corax Corvus caurinus Cinclus mexicanus Troglodytes troglodytes Turdus migratorius Ixoreus naevius Catharus guttatus Regulus satrapa Regulus calendula Anthus spinoletta Dendroica petechia Wilsonia pusilla Passerculus sand:vichensis Scientific Name Oncorhynchus gorbuscha Oncorhynchus nerka Oncorhynchus keta Oncorhynchus kisutch Oncorhynchus tshawytscha Clupea nallasii Hippoglossus stenolepsis Salmo gairdneri Salvelinus malma Salmo clarki clarki Lota lota Prosopiun cylindraceum Scientific Name Balanus sp. Maeet tue adulie Horse Clam (Caper) Tresus nuttallii Butter Clam (Washington Clam) Saxidomus gizanteus Littleneck Clam . Protothaca staminea Cockle Cardiidae Razor Clam Siliqua patula Surf Clam Spisula alaskana Pacific Scallop Patinopecten caurinus Shrimp Pandalidae Dungeness Crab Cancer magister King Crab Paralithodes cantschatica Tanner Crab Chionoecetes bairdi APPENDIX II: Drawings of Power Creek depicting the major physical and biological characteristics from the USGS gauging station to 0.3 mile above the end of the Power Creek road. (Drawings compiled on 4/18/80 and updated 6/3/80 to 6/8/80). MBOL a ~ smail or medium sized boulders O = large boulders @ — jnud silt hh ifr - vi Y} ~~~ ; ——w vapid cP) a pool S< ~ log jam Den - cowned tree ©- gravel bar - o, t Comiters W=brush @ ~ minnow trap loca tions Citlareh and A geil, /9¢0) LA] - minnew tray locations (Sune, !490) — > — main rn Pm Secondary flow Chign water ‘channel) > —- confirmed salmon Spend BEST COPY AVAILABLE \ ? tt ou lders— : t Wy tot feet BEST Copy AVAILABLE \ o ‘ ph Co fp Pow 5 ~ ‘ : ( 4 ‘\ a Yt hed Catt ME we) *, wy Ag Y ag 5 + \ 0 ‘ C fy ‘¢ Ogee Uo ky 0 60 nA i : ae Vy i foo} vo Ze) 3 | x ‘O “Al, ‘) we YU - ov o\ \ 5 a . a: \ vo n ‘ \ “\ . r \ ‘\ v ay a \ ¢ ~ \ . ! \ Ns ' { be EN Rt x 1 We . D vy i at + i a Nad Ake nel { \ \ y al ai Wwe a ~*~ oo ri S ' Ya AW aa Pe iN \ eo NNT A “top? . . . ¥ Suitaaie Sfauinin g gravel ‘\ a o 9 \ \, f£ ca. a! yo : I d X “¥ INn€ Sana, Smal: Qvavel) medium 1S \ : Grave, <i% large reeNs \ ! \ = \ i, { \ i \ 27° Woes \ NN YL - A a J 4 by AS! \s \ Pt ") =—s-BEST.CoPy AVAILABLE pAb | a - . NeW O:, a OO. poe Ge ia ae ey gd Joe } J Ua so/ 4 xD ag i | Cm | BEST.COPY AVAILABLE uitable SPawning J : , araver, Stall qvavel J } 5 j ify (a rae re ch f ! agvavel— fine gsancy wensu es 4 ; 1 il PAeg ¢ Dovlcers i , wi fine ser tt \ A VG | kyl \g \,'! Ol \ 0° \p \ Weep pp Ley Yelocry eee Chura , TT ’ ( N ‘] i i / ; treted 5, r 5 60 (Gaose assem aye Core : Feel . sais . , o f llas qed FT PAWN ING araveim OW tine Gandy Smal! apayie’, wed a all apace’, wes. 7 j } ~+7 / - gravel fgets rae veck, 2-3 fre ps , Limited 5 panning gravel— fine Sand, sina/l gravel) LOM large veck | 3-4 deep BEST COPY AVAILABLE —a____ Ter Groundiwa oO S 9 S ureen BEST_COPY. AVAILABLE + Valdez Interim Southcentral Railbelt Study Allison Lake Hydropower Project Alaska Final Fish and Wildlife Coordination Act Report Submitted to Alaska District U.S. Army, Corps of Engineers Anchorage, Alaska Prepared by: Western Alaska Ecological Services Field Office U.S. Fish and Wildlife Service Anchorage, Alaska May 1980 TABLE OF CONTENTS Page LNTRODUCTION cic'c:0.0 «101014 010) 016[0-0)01010.5/4 10 e/0:0 ole le ciielo cicicicie eisieieisiorse 4 AREA DESCRIPTION. ccccccccvccccccccccccccccccccccccccccccs 4 PROJECT DESCRIPTION. cc cccccccccccccccccccccccccccoscccces 5 RESOURCE INVENTORY .ccccccccccccccccccccccccccccccccccccce 5 PROJECT IMPACTS. .cccccccccccccccccccccccccccccvcccccccccs & DISCUSSION. cccccccccccvcccccccccccccccccccccccccccccccccels RECOMMENDATIONS ..cccccvcccvccccccccccvcvccccccccccccccccels LITERATURE CITED. ccccccccccccccccccccccccccccccccccavesce 20 APPENDIX A: SCIENTIFIC NAMES OF SPECIES. .cccccccccccscserl APPENDIX B: TEMPERATURE DATA. ccccccccccccccccccccecscversd LIST OF FIGURES AND TABLES ™! \ Page Figure 1. Location and Vicinity Map Southcentral Railbelt Study, Valdez Interim...ccccccccccccccccese 48 Figure 2. Valdez Interim Report, Southcentral Railbelt, Allison Lake, Topographic Plan..eeecccee Sa Figure 3. Valdez Interim Report, Southcentral 3 Railbelt, Allison Creek, Topographic Plan...se.eeees 5d Figure 4, Seasonal Variation Population Density — of Harpacticus uniremis...ccccccccccccccccccccccces Ja Figure 5. Bald Eagle Nest Sites, September 14 and 16, 1976.cccccccccccccccccccscccces 88 Table I Prince William Sound Salmon Catch by Species in Numbers of Fish, 1970-79. .scsseeseseceee 6a Table II Value of Prince William Sound Salmon Catch in Pounds, and Value to Fishermen, 1970-79....ee... 6d Table III Allison Creek Salmon Escapement Data...eccocceecees Fe Pd Table IV Allison Creek - Discharge Measurements....seseeeeee 8b Ceeeeeeeeeeeeeeeeeeeeee eee eee eee eer renee a a () INTRODUCTION The Alaska District, Corps of Engineers (CE) is investigating the need for electrical energy at Valdez, Alaska and surrounding commu- nities. In performance of this investigation, the CE analyzed various alternatives and has identified the hydropower potential of Allison Lake. A detailed feasibility analysis of this project is occurring. This final Coordination Act report is being provided to the CE by the Western Alaska Ecological Services Field Office of the U.S. Fish and Wildlife Service (FWS) to assist in that analysis. AREA DESCRIPTION Port Valdez is located in the northeasternmost extension of Prince William Sound, and is surrounded by the Chugach Mountains. The Port is a steep walled, glaciated fiord which is 3 miles wide and extends in an east-west direction about 14 miles. At its western end the fiord bends to the southwest and constricts to a one mile width at Valdez Narrows before opening into the Valdez Arm of Prince William Sound. The steep mountain slopes’extend beneath the water, forming a flat bottomed trough 400 to 800 feet deep. The shore of Port Valdez is steep and rocky, except where river deltas and glacial moraines project into the fiord. Port Valdez is the northernmost ice-free seaport in Alaska, and provides the shortest and most direct route between tidewater and the interior of Alaska. The southern terminus of both the Trans-Alaska Pipeline and the Richardson Highway are located in Vaidez. Approximately 70 earthquakes with a magnitude of five or greater on the Richter scale have been reported at Valdez since 1898, and seven earthquakes have equaled or exceeded a magnitude of eight. The 1964 Alaska Earthquake and the attendant secondary impacts virtually destroyed the original town of Valdez on the Lowe River Delta, A new town has since been constructed on the delta of Mineral Creek on the north side of the bay. Valdez enjoys a maritime climate, characterized by heavy precipita- tion and relatively mild temperatures. The average annual precipi- tation is 59.31 inches, including 244 inches of snow. The average annual temperature at sea level ranges from 39° to 43° F, with a recorded maximum of 87° F and a minimum of minus 28° F. Local winds are influenced by the Chugach Mountains and follow two distinct patterns: (1) from October through March or Aprii prevailing winds are from the northeast, and (2) from May through September prevail- ing winds are from the southwest. Maximum sustained winds of 58 m.peh. and gusts of 115 m.p.h. have been recorded at Valdez. Allison Lake (Figure 1) is located near the Trans-Alaska Pipeline terminal in a glacial cirque lying in a north-south trend. A giacial moraine extends across the valley and impounds the lake at a surface elevation of 1,367 feet. The lake is 1.25 miles long, approximately 0.3 mile wide, and over 190 feet deep. Several small glaciers and permanent snowfields at the nead of the valley drain into the lake. The outlet stream traverses a gentle gradient for approximately 0.6 mile before descending steeply to sea level. ==) oo We, ° 2 2 | A\z5 | mo | a SLENNALLEN iN — 5 ( | i ey “4 “ f hiner , 9 oO Rant Project © Location & ae ie . Bu a 2 a wl \ e M = \ \ eo t WO en ie ( \ i * a\ ow za z | ¥ 3 oe 9 SSILVER Lane | | ae SOUTHCONTRAL RAILGELT STUDY Ss LOCATION AND VICINITY MAP | VALOCZ INTERIM | Figure 1 | | | a Sas PROJECT DESCRIPTION The proposed Allison Lake hydropower facility will consist of a lake tap at 1,250 feet elevation, a rock tunnel from this level to 1,220 =~ feet elevation, and a 48-inch penstock reaching from the lake tap { | through the rock tunnel to one of the two proposed powerhouse alter- ms natives (Figures 2 and 3). Both proposed powerhouse alternatives are located on Alyeska Pipeline Service Company property and either would occupy about i.5 acres. The Alveska terminal site road would provide access to either site, with only an additional 50-100 feet of road construction required. Powerhouse alternative #1 is proposed above the existing weir in Allison Creek, which was constructed by the Alyeska Pipeline Service Company for a partial source of water for the terminal of the Trans— Alaska Pipeline. The proposed powerhouse is at an approximate elevation of 100 feet (Figure 2). The tailrace would run directly into Allison Creek at this location. The CE has not proposed a dual tailrace configuration at this site as described below for powerhouse alternative #2; however, further consideration of such a feature at this site is contained in the discussion section or this report. Powerhouse alternative #2 is proposed near tidewater at an approximate elevation of 10 feet (Figure 3). A combination of two tailraces are proposed by the CE for this powerhouse. One would discharge directly into Port Valdez, the other would discharge into Allison Creek near the proposed powerhouse. CE personnel have stated that the discharge from the proposed powerhouse could be regulated through each tailrace independently or through each simultaneously. For example, flow —— through one tailrace could be constant while flow through the other | would vary according to power generation requirements. In addition, — a six-inch steel diversion pipe is proposed from the penstock to Allison Creek above the existing weir to provide supplemental water if the tributary flow to the creek is not sufficient for the needs of Alyeska, and resident and anadromous fish. To allow disposal of the proposed spoil, excavated from the rock tunnel, an access road approximately 500 feet long will be con- structed from the lower end of the rock tunnel at 1,220 feet elevation due east to the edge of a cliff. About 45,000 cubic yards of rock is proposed to be dumped over this cliff and into a deep gorge. The proposed transmission line will run 3.5 miles from one of the proposed powerhouse sites to the Solomon Gulch substation of the Solomon Gulch hydropower facility, now under construction by the Copper Valley Electric Association. It will closely follow the route of the existing Dayville Road along Port Valdez. RESOURCE INVENTORY Lower elevations of the,coastal forest in this region support dense stands of Sitka spruce= and mountain hemiock with an understory of = Common names of plant and animal species are used throughout this FF report. A list of scientific names is given in APPENDIX A. www” a iil A \ — aioe | aie Fey ZS Pesos Qa irre Ace —. rei > POWER ruwner cane TA? ANO > LU iets ACCESS SHAFT- ROCK TRAP ~~~ ALLISON LAKE ote : i ae Na SURFACE ELEVATION 1260.1 (} Valdez Interim Report | i £ t Southcentral Railbele ' : : : Allison Lake Topographic Plan on gs < at peasant Figure 2 fee soo cn R ( - NO.! Ean SIPA ie Cir wo Tt \ Ou) | ~~ a) J o 3 7 \ te Qe¥ u)- 5 Le @ Ai yw oa } 3 a& —-qQ- a 1 -& / tad ht a AN x oN x Vo \\" \\ \Y ( XS wow ued ow a0 Cc get “a Mort Od Oi] W Ou Am hu oA oO Vv ao Meet oA ow eo ov uo oa u gu no a HG 4h 60 o ot ob el NU rf! O fey Qo. xc oO uw QO ao isa 3.90 pm 4 —-—_~-—— 008 qn a ———_——->- a) ae alder, salmonberry, blueberry, and devilsclub. The steep walls above Allison Lake and upper Allison Creek support alpine tundra, Tall shrub thickets dominated by alder and some balsam poplar occur ~ in the area of lower Allison Creek. The riparian area above the v lake supports mainly willow thickets. The fresh and saltwaters of the Prince William Sound area support a number of valuable fish species which are of great economic impor- tance to the local economy. The short. coastal streams (approxi- mately 700) are important for salmon production. Salmon usage of these small streams is so widespread that, unlike other areas of Alaska, no single stream or small group of streams plays a dominant role in salmon production. In addition, the island-bay complex of the Sound, provides thousands of miles of shoreline distributed in a fiord system particularly suited to early-stage rearing of juvenile salmon. The Prince William Sound area has been a rather consistent salmon producer since 1960. The average total salmon catch of 4.6 million fish represents approximately 10 percent of the statewide salmon harvest (Table I). The economy of the Prince William Sound area is largely dependent on the commercial salmon fisheries (Table II). The sport fisheries in the Prince William Sound area are also important to the economy and are primarily centered around the communities of Cordova, Valdez, and Whittier. The area supports an expanding marine fishery which is concentrated in Valdez Arm near the city of Valdez. Sport fishing is an important tourist attraction for Valdez and a major source of summer recreation for local residents. Saltwater salmon fishing is popular, with coho salmon being the most sought after species. Pink and chum salmon are also caught in large numbers, and a few chinook are occasionally landed. Dolly Varden, halibut, rockfish, dungeness crab, and butter clams are also harvested in the saltwater fishery. Freshwater fishing activity is minor in the Valdez area. Salmon fishing is prohibited in all streams draining into Valdez Bay, and trout habitat and populations are limited. ( } No fish are known to occur in Allison Lake, but fish do inhabit the lower 0.5 mile of Allison Creek. Fish migration above this point is blocked by high water velocity and the steep gradient of the stream. The weir in Allison Creek is also a partial barrier to fish migration. Dolly Varden and sculpin are resident in the creek, while spawning populations of adult pink and chum salmon seasonally occur in the summer and fall. Egg development of salmon occurs through the winter months until out-migration of fry in early spring. Salmon escapement estimates are limited and the available data collected between 1960 and 1971 by the Alaska Department of Fish and Game (ADF&G) are given in Table III. It is apparent that escapement counts on Allison Creek were not conducted on a regular basis; however, numbers of chum salmon counted in 1963 exceeded 2600 and Table I 1 Prince William Sound Salmon Catch by Species, in Numbers of Fish, 1970-79.—/ Year Chinook Sockeve Coho Pink Chum ~*Total 19702/ 1031 104,169 11,485 2,809,996 230,661 3,157,342 1971 3,551 8,368 30,551 7,310,964 574,265 8,007,699 1972 547 197,526 1,634 54,783 45,370 299, 860 1973 2,405 124,302 1,399 2,056,878 729,839 2,915,323 1974 1,590 129,366 BOL 448,773 88,544 669,074 1975 2,519 189,613 6,142 4,452,805 100,479 4,751,558 1976 1,044 112,809 6,171 3,018,991 370,478 3,509,493 #19772/ 632 310,147 804 4,509,260 570,497 5,391,340 ai97e4! 1,043 220,329 1,464 2,785,156 483,559 3,491,551 #19794/ 2,002 146,468 6,780 15,375,339 323,397 15,853,986 Totals 16,364 1,623,597 67,031 42,822,545 3,317,089 48,047,226 10 yr Average 1,636 162,360 6,723 4,282,294 351,709 4,804,722 nol ~ statistics. 29. Does not include Copper-Bering Rivers. Source: 1970-76, Alaska catch and production. Statistical leaflets #21, 23, 25, 26, 27, 28, and Source: Alaska Department of Flsh and Game, Commercial fisheries 1977, Annual Report. =’ Source: Pete Fridgen, Alaska Department of Fish and Game, Cordova, * Preliminary results. (| | Table C0 Prince William Sound Salmon Catch in Pounds, and Value to Fishermen, 1970-79 Year Pounds All Specles % Catch % Catch by weishe Total Value Pinks & Chums Pinks & Clans Cates in Dollars i970! 13,677, 88 89 94 $2,277, 582 ort 41,217,634 v1 07 1,436, 5152! 1972 2,132,510 18 30 2,926, 0612/ 1973 16,314,156 10 93 8,635, 016-/ 1974 3,906,587 67 75 5,811, 6982/ 1975 18,524,038 94 92 5,753,649 1976 17,038,169 86 95 7,395,290 19772/ (26,432,337) 84 (91) data not avallable 19784/ (17,740,921) 80 (91) (6, 832,242) 19792/ (68,660, 829) 97 (98) (27,391,727) Source: 1970-76, Alaska catch and production. Commercial fisheries statistics. Alaska Department of Fish and Game. Statistical leaflets, No.'s 21, 23, 25, 26, 27, 28, and 29. Includes value of salmon from the Copper-Bering River districts also. 1977 data in parentheses are preliminary estimates only and not published by the Alaska Department of Fish and Game. Total pounds calculated using 1976 average weights for each species. Chinook salmon not included. Source: Dennis Haanpaa, Alaska Department of Fish and Game, Anchorage. 1978 data in parentheses are preliminary estimates only and not published by ADF&G. Total pounds calculated using 1976 average weights for each species. Chinook salmon not included. Total value of the catch calculated by using the 1978 average dollar value per fish paid to the fishermen. Chinook salmon not included. Source: Dennis Haanpaa, Alaska Department of Fish and Game, Anchorage. 1979 data in parentheses are preliminary estimates only and not published by ADF&G. Total pounds calculated using 1976 average weights for each species. Chinook salmon not included. Total value of the catch calculated by using the 1979 average price per pound for each species paid to the fishermen and the 1976 average weights for each species. Chinook salmon not included. Source: Dennis Haanpaa, Alaska Department of Fish and Game, Anchorage. 3/ 4/ 5/ ~ w 1976 Average weights by species Sockeye - 7.4 lbs Coho - 8.5 lbs Pink - 4.2 lbs Chum - 9.1 lbs Source: ADF&G, 1976 catch and production. Commercial fisheries statistics. Statistical leaflet #29. 1978 Average price per fish paid to the fishermen Sockeye - $ 7,48/fish Coho - 3.59/fish Pink - 1.29/f£ish dn Chum - 3.28/fish Source: Dennis Haanpaa, ADF&G, Anchorage . 1979 Average price per pound paid to the fishermen Sockeye - $ 1.400/1b Coho - 0,390/1b Pink - 0.377/1b Chum - 0.530/1b \ Source: Dennis Haanpaa, ADF&G, Anchorage yg 4 ' ‘ison Creek Salmon Escapement Data fOr Escapement ra Pink Salmon Chum Salmon GAD 100 --- L94AL 750 --- 1962 560 580 1963 —j= 2,660 1964 -9- 190 965 -0- Bis 1966 -0- = 1969 500-1, 000 _ 1971 _ 300 _ 1973 25 --- Source: ADFSG. ‘Nece: Allison Creek was not regularly checked for escapement by Fish and Game but only as time and funding allowed. A year which shows Zero escapement does not necessarily mean that no fish spawned that year, it only indicates that at the time it was checked there were no fish present. the number of pink salmon counted in 1969 reached 1,000. In even years spawning by both pink and chum salmon occurs almost exclusively in the intertidal reach of Allison Creek, an area estimated to be 40 feet ( wide by 300. feet long. During odd years, when stronger runs of pinks occur in Prince William Sound streams, spawning also occurs in Allison Creek upstream to the existing weir. A basic understanding of the life cycle of pink and chum salmon is necessary to recognize all potential impacts which could occur from the proposed project. Adult pink salmon return to their natal streams to spawn in mid-summer or fall of their second year. Adult chum salmon are predominantly three, four, and five year old fish. Pink salmon enter streams in the Valdez area in July and spawn in August and early September, while chum salmon spawn slightly later. Eggs are deposited in the streambed gravels where development to the fry stage occurs. Alevins (embryos which have emerged from the egg) remain in the gravel until their yolk sacs are completely, or almost completely absorbed. The life cycles of pink and chum salmon are very similar. For chums, the alevin stage (from hatching to emergence) is completed in 30 to 50 days, depending on the water temperature. In Port Valdez, fry emergence of pink and chum salmon begins in mid-April and peaks in May. Both pink and chum salmon fry migrate to salt water during their first summer, generally within a few days to a few weeks after emergence. Once in salt water, the young salmon feed in schools near shore until late July or August; some remain near shore until <= autumn. Between mid-summer of their first year and their second summer, they disperse throughout the offshore waters of the North Pacific Ocean and Bering Sea. In salt water, main foods of young pink and/or chum salmon have been reported to be cladocerans, copepods, barnacle naupli, barnacle cyprids, euphasids, and tunicates (Bakkala, 1970). Other studies have shown harpacticoids to be a major component of the stomach contents of post-emergent pink and chum salmon fry (Kaczynski et. al., 1973; Healey, 1979). The seasonal population density of the copepod Harpacticus uniremis in Port Valdez is shown in Figure 4. Wildlife known to occur in the Allison Lake drainage include brown bear, black bear, mountain goat, wolf, wolverine, marten, porcupine, and snowshoe hare. Upland game birds include willow, rock, and white-tailed ptarmigan and spruce grouse. There is little infor- mation on the occurrence of small mammals and birds in the project vicinity, although lists of species are available for the Valdez area. A general list of species which may occur in the vicinity of Allison Creek is provided in APPENDIX A. Waterfowl use of Allison Lake and the creek is considered quite limited. The lake may occasionally be used for resting, and feeding may occur in the shallow, upper part and along the braided stream channel. Approximately 18 Canada geese have been observed resting (3 comenne 0 too f- 3 -—— Feder, et. al. . aw, pebeaect hated uc Dk Sh De re. ‘ew Are ay me MW Al SEP OCT NOV OIC Jan sofa 1995 —____—--- , 1976. oe ee Uae arn we te TOF aA CUS Labor ee ME SARE Og TAD wie ke St? OCT mov OIC Jan wre ee - - asonal Variation in Population Density of Marpacticus uniremis. Tie ibe toete Td a di The MAR APR way + in the fall at the upper end of the lake by FWS personnel. Also, molting geese were observed in the Allison Lake Basin by FWS per- sonnel during 1979. G Extensive waterfowl use is made of the intertidal area around upper - Port Valdez and the Lowe River Delta. Numerous seabirds inhabit that area also. Waterfowl present in the Valdez area year-round include scoters, goldeneye, common and red-breasted mergansers, mallards, buffleheads, harlequins, and Canada geese. Others sea- sonally present in the Valdez area include pintails, teals, wigeons, oldsquaws, and shovelers. Northern bald eagles are common in the Valdez area. Personnel of the FWS conducted a survey in 1976, locating 23 eagles and 10 nests within Port Valdez (includes all of the shoreline inside of Middle Rock except for the Lowe River flats south of old Valdez). Two nests were identified within three miles on the mouth of Allison Creek, one on each side of the stream (see Figure 5). Congregations of eagles are attracted by salmon to mouths of stream which flow into Port Valdez. The carcasses of salmon are an important addition to the diet of both resident and migratory eagles. Other raptors found in the Valdez area include the osprey, red-tailed hawk, sharp- shinned hawk, goshawk, and Peale's peregine falcon. No terrestrial threatened or endangered species are known to occur in the Valdez area, The endangered finback and humpback whales have been sited in Port Valdez. Peale's peregrine falcon is not listed as an endangered species under the Endangered Species Act of 1973. \ Hunting, hiking, and overnight recreational use in the Allison Lake —_ area appear to be limited, due to the rugged terrain. However, a rough hiking trail to the lake is presently used by local residents. Port Valdez is used, or occasionally visited, by the following marine mammals: northern fur seal, harbor seal, sea otter, northern sea lion, killer whale, humpback whale, Dall's porpoise, and harbor porpoise, The nearshore area from 0.3 mile west of Allison Creek to 0.3 mile west of Dayville Flats Creek has been identified as a feeding area for sea otters and harbor seals. The flow regime of Allison Creek varies from high flow in early summer and fall to low flow in the late winter and early spring. Specific data are lacking and that data available is given in Table Iv. PROJECT IMPACTS Impacts which would result from the project are discussed in two categories: construction, and operation and maintenance, Construction: At present, no access road is planned to Allison Lake. This considerably reduces the possible impacts of the project on the upland area. The road and rock dump associated with the tunnel construction will cover existing vegetation, as well as 4 create a scar visible from Valdez. Weathering of the rock will 16, 1976. ae! September 14 es, Nesct Sit le Bald Eag 5. z<e Figu |, Minerat Create isiands sate 79 in the fall at the upper end of the lake by FWS personnel, Also, molting geese were observed in the Allison Lake Basin by FWS per- sonnel during 1979, Extensive waterfowl use is made of the intertidal area around upper Port Valdez and the Lowe River Delta. Numerous seabirds inhabit that area also. Waterfowl present in the Valdez area year-round include scoters, goldeneye, common and red-breasted mergansers, mallards, buffleheads, harlequins, and Canada geese. Others sea- sonally present in the Valdez area include pintails, teals, wigeons, oldsquaws, and shovelers. Northern bald eagles are common in the Valdez area, Personnel of the FWS conducted a survey in 1976, locating 23 eagles and 10 nests within Port Valdez (includes all of the shoreline inside of Middle Rock except for the Lowe River flats south of old Valdez). Two nests were identified within three miles on the mouth of Allison Creek, one on each side of the stream (see Figure 5). Congregations of eagles are attracted by salmon to mouths of stream which flow into Port Valdez. The carcasses of salmon are an important addition to the diet of both resident and migratory eagles. Other raptors found in the Valdez area include the osprey, red=-tailed hawk, sharp- shinned hawk, goshawk, and Peale's peregine falcon. No terrestrial threatened or endangered species are known to occur in the Valdez area. The endangered finback and humpback whales have been sited in Port Valdez. Peale's peregrine falcon is not listed as an endangered species under the Endangered Species Act of 1973. Hunting, hiking, and overnight recreational use in the Allison Lake area appear to be limited, due to the rugged terrain. However, a rough hiking trail to the lake is presently used by local residents. Port Valdez is used, or occasionally visited, by the following marine mammals: northern fur seal, harbor seal, sea otter, northern sea lion, killer whale, humpback whale, Dall's porpoise, and harbor porpoise. The nearshore area from 0.3 mile west of Allison Creek to 0.3 mile west of Dayville Flats Creek has been identified as a feeding area for sea otters and harbor seals. The flow regime of Allison Creek varies from high flow in early summer and fall to low flow in the late winter and early spring. Specific data are lacking and that data available is given in Table Iv. PROJECT IMPACTS Impacts which would result from the project are discussed in two categories: construction, and operation and maintenance. Construction: At present, no access road is planned to Allison Lake. This considerably reduces the possible impacts of the project on the upland area. The road and rock dump associated with the tunnel construction will cover existing vegetation, as well as create a scar visible from Valdez. Weathering of the rock will 1976-6 16 & 16, } Bald Eagle Nest Sites, September 1, Minerat Crease. © <n QMerEOS, isianas k - Discharge Measurements rn ~ Flow in cubic feet ( Date per second (c.£.s.) 54.9 11.9 tS. 10. 13. 12. 20. 20. ONUOAN NNN & wo bu DwWO ~4 Ww a Ong DOO OrR GH NNMWOOAarAs co wo WDNMNN $e & S WUPwWWuor & we ~ mNuUUNFrn4OWAUNA DO i‘ Data collected by: U.S. Geological Survey Northwest Hydraulic Consultants, Led. JFWAT, George Perkins Inc. {7 occur, and may allow the rock to blend in with the surroundings within several years. Blasting for tunnel construction could temporarily disturb resident wildlife. The above ground portion of ~ the penstock will be a permanent scar on the hillside. Increased erosion and subsequent stream sedimentation may result from cleared areas, The extent of this occurrence will be directly related to construction techniques and can be avoided. Adverse impacts which can occur to aquatic species as a result of siltation are numerous and well documented. Major impacts from siltation, as a result of construction of the proposed project, include decreased vigor or death of incubating salmon eggs by interfering with or preventing respiration, loss of spawning gravels, and physical disturbance to both adult salmon and other resident species. Clearing of approximately 21.5 acres of vegetation would be required for the transmission line. Visual impact would be significant. Clearing and construction activities could disturb nesting eagles which may result in desertion of eggs and young. Bird collisions with power lines will result in mortality. Transmission poles could be the tallest object in the immediate vicinity and may commonly be used by raptors as a perch. Improper line spacing presents the hazard of electrocution to large raptors. Construction activities will disturb terrestrial wildlife and may cause avoidance of the area while construction is occuring. This impact should be minor as no wildiife concentrations or critical habitat areas are known to occur in the immediate area. To prevent debris from reaching the turbines, construction of a acts screen over the penstock intake at the lake will be necessary and could require lake drawdown to the lake tap inlet. This will result in dewatering the upper reaches of Allison Creek. If discharge did mot occur directly to Port Valdez or occur in a carefully controlled manner it could create excessive discharge into the lower stream; possible scouring of the streambed; and depending when this occurred, above normal stream velocities could either prevent returning adults from entering the stream or expose incubating eggs. Also, resident Dolly Varden could be flushed out of the system to marine waters. Operation and Maintenance: During project operation, the lake level would be drawn down as much as 100 feet, primarily over the winter months. Biological impacts to the lake resulting from this drawdown would probably be minor, although the aesthetic impact would be significant. Fortunately, the lake itself is not visible from the town of Valdez. Fluctuating lake levels could cause lake shore erosion leading to landslides in steeper areas with accompanying habitat degradation. During winter, shelf ice formed by the dropping lake level could impede movement of mountain goats. The low number of goats in the area reduces the extent of this occurrence. The impacts which would result from project operation have the greatest potential for adversely affecting the environment of Allison Creek. The drawdown would dewater Allison Creek at its c outlet from the lake; however, the CE expects natural seepage through glacial deposits to provide some flow into the upper creek. Also, tributary flow will provide some stream flow to lower portions of ~ the creek, _ Water for hydropower production would be drawn from deep in the lake and, based upon available information, will be warmer than Allison Creek water in the winter and colder than the stream's water in the summer, Water at lake tap depth may also be deficient in dissolved oxygen. A minimum dissolved oxygen concentration of 6.0 milligrams per liter (mg/l) has been recommended for coldwater fish (Doudoroff and Shumway, 1966). At the present time, dissolved oxygen data at the depth of the proposed lake tap is not available. The passage of water through the powerhouse and energy dissipator is expected to aerate these waters, although the extent of this occurrence in relation to the acceptable limits for fish is not known at present. Temperature has a major influence on the freshwater stages of salmon. Stream temperature data for Allison Creek has been collected by the U.S. Geological Survey and is now being collected by the ADF&G (APPENDIX B). The CE has also collected some temperature data for Allison Lake (APPENDIX B). The ADF&G has also taken intertidal temperatures at Solomon Creek (three miles to the east) since September, 1979, and this data would probably be consistent with salt water temperatures off the mouth of Allison Creek (APPENDIX 8). No intragravel temperatures have been taken. The effects of warm water discharges on developing eggs and alevins _ have been studied in laboratory situations and at most major hatchery | facilities. Increased mortality and abnormal embryonic development yy have been shown to occur if the initial incubation temperatures for developing pink salmon eggs is 4.5°C or lower. At 2.0°C or lower, complete mortality will occur (Bailey and Evans, 1971). Preliminary temperature data from the lake (APPENDIX B) indicates that the water through the powerplant would be 4°C or less. Based upon these data, the potential alteration of the temperature regime in Allison Creek could have a significant adverse impact upon the fish resources of Allison Creek. Low concentrations of dissolved oxygen and exposure to light can increase incubation time, but temperature is the primary factor in regulating the duration and timing of incubation and hatching. Development is normally expressed in terms of temperature units. A temperature unit is defined as one degree above freezing for a period of 24 hours. A given number of temperature units is required for the eggs to hatch. The number of temperature units required is generally specific to the species of fish and even to the particular stock, Hatching and emergence is delayed in colder water temperatures and accelerated in warmer temperatures. A minor temperature increase or decrease could considerably advance or delay hatching. A change in the natural temperature regime of Allison Creek could change the timing of pink and chum salmon fry emergence. The extent of this impact is difficult to assess with the data available; however, significant early development of eggs would result in early emergence and outmigration of frv to Port Valdez at a time when it is questionable that there would be adequate planktonic production to sustain rearing activity. Consequently, a substantial alteration ~ in natural water temperature during the egg to fry development G period would negatively impact run strength. With sufficient data, the number of temperature units required for eggs to hatch under natural stream temperatures can be calculated and compared to the number of temperature units anticipated to exist under altered stream conditions. The difference in temperature units will show if early or late emergence will occur, and if so, give the approximate magnitude of change in the time of emergence. Where intertidal spawning occurs, such as in Allison Creek, the warmer saltwater contributes to higher intragravel temperatures. This adds to the complexity of the temperature regime in intertidal areas because intertidal zone temperatures are influenced by (1) upstream water temperatures, (2) saltwater temperatures exposed to stream gravel, (3) time of exposure to saltwater, and possibly (4) the permeability of gravels. Should early fry emergence occur, sufficient food sources may not exist. Figure 4 illustrates the seasonal variation in population density of the copepod, Harpacticus uniremis, an organism which could be an important food source for post-emergent fry. Healey (1979) found that H. uniremis made up 50% of the overall diet of juvenile chum salmon in the Nanaimo Estuary and greater than 80% of the diet when fry were most abundant. He also found that — the seasonal pattern of abundance of fry and H. uniremis in the estuary was the same, and that fry consumed most of the estimated = production of H. uniremis, Large numbers of this copepod are usually not present in Port Valdez until mid-March to early April. Under natural conditions pink and chum salmon fry emergence begins in mid-April in the Port Valdez area. Radical fluctuations in stream flow contribute most heavily to mortality of developing eggs through erosion, shifting of gravel, or dewatering of spawning beds. Flooding also causes mortality by deposition of silt on spawning areas, which slows intragravel water movement, decreasing the oxygen supply to the eggs, and preventing removal of waste products. Other factors contributing to mortality of eggs are freezing, exposure to light, parasites, predation, high salinity, shock, and superimposition of redds (spawning beds). The tailrace discharge could cause increased velocity in the stream and scouring of the streambed with subsequent removal or burial of spawning gravel, Alterations in natural streamflow could also have adverse impacts upon spawning adults as a result of either high or low flows which are not optimum for spawning. Post-project flow schedules could be beneficial to fish resources by reducing radical flow fluctuations and providing flows optimum for life stage require- ments of pink and chum salmon. Cee ee eee rere ree Ee a a ae aT 21 As stated previously, two alternative sites have been proposed for the powerhouse. Either site would require clearing of approximately 1.5 acres for construction purposes. Some alteration of the stream— bank and streambed will result from installation of the tailrace and sedimentation could occur. The magnitude of these impacts could be reduced significantly depending on the construction techniques utilized and the time of work. Impacts which would result from either of the proposed powerhouse alternatives were described above. Those impacts which would vary, depending on the site selected, are described below. Powerhouse Alternative #1: The discharge of flow from this alter- native is proposed by the CE directly from the tailrace into Allison Creek. Radical flow changes would result and all adverse impacts described previously for alteration of flow would occur. In addition, if instream flows were totally dependent on power generation needs, periods of very low flow could result when the power plant was shut down for maintenance or other reasons. The discharge of all project flows into Allison Creek at thls site would also result in temperature and possibly dissolved oxygen impacts occurring in the total reach of Allison Creek utilized by fish. Flows in the creek above this site may not have any appre- ciable buffering effect for maintenance of natural water quality since they would be low in relation to the flow through the power- house. Powerhouse Alternative #2: Impacts described above for site #1 may also be applicable to this alternative. This alternative has two tailraces proposed. If the tailrace waters were discharged directly into Port Valdez during the summer months, a portion of the salmon population could be diverted away from spawning areas in the natural stream by the larger quantities of Allison Creek water issuing from the tailrace into Port Valdez. Diverting water from the powerhouse through the tailrace positioned in Allison Creek would alleviate this impact; however, those impacts discussed above under powerhouse #1 would occur. When the discharge is diverted back through the tailrace into Port Valdez, some of the redds could be dewatered. Also, the discharge could prove to be such an attractant to adult salmon that they would pool up below the discharge and not utilize other portions of the stream or intertidal area for spawning. Periods of very low flow during powerhouse shut down could also result from this alternative. The proposed 6 inch diversion pipe could be used to add supplemental water to the creek. However, the use of the diversion pipe for long periods to supply water to the stream or as a substantial supplement to natural flows could also cause early fry emergence as dicussed earlier. Diversion of flows directly into Port Valdez during most of the year would result in a reduction of water velocity in the natural stream- bed which could result in sedimentation of the spawning gravel. ) Should a major earthquake occur, this site could be severely damaged or destroyed by seismic sea waves. DISCUSSION With fossil fuel prices continuing on an upward spiral, increasing attention is being given to alternative energy sources. In Alaska, with steep slopes and abundant streams, hydropower is a logical choice. Sites with large hydropower potential close to population centers are limited, but potential small hydropower sites are numerous. Alaska also has abundant fish resources, which frequently inhabit the same drainage systems suitable for hydropower development. Unfortunately, these two resources may not be completely compatible. Allison Creek, cumulatively with the other short coastal streams of Prince William Sound, provides an important contribution to the overall salmon production of the area. Both the commercial and sport fisheries play an important role in the economy of Valdez. In addition, maintenance of natural and wild stocks of salmon in Allison Creek can be viewed as an aesthetic value which cannot be measured in monetary terms. The most significant impacts upon fish and wildlife resources which would occur from construction of the Allison Lake project are the potential changes in the flow and temperature regimes of the creek. All other potential impacts are considered less significant. An analysis of existing data and subsequent impacts indicate that appropriate structural and non-structural features to mitigate major adverse impacts could be incorporated into project design including either of the proposed powerhouse sites which would make the proposal acceptable environmentally. However, baseline data gaps presently exist which preclude a complete assessment of potential impacts. Execution of appropriate studies before or during the advanced engineering and design stage of planning will enable a thorough evaluation of potential impacts to fish and wildlife and refinement/ development of necessary mitigation features. In addition to these studies, a cooperative study jointly scoped by the FWS and CE, and conducted through project construction and operation, would enable refinement of mitigation recommendations; assessment of the accuracy and effectiveness of those recommendations; and provide a comprehensive data base useful in the future planning of similar projects. Available data suggests that peaking or excess flow should be discharged directly to Port Valdez year round and that regulated flows be discharged through the tailrace to Allison Creek, A pre-project instream flow analysis of Allison Creek is needed to derive accurate and specific optimum flow recommendations for fish maintenance. The regulated flows would vary according to life stage requirements of fish and naturai streambed flow. For example, from approximately mid-July to early September adult salmon are present in the creek and a constant flow optimum for spawning should occur in Allison Creek. Peaking or excess flow would continue directly to Port Valdez and this discharge should occur subtidally to at least -10 geet mean lower low water from June through September to eliminate attracting adults. Discharge measurements are sparse and, according to the CE, accurate predictions of the amount of water flowing through the powerhouse cannot yet be determined. Daily discharge measurements of Allison Creek should be taken for a minimum of one year, beginning as soon as possible. However, collection of data for two years or more is recommended. These data should be provided to the FWS quarterly to assist in refining discharge flow schedules through the proposed powerhouse to Allison Creek. The CE has stated that tributary and groundwater flow to Allison Creek will contribute seasonally to base flow in the creek after project operation. The specific amount of this flow is needed for analysis in the development of flow recommendations to Allison Creek from the powerhouse. The CE expects that tributary and groundwater flow will maintain adequate flow in that reach of the stream below the weir; however, during the low flow period of late winter and early spring it may be necessary to supplement instream flow below the weir to 5.0 cubic feet per second (cfs). The proposed 6 inch diversion pipe should be adequate to accomplish this. Temperature profile data of Allison Creek is needed to assess impacts. The CE should conduct temperature profiles in Allison Lake to the proposed lake tap intake depth for a period of one year beginning as soon as possible. A minimum sampling effort should include the months of March, June, September, and December. Concurrently, water samples for testing dissolved oxygen, pH, heavy metal, and turbidity levels, should also be taken at the surface and at the same depth and general location of the proposed lake tap. It may be feasible for the CE to model or accurately predict the thermal regime of Allison Lake with data available for similar alpine lakes. If dissolved oyxgen concentrations are below 6.0 mg/l, corrective measures may be necessary if the dissipators do not insure dissolved oxygen readings of 6.0 mg/l or above. A temperature probe or similar recording device should be installed in the gravel where intertidal spawning occurs to record intragravel temperature for the same time period. The thermograph now installed in Allison Creek should also be maintained throughout the same one-year period. With knowledge of the existing temperature regime for Allison Creek, the temperature of the water coming from the powerplant, the anti- cipated base flow, and the anticipated flow schedules for project operation, the temperature in the spawning beds could be predicted and the effects on developing salmon embryos calculated. Until the extent of adverse impacts can be identified, it is difficult to predict if any other form of mitigation may be appropriate. [It could be determined that regulation of the thermal regime of Allison Creek may be required to protect fish resources. During the first vear of project operations, daily temperature readings should be taken in Allison Creek below the tailrace dis- charge and provided monthly to the FWS and the ADF&G. Depending on the temperatures, it may be feasible that refinement of discharge recommendations could further mitigate potential impacts due to alteration of the temperature regime through mixing base flows in Allison Creek with project flows. An extension of the one year ~ recording period may be necessary. i As additional information is available for a thorough assessment of impacts due to potential changes in flow and temperature regimes, other alternatives for the discharge to Port Valdez may be acceptable or recommended. For example: (1) operation of the project only for base load power production would eliminate the radical flow variations associated with a peaking facility, (2) alterations in the discharge of flow from the tailrace in response to power demand could be done incrementally by a specified discharge in a given time period (ex. 10 cfs/hour), (3) discharge of excess flows directly into Port Valdez could be done via a flume or manmade channel and discharged subtidally only from June through September. Recent information on spawning populations in Allison Creek is also lacking. Beginning in 1980, escapement counts should be taken at least once a month in July, August, and September of each year. These surveys should continue through the planning, construction, and operation phase of the project to allow assessment of project impacts upon salmon populations. A dual tailrace design as proposed for the lower powerhouse alterna- tive should be included in plans for the upper powerhouse alter- native as well. The impacts associated with the potential changes to flow and temperature regimes described previously would occur at ci either powerhouse alternative unless appropriate mitigation features are incorporated into project design. In fact, construction and = operation of the upper powerhouse with the dual tailrace feature is favored slightly because stabilizing the flows in that stream reach between the lower and upper site would benefit fish resources in a greater portion of their habitat. To prevent scouring and downstream sedimentation, energy dissipators should be installed in both the tailrace and outlet of the 6 inch diversion pipe to Allison Creek. Design of the dissipators should insure that the velocity of the discharge into Allison Creek will not exceed the optimum velocity of the natural Stream for fish maintenance. The timing of construction will be of considerable importance in minimizing impacts to fish. The work should be done to avoid cri- tical biological life stages. Disturbance of the water quality or streambed morphology while eggs are incubating or fry are emerging can result in direct mortality through suffocation by burial or physical damage. Disturbance while adults are present can disrupt or prevent spawning and limit production of future generations. The timing of any inwater construction activity cr construction on the banks of Allison Creek should be coordinated with the FWS, National Marine Fisheries Service (NMFS), and the ADF&G to avoid unnecessary impact on the salmon population. Also, because highest densities of populations of spawning salmon occur in odd years, major construction “ affecting flows should be done on even years. Streambed sedimentation can be caused by a variety of activities. Improper construction and clearing techniques can cause increased runoff and excessive erosion. learing for penstock construction ~ above ground should be limited to large shrubs and any trees which may be encountered to reduce ground disturbance and erosion. A - damaged streambank is unstable and can cause sedimentation. Streambanks should be restored to pre-project integrity during the construction season in which they are damaged. Transmission line construction should be initiated after the ground is frozen and some snow. cover exists to minimize erosion and ruttirg. Alteration of the streambed or barriers in the channel can cause scouring and downstream sedimentation. Vegetation and debris should be kept out of Allison Creek and any streams crossed by the tvrans- mission line. Any structures placed in or across streams or water- bodies, as a result of project work, should be removed before the end of the current construction season. An erosion control plan and a plan for any instream work (including transmission lines) should be developed prior to construction and presented for review by resource agencies to insure appropriate precautions are implemented. Care should be taken to prevent the introduction of toxic materials into any waterbody. Fuels, lubricants, and other potential pollutants should be stored in leakproof containers within an area surrounded by a containment berm at a minimum of 300 feet from any stream or \ waterbody. Improper disposal of refuse can serve as an attractant to bears and _ other wildlife and lead to bear/human confrontations, usually ( resulting in removal or destruction of the bear. Feeding of wild- —y life by construction crews is illegal and should not be allowed. During construction, all refuse should be placed in metal containers with heavy lids and be removed from the site regularly. Nesting eagles can easily be disturbed by human activity which may cause them to desert eggs or young as a result. Nest removal or disturbance of bald eagles is prohibited by the Bald Eagle Act of 1940. When the exact transmission line route is established, FWS personnel should be given the opportunity to survey the route for any nests. Restrictions may be placed on construction activity occurring between April 1 and July 15 if nests are found in close proximity. Improper spacing of transmission lines can cause electrocution of raptors. Transmission line design and construction should be governed by "Suggested Practices for Raptor Protection on Powerlines," Raptor Research Foundation, 1975. Use of this information should be made to design the powerline with proper grounding, spacing, and configura- tion, such that it will prevent the electrocution of raptors. Clearing for the transmission line could create a visually displeasing scar on the landscape. To lessen this impact, clearing for the right-of-way should be limited to that needed to string the conductors and allow the passage of construction equipment. To further reduce 4 visual impacts, small shrubs should be left in the right-of-way and \ y along the edge of clearings so the vegetation will blend with the : natural surroundings. It is our intent to protect the existing salmon runs of Allison Creek. Should we be unsuccessful in adequately protecting those resources, other mitigation measures such as providing artificial ~ hatching, spawning, and/or rearing areas may be determined necessary. 1G A final analysis to determine whether or not any of these mitigation = measures would be acceptable or are favored cannot be made with data now available. However, based upon present flow and temperature data, we have tenatively determined that excess flows from the powerhouse should be discharged directly to Port Valdez to mitigate potential adverse impacts to fish resources. Additional data needs which have been identified should be satisfied’ as soon as possible. Those studies are: a comprehensive analysis of the pre— and post-project temperature regimes, salmon escapement surveys, bald eagle nest surveys, and an instream flow assessment. These studies should be conducted cooperatively by the FWS and CE. Execution of these studies would satisfy data needs for refinement/ development of mitigation recommendations and provide data needed for preparation of a supplement to this report. A cooperative study through project construction and operation would allow further refinement of mitigation recommendations, assessment of the accuracy and effectiveness of these recommendations, and provide baseline data for use in the planning of similar projects in the future. An amended scope of work and associated transfer of funds to the FWS would be required. RECOMMENDATIONS —_— l. That the design of the powerhouse allow the release of | regulated flows to Allison Creek through the tailrace and —— excess flows to Port Valdez through the other tailrace. 2. That flows from the powerhouse tailrace to Port Valdez be discharged subtidally to at least -10 feet MLLW from June through September. 3. That the proposed start-up of project operation affecting the natural flows in Allison Creek occur in an even year. 4. That the timing of proposed construction activities in or on the banks of Allison Creek be coordinated with the FWS, NMFS,and the ADF&G. 5. That streambanks be restored to pre-project integrity during the construction season in which they are damaged and debris or vegetation be kept out of streams. 6. That any structures placed in or across streams be removed during the same construction season. Ie That clearing for the penstock construction be limited to large shrubs and any trees which may be encountered. on 8. 10. Ll. 13. 14, 15. 16. 18. Se That during the construction phase, bulk fuels, lubricants, and other potential pollutants be stored in leakproof containers within an area surrounded dy a containment berm at a minimum of 300 feet from any stream or water body. That no feeding of wildlife occur and all refuse be placed in metal containers with heavy lids and removed regularly. That transmission line construction be governed by "Suggested Practices for Raptor Protection on Powerlines," Raptor Research Foundation, 1975. That clearing for the transmission line right-of-way te limited to only that area needed for construction and be reduced by leaving shrubs and blending the edges of the clearing with the surrounding vegetation. That an erosion control plan and instream work plan be prepared and made available to resource agencies for review and comment before construction. That the CE collect natural discharge data of Allison Creek continuosly for at least one year, beginning as soon as possible. That the CE maintain the thermograph in Allison Creek to collect natural temperature data continuously during the one year period that other temperature data is recorded. That the CE collect intragravel temperature data of Allison Creek continuously for at least one year, beginning as soon as possible. That the CE take temperature profiles of Allison Lake to the lake tap depth and temperature, dissolved oxygen, turbidity, heavy metal, and pH readings at the lake surface as well as the depth of the lake tap. These measurements should be collected as soon as possible. A minimum sampling effort would include the months of March, June, September, and December. That the CE collect continuous temperature data below the proposed tailrace into Allison Creek for at least the first year of project operation. That the CE determine the base flow in Allison Creek expected above the powerhouse after project operation. That provisions be included in advanced project planning for the FwS to survey the selected transmission line route for eagle nests. That provisions be included in advanced project planning for escapement surveys of salmon in Allison Creek by the FWS or ADF&G. nN lo That provisions be made in advanced project planning for instream flow analysis of Allison Creek by the FWS to determine optimum flow schedules and the velocity of supplemental flows to Allison Creek. That a cooperative study of the proposed Allison Creek Hydropower project, jointly scoped by the CE and FWS and funded by the CE, be conducted through project construction and operation. That, if after execution of the recommended additional studies, it is determined that some losses to fish and wildlife are unavoidable, those losses be offset by implementation of mitigation measures mutually acceptable to the FWS and the CE. 21 LITERATURE CITED Bailey, Jack E., and Dale R. Evans. 1971. The low-temperature threshold for pink salmon eggs in relation to a proposed hydro- electric installation. Fishery Bulletin 69(3): 595-613. Bakkala, Richard G. 1970. Synopsis of biological data on the chum salmon Oncorhynchus keta (Walbaum) 1972, FAO Fisheries Synopsis No. 41, Circular 315, U.S. Department of the Interior, Washington, D.C. Doudoroff, Peter and Dean L. Shumway. 1966. Dissolved oxygen criteria for the protection of fish. American Fisheries Sociey, Special Publication No. 4, A symposium on Water Quality Criteria to Protect Aquatic Life. Feder, Howard M., L. Michael Cheek, Patrick Flanagan, Stephen C. Jewett, Mary H. Johnston, A.S. Naidu, Stephen A. Norrell, A.J. Paul, Arla Scarborough, and David Shaw. 1976. The sediment environment of Port Valdez, Alaska: the effect of oil on this ecosystem. For: Corvallis Environmental Research Laboratory, U.S. Environmental Protection Agency. Corvallis, Oregon. Healey, M.C., 1979. Detritus and juvenile salmon production in the Nanaimo Estuary: I. Production and feeding rates of juvenile chum salmon (Oncorhynchus keta). J. Fish. Res. Board Can. 36: 488-496. KaczynskLl, V. W., R. J. Feller, and J. Clayton. 1973. Trophic analysis of juvenile pink and chum salmon (Oncorhynchus gorbuscha and 0. keta) in Puget Sound. J. Fish. Res. Board Can. 30: 1003-1008. APPENDIX A: SCIENTIFIC NAMES OF SPECIES Plants mo Sitka spruce - Picea sitchensis Mountain hemlock - Tsuga mertensiana Balsam poplar - Populus balsamifera Willow - Salix spp. Alder - Alnus spp. Salmonberry - Rubus spectabilis Devils club - Oplopanax horridus Blueberry - Vaccinium spp. Animals Invertebrates Dungeness crab ~ Cancer magister Butter clam - Saxidomus spp. Copepod - Harpacticus uniremis Fish Pink salmon - Oncorhynchus gorbuscha Chum salmon - Oncorhynchus keta Coho salmon - Oncorhynchus kisutch Sockeye salmon - Oncorhynchus nerka —_ Chinook salmon - Oncorhynchus tshawytscha | Dolly Varden - Salvelinus malma Trout - Salmo spp. : Rockfish - Sebastes spp. Sculpin - Cottus spp. Halibut - Hippoglossus spp. Birds Canada goose - Branta canadensis Mallard - Anas platyrhynchos Pintail - Anas acuta Green-winged teal - Anas crecca American wigeon - Anas americana Northern shoveler - Spatula clypeata Goldeneye - Bucephala spp. Bufflehead - Bucephala albeola Oldsquaw - Clangula hyemalis Harlequin - Histrionicus histrionicus Surt scoter — Melanitta perspicillata Black scoter - Oidemia nigra Common merganser - Mergus merzanser Red-breasted merganser - Mergus serrator Goshawk - Accipiter gentilis — Sharp-shinned hawk - Accipiter striatus. Red-tailed hawk - Buteo jamaicensis Northern bald eagle - Haliaeetus leucocephalus alascanus Osprey - Pandion haliaetus Peale's peregrine falcon - Falco peregrinus pealei Spruce grouse - Canachites canadensis Willow ptarmigan - Lagopus lagopus Rock ptarmigan - Lagopus mutus White-tailed ptarmigan - Lagopus leucurus Mammals Black bear - Ursus americanus Brown bear - Ursus arctos Wolverine - Gulo luscus Marten — Martes americana Short-tailed weasel - Mustela erminea Mink - Mustela vison River otter - Lutra canadensis Lynx- Lynx canadensis Coyote - Canis latrans Gray wolf - Canis lupus Porcupine - Erethizon dorsatum Snowshoe hare - Lepus americanus Mountain goat - Oreamnos americanus Marine Mammals Sea otter - Enhydra lutris Northern sea lion - Eumetopias jubata Northern fur seal - Callorhinus ursinus Harbor seal - Phoca vitulina Killer Whale - Orcinus rectipinna Harbor porpoise - Phocoena phocoena Dall's porpoise - Phocoenoides dalli Humpback whale - Megaptera novaeangliae APPENDIX 3 TEMPERATURE DATA IZ Allison Creek Temperature Data | re eR RE RR Date Temperature ~C 09/23/71 5.0 02/15/72 1.0 05/23/72 3.0 07/24/72 7.0 10/12/72 2.5 04/04/73 2.5 06/17/73 4.0 ——— — ——— —————————— — - Source: U.S. Geological Survey Thermograph Readings ALLISON CREEK ~~ August 1979 July 1979 June 1979 Aver. Low Aver. Low Aver. Low High High Temp. High Temp. Temp. Temp. Temp. Temp. Temp. Temp. Temp. 00] 00] os} 00] 00] 00) tm] roof] st} in] fun] st cof cof C] SIN TRIB IRI RN ofiope or}. o| 0 cof 00} 00] cof co} co ny ffunfun] en] us|in}in st} en unfun| st W/O} wo} o}w ANMTNONMDHNOHAMYSTN Ad AA wh] lo so] Win} wr] oO]o NO }oOl™ Ir ]o0o nonmrnon Addie ofr} 0] 0]. ] 00 ft] 0o|r-] 00) tN] oof oo] ~ be [1] [00 [oo] coir foojayjoy NANN 00] 0O Ww} ,olrmimeire. DOO whwo}ofwlr|rfrolo A] INf iN} fir fwolwnfinfo | a) oe runNOonrnmOoOnoO NANNNANNS ; Alaska Department of Fish and Game- Source: WOMAN AUF WN ALLISON CREEK September 1979 October 1979 November 1979 ce? High Low Aver. High Low Aver. High Low Aver. Temp. Temp. Temp. Temp. Temp. Temp. Temp. Temp. Temp. 55 35 8 6 7 a5 3.5 8 5 6.5 5.5 3 2 2.5 9 7 8 5.5 2 1 TES 7 6 6.5 5S 1 7 6 6.5 5.5 Z 0 iz 7 5 6 5 2 1 es 8 6 7 6 5 535 3 2 225 8 5 7 55 3 7 6 6.5 5.5 3 2 2.5 8 6 7 se 2 9 7 8 5.5 3 9 8 8.5 5 2.5 9 8 8.5 5 4 4.5 3 2 EE 8 7 7.5 5 4 4.5 2 7 5 2 1 1.5 7 5 4 4.5 1 7 4 0 S 1 0 0.5 3 L Z 3 555 2 1 1.5 4 2 a 2 4 2 0 1 4 0 a 3 BES 0 6 5 Sao 4 I 0 0.5 6 5 5.5 4 2 0 1 5 6 6.5 4 2 6 5 5.5 Z 2 iz eS: Source: Alaska Department of Fish and Game. ALLISON CREEK December 1979 January 1980 February 1980 a SESE CRESS ee \ High Low Aver. High Low Aver. High Low Aver. Temp. Temp. Temp. Temp. Temp. Temp Temp. Temp. Temp. l it -0.3 -0.3 -0.6 -0.5 oe 0 0.5 -0.3 0.1 -0.4 -0.2 3 0.5 0.0 “0.4 <-0.2 0.1 0.0 0.1 4 Q 0.1 0.0 0.0 0.0 J 0) 0.4 0.1 0.2 0.0 -0.4 -0.2 6 -0.3 -0.3 0.6 0.5 0.5 0.1 0.0 0.1 7 -0.3 0.6 0.5 0.5 0.1 8 -0.3 0.5 0.1 9 -0.3 0.5 0.0 0.4 0.1 0.1 0.0 10 -0.3 0.0 “0.4 -0.3 0.3 70.2 0.0 om ll -0.3° -0.4 “0.5 <-0.5 0.5 0.3 0.4 = 12 -0.3 -0.4 -0.3 -0.5 0.4 0.2 0.3 13 0.3 -0.1 -0.6 -0.3 0.2 0.0 0.1 14 -0.3 -0.4 -0.4 0.2 -0.1 0.1 0.1 15 -0.3 -0.5 0.4 0.2 0.1 0.0 0.0 16 0.2 <=0.2 0.1 0.6 0.2 0.3 0.1 -0.1 0.0 17 0.4 6.3 0.4 0.5 0.1 0.2 0.0 -0.7 -0.4 18 0.2 <-0.3 -0.1 0.3 0.1 0.2 -0.5 19 0.3 -0.2 0.1 0.4 0.1 0.2 -0.4 -0.7 -0.5 20 0.6 0.4 0.5 0.2 0.0 0.1 -0.2 0.4 -0.3 21 Oso ae 0.3 0.1 -0.3 0.0 0.0 -0.2 -0.1 oe see Oe) Lt 0.1 -0.4 0.5 0.5 0.3 0.9 0.1 23052 0-1 0.2 0.5 0.8 0.4 0.6 24 0.6 0.2 0.4 -0.5 -0.7 -0.6 0.9 0.7 0.8 37 ALLISON CREEK December 1979 January 1980 February 1980 ir Tesi ere TTT ire High Low Aver. High Low Aver. High Low Aver. Temp. Temp. Temp. Temp. Temp. Temp Temp. Temp. Temp. 26 0.8 0.5 1.0 0.7 0.8 27 «(0.8 0.7 0.8 0.2 0.5 -0.3 1.0 28 0.8 0.2 -0.1 0.1 29 0.8 0O.5 0.7 0.1 -0.7 0.4 30 0.3 O.1 0.2 -0.6 Source: Alaska Department of Fish and Game. Allison Lake Temperature Data May 7, 1979 =~ i \ Type Probe #1 Probe #2 Probe #3 Ice Thickness Le EaGie 3A 6 Ft. Overflow dnd | ee 0 0.5 Fe. Temperature. cc ° Surface (top of ice) ~0. 25° -0.25 +0.25° l Meter -0.25 -0.25 0.00 2 -0.25 0.00 0.00 2.5 +0.25 +0.25 5 Ones +0, 25 0.30 365 0.50 +0.75 Guz5 4 1.00 E25 1.50 4.5 2.00 1.90 2.40 5 2.25 2.40 2.50 5.5 75 2.73 6 295 3.00 2.90 6.5 3.00 3.00 7 3.00 3425 3.10 a 8 3.20 2.23 3.23 8c5 9 Se2o S25 3.30 on5 10 Se25 3.30 3.28 ee 0.3 ll S225 3.30 3.30 ~<y 12 Bottom@ 12.25 M 3.30 3.30 be 3.40 3.30 Source: Corps of Engineers. WOnNDUFWNEHE SOLOMON CREEK September 1979 October 1979 November 1979 c° High Low Aver. High Low Aver. High Low Aver. Temp. Temp. Temp. Temp. Temp. Temp. Temp. Temp. Temp. 12 2 6 3 12 6 2 3 6 8 3 il 6 7 3 6 5 7 2 12 5 7 - i 8 1 > 8 E 10 3 8 0 12 i it 5 2 L az 7 5 3 2 73 8 5 3 2 12 9 5 2 1 13 8 > LAS 8 4.5 4.5 135 oS 4.5 Zai9 6 15 7 7 4 6 2 7 6 10 4 6 1 7 10 4 6 iL E it 4 5 0 7 6 10 3 7 1 6 9 2 7 1 6 3 2 7 1 6 9 2 6 i 6 9 3 6 1 6 9 3 6 1 6 9 3 5 i 9 6 8 3 6 1 il 6 9 3 5 i 6 9 3 6 1 Source: Alaska Department of Fish and Game. RESPONSES TO RECOMMENDATIONS of the U.S. Fisn and Wildlife Service in the Final Coordination Act Report. 1. That the design of the powernouse allow the release of regulated flows ta Allison Creek throught the tailrace and excess flows to Port Valdez through the other tailrace. Response: The selected plan includes a two tailrace system which would allow regulated flows to both Allison Creek and Port Valdez. 2. That flows from the powerhouse tailrace to Port Valdez be discharged subtidally to at least -10 feet MLLW from June through September. Response: Ouring the advanced engineering and design phase, studies will be conducted to determine stream temperatures with project operation. If these studies indicate the stream temperature during the spawning would be below the critical level and all the project discnarge could not be discnarged into Allison Creek during spawning, mitigative measures, sucn as a subtidal outlet would probaoly be employed. 3. That the proposed start-up of project operation affecting the natura] flows in Allison Creek occur in an even year. Response: The initial drawdown for securing the tap and the placement of trash racks would probably occur during the winter months when flows into the Port Valaez tailace and would have no impacts on the incubating eggs within Allison Creek and the intertidal area. Project operation would Probably occur with the refilling of the lake the same year as the drawdown. It would be impossible at this time to insure project startup would occur in an even year. 4, That the timing of proposed construction activities in or on the banks of Allison Creek be coordinated with the FWS, NMFS, and the ADF&G. Response: This recommendation will be included in the stipulations to the contractor. 5. That streambanks be restored to preproject integrity during the construction season in which they are damaged and debris or vegetation be kept out of streams. Response: Refer to response to number four. 6. Tnat any structures placed in or across streams be removed during the same construction season. Response: Refer to response to number four. 7. Tnat clearing for the penstock construction be limited to large snruds and any trees wnich may be encountered. & Response: Some clearing to base ground would be required for the footing = of the penstock braces. Stipulations to the cantractor would inelude revegetation in areas where erosion could possibly occur. 8. That during the constuction pnase, bulk fuels, lubricants, ana other potential pollutants be stored in leakproof containers within an area surrounded by a containment berm at a minimum of 300 feet from any stream or water body. Response: Refer to response to number four. 9. That no feeding of wildlife occur and all refuse be placed in metal containers with heavy lids and removed regularly. Response: kefer to response to number four. 10. That the transmission line construction be governed by "Suggested Practices’ for Raptor Protection on Powerlines," Raptor Research Foundation, 1975. Response: The design of the transmission lines will follow the above pract.ices. 11. That clearing for the transmission line right-of-way be limited to only that area needed for construction and be reduced by leaving shrubs and blending the edges of the clearing with the surrounding vegetation. Response: Refer to response to number four. 12. That an erosion control plan and instream work plan be prepared and made available to resource agencies for review and comment before construction. Response: Little instream work is anticipated, however the recommendation will be included in the stipulations to the contractor. 13. That the CE collect natural discharge data of Allison Creek continuously for at least one year, beginning as soon as possible. Response: At least one stream gage will be installed on Allison Creek during the advanced engineering and design phase and it will collect data for several years. 14. That the CE maintain the tnermograph in Allison Creek to collect natural temperature data continuously during the one year period that other temperature data is recorded. Response: The thermograpn is in place at this time and will remain coliecting temperatures weli after project completion. on 15. That the CE collect intragravel temperature data of Allison Creek continuously for at least one year, beginning as soon as possible. Response: Intragravel temperature data will be collected during the advanced engineering and design phase. 16. That the CE take temperature profiles of Allison Lake to the lake tap depth and temperature, dissolved oxygen, turbidity, heavy metal, and pH readings at the lake surface as well as the depth of the lake tap. These measurements should be collected as soon as possible. A minimum sampling effort would include the months of March, June, September, anda December. Response: Refer to response to number 15. 17. That the CE coilect continuous temperature data below the proposed tailrace into Allison Creek for at least the first year of project operation. Response: The tnermograph which is now operating in Allison Creek will continue to collect data for at least the first year after project completion. 18. That the CE determine tne base flow in Allison Creek expected above tne powerhouse after project operation. Response: Preliminary estimates have been completed and are included in this report. A gage will be installed during AE&D and maintained after project completion. 19. Response: An eagle nest survey will be conducted prior to any construction associated with the project. 20. That provisions be included in advanced project planning for escapement survey of salmon in Allison Creek by the FWS or ADF&&G. Response: AOF&G, has indicated they would increase their effort on Allison Creek. During AE&D at least one year of intensive an escapement survey will be conducted. 21. That provisions be made in advanced project planning for instream flow analysis of Allison Creek by the FWS to determine optimum flow schedules and the velocity of supplemental flows to Allison Creek. Response: Provisions for flow analysis of Allison Creek will be included in the AE&D phase. Whether an extensive instream flow analysis is required is not known at this time. SOLOMON CREEK bE > @ te c ° ES = FF spe eel a og SOE yt KRY Ysa en) eat SiC ot co e]elecle}clejele CISISISISIS cic c 1S1¢ 5 de ASISISESESL S| FETT S1T1 F191 991 FGETS u 5 iS ‘opie YS HON SINT SLSR ST CIN] OF Cle] ef Cpecpc ny cic is as tfc] caf] cl] cl] cf ef af af cl] af a] a] af af ed] cf el] cf cl] cu] es ii] eo] jaa 7 o£ 6 @ th © o > & MUSINIAT AAT} cholerj inter ented cueuteu evi ea inpeny ent ini spiny wie a ° cw FISISIFIFISIFIFISIFISISISISISISISISISISISISIT “e]elelclala Felon corpen tal es CPU O TUE eta re UL ere) Ce eet ' OF CL eet oO ov z is S a 00 | Ape fe [eApeaien [edits [oer o| | O14} on] Of ea} oO] O] Choc Hyer estoc or ° ° . a Alt feifesfea}esfenfea] efetfca}ed}ed] eafedfesfaafed] ca] ed] en] ea] a & MO oF oa > wv aad tH oy eo u »& Hpopopopapenfeaye| aes [tea st ae cae 2 ow Hlelafalole|clolo|d}eldfdicle|e}d|afele|djafc}c}elafc|alaja 5 Hh PPePepPepepepepepepepepepepepepepepepepe Vv a e FF efoto ys cron per tieruce oo e] ef e} el ef el ef « ae whole |r| pode folini S]eafed] sea} t| t]t | tt] 3] ea] a] ale ANIM TNCMm ODAC HO TFWMWCKHRDADHDCHANNMNTYH SO a or RAHA HAM AHHANANAN NN OCEANS ° 2 Alaska Department of Fish and Game. Source: — 22. That a cooperative study of the proposed Allison Creek Hydropower Project, jointly scoped by the CE and FWS and funded by the CE, be conducted through project construction and operation. Response: The U.S.F.W.S. will be involved in the scoping process for environmental studies during the AE&D. 3. That, if after execution of the recommended additional studies, it is determined that some losses to fisn and wildlife are unavoidable, those losses be offset by implementation of mitigation measures mutually acceptable to the FWS and the CE. Response: The CE is in full accord. CORDOVA-VALDEZ DC TRANSMISSION TIE LINE FEASIBILITY REPORT ALCAT ENGINEERING MAY: .1,. 1982 E. J. HARRINGTON, P. E. A. W. MOODY, P. E. — TABLE OF CONTENTS Samara PAGE NO. 1. INTRODUCTION iL 2. SCOPE OF ANALYSIS 1 3. TRANSMISSION PLANS L 4. CONVERTER SUBSTATION AND CABLE TERMINAL LOCATIONS 3 5. TECHNOLOGY AND COST CONSIDERATIONS 4 A. DC PLAN 4 B. AC PLAN 5 C. MONOPOLAR VERSUS BIPOLAR 6 D. TRANSMISSION LOSS 7 E. CONDUCTOR SIZE SELECTION 7 F. VOLTAGE LEVEL 8 G. GROUND ELECTRODES 8 H. CABLE CONSTRUCTION 9 I. CABLE INSTALLATION AND ROUTING 9 J. AC OVERHEAD LINE 10 K. AC SUBMARINE CABLE 10 L. DC OVERHEAD LINE 10 aw M. COMMUNICATION CHANNELS iL N. SYNCHRONOUS CONDENSERS I 6. OPERATION AND MAINTENANCE 12 A. OPERATION OF DC SYSTEMS EZ B. SYSTEM AVAILABILITY 12 (1) Cable Failure Rate, Repair Time 12 (2) Converter Availability, Repair Time 13 (3) Ancillary Equipment (Synchronous Condensers, etc.) 13 ~ (4) Overhead Line Outage Rate 14 (5) Summary - Outage Rates of Cordova-Valdez Line 14 C. OPERATING COST ITEMS -— OPERATORS 14 D. MAINTENANCE AND REPAIR COSTS a E. SUMMARY OF SYSTEM OPERATION AND MAINTENANCE COSTS 15 7. ENVIRONMENTAL ASPECTS OF DC SYSTEM 16 A. GROUND ELECTRODES 16 B. OVERHEAD LINES 19 8. SUMMARY N oO 10. TABLE OF CONTENTS (Continued) TABLES AND MAPS TABLE TABLE TABLE TABLE WPF FIG.. 1 FIG. 2 FIG. 3 APPENDIX 1 PAGE NO. CORDOVA=VALDEZ DC TIE LINE COST - 12000 Kw 22 CORDOVA-VALDEZ DC TIE LINE COST - 9000 KW 25 CORDOVA-VALDEZ AC TIE LINE COST - 12000 KW 28 CORDOVA-VALDEZ AC TIE LINE COST - 9000 KW 30 MAP OF DC CABLE ROUTE MAP OF CORDOVA TERMINAL AND OVERHEAD LINE ROUTE MAP OF VALDEZ TERMINAL AND OVERHEAD LINE ROUTE SITING SEA ELECTRODES SEA ELECTRODE COSTS SEA ELECTRODE DESIGN SAMPLE CALCULATIONS FIG... 1 FIG. 2 COMPASS ERRORS CAUSED BY DC CABLES SAMPLE CALCULATIONS A-5 A-6 A-8 A-11 A-12 A-13 A-14 PRELIMINARY FEASIBILITY STUDY OF DC TRANSMISSION CABLE FROM CORDOVA TO VALDEZ, ALASKA INTRODUCTION This study was undertaken as part of the "Cordova Power Supply Alternatives Feasibility Analysis" sponsored by the Alaska Power Authority. It includes an investigation of AC and DC submarine cables as a means of interconnecting Cordova and Valdez. Power flow may be in either direction. The amount of power to be transferred is 12000 KW and an estimate of the cost of a 9000 KW system is also included. Although, the majority of the inter- connection is made with underwater cable, there will be short runs of overhead line at each end connecting the converter sta- tions with the point where the cable emerges from the water. Also, an overhead line will be used at each end, running from the converter ground terminal to the shore adjacent to the location of a salt water immersed ground electrode. SCOPE OF ANALYSIS The report describes the component parts of the system and also lists the estimated cost of the various parts, including the labor of installation. Costs are based on 1982 dollars. Fig- ures on the major items, such as cables and converter stations, have been obtained from the manufacturers of such equipment, and the remainder estimated by our engineers. Estimated losses, outage rates, operating costs, maintenance and cable repair costs have also been calculated or estimated by staff members. Route selection was made from chart studies and one helicopter flight over the route. No underwater or land surveys are in- cluded. The optimum voltage level and conductor size were wer investigated in this study but were based on a previous studyl in which a range of values was investigated to determine, approxi- mately, the most economical values. No taps or intermediate substations were considered for the DC system, but the AC system requires one or more intermediate substations for compensating reactors. TRANSMISSION PLANS - ALTERNATING CURRENT VERSUS DIRECT CURRENT Building overhead AC transmission lines in Southern Alaska is costly for the following reasons: A. Lack of roads along transmission routes. l"Snettisham-Ketchikan Transmission System". DOE Contract No. 85-79 AP10008,00 35 (Continued) B. Heavily timbered rights-of-way that have extremely high clearing costs. C. Rugged, mountainous terrain in some areas. D. Many bays and inlets along the shore, requiring long spans or underwater cable crossings, E. Severe wind loading, particularly where lines go over ridges or cross valleys requiring long spans. F. Heavy snow and ice loading in some places, G. Tall trees which require removal or wider rights-of-way to minimize outages caused by falling trees, H. Environmental restrictions, An alternative to overhead lines, especially for terminals lo- cated near the sea shore is to use underwater cable,, AC trans- mission is possible up to about 50 miles over cable, and above this distance intermediate compensating reactors are needed along the way. When long cables are needed to connect two points on a power system, it becomes more economical to convert the power to DC at the source end and back to AC at the load end. This eliminates the problems caused by charging current on AC cables. For the cables considered in this study, the charging current at each end equals the thermal current rating of the cable (230 amps) for a cable 70 miles long, if no compensating reactors are used. The converters for changing AC to DC and DC to Ac in this analysis are identical, so that power flow can take place in either direction. The converters use all solid state devices and have been demonstrated to have a very high degree of reliabili- ty. Converters cost considerably more than the substations normal- ly used at the ends of an AC transmission tie line, but this added cost may be easily offset by the saving in cable. The monovolar DC system proposed for the Cordova-Valdez tie requires only one cable. The return current flows through the earth via the ground electrodes. Since DC is involved, this return current flows deep in the earth and causes no interference with other equipment, as long as the ground electrodes are properly de- signed and located. The saving resulting from using one cable with DC versus three cables for AC usually offsets the added cost of the DC converters for distances in excess of 30 miles. This report includes a cost estimate on both an AC and a DC system. The DC system costs were substantially lower. es 3. (Continued) The AC and DC cable alternatives both have an 11 mile length of overhead line from Jack Bay to the City of Valdez and short sections of overhead line from Cordova to Bluff Point and across Hawkins Island. The total length of overhead line is 18.3 miles. For the purpose of having a complete cost for the cable approach to this transmission problem, an approximate cost for the overhead line has been included. Dryden and LaRue may wish to replace the overhead estimates with more accurate figures. This analysis includes estimates of systems with power carry- ing capability of 12000 KW and 9000 KW. The cost of underwater cable used for this application is not very sensitive to conductor size. Therefore, little difference is shown between the cable costs for a 9000 and 12000 KW system, either AC or DC. Since DC converter cost estimates were based on an installed cost of $159 per KW, there is a modest saving by dropping from the 12000 KW to 9000 KW rating on the DC system, The sub- station transformers are the only items in the AC system which show a significant cost reduction when the size is reduced from 12000 to 9000 KVA. For the above reasons, the cost reduction in going from a 12000 KW to a 9000 KW system is very modest. CONVERTER SUBSTATION AND CABLE TERMINATION LOCATIONS CORDOVA Appendix 1 includes a discussion of several alternate locations for the underwater cable termination and the ground electrode. For this analysis, it was assumed that the DC converter station would be located on the outskirts of Cordova and that an over- head line would be run to Bluff Point, a distance of about 7.3 miles. This DC wood pole line would carry the main power conductor, 336 MCM ACSR, insulated for 70 KV DC to ground. In addition, it would carry a ground wire of the same size insulated for 5 KV DC.to ground. At Bluff Point, both conduc- tors would be changed to armored submarine cable for the Orca Inlet crossing. The cables would be ditched across the inlet to eliminate problems caused by anchors, fishing gear, or shifting mud and sand. On emerging from the water on Hawkins Is- land, both cables would continue with overhead construction to the South end of Canoe Passage, where the ground conductor would terminate at a sea electrode submerged in Canoe Passage. The 70 KV conductor would continue in a Northwesterly direction along Canoe Passage for at least one mile before entering the sea and heading toward Valdez. This arrangement keeps the ground electrode away from other known submarine cables or man-made metallic structures which might suffer from ground currents. ae 4. (Continued) VALDEZ Appendix 1 includes a discussion of alternative locations. For this analysis, it was assumed that the converter location would be near where Solomon Creek enters Port Valdez (bay). From here a DC wood pole line would carry the main power conductor, 336 MCM ACSR, insulated for 70 KV DC to ground. In addition, it would carry a ground wire of the same size insulated for 5 KV to ground. At a bay located midway between Sawmill Spit and Anderson Bay, the ground wire would be terminated at a sea electrode located in this bay. From here the wood pole line carry- ing only the power conductor would continue southwesterly over a mountain pass to an inlet on the north side of Jack Bay. This arrangement insures good isolation of the ground electrode from the power cable ground sheath or any other known metallic structures which might suffer from ground currents. A substantial saving in transmission line cost could be effected by having the main power cable enter the sea at Anderson Bay, thus saving the mountain crossing. The Anderson Bay location, however, may be dangerous because of the precipitous nature of the shore where the cable must go to reach deep water. It is possible that further investigation may reveal this to be a more economical location than the Jack Bay location used in this analy- sis. A. C. SYSTEM For the purpose of appraising an AC cable transmission tie, it was assumed that a 3 conductor 187 MCM, 70 KV (line to line) armored cable followed the same path as the DC cable. The over- head line portion of the 3 phase AC circuit would follow the same route as the DC overhead power cable. A compensating reactor would have to be located about midway between the Canoe Passage and Jack Bay cable termination. This would in- volve a cable landing and a substation near Goose Island off Knowles Head. TECHNOLOGY AND COST CONSIDERATIONS A. DC PLAN The DC plan requires a converter at each end of the line to convert power from DC to 60 HZ AC. These converters are planned to be identical and they allow power to be trans- ferred in either direction. A DC system requires a syn- chronous machine at the receiving end of the line. Since it is possible that Cordova might wish to shut down its. synchronous generators and obtain all of its power from Valdez on some occasions, a synchronous condenser has been included in the =h= A. (Continued) plans to permit such operation. The synchronous condenser consumes no power except for its losses. A new machine was included in the estimate, but a great many synchronous con- densers are available on the surplus market, and it is almost certain that one could be purchased for a fraction of the new machine cost. The converters used in this estimate are solid state devices. They have 15% redundancy in the SCR circuitry, so that several SCR's could fail simultaneously and still not require shut- ting the converter down. The manufacturer who supplied the prices advised that he is willing to guarantee an availabili- ty of 98% for each converter and that the forced outage rate is 1.4% per converter. DC transmission systems have the advantage that they can be set to transfer a fixed amount of power between two AC systems, regardless of load or frequency variations. on the AC systems. Controls can also be provided to vary the amount of power transferred between two systems, so as to hold constant frequency on the receiving system, if desired. The estimated cost of the DC system is shown in the cost summaries of Tables 1 and 2. AC PLAN An AC transmission tie line from Cordova to Valdez via sub- marine cable was also estimated. A minimum cost system was selected to see if there was any chance that it could compete in capital cost with DC for so long a cable tie. The volt- age selected was 70 KV (line to line). A 187 MCM, 3 con- ductor armored cable was used for the underwater portion and 4/0 ACSR for the overhead portion. The transmission losses are approximately 20%. The voltage drop at full load is 15% which would be tolerable if step voltage regulators were properly applied. The estimated cost of a 12000 KW AC tie, including both underwater and overhead portions, terminal substation and compensating reactors is $46,394,000. This is $16.6 million more than the DC system. In addition, the full load losses are more than double and the voltage drop more than triple that of the DC system proposed. It is also significant that the outage probability is greater with either 3 conductor cable or 3 single phase cable used for the AC system. In view of the great superiority of the DC system, it is recommended that the AC cable system be dropped from further consideration. K.! Sis (Continued) c. MONOPOLAR VERSUS BIPOLAR Most of the DC transmission systems that have been installed worldwide are of the bipolar type. This means that there are two converters at each terminal, connected in series, with the midpoint grounded. Two cables are required be- tween terminals, and the current in normal operation, flows down one cable and back the other. If one cable or one converter fails, the bipolar system can still operate at half capacity by shutting one-half down and letting the return current flow through the earth. There are also a few systems installed which work only in the monopolar mode. These systems have one converter at each end and one interconnecting cable. The earth carries the return current continuously rather than during emer- gencies only. Monopolar systems require a good ground such as the sea provides. Also, it is desirable to have the sea electrode located a mile or more from armored cables or pipelines, Both of these ground electrode requirements can be met by the seaport cities in Southern Alaska, without having to run long lines to the electrodes. A monopolar system can always be converted to bipolar operation later, but this requires adding a new cable and converters at each end, It is an economical way of delaying part of the investment, if future expansion is planned, since adding the second pole and cable doubles the transmission capacity. The fact that only one cable is required for a monopolar system makes it more attractive for installations some distance apart, since the cable is often the most expen- sive item in the package. The monopolar system requires somewhat more elaborate ground electrodes, but this is only a minor part of the system cost. It is recognized that a monopolar system has a greater probability of a total transmission outage than a bipolar, which can operate at half capacity for either a cable or converter failure. On the other hand, it is probable that Cordova would not wish to place total dependence for power on a transmission tie, anyway. To avoid being totally shut down, the city will probably wish to maintain 100% back-up capacity in Cordova. If this is so, then a large expendi- ture for a small gain in transmission tie availability is hard to justify and the monopolar system would be the economic choice. The Isle of Gotland, off the coast of Sweden has been successfully served by such a monopolar sys- tem since 1954. Y 5. (Cantinued) Dd. TRANSMISSION LOSS A loss optimization calculation is beyond the scope of this study, but previous work has indicated that the high value of power in the Cordova area dictates the use of oversize trans- mission conductors for maximum system economy. With this in mind, 300 MCM copper cable was used in the DC analysis even though the current is only 171 amperes. Prices were obtained from a cable manufacturer on 70 KV DC., copper con- ductor, paper insulated, lead covered, armored cable, F. O. B. Seattle, as follows: 300 MCM $ 97,750/mile 500 MCm 104,150/mile As can be seen, the sensitivity to conductor size is not as great as one might suppose, The total resistance of the 72.2 mile cable and the 18.3 miles of 336 MCM ACSR overhead DC line is 18.5 ohms and the loss is 4.5% for a 12000 KW load. Adding the converter loss at each end brings the total line loss to 7.0%. At 48% load factor, the loss factor would be about 0.30. The 10000 KVA synchronous condenser operating at 48% load factor would add about 53 KW average loss. Estimated Losses at 48% Load Factor for Cordova-Valdez Line DC System Power Rating 9000 KW 12000 KW Cable size, MCM 225 300 Converter loss in KW (both ends) 146 195 Cable loss in KW (at 48% load factor, .30 loss factor) 122 163 Synchronous condenser loss 40 52 Total estimated loss in KW 308 411 7 Percent total loss at 48% load factor 3.4% 3.4% CONDUCTOR SIZE SELECTION A comprenehsive loss optimization study requires that the effects of changing the system operating voltage and the effect of changing conductor size be analyzed simultaneous- ly, which is beyond the scope of this analysis. The 300 MCM fi = 5. E. (Continued) cable size was selected as being adequately large to keep the losses low, but may be larger than required for opti- mum economy. The value of power in southern Alaska is high enough to warrant careful analysis of losses in a transmission sys- tem. Previous work done on this subject! indicated that a conductor rated at two or more times the rated system current could be justified. F. VOLTAGE LEVEL The price of AC to DC converters is not terribly sensi- tive to the operating voltage level of the line. From 40 to 70 KV, one manufacturer advised the price per KW of capacity would only increase about 5% per KW. Cable prices drop very slightly if the voltage rating is increased and the current rating (conductor size) is decreased pro- portionally for the cables considered on this project. Thus, both major components of a DC transmission system vary only slightly for a modest change in voltage. Based on experience with other studies, 70 KV is believed to be close to the optimum voltage for a 12000 KW DC cable system. G. GROUND ELECTRODES In order to minimize the tendency for current from the sea electrodes to travel in the power cable armor, the plans call for locating the sea electrodes at least one mile from the power cable or any other armored cable. The details for an electrode suitable for a 30-year life carrying 175 amps DC at 48% load factor are shown in Appendix 1. Only the anode electrode is consumed, but in order to provide for in- stantaneous reversal of power flow, an anode has been in- cluded in the plans for each end of the line. Thus, power flow can occur in either direction without the need for polarity reversing switches, It is desirable that the ground electrode be located where the sea water salinity is not decreased by fresh water dilution. It should also not be exposed by the tide. It should be in deep water or a protected area, where anchors or trawl boards will not disturb it. It is proposed to support the individual electrodes in a concrete box that prevents fish from getting too close. (See Appendix 1 for more information. ) lsee "Snettisham-Ketchikan Transmission System", a report prepared for U. S, Department of Energy, Alaska Power Administration, Contract No. 85-79 AP 10008.00 -8- 5. (Continued) H. CABLE CONSTRUCTION The DC cables proposed in this report are insulated with oil impregnated paper, encased in a lead sheath. A 300 MCM copper conductor is proposed. A polyethelene cover will go over the lead sheath and underneath the galvanized iron armor wires. It may be desirable to specify that the individual armor wires be polyethelene covered, so that cathodic protection could be added, if necessary. The current rating of this cable is over 450 amps. I. CABLE INSTALLATION AND ROUTING It is proposed that the cable be manufactured in one con- tinuous length for each run, 66 miles for the longer run and 6.6 miles for the one across Orca Inlet. These could both be shipped on one special cable laying ship or barge directly to the Cordova area, even if foreign manufacturers are involved, Information on cable installation was furnished by the firm, "Jacobson of Seattle", which has laid a large num- ber of cables, including the 138 KV ones across Taku in- as let near Juneau. <p It is proposed to bury the line ends out to a depth of 50 feet or greater, if there is heavy ship traffic in the area. Burial would be to a depth of four feet in the earth. It is also proposed to Bury the cables crossing Orca Inlet for their entire length. In selecting the route for the 66 mile cable run from Hawkins Island to Jack Bay, the following criteria should be considered. 1. The shore ends of the cable must be protected so that damage will not result from storms, wave action, ice, tidal currents, ship traffic, etc. 2. The cable must not pass over sharp projections or ledges sufficient to damage it, either immediately or long term. 3. The cable should not traverse slopes greater than 450F, If this is unavoidable, it should be securely anchored at intervals. 4, Cable must not be subject to strong water currents (tidal or other). If such are unavoidable, . s. (Continued) suitable protection must be provided, such as bury- ing, anchoring, covering with cement bags, etc. 5. The cable location should avoid areas where ship anchors, beam trawls, etc,, are likely to cause damage. Ship lanes should be avoided unless the depth is adequate to avoid these problems. 6. Areas where electrical gradients exist should be avoided. If this is not possible, cathodic pro- tection should be provided. AC OVERHEAD LINE Short sections of AC overhead lines are included at the cable ends. No detailed work on the 70 KV wood pole line design was done. Costs were estimated on the basis of similar lines through similar terrain. Dryden and LaRue may elect to modify these costs, since they have the responsibility for options involving AC overhead lines. AC SUBMARINE CABLE The AC cable considered for this option had an aluminum conductor, 187.5 MCM cross-section with a current rating of 230 amps. Full load current at 12000 KW and .95 P. F. is 104 amps. The insulation is oil impregnated paper. Outside of the insulation is an insulation screen, a 1 mm lead sheath, armor bedding, 42-5.6 mm armor wires, and a polypropylene yarn and asphalt outer covering. It has an impedance of .563 + J.241 ohms per mile and a capacitance to ground of .43 mfd. per mile. No attempt was made to optimize the conductor size for this option. The AC cost estimate was much higher than the DC alternative. Assuming full load at 95% power factor and compensating reactors at the middle and the two ends, the loss on the AC tie is about 20%. DC OVERHEAD LINE Two types of DC overhead construction are proposed for the short sections of overhead lines needed at the extremi- ties of the DC system. It is assumed that the isokeraunic level in this area does not make an overhead ground wire necessary for lightning protection. Therefore, in situations where the ground return circuit has already entered the sea, only one conductor is needed for the DC overhead lines, -10- 5. L. (Continued) It would probably be most economical to use a single post type insulator on top of the pole. In situations where the ground wire must be included to carry current to a ground electrode, the overhead DC transmission line must carry two wires. Post type insulators could be used with a 5 KV insulator on top carrying the ground wire and a 70 KV DC post type insulator mounted horizontally for the power con- ductor. Line insulation behaves differently under DC stress than AC. Voltage distribution over the line insulator is deter- mined primarily by the capacitance in the AC case and by leakage in the DC case. Special, long creep insulators have been developed for DC that reduce the tendency for contamination flashovers and work is still proceeding in this area2. The cost of DC overhead lines is significantly less than AC and the amount is dependent, in part, on whether one conductor or two is required for the DC line. The cost estimates reflect this saving, COMMUNICATION CHANNELS A DC transmission system is designed to be self-regulating at a preset current level. Thus, if there is a breakdown in communication between the rectifying station and the in- verting station, the system will continue to transmit the same amount of power, Nevertheless, communication is nec- essary whenever the receiving power system desires to change the amount of power it is receiving, Also, communi- cation is. extremely important during emergencies and faults. For purposes of this report, it is assumed that two reliable voice grade channels will be required for communication be- tween the terminal stations. One of these would be used for voice and the other for multiple tones. For this study it has been assumed that voice grade tele- Phone channels can be leased for $10.00 per airline mile per month. The airline distance between Cordova and Valdez is approximately 45 miles and the estimated charge for two voice grade channels would then be $900 per month or $10,800 per year. SYNCHRONOUS CONDENSERS As mentioned previously under 5A, a synchronous condenser or synchronous generators must be on line at the receiving end of a DC transmission system to insure proper commuta- tion. Since Cordova may, at times, wish to shut down all of its generators, a synchronous condenser has been included 2"Contamination of DC Insulators", EPRI Report EL-2016 -ll- 5. N. (Continued) in the plans. It could be an indoor or outdoor machine, but for a unit in Alaska, an indoor unit is recommended. If hydro generators are later installed on the Cordova sys- tem, it is probable that the synchronous condenser can be shut down or retired, If no local generators are running, the synchronous con- denser provided must have a rating that will produce a short circuit KVA equal to three times the converter terminal KW rating based on its transient reactance, For the 9 MW system a 7500 KVA synchronous condenser is pro- posed and for the 12000 KW system a 10000 KVA condenser. 6. OPERATION AND MAINTENANCE A. OPERATION OF DC SYSTEMS The normal mode of operation for a two terminal DC line is constant current. This results in constant power if the DC voltages remain constant. If the system AC voltages vary at the converters, the DC power transmitted will vary. AC voltages at the converter terminals should be regulated. Automatic frequency control of the receiving system may be accomplished by controlling the power transmitted over the line with signals from a time standard. SYSTEM AVAILABILITY (1) Cable Failure Rate, Repair Time The 1980 Cigre Report on HV DC systems, 14-08 stated that for all DC cable systems, the cable outage rate for the four-year sampling period was one outage per 100 KM/year. This corresponds to 1.6 per 100 miles/year. The Cigre report also indicates that almost none of the outages were caused by electrical failures of the cables, and those that were reported were at splices. (No cable splices are planned for the proposed Cordova-Valdez DC cable.) The mechanical failures were almost all caused by trawl boards or anchors and were effectively eliminated by burying the cables in shallow waters. It is also noted that on the two most recent installations, installed since these pro- tective procedures were developed, only one cable fail- ure has been reported for both installations, These two are across the Skagerrak, the Strait of Georgia, Vancouver to Vancouver Island, Their outage rate works out to be .24 outages per 100: miles/year, -12- B. (1) (2) (3) (Continued) It should he noted that on the long cable from Hawkins Island to Jack Bay, 92% of the lay will be ata depth over 50 fathoms (300 feet), which virtually elimin- ates trawl board or anchorage problems, The line ends of this run would be ditched out to about a 50 foot depth and the cable across Orca Inlet would be ditched for its entire length. With proper installation tech- niques, it should be possible to reduce the incidence of cable failure well below the .24 outages per 100 miles/year figure reported above. Based on an outage rate of .24 per 100 miles/year, we could expect to have ,174 outages per year on the 72.6 miles of cable between Cordova and Valdez. Advice from Jacobson of Seattle, marine cable laying and repair experts, indicates that for less than one outage per year, it is more economical to hire the nec- essary equipment for repair rather than purchasing it. The price for hiring the necessary men and equipment is estimated at $15,000 per day or $450,000 per month. The estimated time to recover, repair and replace a damaged cable section in average weather is 1 month. If we add 20% for contingencies, we arrive at an esti- mated cost for repair operations of $540,000 per month of repair time. Multiplying by the annual failure rate, we get annual cable maintenance costs and outage times as follows: -174 repairs/year X $540,000 = $94,000/year -174 X 30 days = 5.22 days (125 hours) /year The estimated scheduled outage time for inspection and maintenance is 16 hours per year. Converter Availability, Repair Time The estimated converter availability is 98%, but this includes .6% for scheduled maintenance. The remaining 1.4% is forced outage time and comes to 2.8% for both terminals. This is equal to 245 hours or about 10 days/ year. Scheduled outages are 105 hours per year. Ancillary Equipment (Synchronous Condenser, Ground Electrodes, etc.) There is very little data available on outage rates for these types of equipment, and it is proposed to use a figure of one-half of one converter's outages-to cover -13- ~ 6. B. (3) (Continued) all of it. This results in 0.7% or 61 hours (2,5 days) per year. For scheduled maintenance, three days or 72 hours/year has been assumed. (4) Overhead Line Outage Rate For the 18,3 miles of overhead DC line, it is assumed that the forced outage rate is ,06 ver mile/year, or one-third the rate being experienced on the Snettisham- Juneau 138 KV line on which good records are avail- able. This results in a forced outage time as follows; .06 X 18.3 X¥ 12,5 hours/outage = 14 hours/year The scheduled outage time for the overhead line portion is estimated at 10 hours per year, (5) Summary = Outage Rates of Cordova-Valdez Line Forced outages; 7 Hrs/Year eo £ Time Cable 125 1.4 = Converters (both ends) 245 2.8 Ancillary equipment 61 of Overhead line 14 sie Total 445 Fel Scheduled outages; Hrs/Year % of Time Cable 16 oa Converters (both ends) 105 1é2 Ancillary equipment 72 «8 Overhead line 10 el Total 203 2.3 C. OPERATING COST ITEMS, OPERATORS J It is assumed that an operator will be on duty at the Solomon's Gulch Hydro Plant, and if so, no additional opera- tor would be required for a DC converter added at that loca- tion. There is no need of an operator on continuous duty at the Cordova converter. The system operator could advise the 3 -14- c. (Continued) operator at Solomon*s Gulch of any changes in power orders if they were on a fixed schedule. If frequency control of the Cordova system is to be accomplished with the DC tie line, the amount of DC power transmitted must be under auto- matic control of the time-frequency control system. MAINTENANCE AND REPAIR COSTS It is estimated that one maintenance man, trained in the servicing of DC converter stations, would be needed at each terminal. There would not be enough work to keep one man busy eight hours per day, but the need for prompt maintenance would probably justify having one man located at each station. He could handle other duties for the utility, as well. Assuming the cost per man at $96,000 per year, including overhead, the charge for maintenance labor would be $192,000 per year. It is estimated that each converter station would require $5,000 per year in specialized maintenance labor and the $20,000 per year in repair parts for a total of $50,000 per year for the two stations, The estimated maintenance cost from part 6B (1) is $94,000 per year for the submarine cable. The maintenance of ancillary substation equipment is esti- mated at $10,000 per year per station and for the 18,3 miles of overhead line, $15,000 per year. SUMMARY OF SYSTEM OPERATION AND MAINTENANCE: COSTS Cost per Year 1.: Additional maintenance manpower at converter stations $192,000 2. Converter station, specialized main- tenance and parts (for both converters) 50,000 3. Cable maintenance 94,000 4. Ancillary equipment (two stations) 20,000 5. Overhead line 15,000 Total $371,000 Contingencies at 20% 74,000 Grand Total $445,000 -15- 7. ENVIRONMENTAL ASPECTS OF DC SYSTEM A. GROUND ELECTRODES Several possible locations for ground electrodes were selected by aerial survey or from maps of Cordova and Valdez. Only seawater locations were considered because the expense is reduced and the performance improved com- pared to ones located in the earth, Known environmental effects are listed below, (1) (2) (1) In sea water, chlorine gas is released at the anode surface, (2) Electrical voltage gradient can affect sea life - principally fish. (3) Buried or submerged metallic structures may form part of the earth return current path, resulting in corrosion or loss of metal at locations where the current leaves the structures, (4) Magnetic compass deviation may occur. Chlorine Release. Where a sea electrode is designed with electrode area great enough to produce the low resistance desired, and a voltage gradient low enough that the effect on marine life is acceptable, the chlorine release will be diluted in such a large volume of water that effects will be negligible. Effects on Marine Life, Considerable research has been done on the electrical gradient effect upon fish, and maximum gradient criteria have been established by several agencies and researchers throughout the world. These criteria can be met by incorporating sufficient surface area in the electrode to hold the gradient to less than the established maximum. The British Columbia Department of Fisheries, for example, requires that the voltage gradient be limited to 1.65 volts. per meter in areas accessible to large fish, The design proposed in Appendix 1 limits the gradient to .6 volts per meter outside of the concrete shield. The concrete shield would prevent fish from getting close to the electrode surface. Therefore, no bad effects on fish are anticipated with the electrode design proposed. -16- _ 7. <A. (Continued) Y (3) Galvanic Corrosion, This phenomena is not directly related to the electrode but to the use of the earth as a current path. The electrode comes into the pic- ture because it is only in the vicinity of the electrode that the voltage gradient becomes great enough to create a problem. Any metallic structure in contact with the earth or sea will be subject to the passage of electric currents. These currents may enter and leave the structure at few or many locations, Mainly, these currents arise from three sources. One is due to galvanic cells set up by electro-chemical action between the struc- ture and other material which is higher or lower in the electromotive series. A second source is earth currents that are present due to natural causes (sun- spot activity) which may enter and leave the structure if it parallels their path, The third source is man- made currents that may be created by installations such as the DC system under discussion. Currents entering and leaving a metallic structure create problems because metal is removed at the points where the current leaves the structure. This action can be prevented by making sure that any current enter- <=y ing the structure leaves it by way of a metallic path connecting it to an anode some distance away through which the current returns to earth or sea. This anode material is sacrificed in lieu of the protected struc- ture. Current flow in the proper direction is established by choosing an anode material higher in the electromotive series than the metallic structure, or by interposing a DC current source of correct polarity and of sufficient voltage to overcome any gradients that would tend to cause current to leave the structure at locations other than the established metallic path. Such an approach is termed a cathodic protection system. It is termed a passive system if current flow is established by using an anode material higher in the electromotive series and an active system if the desired current flow is set up by a separate DC source. Metallic structures in contact with earth over a wide area such as buried pipe lines may have very low resistance to earth. To protect such structures over their entire length would require numerous anodes and current sources and involve the circulation of a large amount of current. To overcome this problem, the pipe line or structure can 4 be coated with a low cost insulating material. If this 9 ee 7. A. (3) (Continued) material were to be installed and maintained perfect- ly, no cathodic protection would be necessary. Inas-— much as this would be both difficult and costly, cathodic protection is applied to prevent the departure of current at any locations where the insulation is flawed. This holds the number of cathodic protection sources and the current flows to reasonable values. Large marine installations where insulation is im- practical, such as sheet piling, etc,, may require the circulation of thousands of amperes to insure protection, From the above, it may be concluded that it is of prime importance that the terminal sea electrodes be located in an area sufficiently remote from buried metallic structures. For a land electrode, this separation may amount to several miles. In the case of a sea electrode, if the salinity of the water is high, a separation of approximately one mile usually brings the gradient to the point where the current contribution from the trans- mission system will be minor. If sufficient separation cannot be achieved, any accel- eration of corrosion of the structure can usually be avoided by increasing the existing cathodic protection or adding such protection, if non-existent. One metallic structure that will frequently be in the vicinity of the converter station is the armared AC submarine cable, For this reason, it may become nec- essary to locate the sea electrode some distance from the converter station. If such separation conflicts with other structures, it may be necessary to decrease the electrode separation and add cathodic protection to the cable armor. For this to be practical, insulated armor wires may be required and this will add to the cost of the cable, Costs used in this study were based on cables armored with bare galvanized wire, The jute-asphalt covering over this armor is not of a quality to constitute in- sulation of the armor. If these cables are to be "fished" and repaired in case of fault after laying, it is essential that the armor remain intact over the life of the cable. Final design of the cable should include an indepth study of the factors affect- ing life of the armor in the Alaskan environment, effect of ground electrode and possible savings by lo- cating it closer to the terminal, etc. Results of such study may make it prudent to insulate the armor and incorporate cathodic protection on some or all of the cable installations, Care should be exercised to choose an insulation method that is amenable to laying without high risk of damage, -18- A. (3) (Continued) The scope of this study covers only a somewhat cursory exploration of electrode sites with little search for the presence of structures susceptible to damage by ground current; therefore, it can only be stated that the sites mentioned have a reasonable chance of being acceptable. (4) Compass Deviation. A monopolar DC system using sub- Marine cable has an uncancelled magnetic field sur- rounding the cable. If this field is misaligned with earth's magnetic field, it can produce an error of deviation of any magnetic compass in the vicinity. The magnitude of the error is contingent upon a num- ber of factors, all of which are known. This allows the deviation to be calculated, The appendix contains material illustrating how these calculations can be made and typical curves plotted from computed data. These curves illustrate two facts: (1) The compass deviation can be relatively large where the cable lies in shallow water, but becomes small for areas 100 feet or more from cable centerline. (2) Compass deviation becomes relatively in- significant for all areas where cable depth is 250 feet or greater. Inasmuch as all but a very small portion of the cable can be laid at depths greater than 250 feet, no serious problem due to compass deviation is anticipated, OVERHEAD LINES The environmental impact of a DC overhead line is, in all respects, less than a comparable AC line. A single con- ductor monopolar line probably achieves the irreducible minimum as far as overhead line impact is concerned. Such a line can be located so as to avoid eagle nesting places and involve minimum right-of-way clearing and danger-tree removal. Poles would be minimum height and would blend with the background, Use of a single conductor and the absence of crossarms appreciably reduces visual impact. At the voltage contemplated, audible noise is essentially non-existent, television interference should impose no problems, and, even though some radio interference may be present during foul weather conditions, this effect will -19— =~ elie (Continued) exist only in close proximity to the line. Furthermore, radio interference created by DC voltages is tolerable to a much greater extent than that produced by AC voltages. In addition, if reliability factors dictate the use of the oversize conductor as contemplated in this study, radio noise during foul weather will be considerably less than the more common construction where, conductor selection is based more on economic factors, It is worth repeating: A single conductor, monopolar, over- head DC line, if properly designed and located, probably achieves the minimum environmental impact possible for overhead line construction. 8. SUMMARY: A. cost The use of DC instead of AC makes long submarine cable interconnection more economically attractive. In this report, AC and DC cable systems are compared for a 90.9 mile interconnection over the same route with costs as follows (Data from Tables 1 through 4): Cost in Millions of $ 9000 KW 12000 Kw AC 45.4 46.4 pc 28.1 29.8 ENVIRONMENTAL In an area known for its natural beauty, a submarine cable causes less degradation of the scenery than overhead trans- mission line. No attempt has been made to place a dollar value on this feature. (See Section 7). : ; FORCED OUTAGE RATE The predicted forced outage rate for the proposed DC cables (including the 18.3 miles of overhead lines) is 139 hours per year. (See Section 6B). By comparison, a 68 mile 138 KV overhead line would have an estimated outage rate of .178/mile/year and an average repair time of 12.5 hours3. This results in a forced outage time of 151 hours per year. Statistically, the estimated outage time of the submarine 3Data from Alaska Power Administration for 138 KV line from Snettisham to Juneau, February 2, 1977, through March 3, 1979. =20=— 8. c. (Continued) cable tie line appears to be about the same as a 63 mile overhead line in the rugged terrain of Southern Alaska. OPERATION AND MAINTENANCE The estimated operating and maintenance cost for either the 9000 KW or 12000 KW DC system is $445,000 per year (from Section 6E). COMMUNICATION CHANNELS The charges for communication channels needed for operation of the DC system are estimated at $10,800 per year for the 9000 or 12000 KW size. REPLACEMENT POWER No attempt was made to calculate the cost of replacement power since power costs in this area are not known, The estimated forced outage time for the DC system is 445 hours and the scheduled outage time 203 hours for either the 9000 or 12000 KW DC system. It should be noted that the cost per KW of DC systems goes down rapidly with size in the 10 to 20 MW capacity range. A report on a similar system in Southeast Alaska showed that its capacity could be doubled for a 30% increase in cost, -21- TABLE 1 CORDOVA-VALDEZ DC TIE LINE 12000 KW SYSTEM COST Cost in 1,000's Cost in 1,000's 72.6 mi. of 70 KV, 300 MCM, armored cable at $97,750/mi, delivered in Seattle, includ- ing duty charges. Engineering and administration at 10% Laying 66 mi. cable run from Canoe Passage to Jack Bay at $52,800/mi. Engineering and administration at 20% Laying and ditching 6.6 mi, cable run across Orca Inlet, (Includes ground cable). Engineering and administration at 20% Cost of 4 cable terminations, including ditching at Canoe Passage and Jack Bay terminals, (Orca ditching included in Item 3 above). Engineering and administration at 20% Total installed cable cost 7 mi. of 2 conductor overhead line, Solomon Gulch to ground electrode. 6.2 mi. of 2 con- ductor OH line, Cordova to ground electrode. Total 13.2 mi. 2 conductor OH line at $150,000/mi. Engineering and administration at 20% 4 mi. 1 conductor, OH line from Valdez ground electrode to Jack Bay and 1 mi. 1 conductor, OH line from Canoe Passage ground electrode to Canoe Passage cable entry. Total 5 mi. 1 con- ductor OH line at $125,000 mi, Engineering and administration at 20% -22- $7,097 710 3,480 696 1,740 348 600 120 1,980 396 625 125 $14,791 Cy TABLE 1 (Continued) CORDOVA-VALDEZ DC TIE LINE 12000 KW SYSTEM COST Cost in 1,000's Cost in 1,000's 8. Total cost of OH line $ 3,126 9. Valdez converter cost at $159/KW installed* $1,908 Engineering and administration at 10% 191 10. Sea electrode 105 Engineering and administration at 20% — 2 11. AC substation including 13.8 KV breaker, bus and dis- connects, installed 150 Engineering and administration at 20% 30 12. Site preparation at Solomon Gulch . 500 Engineering and administration at 20% 100 13. Total for Valdez terminal * $3,005 14. Cordova converter cost at $159/KW installed* 1,908 Engineering and administration at 10% LSt. 15. Sea electrode 105 Engineering and administration at 20% ‘ 2a 16. AC substation including 34.5 KV breaker, bus and disconnects, installed 200 Engineering and administration at 20% 40 17. Site preparation at Cordova 500 Engineering and administration at.20% 100 *Installed turnkey estimating price supplied by manufacturer, =23= ~ ; TABLE 1 (Continued) K CORDOVA-VALDEZ DC TIE LINE 12000 KW SYSTEM COST Cost in 1,000's Cost in 1,000's 18. 10,000 KVA synchronous con- denser, with circuit break- er, regulator, and start- ing motor, installed $ 700 Engineering and administration at 20% 140 19. Total for Cordova terminal $3,905 So 20.. - Total $24,827 Contingencies at 20% ~\ 4,965 Project cost > $29,792 -24- TABLE 2 CORDOVA-VALDEZ DC TIE LINE 9000 KW SYSTEM COST Cost in 1,000's 72.6 mi. of 70 KV, 225 MCM, armored cable at $95,000/mi. delivered in Seattle, in- cluding duty charges $6,897 Engineering and administration at 10% 690 Laying 66 mi. cable run from Canoe Passage to Jack Bay at $52,800 35.485 Engineering and administration at 20% 696 Laying and ditching 6.6 mi. cable run across Orca Inlet. (Includes ground cable). 1,740 Engineering and administration at 20% 348 Cost of 4 cable terminations, including ditching at Canoe Passage and Jack Bay terminals. (Orca ditching included in Item 3 above). 600 Engineering and administration at 20% 120 Total installed cable cost 7 mi. of 2 conductor overhead line, Solomon Gulch to ground electrode. 6.2 mi. of 2 con- ductor OH line, Cordova to ground electrode. Total 13.2 mi. 2 conductor OH line at $150,000 mi. 1,980 Engineering and administration at 20% 396 4 mi. 1 conductor, OH line from Valdez ground electrode to Jack Bay and 1 mi. 1 conductor, OH line from Canoe Passage ground electrode to Canoe Passage cable entry. Total 5 mi. 1 con- ductor OH line at $125,000 mi. 625 Engineering and administration at 20% £25) =25— $14,576 ¢ 10. il. r2, i. 14. L5i 16. 17. TABLE 2 (Continued) CORDOVA-VALDEZ DC TIE LINE 9000 KW SYSTEM COST Total cost of OH line Valdez converter cost at $159/KW installed* Engineering and administration at 10% Sea electrode Engineering and administration at 20% "| AC substation including 13.8 KV breaker, bus and dis- connects, installed Engineering and administration at 20% Site preparation at Solomon Creek Engineering and administration at 20% Total for Valdez terminal Cordova converter cost at $159/KW installed* Engineering and administration at 103% Sea electrode ; Engineering and administration at 20% AC substation including 34.5 KV breaker, bus and disconnects, installed Engineering and administration at 20% Site preparation at Cordova Engineering and administration at 20% Cost in 1,000's $1,431 143 100 20 150 30 500 100 1,431 143 100 20 200 40 500 100 Cost in 1,000's $3,126 $2,474 *Installed turnkey estimating price supplied by manufacturer. -26- ~ TABLE 2 (COntinued) v CORDOVA-VALDEZ DC TIE LINE 9000 KW SYSTEM COST Cost in 1,000's Cost in 1,000's 18. 7,500 KVA synchronous con- denser, with circuit break- er, regulator, and start- ing motor, installed $ 560 Engineering and administration at 20% ri2 19. Total for Cordova terminal $ 33207 20. Total $23,383 Contingencies at 20% 4,677 Project cost $28,060 -27- TABLE 3 CORDOVA-VALDEZ AC CABLE TIE LINE 12000 KW SYSTEM COST Cost in 1,000's Cost in 1,000's 1. 72.6 mi. of 3 conductor 187 MCM, 70 KV armored cable at $273,000/ mi. $19,820 Engineering and administration at 10% 1,982 2. Laying of cable run from Canoe Passage to Jack Bay - 66 miles at $68,000/mi, 4,490 Engineering and administration at 20% 17 898 3. Laying and ditching cable across Orca Inlet - 6.6 miles 1,740 Engineering and administration at 20% 348 4. Cost of 6 cable terminations including ditching at Canoe <y Passage and Jack Bay. (Orca . ditching included in Item 3 above) . 1,160 Engineering and administration at 20% , 232 5. Total installed cost of cable $30,670 ee 6. 2-15000 KVA and 1-30000:KyA shunt reactors at $25/KVA, installed. 1,500 Engineering and administration at .20% 300 7. Site preparation of compensating reactor station on Goose Island 500 Engineering and administration at 20% 100 8. 2-13.3 MVA-70 KV substations, including power transformer, HV and LV breaker at 500,000 each, installed 1,000 Engineering and administration at 20% 200 9. Total installed cost of sub- stations $_3,600 -28- TABLE 3 (Continued) CORDOVA-VALDEZ AC CABLE TIE LINE 12000 KW SYSTEM COST Cost in 1,000's Cost in 1,000's 10. 18.3 mi. of 70 KV, 3 phase, overhead transmission line at $200,000/mi. $ 3,660 Engineering and administration at 20% 732 1l. Total cost of overhead lines $ 4,392 SS 12. Total $38,662 Contingencies at 20% Tae Project cost $46,394 -29— TABLE 4 CORDOVA-VALDEZ AC CABLE TIE LINE 9000 KW SYSTEM COST 72.6 mi. of 3 conductor i187 MCM, 70 KV armored cable at $265,000/ mi. Engineering and administration at 10% Laying of cable run from Canoe Passage to Jack Bay - 66 miles at $68,000/mi. Engineering and administration at 20% Laying and ditching cable across Orca Inlet - 6.6 miles Engineering and administration at 20% Cost of 6 cable terminations including ditching at Canoe Passage and Jack Bay. (Orca ditching included in Item 3 above). Engineering and administration at. 20% Total installed cost of cable 2-15000 KVA and 1-30000 KVA shunt reactors at $25/KVA, installed Engineering and admistration at 20% Site preparation of compensating reactor station on Goose Island Engineering and administration at 20% 2-10 MVA-70 KV substations, including power transformer, HV and LV breaker at 425,000 each, installed Engineering and administration at 20% Total installed cost of sub- stations -30- Cost in 1,000's $19,239 1,924 4,490 898 1,740 348 1,160 232 1,500 300 500 100 850 170 $30,031 “$ 3,420 10. a1. rz. TABLE 4 CORDOVA-VALDEZ AC CABLE TIE LINE 9000 KW SYSTEM COST Cost in 1,000's Cost in 1,000's 18.3 mi. of 70 KV, 3 phase, overhead transmission line at $200,000/mi. $ 3,660 Engineering and administration at 20% 732 Total cost of overhead lines $ 4,392 Total $37,843 Contingencies at 20% 7,569 Project cost $45,412 ————— “31- PRINCE WILLIAM SOUND ~ amas i a GROUND ELECTRODE s*ocL ae. aie «ee -POTHEAD ¢7,/ POTHEAD caf Figure 1 DC CABLE ROUTE 0, \"y <> POTHEAD oe ill ~POTHEAD ws) oe CONTOUR INTERVAL 100 FEET OALUM IS MEAN SEAS EVEL DLP CURVES AND SOUMDNGS 1 FEET SOME ShOMN MEMES MES Ht APP somes 233 tooo #48 ue socom ns, a MEAN (Om LO ALE on LAN Gt WAI orem Figure 2 CORDOVA TERMINAL A0582117 = GAGs. = i 8 w 1400 000 FEET APPROKIMATE MEAN DECLINATION, 1960 A0582121 CONTOUR INTERVAL 100 FEET DATUM (S MEAN SEA LEVEL EPI CURVES AND SOUNDINGS IM FECT OATUM IS MEAN LOWER LOW WATER ‘SHONELINE SHOWN REPRESENTS. Til APYHOMMATE LIME OF MEAN HwGat WAILR Wi MEAN RANGE OF TOE 1 APPROMHATELY 10 HEE Figure 3 VALDEZ TERMINAL ‘- APPENDIX 1 Siting Sea Electrodes Sample Calculations Sea Electrode Costs Sea Electrode Design Compass Errors Caused by D.C. Cables Sample Calculations \ Siting of Sea Electrodes Discussion The most cnucial factor in locating a sea electrode is to achieve suffi- cient separation from other buried or marine structures to prevent electrolytic corrosion or stray current effects. This includes the effect upon the armor of the project's own submarine cable. If ade- quate separation is not possible cathodic protection may be employed. Given the current magnitude quoted for this project, electrode size assumed and a sea waterjf of not over 0.2 ohm-meter, a separation of 1 mile from the nearest buried or submerged metallic structures (pipe lines, steel piling, armored cables etc.) should be adequate.” Other important requirements are: Relatively deep water - but not beyond diving depths. A sound bottom not subject to silt or sand deposition or shifting an i.e. stable bottom conditions. = Maximum salinity - low fresh water intrusion. If fresh water in- flow cannot be avoided the site may be acceptable if little mixing occurs and the salinity at the bottom remains high. Non fishing area - not subject to disturbance in the electrode area by beam trawls, anchors, set lines etc. Tidal currents must be low. Low wave action at the shoreline is desirable to reduce burial expense. Moderate slope from feed cable entrance points at shoreline to bottom location of electrodes. Cable should not traverse slopes greater than 45° nor should it hang over ledges or span fissures unless special measures are taken to avoid early failure due to such conditions. i Cordova Several potential locations for sea electrode were sighted during a helicopter survey of the Cordova terminal. Assuming the converter A-l Cy g Cordova_ continued station will be located near the present generating plant, all potential electrode sites could be served by a wood pole overhead line which might also carry an overhead conductor connected to the submarine DC power cable shore terminus. Site #1. This location would involve a submarine cable from Site #2. ‘ Site #3. Cordova across Orca Inlet to the mouth of Shipyard Bay, thence overland via wood pole line to the nearest arm of Deep Bay. The Electrode would be just off shore in the Deep Bay cove. This is the nearest site and probably the one with minimum cost. It suffers from the fact that it requires crossing the busy part of Orca Inlet with the ground cable. The site is also rela- tively close to the present cable area and area where it might be desirable to lay the DC cable. No man made marine or buried pipe structures are nearby. This location is reached by overhead line to Bluff Point, then submarine cable across Orca Inlet to a point on Hawkins Island near the mouth of the shallow bay pointing toward Canoe Passage, then overland by pole line to a suitable location along the shore of Canoe Passage. If it becomes essential to hold costs to an absolute minimum it might be possible to install a sea electrode on the Cordova side of Orca Inlet along the shoreline approxi- mately two thirds of the distance up the shore from the Cordova boat basin to the Orca Cannery. This location would be the least desirable because of the potential installation of pipelines, etc. sometime in the future. It is probably remote enough to avoid any trouble A-2. @ Cordova continued with present structures. It involves an overhead line only (no submarine cable) and is served by a road whose right of way is probably wide enough to accept the woodpole line. Of these three preliminary sites #2 was selected for purposes of this estimate. This is a conservative approach in a number of aspects. It is most remote (12.5 miles). No manmade structures are located closer than 5 miles (cable area 5 miles offshore). The Site may be accessed by boat and barge. It is protected from wave action. There is no major ship traffic and bottom conditions appear good as nearly as could be determined from the air. The submarine cable crosses Orca Inlet in shallow areas which should be free from any large boat traffic. The cable probably should be plowed in for protection. The cost of the ground electrode line would be reduced because it could be carried on the same wood poles that are needed to carry the main power line for the overhead portion from Cordova to Canoe Passage. Valdez Two sites, one on Jack Bay and one on Port Valdez (Bay) half way between Anderson Bay and Sawmill Spit (on Section 20 of the Valdez A-7 quadrangle) appear to be possible locations for the ground electrode. The route over the ridge from Port valdez (Bay) to Jack Bay could not be surveyed from the air because of the rapidly lowering ceiling and an approaching snow storm. There appears (from the map) to be a suitable route over the ridge without exceeding 2000 foot elevation. This involves heading approximately NE from the northern arm of Jack Bay to the shore of Port Valdez (Bay) at the N. E. corner of Section 20. If Jack Bay is selected for the power cable entry to the water, the entry could be located on the short arm on the north side of Jack Bay. The ground electrode could be located to the east of this location Cy Valdez continued about 1 or 2 miles up the longer arm of Jack Bay. This location of the ground electrode would require bringing both the power conductor and the ground wire over the ridge from Port Galdez on a wood pole line. The other location for the ground electrode is on the south side of Port Valdez (Bay) just east of Anderson Bay at the NE corner of section 20. The marine chart of this area indicates that there is a shelf along the shore where the depth is around 5 to 10 fathoms. This should be suitable for a ground electrode. The main power conductor would then proceed over the ridge to Jack Bay on a wood pole line over the route described above. This means that the pole line over the ridge would carry only one conductor unless the lightning incidence is such that an overhead ground wire is needed. The option desc ribed in this paragraph is the one selected for this report. If the DC tie line is deemed worthy of further study, a third option should be investigated. This would involve locating the ground elec- trode on the NE corner of Section 20 as described above and then run- ning the overhead line carrying the main power conductor west along the shore of Port Valdez (Bay) to the vicinity of Entrance Island, Section 14, where the main power cable would enter the water. This site for the cable entrance is dependent on being able to route the cable to deep water without running it over any under-water cliffs. The shores of Valdez inlet are so steep that it is questionable whether this is possible along the south shores A bottom survey would be necessary before proceeding with this approach. Cy Sea Electrode Costs Cordova Electrode Assembly Proper Materials 20 Type SM anode assemblies 20-2' x 2' x 8' concrete vaults 4 Reference electrodes 4 Buoy Units 6 Undersea connector cables (5 anode connectors + 1 reference electrode) 1 Beach control vault Estimated Material Cost $60,000.00 Labor Divers Boats, Barges, Cranes Stage and Living Expense Estimated Labor Costs 34,000.00 <7 Engineering Environmental Studies System Design Supervision System Tests Estimated Engineering Costs 18,000.00 Total $112,000.00 Valdez i Same $112,000.00 Both Terminals Total (Allowing for some engineering savings) $210,000.00 Sea Electrode Design Discussion This design was chosen to be very similar in construction to the sea electrode on the Los Angeles end of the Pacific N.W.-Pacific S.W. DC Intertie. The voltage gradients near the electrodes are, however, much more conservative (approximately 16% of those at Los Angeles). The maximum current rating is also less than 10% of the Los Angeles design. In spite of these factors there are other differences that require the electrode to be nearly as large as that at Los Angeles. Two assumptions were made that,in turn, dictate the size and cost of the design. ae The electrode elements should have a reasonably long life and the composite electrode should be essentially maintenance free. Any maintenance required should be capable of performance with- out taking the composite electrode out of service except for brief periods. With this in mind a minimum element life of @Q years was chosen. b. Resistance of the electrode should be as low as physically and economically feasible. The anodic electrode of a given composition loses material at a rate that is a function of a constant multiplied by the ampere-hours of operation. This means that for a givenpattern of operation (current flow) the desired life is achieved by installing a given weight of anode material. Fortunately, in this case, when a reasonably long life is selected for the design (30 years), all of the other criteria essential to good design are automatically satisfied. r a. Current density in the immediate electrode vicinity drops to a very low value. This means very low voltage gradients with essentially no adverse effects on marine life. b. Chlorine production so low that absorption will be practically au \ Sea Electrode Design (continued) immediate and the density so low that effects will be prac- tically nil. c. Composite electrode resistance will be quite low (approximately 0. O330hms) per terminal. Cost of the losses in the return current path will thereby be very low. d. In the Los Angeles design, very large concrete vaults (9 tons each) are used to protect each pair of electrode elements from injury, to support them above the sea floor, to prevent burial by sediment and to keep marine life (essentially fish) out of the high electrical gradient zone. For the case at hand, the much lower gradients will allow use of a much smaller and lighter protective structure and appreciable savings as a re- sult. The gradient at vault surface will be under 0.5 V/meter. Design The design selected was a linear array of 20 elements spaced 25’ apart. As in Fig. 2 each group of four elements is fed by a separate cable brought out to a shore based disconnect that will permit each group to be disconnected for service. A separate reference electrode is included to enable diagnostic checks during life of the installation. On the Pacific Intertie* two electrodes are suspended by polypropylene ropes from the box lid and each box is ll feet long by 7 feet wide by 5 feet high and weighs 9 tons. For the case at hand a vault 2 feet square by 8 feet long should be adequate and theweight should be less than 2 tons. Any concrete reinforcement must be nonmetallic (Fibreglass for example). Fig. 1 shows the approximate gradient adjacent to an individual electrode element. * See "The Los Angeles HVDC Ocean Electrode” by G. R. Elder and D. B. Whitney. Also shown in "Direct Current Transmission", Page 475, a book by E. W. Kimbark. Cy Sea Electrodes - Calculations Assumptions: 175 amperes continuous current Both Valdez and Cordova electrodes designed as anodes Specific resistivity of sea water at sites selected (©) not greater than 20 ohm-cm. 48% load factor Electrode useful life = 30 years (Based upon 50% loss of electrode material) Durco 51 Type SM electrodes (4.5" x 5' rods 220# weight. Material loss 0.85#/amp.-yr) 9 (12 would be satisfactory but 9 amps. selected Amperes/anode to keep electrical gradient low. Calculations: Weight loss per 175 amp. @ .48 LF = 84 x .85# x 30 yrs. = 2142 # No. Rod @ 9 amp/rod = 175/9 = 19.4 (use 20) Weight loss/rod =2142/20 = 107# Each rod can stand loss of 110# of material. Therefore: 110/107 x 30 + 30.8 years actual life Anode Consumption Use 20 DURCO 51 Type SM 220#/ electrode At 175 amp. full load with 48% Load Factor Ampere hrs/yr = 175 * .48 * 24 * 365 = 736,000 amp. hr./yr or 84 amp. yrs/yr A-8 Cy Anode Consumption (continued) Electrode Loss = 0.85#/amp. yr 175 amp. & .48% LF Loss = 0.85 * 84 = 71.4#/yr 20 electrodes may safely lose 110# each Life = 20 * 71. Max. Amp./Rod Area/Rod 110 = 30.8 years 4 = 175/20 = D*tL = 3.14 * .375 * 5 = 5.9 sq. ft. 8.75 amp. Current Density (max) = 8.75/5.9 Total Area = 1.48 amp/ft? 5.9 x 20 1s ft? Los Angeles sea electrode has area 192 £2 and a resistance of .02 ohms. Ratioing for max (E) = (E) = Ratioing areas gives 192 x .02 = 0.0325 ohms for this design 118 gradient as compared to Los Angeles gives 2.5 x 1.48 (amp/£t7)/ 9.375 (amp/ft*) 0.395 volts/meter (approx. ) or about 16% of the Los Angeles gradient near electrode. A-9 Gradient (E) = @ * 1 A (.1143)m P = 0.2 ohm-meter Az * 4,5" * 2.5 cm et Sx 2 25 100 100 0.53 m= At Electrode surface «5143 (E) = 0.2 * 8.75/0.53 =— = 3.30 v/m -2M At 20 cm A = 3.14 * .5143 * 1.52 = 2.45 sq. m (E) =_.2 * 8.75 2.45 = .714 v/m At 40 cm A = 3.14 * 1.52 *.914 = 4.355 (E) = 1.75/A = 1.75/ 4.355 = 0.40 v/m At 60 cm (E) = 1.75/ 3.14 * 1.52 * 1.31 ~ = .280 v/m At 100 cm (BE) = 1.75/ 3.14 * 1.52 * 2.11 - = .173 v/m A-10 iF a x : Ir ae & EEC ee ory as 7 f [ 7 Coo C saan é f a [Co r re T t 4 | Pe Core C t i & Tt a ee CCCCC CCE eee “SEER: : 5 He He oer COCO eee eI L HE H AEA PEEEEEEH tHe as CEE PERE EEE CECE: re i a Te & E a ty a 4 aSe t Ty HEE pry Tr z 1) Lee CO 3 4 r : Rom Fi CeCe SRORRR REEL Rees cee ae 4 co o . Por ert | {- dl anaeu ros I Seneennn 2 SECA EEE EEE EEE FAA HE H H H AEE EEE T r Tt T ty ar ; ae f tt AHH -f HHH 1 H Coc Ht C1 EHH Hp HH ¢ Hit FEAT EEREE HEE BEL EE TT EEE E HUH HET HEHEHE LT ET HEHEHE eT FEE EEE EE ET HEE HEE PEELE EPEC Lt HEHE EEEH EH HER ARRUL TPT ee EEEEEEEEEEEEEE EEE TEEPE eee eT EEE EEFEEHL FEEL HBP Ht THEFT FUE ELH FEEHE FEE EHE FET HEHE EEE HE EE HETEHUETE LLL HELE aR + “HHH BH. 4 HHT HHL CEE EAA EEE EEE i HE PALE +H H : H+ FAEEEEEEEEEH BH Let CCC ese “HEE ; See r 5 a PERCE EE HEE EEE SHEE HEH | a ; EEE PERE EEE I cee ae TrrA Hy re H 7 CECE FEE HEE EEEEEEEEEEEEE HEE EEE LEH EE PEA PEE: HEE HEHEHE a Fi Coe q : t HEH Hy L oo oo br os Ht CoC ~ a Tasae eee (ne-0) ~wet7e-N Ovel 9b dD VSN NIZQVN ‘OD HASS3 B 1344Nay S3H™ ar vp eHAAN AYE OF a7 W OZ 20H 2 COMPASS ERRORS CAUSED by D.C. CABLES Compass error can be calculated quite accurately if the strength of the earth's magnetic field is known. This has been checked on both the English Channel Crossing and the Konti-Skan projects. On the Gotland cable crossing a check was made when the sea was frozen and measurements made on the ice. The curves of compass error were plotted from data calculated by the following equation: Compass error = § = tan "(Hy .cos@/H,) Where (see Figs. (a), (b) : Hg, =horizontal component of field due to cable H, s=horizontal component of earth's field* A sangle cable makes with direction of H, Iq h Zoe = Igh/2r(h“+x*) amp./meter = = d Where: Ig= Direct current in cable, Amperes Hac h= Height of compass above cable, meters x = Horizontal distance of compass from cable, m. r= Slant height of compass from cable, m. * He varies with latitude. It is approximately 16 A/m in the temperate zone. This value was used in the calculation. A-13 Cr (a) A-14 aE ae pee ey azz apap : “Ns Jace d Ver @/ SO wo ee See eyes Ler Verveus Lheeybs 93 A. Penasiel? 02 Fer 17 oF @é le oe Fo°. +o ferar rit - ; Cobb LepVb- §o— * Cable apy O 250° | Coble Lewp 17° | , Coble Soot 650° 40° é0 aP YG Sp Labia Compass “hk Normal \". FO Cr, aie oF Coble ei Coftse Sear aLiee Ha ae i Z “AelS “fo. + | : { i i: , ' | j i \ i. ene 1. ee cae a pe ee ee A | : | : ; rE ‘4 { & | : } i | i i | |. = : ster i C. ompass Error As A Fanetion | Depth | | eS Fe "" Ceble Current 250 emp. ot } . Lorish fresd sO om (eter i oe ere fer Li oble ee j i t i mee he Se oe ecg ent cere Semauacactacel oemslnoncireseaielinete nad miocsperaay | ' { | ! = bas Coble 90° vo corr iets | & ‘ | j ' é; oOnNpass Soiibe ja Degrees oO hy o 500 . 4000 S500 s | ane of moa jf? yee ee | ere ees ae pr i et : | v | | | i i 1 | / A-16 : i i ! | ; Technical Report METEOROLOGICAL EVALUATION OF THE PROPOSED ALASKA TRANSMISSION LINE ROUTES MRI 82 FR-1855 Submitted to: Lemco Engineers, Inc. P. 0. Box 28549 West County Branch St. Louis, Missouri 63141 Purchase Order No. 11020 Date: 25 January 1982 By: S. C. Gouze M. C. Richmond Meteorology Research, Inc. Box 637, 464 West Woodbury Road Altadena, California 91001 Telephone (213)791-1901 Telex 67542! A Subsidiary of Cohu, inc. TABLE OF CONTENTS SUMMARY I. INTRODUCTION IT. SCOPE OF STUDY IIT. DATA SOURCES A. Climatological Data B. Supplementary Data IV. REGIONAL METEOROLOGICAL CHARACTERISTICS Ve WINDS A. General Considerations B. Wind Speed and Wind Gust Relationships C. Variation of Wind Speed with Height D. Wind Data Analysis E. Wind Speed Span Factors VI. ICING ALONG THE PROPOSED ROUTES A. General Considerations B. Identification of Icing Areas Along the Proposed Routes VII. LOADING PROBABILITIES BY SEGMENT A. Division of the Route into Segments B. Ice and Wind Loadings by Segment VIII. OTHER WEATHER PHENOMENA IX. CONCLUSIONS X. RECOMMENDATIONS A. Transmission Line Placement Due to Meteorological Factors B. Supplemental Data Collection REFERENCES SUMMARY A meteorological study was conducted for the purpose of determining probable extreme values of wind, ice loading, and combined wind on ice load- ing to be experienced along the proposed six transmission line routes in the Cordova/Valdez area. The study consisted of three phases: a field survey, climatology survey, analysis and application to the proposed route. The field survey consisted of one aerial survey of a portion of the six routes from Valdez to Cordova along the Prince William Sound to the Carbon Creek Coal Plant. Local variations in terrain were studied with regard to elevation and exposure. Evidence of strong windy areas were identified by the use of vegetative indicators such as tree flagging and blow down areas. In addition, interviews were conducted with personnel who live and work in the area and are familiar with the winds and storms which occur there. Also, weather records were secured from agencies in and near the route area. The climatology survey consisted of a review of all pertinent materials available in-house at Meteorology Research, Inc. (MRI), and summarized data from the National Climatic Center (NCC). In addition, weather records were secured in the study area from the U.S. Forest Service, University of Alaska Arctic Environmental Information Data Center, National Weather Service Office, State of Alaska Department of Environmental Conservation, and the City of Cordova. In the analysis phase, the weather data collected from the reporting stations were processed and analyzed to develop probabilities of occurrence of extreme winds, vertical ice loads, and transverse wind on ice loads along the proposed route taking into account terrain effects. The proposed transmission line routes will be susceptible to rime icing above 2000 feet mean sea level (msl) and to wet snow icing below 2000 feet msl. Heaviest rime icing for the six transmission line routes will occur on ridge locations west of Meteorite Mountain with a 50-year return period verti- cal load of 22.0 1bs/linear ft (conductors). Heaviest wet snow vertical loads for the six transmission line routes will occur from the Copper River delta to Baird Canyon with a 50-year return period of 23.9 Ibs/linear ft (conductor). Highest transverse wind on ice loads are expected to occur in Baird Canyon of the Copper River Valley with 50-year return period values of 9.3 1bs/ linear ft due to wind on wet snow. Highest 50-year return period values for extreme winds on bare wire are expected to occur in Baird Canyon with magni- tudes of 125 mph from the north. Vii I. INTRODUCTION Lemco Engineers, Inc. is studying the technical feasibility of transmission line construction to provide electricity to the City of Cordova. Several routes are being considered for the transmission lines. The Bering River transmission route would provide power from the proposed Carbon Creek Coal Plant. The Silver Lake transmission route would provide power from the proposed Silver Lake Hydroelectric Plant. A third source of power for Cordova would be from electricity generated in Valdez and transmitted via two proposed interties. One intertie would connect Valdez to the Silver Lake transmission line. The second proposed intertie would connect Valdez and Cordova with a transmission line through Heiden Canyon and the Copper River Valley. Then, the line would parallel the Bering River coal power transmission route into Cordova. A meteorological study was conducted to determine the probable ex- treme values of ice loading, wind loading, and wind on ice loading along the planned routes. This report presents the results of that study. The scope of the study and data sources are outlined in Section II and III, respectively. The regional meteorological characteristics are discussed in Section IV, and the winds are analyzed in Section V. Analyzed in Section VI is icing, and line segment load values are tabulated in Section VII. Other weather phenomena associated with the proposed route is discussed in Section VIII. Finally, conclusions are summarized in Section IX. Finally, recommendations are discussed in Section X. Il. SCOPE OF STUDY This transmission line study consisted of three phases, as follows: . Field survey . Climatology survey . Analysis of data and application to the proposed route The field survey consisted of an aerial survey by helicopter and air- plane by the meteorologist who related the station data to the actual route. Local variations in terrain were studied with regard to elevation and exposure. Evidence of strong windy areas was identified by the use of vegetative indi- cators such as tree flagging and blow down areas. In addition, interviews were conducted with personnel who live and work in the area and are familiar with the winds and storms which occur there. Also, weather records were secured from agencies in the route area. The climatology survey consisted of a review of all pertinent materials available in-house at Meteorology Research, Inc. (MRI), as well as microfiche records, and summarized data from the National Climatic Center (NCC). The NCC data included records of maximum wind speed tabulations and hourly observations. In addition, weather records were secured in the study area from the U.S. Forest Service, Chugach National Forest; University of Alaska, Arctic Environmental Information Data Center; National Weather Service Office, Anchorage, Alaska; State of Alaska, Department of Environmental Conservation; and City of Cordova and reviewed. In the analysis phase, the climatological data was processed and return period probabilities were developed for maximum wind speeds, ice loads, and combined wind on ice loads. Then the return period probabilities developed in the analysis phase were utilized in combination with terrain effects to estab- lish estimates of wind and ice loads to be expected along the proposed trans- mission line route. Ill. DATA SOURCES Data utilized in the preparation of this study consisted of climato- logical and supplementary data. A. Climatological Data Historical meteorological data from the Federal Aviation Administration weather station at Cordova/Mile 13 Airport were obtained from the archives of the National Climatic Center (NCC), Asheville, North Carolina. This data in- cludes hourly observations of wind speed and direction, temperature, preci- pitation, and cloud conditions. Microfiche copies of the hourly data were obtained for the period January, 1956 through December, 1979. Additional data for Cordova in the form of annual maximum hourly wind speed summaries were obtained from the NCC for the periods January 1, 1946 through December 31, 1964. In previous projects, the NCC has developed for MRI a computer program for summarizing maximum wind speeds, and this was used once again in this project. Additional meteorological data was obtained through the University of Alaska, Arctic Environmental Information and Data Center (AEIDC) in Anchorage, Alaska. These data are listed below. Microfiche records of the hourly surface weather observations included: Cape St. Elias January - December, 1973 Valdez (City) January, 1973 - August, 1981 Valdez (Airport) January, 1976 - December, 1977 Paper copies of the summary of percentage frequency of occurrence of weather conditions from hourly observations were available for Cordova Mile 13 Airport site for the period 1946-1970. Weather conditions included thunder- storms, rain and/or drizzle, freezing rain and/or drizzle, snow and/or sleet, hail, percent of observations with precipitation, fog, smoke and/or haze, blowing snow, dust and/or sand, and percent of observations with obscuration to vision. Paper copies of the annual and monthly percentage frequency of wind direction and speed from hourly observations were available for Cordova/ Mile 13 Airport for the period 1946-1970. Paper copies of the original sur- face weather observations were obtained for Thompson Pass. This data included monthly average maximum and minimum temperature, highest and lowest tempera- ture and date, monthly precipitation, day and amount of the greatest observed precipitation, total monthly and seasonal snowfall, and greatest snowfall in 24 hours. Period of record was 1952-1970. Extracted from the records at AEIDC were the highest annual observed gust for Valdez Airport for the period 1963-1967 and the annual fastest mile of wind for the period 1968-1970. Additional climatological data obtained were in the form of publications. These publications are described below. Summary of Synoptic Meteorological Observations were available for the Alaska Coastal Marine Area. The marine area includes Valdez and Cape Hinchinbrook. Summaries of meteorological and oceanographic data were available in the publication, Climatic Atlas of the Outer Continental Shelf Waters and Coastal Regions of Alaska. Microfiche copies of hourly wind speed, wind direction, and temper- ature measurements were available from the RCA tower and quarry sites at the Valdez oil pipeline terminal. The data was obtained from the State of Alaska, Department of Environmental Conservation for the period of 1978-1979 at the RCA tower and 1975-1979 for the quarry site. Paper copies of the daily rainfall, weather conditions, maximum temperatures and minimum temperature records for Cordova were obtained from the City of Cordova for the periods January 1, 1980 through December 27, 1981. Climatological data summaries for Alaska were obtained from the National Weather Service office in Anchorage, Alaska. This data included means and ex- tremes of temperature and precipitation at Cordova for the period of 1951-1975. Additional summaries were available for Valdez in the form of paper copies of the local climatological data. The local climatological data contains daily, monthly, and annual temperature extremes and means, precipitation, wind and sunshine. As well, hourly precipitation amounts are tabulated on the monthly summaries. Three hourly observations of weather, visibility, cloud cover, wind, and temperature are also tabulated on the monthly summaries. Period of record for the Local Climatological Data is July, 1975 through December, 1981. Mean annual precipitation isohyet map for the Chugach National Forest was secured through the regional office of the U.S. Forest Service in Anchorage, Alaska. Climatological data was also available in-house at MRI. Pertinent data included monthly average precipitation tabulations for Cordova and Valdez from a NOAA publication entitled, "Climates of the States." B. Supplementary Data At the time of the route survey and data acquisition survey in Anchorage, several people with first-hand experience with the winds and icing periods in the area of the proposed transmission line route were interviewed. Forecasters with the National Weather Service in Anchorage and Valdez were interviewed for the synoptic conditions conducive to extreme wind and icing events. Personnel with the U.S. Forest Service, Chugach National Forest were interviewed for first-hand field experience with snowfall amounts along the proposed routes. The City of Cordova Utility Engineer was interviewed for his observations of ice accumulations and wind damages to local power lines. Pilots in the area were interviewed for their experience in remote areas of extreme winds and icing. Meteorologists in-house at MRI were interviewed for their forecasting experience related to extreme weather events along the south coast of Alaska. IV. REGIONAL METEOROLOGICAL CHARACTERISTICS The Valdez-Copper River-Cordova area is represented by a maritime type climate. The area is characterized by relatively warm winters, cool summers, and heavy precipitation. Winter temperatures along the coastal areas of the Prince William Sound are relatively warm with extremes to -20°F at Valdez and -2°F in Cordova City (see Table IV-1). The interior sections of the area experience cooler winters with extremes reaching -39°F at Thompson Pass and -30°F at Cordova Airport. Cordova Airport is 13 miles east of the city and separated in between by the Heney Mountain Range. The cooler wintertime ex- treme low temperature is the result of its location on the western fringes of the Copper River delta, where cold air from the interior of Alaska drains southward into the Gulf of Alaska. Summer maximum temperatures in the area are usually in the upper 60's and low 70's away from the coast with a few days each summer reaching near 80. Coastal extreme temperatures on rare occasions reach into the 80's. Precipitation is the most variable item of climate in this area. Parts of the Prince William Sound receive close to 200 inches of precipitation annually as seen in the Cordova City measurements. Elsewhere, precipitation amounts typically are 50-100 inches along the coast. Precipitation amounts in this region vary within short distances because of changes in terrain. The glaciers that dominate the upper elevations of the mountains are evidence of precipitation amounts exceeding 200 inches. Heaviest total precipitation (rain and snow combined) occurs during the fall and winter months. Thunder- storms occur mainly in the summer and fall months as is shown in Table IV-1, but occur with very low frequency. Va le '-t TEMPERATURE FXTRFMES, PRECIF(T/ 1:CN, ANL THUNI'FFETORM LAT ECR VARIGUS ALASKA CLIMAT C STATICNS “Absolute Temperature Extremes Hean Number Waxtmum Wintmum Mean Precipitation Mean Snowfall Of Days With (°F) {).. (Inches {Inches Thunderstorms z Thompson Cordova Cordova ‘Valdez Thompson Cordova Cordova Valdez Thompson Cordova Cordova lez Thompson Cordova Tordova Pass Airport City Pass Airport City Pass _ Airport City Pass Airport Airport “4 58 47 -20 -90 -30 0 5.06 6.90 4.61 28.46 60.5 1.1 21.4 0 48 52 49 -3 -28 -21 12 5.30 9.36 6.49 17.33 50.8 107.5 26.4 0 48 59 52 -6 -28 -24 15 4.33 7.16 5.28 10.72 35.7 68.4 28.2 0 54 65 57 5 -10 2 2 3.06 5.99 5.69 9.85 13.4 57.2 17.3 0 NA 82 70 2 0 19 30 3.20 1.67 5.83 11.89 2.4 15.3 1.8 0 MA 84 69 uv NA 29 37 2.70 1.95 4.66 3.88 0 T 0.1 NA 84 70 33 NA u 42 431 4.03 6.94 12.57 0 0 0.3 NA 84 n %6 NA uv 40 5.80 4.63 8.52 40.42 0 0 0.2 WA n 66 2 20 20 26 7.74 9.08 12.47 16.03 0.2 8.9 0.3 51 70 $2 8 -3 -1 23 6.75 10.48 12.04 27.58 9.0 60.4 0.3 42 55 48 5 -23 -7 15 5.67 10.09 7.98 16.33 4.0 89.0 11.4 0.5 42 54 43 -6 -39 -23 -2 5.39 10.97 7.53 7.65 54.7 105.0 26.6 0.2 NA 84 rT -20 -39 -30 -2 59.31 82.51 88.04 202.69 260.7 582.8 136.5 1.9 vatlable Data Sources Valdez: Local Climatological Data, NOAA, 1941-1970. Snowfall from World Wide Airfield Summaries, 42 Year Period of Record. Thompson Pass: Original Weather Bureau Records, 1952-1970. Cordova Airport: Climate of Cordova, Alaska, NOAA, 1951-1975. Thunderstorm Data from World Wide Airfield Summaries, 17 Years of Record. Cordova City: From City Records, 1980-1981 (15 Days Missing). V. WINDS A. General Considerations Three types of meteorological conditions can result in strong winds over the area traversed by the proposed transmission line routes. Summer and fall thunderstorms occur, but are of a significantly low frequency of occurrence. However, the winds associated with these thunderstorms can be strong and gusty, but are difficult to predict due to the localized nature of these storms. The second type of wind flow pattern producing strong winds occur in conjunction with storms associated with low pressure centers in the Gulf of Alaska. These moist winds are generally from the east to southeast and are associated with rain and/or snow storms that move through the area in the fall through spring months. The third type of strong wind occurs from a high pressure area build- ing in the interior of Alaska with an approaching low pressure center in the Gulf of Alaska during the winter months. These pressure gradient winds are extremely strong when accompanied by strong north to east winds aloft. At the surface these strong winds are accelerated through mountain passes, canyons, and long glacial tongues oriented in the same direction of the wind. B. Wind Speed and Wind Gust Relationships The actual duration of the sustained wind speed reported at a weather station depends greatly on the weather observer. The observer reads the value from dial or chart once each hour and records it in a log. Occasionally, if weather conditions (cloud cover or visibility) are changing rapidly, he may record special observations between the scheduled hourly observations. The hourly wind speeds recorded at these locations are one-minute average wind speeds occurring sometime during the ten minutes prior to the hour. In practice, the dial is probably observed for less than a minute. When the wind speed is fluctuating rapidly, the observer may record an average or most frequent value and a maximum (gust) speed occurring during the minute of observation. Wind speed data used in this study were derived from one-minute aver- ages of climatological station records. Gusts reported in the records were of unknown duration and it is doubtful that they were the peak gusts which occurred. Many studies of the relationship of gusts to the steady wind and their variation with speed, height, thermal stratification, and terrain have cul- minated in general agreement concerning the nature of these relationships (Sissenwine et al., 1973; Brook and Spillane, 1970; Ficht] et al., 1969; Camp, 1968; Davis and Newstein, 1968; Boyd, 1965; Shellard, 1965; Mitsuta, 1962; Durst, 1960; Deacon, 1955; Sherlock, 1947 and 1952; and others). However, quantitative results have varied, depending on the analytical methods and data used. Most studies of gustiness are from micrometeorological research. Because of refined anemometry, measurements obtained from such experiments are generally superior to operational data; however, such studies seldom provide data for the very high wind speeds important in design of trans- mission towers and conductors. Sissenwine, et al. (1973), analyzed a more meaningful spectrum of wind speeds and this work appears to be one of the better recent efforts in this field. Their study included the analysis of 548 wind observations taken at anemometer heights varying from 10 to 85 feet, with one-minute wind speeds varying from 20 to over 70 knots, and locations varying from tropical Pacific islands to Alaska and Greenland. Since recorder charts of steady winds greater than 70 knots were scarce (only 10 cases of the 548 studied), they also used 26 observations of gust factors for five-minute steady winds, ranging from 71 to 163 knots taken at Mt. Washington, New Hampshire, and four values derived from wind data taken during hurricanes that passed close to the Blue Hill Observatory near Boston, Massachusetts. Sissenwine, et al. (1973), found that a least-squares relationship (G.F. = 1 + 0.55 e-9-0093V) best fit the median (50 percentile) two-second gusts related to five-minute steady speeds. Two-second gusts thus derived ranged from 1.46 times a five-minute steady speed of 25 knots (29 mph) to 1.22 times a five-minute steady speed of 100 knots (115 mph). In Table V-1 and Figure V-1, they show the relationship of other gust durations to five-minute steady speeds. One of the most widely used relationships for computing gust speeds was derived by Boyd (1965). His formula, G = 5.8 + 1.29 V, gives gust speeds (G) in miles per hour based on hourly wind speeds (V) in miles per hour. At the time he derived this formula, the gust data used were thought to be of approximately three-second duration; however, in a recent telephone conversation, Mr. Boyd stated that he now believes the response time of the pressure tube anemometer and its recorder, from which his data were collected, to be on the order of five to eight seconds. Another often referenced authority, Durst (1960), developed a statis- tical model based on samples taken with a high speed recorder. Although his empirical data were taken at speeds less than 42 miles per hour, he applied his model to class intervals of speed up to 80 mph. As Table V-2 shows, his probable gust factors for various duration gusts are nearly the same for all speed classes. If we combine the Durst relationships for hourly speeds to five- minute gusts (interpolated) with the Sissenwine, et al. (1973) relation of five-minute to two-second speeds, we find that the resulting gust factors for two-second gusts from hourly winds vary from 1.6 to 20 mph to 1.4 at 80 mph. This is nearly exactly what the Boyd formula of G = 5.8 + 1.29 V results in for five-second gusts. Table V-1 GUST FACTORS VERSUS 5-MINUTE STEADY WIND SPEED (Sissenwine, 1973) 5-min Gust eceer (GF) Speed -sec -sec -sec (knots) 20 1.120 1.172 1.4566 30 1.105 Torst 1.4160 40 1.094 1.134 1.3791 50 1.085 1.121 1.3454 60 1.077 1.111 1.3147 80 1.066 1.095 1.2613 100 1.057 1.081 1.2170 125 1.049 1.069 1.1719 150 1.042 1.059 1.1363 175 1.035 1.050 1.1080 200 1.028 1.040 1.0856 Table V-1 GUST FACTORS VERSUS 5-MINUTE STEADY WIND SPEED (Sissenwine, 1973) -Minute ust Factor Speed 0-sec O-sec -sec (knots ) 20 1.120 1.172 1.4566 30 1.105 1,131 1.4160 40 1.094 1.134 1.3791 50 1.085 T.121 1.3454 60 1.077 ToFit 1.3147 80 1.066 1.095 1.2613 100 1.057 1.081 1.2170 125 1.049 1.069 1.1719 150 1.042 1.059 1.1363 17s 1.035 1.050 1.1080 200 1.028 1.040 1.0856 1000 soo 100 TIME (sec) 10 GUST FACTOR Figure V-1. GUST FACTORS VERSUS 5-MINUTE STEADY WIND SPEED (Sissenwine, 1973) 10 Table V-2 PROBABLE (50 PERCENT) GUST FACTORS FOR 20- TO 80-MPH AVERAGE HOURLY SPEEDS USING DURST's MODEL Mean Hourly Gust Factor (GF) Speed 600 sec 60 sec 0 sec 0 sec 0 sec sec (mph) 20 1.05 1.25 1.30 1.35 1.40 1.50 30 1.07 1.23 1.33 1.37 1.43 1.47 40 1.07 1.25 1.32 1.35 1.42 1.48 50 1.06 1.24 1.32 1.36 1.42 1.48 60 1.07 1.24 1.32 1.35 1.42 1.48 70 1.06 1.24 1.31 1.36 1.41 1.49 80 1.06 1.24 1.33 1.36 1.43 1.48 ee 11 From the above discussion of the most frequently referenced sources currently, it is apparent that there are no hard and fast relationships to use in relating speeds of different averaging times. Wind near the earth's surface is very sensitive to the terrain; consequently, any particular location is likely to have its own gust characteristics. Since many of the data available for study are in the form of hourly wind speeds, we feel that Boyd's formula is still the most applicable. Based on his current understanding of the response time of the equipment used in - the formation of his data base, we recommend that his formula be used for predicting five-second gust speeds from hourly-average wind speeds and two- second gust speeds from five-minute average wind speeds. The higher value of 6.4 + 1.43 V should be used for predicting two-second gust speeds from hourly average wind speeds. Gc Variation of Wind Speed with Height In the extrapolation of station data to remote transmission line routes, it is necessary to take a number of factors into consideration. Among these are differences in elevation and exposure, type of terrain in the area, possible areas of channeling or funneling of gradient winds, and height above the terrain of the conductors. A height of 30 feet above the ground surface was chosen as the level to compute the wind speeds for this study. If a lower or higher effective height is desired, the wind speeds could be reduced or increased slightly, accordingly. is There have been many studies undertaken and theories presented on the variations of wind speed with height above the surface. There is general agreement that wind profiles tend to obey a power law (Munn, 1966; De Marrais, 1959; and Johnson, 1959). This relationship is normally used wheg neutral stability exists. The power law is of the form Vo/Vj = (Zo/ Z;) >» where V, is the wind speed at some known level, Z1; and V5 is the wind speed at the desired level, Zo. The exponent, P, iS dependent on the atmospheric temperature lapse rate, wind speed, and ground roughness. There is less agreement as to what the value of P should be. It is larger under a stable vertical temperature gradient and smaller for neutral and unstable conditions; it decreases with increasing wind speeds and increases somewhat with terrain roughness (De Marrais, 1959). The typical value used for P is 1/7 or 0.143 (Sherlock, 1952). Even Sherlock recognized that this P value was applicable to steady or mean winds and that gusts were better described with a value of P = 0.0625. Shellard (1968), in the Table of Surface Wind Speed and Direction over the United Kingdom, used P values of 0.17 for mean hourly wind speeds and 0.085 for three-second gusts. The majority of studies of wind profiles are made under regimes of light-to-moderate wind speeds and P values resulting from such studies may not be applicable to high wind speeds. Sissenwine, et al. (1973), using high wind speed data collected at the Argonne National Laboratory instrumented tower in Argonne, Illinois, derived the empirical equation P = 0.077 + 1.56/ Vy, where the limiting P value approaches 0.077 as Vj becomes very large. The Argonne National Summaries present a percentage frequency of P values versus the ten-minute average wind speeds. The data for the table Contain about 35,000 observations. For wind speeds greater than 24 mph, the median P value is about 0.125. For computations in this study, we have used a P value of 0.125 for wind speed (V;) values up to 50 knots (58 mph) and a P value of 0.080 for values of Vy over 50 knots. The anemometer heights during the period of record for Cordova Mile 13 Airport used in this study is listed in Table V-3. Table V-3 PERIODS OF RECORD OF ANEMOMETER HEIGHTS FOR CORDOVA MILE 13 AIRPORT USED IN THE ANALYSIS “Years Height Above Ground Level (ft) 1-46 to 6-49 32 7-49 to 4-65 34 5-65 to present 20 D. Wind Data Analysis The first step in the analysis was to rank all yearly extreme speeds for Cordova Mile 13 Airport in ascending order, compute the probability of occurrence of each speed, and plot the points on extreme probability paper of the Fisher-Tippett type I or Gumble distribution (Fisher and Tippett, 1928; U.S. Department of Commerce, 1953). This is a symmetric, extreme probability distribution cited by Court (1953) as particularly applicable to extreme surface winds and the distribution adopted by the Canadian Depart- ment of Transport (1968). Figure V-2 shows the plot for Cordova Mile 13 Airport. The mean and standard deviation of Cordova's extreme wind distribution was calculated and the characteristic line drawn using the relationship given by Weiss (1955). The line is shown in Figure V-2. (If the data points ina particular figure had a truly Gumble distribution, they would all fall on the solid line.) The speed to be equalled once in a given return period can be determined from these lines. The 25-, 50-, and 75-year return period wind speeds for 30 feet above the ground are summarized in Table V-4 for Cordova Mile 13 Airport. Included is the number of years of record and the probable direction of the extreme wind. g ~ \ EXTREME PROBABILITY PAPER RETURN PERIOD (Yeers) a 2 ts tats fant T T TT } } t | | 14 ' ' i { ' i i ' | i } i : ‘ ' ; aT z if | | | | TEM E TT CCC ; ce HSGEaRaaRe pit Cabell! as ede ELL Por PN ea ae Trai t-diiti PO Pr mr eal WS RA B.S ee Se fealetbart heehee ebay eg eae Sica eR hie ke Ld I ee eel eed eee te Pe ed Eel Aere Te Nes Te ere Tia te rota l ierectstec ctl Te erz p+ Ns Pe ; Pet PRE TER ia X POSES EET Ba en & bth et eae aa | > ar a ee He 22 oO = ST A etd Fister ‘ fest eager tta streets at coo = i soliestlislinedlieadlateetn i natdennitattedntinteattielinnteatigememnaeil coche (udw) @33dS GNIM oo Alaska (Data Base ed Probabilities for 30-foo Airport, Figure V-2. Maximum Wind see Cordova Mile 1 Table V-4 RETURN PERIOD VALUES OF MAXIMUM ONE-MINUTE HOURLY WINDS FOR CORDOVA MILE 13 AIRPORT Number of Years Return Period Probable of Record 25 50 5 Direction 19 64 70 73 ESE The distributions of extreme winds by month and direction for Cordova Mile 13 Airport and Valdez are given in Tables V-5 and V-6, respectively. An extreme probability analysis was not done for Valdez due to a lack of a signi- ficant period of record of hourly wind observations. Valdez has eight years of hourlies; however, a minimum of 10 years is needed for a probability analysis. Table V-5 ANNUAL EXTREME WIND DISTRIBUTION BY MONTH Cordova Mile Month 13 Airport Valdez (19 Years) (8 Years) = January 4 3 February 2 2 March 0 0 April 2 0 May 1 0 dune 0 0 July 0 0 August 0 0 September 1 0 October 5 0 November ir 2 December 5 1 When, in a particular year the annual extreme one-minute average wind speed occurred in more than one month and/or from more than one direction, each occurrence was counted. Thus, the totals for each station do not necessarily equal the years of data. Most of the extreme wind speeds have occurred during October through February for both Cordova and Valdez. This coincides with the fall and winter storm periods. The distribution of extreme wind directions however indicates a more site specific source of extreme winds. The majority of extreme winds for Cordova Mile 13 Airport occur from the east-southeast. 15 Table V-6 ANNUAL EXTREME WIND DISTRIBUTION BY DIRECTION Cordova Mile Direction 13 Airport Valdez (19 Years) (8 Years) N 1 3 NNE NE ENE e ESE 1 SE. SSE Ss SSW SW WSW W WNW NW NNW wonor oa Reoooooeooeooeoeoeoen Kf e oo oqoooeo‘oooeoo @ This persistence indicates that Cordova's extreme winds originate from storms associated with deep, low pressure systems in the Gulf of Alaska. One ex- treme wind did occur from the north. This would indicate drainage possibly off the Sheridan Glacier could result in an extreme wind event. However, the magnitude of the extreme wind from the north was one of the lower values. For Valdez, the distribution indicates that extreme winds originate mostly from cold air drainage from the interior of Alaska. Thus, the persis- tence of north through east extreme winds. In an interview with the local weather forecaster in Valdez, he indicated that the extreme winds mainly come down from the Valdez Glacier to the north. Strong outflow winds from the glacier are highly localized and mainly hit the airport area. Outflow winds were considerably lower (~35%) once they reached the new town of Valdez to the west of the airport. The distribution of extreme wind directions also included winds from the east-northeast. Such easterly type winds are also the result of cold air drainage from the interior of Alaska. Such strong winds are accompanied mostly by clear skies. No significant wind measurements were found for the Copper River Valley south of the Tasnuna River. One estimated gust of 90 + mph was made in May 1971 at the Copper River delta fishing grounds, where a storm ac- companied by high winds and rough seas sank three fishing vessels and ran another four aground. In another wind event, a truck was stripped of its paint at Flag Point in the Copper River delta. ES Wind Speed Span Factors Span factors for transmission lines are a function of the scale of wind experienced by the cable. The scale of wind is dependent on the aver- _ aging period and terrain encountered. Wind gusts of five seconds are of small scale extent, covering perhaps 100 feet of span at one time. Steady winds upwards of one minute may engulf up to 1000 feet of span at one time. Steady winds produced by low pressure center storms can be steady for periods upwards of one to two days and engulf a large area of 100's of miles. How- ever, mountainous terrain can create very complex wind patterns and turbulence. Therefore, over mountainous terrain winds can be highly unsteady and unpredictable. 17 VI. ICING ALONG THE PROPOSED ROUTES A. General Considerations The basic theory of ice growth and the accretion of snow on cylinders (transmission lines) was developed by Langmuir and Blodgett (1945) from studies conducted on Mt. Washington. Additional studies of icing of trans- mission lines during various meteorological conditions have been conducted by the Japanese (Kuroiwa, 1965), the Germans (Leibfried and Mors, 1964), the Americans (Leavengood and Smith, 1968; Hallanger and Richmond, 1972; and Richmond and Boomer, 1974), the Russians (Bourgsdorf, et al., 1968), and the Canadians (McKay and Thompson, 1969; and Young and Schell, 1971). Basically, four types of frozen deposits will accumulate on trans- mission lines. These are classified according to the density of the ice accreted as: glaze, rime, wet snow, and hoar frost. I. Glaze Glaze with a density of 0.9 to 0.92 g/cm? is equal to pure ice. Glaze grows under the conditions that the impingement rate is greater than the freezing rate. The deposited water drops cannot freeze unless the latent heat of fusion is transferred away by convection, evaporation or conduction. Because it is necessary for excess water to be present for glaze to form on exposed surfaces, often the excess water may freeze into icicles or other dis- tended shapes. In actual practice, glaze can be seen to form on conductors in a wide variety of shapes. They range from the classical, smooth cylindrical sheath, through crescents on the windward side and icicles hanging on the bottom, to large irregular protuberances spaced along the conductor. In most cases, glaze on structures develops as a fairly smooth layer on the windward surfaces, with icicles forming below horizontal members as the excess water flows to the bottom and drips off. The shape of the glaze is apparently dependent on a combination of factors, such as wind speed and variations in wind speed, the angle the wind flow makes with the line, the turbulence of the flow, movement of the conductor, the ability of the con- ductor to rotate, small variations in air temperature, and storm duration. Glaze is usually formed from freezing precipitation, rain or drizzle, or from clouds with large liquid water content and large drop sizes. 2s Rime Rime has a density of 0.3 to 0.9 g/cm3, Soft rime, with density less than 0.6 g/cm3, grows in a granular structure that is white and opaque, with many air bubbles within the structure. It usually grows in a triangular or pennant shape pointed into the wind. The granular structure results from the rate of freezing of the individual drops, each drop freezing completely be- fore regen: | one impinges on the surface. Hard rime, with density from 0.6 to 0.9 g/cm3 , tends to grow in a layered structure with clear ice mixed with ice containing air bubbles. In this case, the freezing rate of the droplets is equal to the impingement rate of the droplets. 18 In general, for rime to form, it is necessary to have supercooled water droplets (cloud or fog) impinge on a surface. Large supercooled cloud droplets in the temperature range from -1°C to -5°C will partially freeze on impact, resulting in hard rime. Small cloud droplets in the temperature range from about -5°C to -15°C will freeze on impact, result- ing in soft rime (Kravitz and Leavengood, 1973; and Griffing and. Leavengood, 1973). Large concentrations of supercooled droplets are not common in ambient temperatures below -15°C. At lower temperatures, ice crystals are likely to form. These grow at the expense of the supercooled water and largely remove the icing condition. 36 Wet Snow A density of 0.3 to 0.8 g/cm3 is usually defined as snow which falls with temperatures 231° F (-0.5°C). Under these conditions the snow is sticky enough to adhere to surfaces easily and accumulate rapidly. Wet snow tends to build on tops and windward surfaces of structures and in cylindrical layers around conductors. At temperatures colder than about -2°C, snow particles are usually too dry to adhere to surfaces in appreciable quantities. It has previously been believed that damaging wet snow accumulations occurred in conjunction with light winds (Kuroiwa, 1965). However, recent experiences and studies indicate that wet snow will accumulate on conductors with wind speeds up to 45 mph and temperatures up to near +2°C. Cases of cohesive wet snow building up to a symmetrical thickness of four inches radially have been documented (Higuchi, 1973). Investigations in Japan (Higuchi, 1974), have indicated that exten- sive damage has occurred with what is referred to as the Hokkaido Type snow storm. This type is characterized by temperatures at or slightly above 32° F and wet snow with densities as high as 0.6 to 0.8 g/cm3 which may not be blown off conductors even when the wind exceeds 25 mph (11 m/s). The damaging storms in southern Alberta and southwestern Saskatchewan in April and May, 1974, are recent examples of this in Canada. In these cases, heavy, wet snow was ac- companied by wind speeds over 40 mph (18 m/s). 4. Hoar Frost Hoar frost has a density of less than 0.3 g/cm3 and is a deposit of interlocking ice crystals formed by direct sublimation of water vapor in the air onto objects. The deposition of hoar frost is similar to the process by which dew is formed, except the temperature of the frosted object must be below freezing. It forms when air with a dew point below freezing is brought to saturation by cooling. Hoar frost is feathery in appearance and will occasionally build to large diameters with very little weight. 19 F B. Identification of Icing Areas Along the Proposed Routes ie Bering River Coal Power Transmission Line Routes Significant ice accumulations are expected along the portion of the route which crosses the Copper River. Such accumulations are expected from wet snow. High wind speeds fairly normal to the line during wet snow epi- sodes will be responsible for the large accumulations. 2. Intertie Route 3 (Via Copper River) Significant ice accumulations are expected along the route through the Copper River Valley and Marshall Pass areas. Significant accumulations of wet snow are expected through the Copper River Valley due to strong chan- nelled winds down the valley during wet snow episodes. Large accumulations of rime ice are expected through the Marshall Pass, because of strong chan- nelled winds combined with low cloud ceilings. Se Intertie Route 2 (Via Prince William Sound) Significant accumulations of ice from wet snow are expected between 500-2000 feet ms! along the entire length of the route. Such accumulations are the result of large amounts of precipitation that occur during storms along the Prince William Sound from Cordova to the Meteorite Mountain area. Accumulations are expected to be lighter below 500 feet ms] due to warmer temperatures and lower precipitation amounts. Heaviest accumulations will occur where the line is transverse to the storm winds between 500-2000 feet msl. Heaviest accumulations are expected from rime ice along the ridge southwest of Meteorite Mountain. Such accumulations are the result of funnelled winds combined with low cloud ceilings. 4. Silver Lake Transmission Route Significant accumulations of ice are expected from wet snow between 500-2000 feet ms] in the Silver Lake area, and Port Fidalgo areas due to significant precipitation amounts along the Prince William Sound. 5. Solomon Gulch Alternate Route Significant amounts of rime ice are expected above 2000 feet ms] due to strong winds and low persistent cloud ceilings. Rime ice is expected above 2000 feet msi along the ridge line southeast of Mount Kate. 6. Jack Bay Alternate Route Significant accumulations of wet snow are expected along the Prince William Sound portion between 500-2000 feet msl. Heaviest accumulations are expected in the Jack Bay area of the route due to heavy precipitation along the Prince William Sound. on VII. LOADING PROBABILITIES BY SEGMENT A. Division of the Route into Segments The transmission line route is divided into six sections. Each section is divided into segments based on elevation and exposure. The sections and their respective segment number classification are listed below. Segment Number Section Name Category 1. Bering River Coal Power Transmission Line Route 1- 14 2. Intertie Route 3 15 - 30 3. Intertie Route 2 31 - 85 4. Silver Lake Transmission Route 86 - 97 5. Solomon Guich Alternate Route 98 - 105 6. _ Jack Bay Alternate Route 106 - 113 The segment numbers are shown in Figures VII-1 through VII-34. Segment boundaries are denoted by short lines perpendicular to route line. B. Ice and Wind Loadings by Segment The probable extreme wind, vertical ice, and transverse wind on ice loadings in the form of 25-, 50-, 75-year return period values are listed in Tables VII-1 through VII-18. These section values computed for 30 feet above the ground are based on Cordova values modified for altitude and exposure. Additional meteorological data collected at Valdez and other locations were used in extrapolating the Cordova data throughout the six routes. Also taken into consideration were comments from personnel who live and work in the area and are familiar with wind or icing problems that may have occurred. The probable maximum wind speed and direction per 25-, 50-, and 75-year return period are one-minute averages. Wind gusts (G) are five seconds in duration and are calculated from the maximum wind speeds (V) by the formula G = 5.8 + 1.29 V. Return period values for wet snow vertical loadings were computd using the yearly maximum wet snow icing accumulation episode determined by the MRI wet snow icing model. Wet snow icing episodes were identified from the Cordova Mile 13 Airport (41 feet elevation) hourly weather observations by the criteria of moderate or heavy snow falling between temperatures of 31° - 35°F at wind speeds greater than 10 mph for periods greater than six hours. The Cordova Mile 13 Airport is situated in a well sheltered area surrounded by trees, and to the north by mountains. Therefore, loading values calculated for Cordova would be very site specific. 21 ‘ (| C, Table VII-1 PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON THE BERING RIVER COAL POWER TRANSMISSION ROUTE 25-YEAR RETURN PERIOD Extreme Wind on Bare Wire Wet Snow Icing 0.5 g cm-3 Rime Icing 0.49 cm-3 issoc late Wax Tmum 0.375" Dia. 0.927" Dia. WaxTmum 0.375" Dia. Wind Transverse Shield Wire Conductor Transverse Shield Wire Segment Direction Storm Wind bs/tinear Ft bs/Linear Storm Wind b Number |Length Speed Dimension |Vertical [Transverse|Vertical |Transverse| Speed Dimension Hiles (mph) _.| (Radial_In. _{mph) Radial In. 1 1.4 s 35 2.0 3.2 1.2 4.0 3 2 2.5 SE 35 2.5 4.9 1.4 5.8 6 3 8.0 E 45 2.0 3.2 1.9 4.0 2 4 1.3 E 35 2.5 4.9 1.4 5.8 6 § 1.3 Ec : 35 1.5 1.9 0.9 2.5 0 6 1.0 E 35 2.6 4.9 1.4 5.8 6 7 2.0 E 35 1.5 1.9 0.9 2.5 0 8 6.0 SE 35 1.5 1.9 0.9 2.5 0 9 2.0 NNE 55 4.0 11.8 5.5 13.3 9 10 13.0 NE 45 4.0 11.8 3.7 13.3 9 i 18.5 ESE 35 1.5 1.9 0.6 2.5 8 12 3.0 ESE 45 2.0 3.2 1.5 4.0 7 13 2.0 ENE 45 2.0 3.2 1.5 4.0 7 4 1.0 E 36 2.5 4.9 1.2 5.8 3 ey alg Oy Table VII-2 PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON THE BERING RIVER COAL POWER TRANSMISSION ROUTE 50-YEAR RETURN PERIOD Extreme Wind on Bare Wire Wet Snow Icing 0.5 g cm-3 Rime Icing 0.49 ca-3 T-Minute[ Assoctati issoctat “Max Tmum P a. 0.927" Dia. Vaxtmum 0.375" Dia. 0.927" Dia. Average | 5-Second Wind Transverse hield Wire Conductor Transverse Shield Wire Conductor Segment Wind Gust Direction Storm Wind Storm Wind b Number jLength Speed Speed Speed Dimension Speed Dimension Miles)| (mph) (mph) (mph) Radial In. (mph) Radial In. 1 1.4 84 14 s 40 2.5 4.9 9 5.8 2.1 iz 2.5 70 96 SE 40 3.0 6.8 2 8.0 2.4 3 8.0 95 128 E 50 2.5 4.9 9 5.8 3.2 4 1.3 95 128 E 40 3.0 6.8 2 8.0 2.4 5 1.3 95 128 ce 40 2.0 3.2 5 4.0 1.7 6 1.0 95 128 E 40 3.0 6.8 - 2 8.0 2.4 7 2.0 95 128 E 40 2.0 3.2 5 4.0 1.7 8 6.0 84 14 SE 40 2.0 3.2 5 4.0 1.7 9 2.0 115 154 NNE 60 5.5 21.8 9 23.9 9.3 10 13.0 115 154 NE 50 5.5 21.8 2 23.9 6.5 1 18.5 84 14 ESE 40 2.0 3.2 2 4.0 1.4 12 3.0 100 135 ESE 50 2.5 4.9 4 5.8 2.7 13 2.0 100 135 ENE 50 2.5 4.9 4 5.8 2.7 4 1.0 100 135 — 40 3.0 6.8 9 8.0 2.1 . C & Table VII-3 PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON THE BERING RIVER COAL POWER TRANSMISSION ROUTE 75-YEAR RETURN PERIOD Extreme Wind on Bare Wire Wet Snow Icing 0.5 g cm-3 Rime Icing 0.4 9 cm-3 T-Ainute| Assoctate ssoctal xTmum 0.927" Dia. Haxtmum 0.375" Dia. 0.927" Dia. Average | 5-Second Wind Transverse Conductor Transverse hield Wire Conductor Segment Wind Gust Direction Storm Wind Storm Wind Number |Length Speed Speed Speed Dimension Speed Dimension Miles)| (mph) _(mph) Radial In. (mph) Radial In. 1 1.4 88 119 s 45 3.0 6.8 2.8 8.0 3.0 2 2.5 13 100 SE 45 3.5 9.2 3.2 0.5 3.5 3 8.0 100 135 E 55 3.0 6.8 4.2 8.0 4.5 4 1.3 100 135 € 45 3.5 9.2 3.2 10.5 3.5 5 1.3 100 135 E 45 2.5 4.9 2.4 5.8 2.6 6 1.0 100 135 cE 45 3.5 9.2 3.2 10.5 3.5 7 2.0 100 135 3 45 2.5 4.9 2.4 5.8 2.6 8 6.0 88 ng SE 45 2.5 4.9 2.4 5.8 2.6 9 2.0 120 161 NNE 65 6.0 25.9 11.3 26.1 1.8 10 13.0 120 161 NNE 55 6.0 25.9 8.1 26.1 8.5 et 18.5 88 119 ESE 45 2.5 4.9 1.9 5.8 2.2 12 3.0 105 41 ESE 55 3.0 6.8 3.5 8.0 3.9 13 2.0 105 141 ENE 55 3.0 6.8 3.5 8.0 3.9 4 1.0 105 41 3 45 3.5 9.2 2.8 10.5 3.0 @ (Oy Table VII-4 PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON INTERTIE ROUTE 3 25-YEAR RETURN PERIOD Extreme Wind on Bare Wire Wet Snow Icing 0.5 9 cm-3 Rime Icing 0.4 g cm-3 T-Minute] Assoctate: ssoctated HaxTmum 0.375" Dia. 0.927" Dia. Haxtmum e a. 0.927" Dia. Average | 5-Second Wind Transverse Shield Wire Conductor Transverse Shield Wire Conductor Segment Wind Gust Direction Storm Wind b Storm Wind Number jLength Speed Speed Speed Dimension (Vertical [Transverse Speed Dimension Miles)| (mph) (mph) (mph) Radial In. (mph) Radial In. 15 1.0 92 124 E 35 2.5 4.9 1.2 5.8 1.3 16 2.0 92 124 ENE 45 2.0 3.2 1.5 4.0 1.7 vi] 3.0 92 124 ESE 45 2.0 3.2 1.5 4.0 1.7 18 18.5 ” 105 ESE 35 1.5 1.9 0.6 2.5 0.8 19 27.0 105 141 NE 45 4.0 11.8 3.7 3.3 3.9 20 11.0 115 154 N 55 4.0 11.8 5.5 3.3 5.9 al 12.0 105 141 NW 45 3.0 6.8 2.8 8.0 3.0 22 18.0 85 115 E 45 2.5 4.9 1.9 5.8 2.2 23 6.0 90 122 ESE 45 3.0 6.8 2.4 8.0 2.6 24 1.0 95 128 ESE 45 1.0 1.0 3.7 1.3 1.3 45 4.0 25 8.0 85 5 E 36 2.5 4.9 1.2 5.8 1.3 26 5.0 95 128 NE 45 2.5 4.9 1.9 5.8 2.2 27 3.0 100 135 NNE 35 2.5 4.9 1.2 5.8 1.3 28 2.0 95 128 ENE 45 2.0 3.2 1.5 4.0 1.7 29 11.0 90 122 ESE 35 2.0 3.2 0.9 4.0 1.0 30 1.5 85 115 NE 36 2.0 3.2 0.9 4.0 1.0 or e 7 Table VII-5 PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT : ON INTERTIE ROUTE 3 50-YEAR RETURN PERIOD Extreme Wind on Bare Wire Wet Snow Icing 0.5 g cm-3 Rime Icing 0.4 9 cm-3 T-Ainute| AssocTated | AssocTat xTmum 375" Dia. 0.927" Dia. WaxTmum 0.375" Dia. 927” Dia. 5-Second Wind Transverse Shield Wire contuctor Transverse Shield Wire Conquctor Gust Direction Storm Wind Storm Wind t ertica Speed Dimension Transverse|Vertical | ransverse Vertica ransverse|Vert ical] Transverse Speed Dimension (mph) Radial In. Speed (mph) Radial In, 1.0 E 40 3.0 6.8 1.9 6.0 2.1 2.0 ENE 50 2.5 4.9 2.4 5.8 2.7 3.0 ESE 50 2.5 4.9 2.4 5.8 2.7 18.5 ESE 40 2.0 3.2 1.2 4.0 1.4 27.0 NE 50 5.5 21.8 6.2 23.9 6.5 11.0 N 60 5.5 21.8 8.9 23.9 9.3 12.0 NW 50 3.5 9.2 4.0 10.5 4.3 18.0 £ 50 3.0 6.8 2.9 8.0 3.2 6.0 ESE 50 3.5 9.2 3.5 0.5 3.8 1.0 ESE 50 1.5 1.9 1.8 2.5 2.1 50 5.0 4.5 8.0 c 40 3.0 6.8 1.9 8.0 2.1 5.0 NE 50 3.0 6.8 2.9 8.0 3.2 3.0 NNE 40 3.0 6.8 1.9 8.0 2.1 2.0 ENE 50 2.5 4.9 2.4 5.8 2.7 11.0 ESE 40 2.5 4.9 1.5 5.8 1.7 1.5 NE 40 2.5 4.9 1.5 5.8 1.7 o ; ( ( & _ Table VII-6 PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON INTERTIE ROUTE 3 75-YEAR RETURN PERIOD Extreme Wind on Bare Wire Wet Snow Icing 0.5 g cm-3 Rime Icing 0.4 g cm-3 xTmum le a. 0.927" DTa. Wax Tmum 0.375" Dia. 0.927" Dia. Transverse Shield Wire Conductor Transverse Shield Wire Conductor Segment Storm Wind | _Ubs/ltnear FE | Storm Wind B Number |Length Speed Dimension [Transverse| Speed Dimension Miles (mph) Radial In. (mph) Radial In. 15 1.0 45 3.5 9.2 2.8 10.5 3.0 16 2.0 55 3.0 6.8 3.5 8.0 3.9 v7 3.0 55 3.0 6.8 3.5 8.0 3.9 18 18.5 45 2.5 4.9 1.9 5.8 2.2 19 27.0 55 6.0 25.9 8.1 28.1 8.5 20 11.0 65 6.0 25.9 1.3 28.1 1.8 21 12.0 55 4.5 14.8 6.1 16.5 6.5 22 18.0 55 3.5 9.2 4.2 10.5 4.5 23 6.0 55 4.0 1.8 4.8 13.3 5.2 24 1.0 55 2.0 3.2 2.9 4.0 3.2 55 6.0 25 8.0 45 3.5 9.2 2.8 10.5 3.0 26 5.0 55 3.5 9.2 4.2 10.5 4.5 27 3.0 45 3.5 9.2 2.8 10.5 3.0 28 2.0 55 3.0 6.8 3.5 8.0 3.9 29 11.0 45 3.0 6.8 2.4 8.0 2.6 30 1.5 45 3.0 6.8 2.4 8.0 2.6 @ A, Table VII-7 PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON INTERTIE ROUTE 2 25-YEAR RETURN PERIOD Extreme Wind on Bare Wire Wet Snow Icing 0.5 g cm-3 Rime Icing 0.4 g cm-3 T-Ainute| Assoctated | AssocTated HaxTmum 0.575" Dia 0.783" Dia. Waxtmum 0.375" Dia. 0.783" Dia. Average | 5-Second Wind Transverse Shield Wire Conductor Transverse Shield Wire Conductor Segment Wind Gust Direction Storm Wind Storm Wind Number = jLength Speed Speed Speed Dimension Speed Dimension [Transverse|Vertical [Transverse Miles (mph) (mph) (mph) Radial In. {mph) Radial In. 3 0.5 92 124 € 40 4.5 4.8 3.3 6.1 3.4 32 2.6 77 105 NE 25 4.0 1.8 1.1 2.9 1.2 33 1.5 1 105 NE 25 3.0 6.8 0.9 7.7 0.9 34 0.7 72 99 ENE 40 3.5 9.2 2.6 10.1 2.7 35 > 1.3 72 99 ENE 30 3.0 6.8 1.2 7.7 1.3 36 0.6 72 99 ENE 40 4.5 14.8 3.3 16.1 3.4 37 0.4 82 112 NE 45 4.5 14.8 4.1 16.1 4.3 38 0.9 22 99 NNW 25 4.0 11.8 1.1 12.9 1.2 39 2.5 105 NE 25 4.0 11.8 Le 12.9 1.2 40 1.6 1 105 NE 45 3.5 9.2 3.2 10.1 3.4 41 0.3 ” 105 NE 45 4.0 11.8 3.7 12.9 3.9 42 5.7 1 105 NE 25 4.0 11.8 11 12.9 1.2 43 2.2 72 99 NE 30 3.5 9.2 1.5 10.1 1.5 44 1.0 72 99 NE 30 4.5 14.8 1.8 16.1 1.9 45 1.3 77 105 NE 25 4.0 11.8 1.1 12.9 1.2 46 0.5 7 105 NE 25 4.0 11.8 1.1 12.9 1.2 47 1.1 1 105 NE 45 3.5 9.2 3.2 10.1 3.4 48 0.9 7 105 NE 30 4.5 14.8 1.8 16.1 1.9 49 0.5 1 105 NE 35 3.5 9.2 2.0 10.1 2.1 50 0.9 7 105 NE 30 4.0 11.8 1.6 12.9 1.7 51 0.6 1 105 NE 40 3.5 9.2 2.6 10.1 2.7 52 0.8 64 88 SE 25 4.0 11.8 1.1 12.9 1.2 53 0.6 64 88 SE 35 3.0 5.5 54 0.1 ul 105 ESE 40 4.0 9.5 55 0.1 64 88 SE 3 3.0 5.5 56 1.3 64 88 SE 25 4.0 11.8 57 0.6 64 88 SE 30 3.0 6.8 58 1.2 7 105 NE 25 3.0 6.8 59 1.2 7 105 NE 25 4.0 11.8 60 1.0 72 99 NE 30 4.0 11.8 61 0.4 82 112 NE 35 4.0 11.8 wi C Cy Table VII-7 (Continued) PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON INTERTIE ROUTE 2 25-YEAR RETURN PERIOD Extreme Wind on Bare Wire Wet Snow Icing 0.5 g cm-3 Rime Icing 0.4 g cm-3 T-ATnute] AssocTat ssoctat “Haxtmum 0.375" Dia. 0.783" Dia. Wax tmum 0.375" Dia. ~ 0.783" Dia. Average | 5-Second Wind Transverse Shield Wire Conductor Transverse acer Wire Conductor Segment Wind Gust Direction Storm Wind racticat{Teansearse} Storm Wind | _tbs/ilnear Ft ‘| Number jLength Speed Speed Speed Dimension Speed Dimension Vertical|Transverse|Vertical [Transverse | Miles)| (mph) jh (mph) Radial In. (mph) Radial In. 62 0.9 ” ESE 40 4.5 14.8 3.3 3.4 63 41 7 ESE 36 4.5 14.8 2.5 2.6 64 1.5 1 ESE 40 3.5 9.2 2.6 2.7 65 1.0 ul ESE 40 4.5 14.8 3.3 3.4 66 1.0 1 ESE 3 3.5 9.2 2.0 2.1 67 1.6 1 ESE 30 4.0 11.8 1.6 1.7 68 0.5 82 ESE 30 4.0 11.8 1.6 1.7 69 0.5 64 NE 30 4.0 11.8 1.6 12. 1.7 70 0.3 64 NE 30 3.0 6.8 1.2 7. 1.3 m1 0.6 77 NE 35 3.5 9.2 2.0 0. 2.1 72 1.1 7 NE 30 3.5 9.2 1.4 0. 1.5 73 0.9 7 NNW 30 3.5 9.2 1.4 0. 1.5 14 0.6 85 NE 35 3.5 9.2 2.0 0. 2.1 75 0.4 85 NE 40 4.5 14.8 3.3 6. 3.4 76 2.1 85 NE 35 1.5 1.9 0.9 2 1.0 35 3.0 5.5 7 0.5 95 NE 45 5.0 14.5 718 0.2 90 ESE 40 3.0 5.5 79 0.6 90 ESE 3 1.5 1.9 0 36 2.0 2.6 80 0.6 90 ESE 35 3.0 6.8 8 81 2.5 85 SSE 30 3.0 6.8 3 82 2.5 95 NE 45 2.5 4.9 5 83 2.3 90 E 45 2.5 4.9 5 84 3.0 90 ESE 35 2.0 3.2 0 85 1.5 85 NE 36 2.0 3.2 0 w C ) Table VII-8 PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON INTERTIE ROUTE 2 50-YEAR RETURN PERIOD Extreme Wind on Bare Wire Wet Snow Icing 0.5 9 ca-3 Rime Icing 0.49 ca-3 tute] Assoctated | Assocta' ‘HaxTmum 0.375" Dia. 0.783" Dia. Max Tum 0.375" Dia. 0.783" Dia. Average | 5-Second Wind Transverse Shield Wire Conductor Transverse Shield Wire Conductor Segment Wind Gust Direction Storm Wind Storm Wind Number jLength Speed Speed Speed Dimension Speed Dimension Miles)| (mph) (mph) (mph) Radial In. (mph) Radial In. 31 0.5 100 135 E 45 5.5 21.8 5.0 5.2 32 2.6 84 114 NE 30 5.0 18.2 2.0 2.1 33 1.5 84 14 NE 30 4.0 11.8 1.6 1.7 34 0.7 79 108 ENE 45 4.5 14.8 4.1 4.3 35 1.3 79 108 ENE 35 4.0 11.8 2.2 2.3 36 0.6 79 108 ENE 45 5.5 21.8 5.0 5.2 37 0.4 89 121 NE 50 5.5 21.8 6.2 6.4 38 0.9 719 108 NNW 30 5.0 18.2 2.0 2.1 39 2.5 84 14 NE 30 5.0 18.2 2.0 2.1 40 1.6 84 114 NE 50 4.5 14.8 5.1 5.3 41 0.3 84 114 NE 50 5.5 21.8 6.2 6.4 42 5.7 84 114 NE 30 5.0 18.2 2.0 2.1 43 2.2 79 108 NE 35 4.5 14.8 2.5 2.6 44 1.0 79 108 NE 35 5.5 21.8 3.0 3.1 45 1.3 84 4 NE 30 5.0 18.2 2.0 2.1 46 0.5 84 114 NE 30 5.0 18.2 2.0 2.1 47 11 84 14 NE 50 4.5 14.8 5.1 5.3 48 0.9 84 4 NE 36 5.5 21.8 3.0 3.1 49 0.5 84 14 NE 40 4.5 14.8 3.3 3.4 50 0.9 84 14 NE 35 5.0 18.2 2.8 2.9 51 0.6 84 14 NE 45 4.5 14.8 4.1 4.3 52 0.8 70 96 SE 30 5.0 18.2 2.0 2.1 53 0.6 70 96 SE 40 4.0 54 0.1 84 14 ESE 45 5.0 55 0.1 70 96 SE 40 4.0 56 1.3 70 96 SE 30 5.0 18.2 2.0 57 0.6 70 96 SE 35 4.0 11.8 2.2 58 1.2 84 14 NE 30 4.0 11.8 1.6 59 1.2 84 4 NE 30 5.0 18.2 2.0 60 1.0 79 108 NE 35 5.0 18.2 2.8 61 0.4 89 121 NE 40 5.0 18.2 3.6 Table VII-8 (Continued) PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON INTERTIE ROUTE 2 50-YEAR RETURN PERIOD Wet Snow Icing 0.5 g cm-3 Rime Icing 0.4 9 cm-3 MaxTmum 0.375" Dia. 0.783" Dia. HaxTmum 0.375" Dia. 0.783" Dia. Extreme Wind on Bare Wire T-Minute] AssocTate issocta Average | 5-Second Wind Transverse Shield Wire Conductor Transverse Shield Wire Conductor Segment Wind Gust Direction Storm Wind Storm Wind Number |Length Speed Speed Speed Dimension Speed Dimension Miles jh (mph) (mph) Radial In. (mph) Radial In. 62 0.9 84 14 ESE 45 5.5 5.0 5.2 63 4 84 114 ESE 40 5.5 3.9 4.1 64 1.5 84 14 ESE 45 4.5 4.1 4.3 65 1.0 84 114 ESE 45 5.5 5.0 5.2 66 1.0 84 114 ESE 40 4.5 3.3 3.4 67 1.6 84 114 ESE 35 5.0 2.8 2.9 68 0.5 89 121 ESE 35 5.0 2.8 2.9 69 0.5 70 96 WE 35 5.0 2.8 2.9 70 0.3 70 96 NE 35 4.0 2.2 2.3 1 0.6 84 114 NE 40 4.5 3.3 3.4 72 1.1 84 114 NE 35 4.0 2.2 2.3 73 0.9 84 14 NNW 35 4.0 2.2 2.3 74 0.6 95 128 NE 40 4.0 2.9 3.0 75 0.4 95 128 NE 45 5.0 4.6 4.7 716 2.1 95 128 NE 40 2.0 1.5 1.7 40 4.0 7 0.5 105 141 NE 50 6.0 78 0.2 100 135 ESE 45 4.0 19 0.6 100 135 ESE 40 2.0 40 2.5 80 0.6 100 135 ESE 40 3.5 81 2.5 95 128 SSE 35 3.5 82 2.5 105 41 NE 50 3.0 83 2.3 100 135 E 50 3.0 84 3.0 100 135 ESE 40 2.5 85 1.5 95 128 NE 40 2.5 @ (| Table VII-9 PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON INTERTIE ROUTE 2 75-YEAR RETURN PERIOD Extreme Wind on Bare Wire Wet Snow Icing 0.5 9 cm-3 Rime Icing 0.4 9 cm-3 T-Minute] Assoctated | AssocTat “Max Timum 0.375" Dia. 0.783" DTa. Waxtmom o. Dia. 0.753" Dia. Average | 5-Second Wind Transverse Shield Wire Conductor Transverse Shield Wire Conductor Segment Wind Gust Direction Storm Wind Storm Wind Speed Speed Speed Dimension Speed Dimension (mph) (mph) (mph) Radial In. (mph) Radial In. 105 M1 e 50 6.0 6.7 6.9 2.6 88 119 NE 35 5.5 3.0 3.1 1.5 88 ng NE 35 4.5 2.5 2.6 0.7 84 14 ENE 50 5.0 5.6 5.8 1.3 84 14 ENE 40 4.5 3.3 3.4 0.6 84 114 ENE 50 6.0 6.7 6.9 0.4 93 126 NE 55 6.0 8.1 8.4 0.9 84 114 NNW 35 5.5 3.0 3.1 2.5 88 1g NE 36 5.5 3.0 3.1 1.6 88 119 NE 55 5.0 6.8 7.1 0.3 88 119 NE 55 6.0 8.1 8.4 5.7 88 119 NE 35 5.5 3.0 3.1 2.2 84 4 NE 40 5.0 3.6 3.7 1.0 84 114 NE 40 6.0 4.3 4.4 1.3 88 119 NE 356 5.5 3.0 3.1 0.5 88 19 NE 36 5.5 3.0 3.1 1.1 88 1g NE 55 5.0 6.8 71 0.9 88 119 NE 40 6.0 4.3 4.4 0.5 88 119 NE 45 5.0 4.6 4.7 0.9 88 1g NE 40 5.5 3.9 4.1 0.6 88 119 NE 50 5.0 5.6 5.8 0.8 13 100 SE 35 5.5 3.0 3.1 0.6 73 100 SE 45 4.5 0.1 88 119 ESE 50 5.5 0.1 73 100 SE 45 4.5 1.3 73 100 SE 35 5.5 21.8 3.1 0.6 73 100 SE 40 4.5 14.8 3.4 1.2 88 119 NE 35 4.5 14.8 2.6 1.2 88 1g NE 35 5.5 21.8 3.1 1.0 84 114 NE 40 5.5 21.8 4.1 0.4 93 126 NE 45 5.5 21.8 5.2 Table VII-9 (Continued) PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON INTERTIE ROUTE 2 75-YEAR RETURN PERIOD Extreme Wind on Bare Wire Wet Snow Icing 0.5 9 cm-3 Rime Icing 0.49 cm-3 T-Atnute| Assoctate: ssoctat Maximum 8 a. 0.763" Dia. ‘HaxTmum 0.375" Dia. 0.753" Dia. Average | 5-Second Wind Transverse Shield Wire Conductor Transverse Shield Wire Conductor Segment Wind Gust Direction Storm Wind D Storm Wind Number jLength Speed Speed Speed Dimension Speed Dimension Miles jh _(mph) (mph) Radial In. (mph) Radial In. 62 0.9 88 119 ESE 50 6.0 6.7 6.9 63 4.1 88 ng ESE 45 6.0 5.4 5.6 64 1.5 88 119 ESE 50 5.0 5.6 5.8 65 1.0 88 119 ESE 50 6.0 6.7 6.9 66 1.0 88 119 ESE 45 5.0 4.6 4.1 67 1.6 88 119 ESE 40 5.5 3.9 4.1 68 0.5 93 126 ESE 40 5.5 3.9 4.1 69 0.5 13 100 NE 40 5.5 3.9 4.1 70 0.3 13 100 NE 40 4.5 3.3 3.4 1 0.6 88 119 NE 45 5.0 4.6 4.7 72 1.1 88 119 NE 40 4.5 3.3 3.4 73 0.9 88 119 NNW 40 4.5 3.3 3.4 74 0.6 100 135 NE 45 4.5 4.1 4.3 15 0.4 100 135 NE 50 5.5 6.2 6.4 76 2.1 100 135 NE 45 2.5 2.4 2.5 45 5.0 1 0.5 110 148 NE 55 7.0 718 0.2 105 141 ESE 50 5.0 19 0.6 105 4 ESE 45 2.5 45 3.0 80 0.6 105 141 ESE 45 4.0 81 2.5 100 135 SSE 40 4.0 82 2.5 110 148 NE 55 3.5 83 2.3 105 41 E 55 3.5 84 3.0 105 141 ESE 45 3.0 85 1.5 100 135 NE 45 3.0 PROBABLE Table VII-10 25-YEAR RETURN PERIOD MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON THE SILVER LAKE TRANSMISSION ROUTE Extreme Wind on Bare Wire Wet Snow Icing 0.5 g cm-3 Rime Icing 0.4 g cm-3 T-ATnute] AssocTate ssoctated Waxtmum 0.375" Dia. 0.783" Dia. ‘HaxTmum 0.375" Dia. 0.763" Dia. Average | 5-Second Wind Transverse Shield Wire Conductor Transverse Shield Wire Conductor Segment Wind Gust Direction Storm Wind Storm Wind b | Ubs/linear Ft | Number jLength Speed Speed Speed Dimension Speed Dimension [Vertical [Transverse | (Miles)| (mph) (mph) (mph) Radial In. (mph) Radial In.) 86 1.2 1 105 NE 30 3.0 8 2 77 87 2.9 ” 105 NE 30 4.0 11.8 6 12.9 88 0.3 82 112 E 40 3.0 5.5 2.4 89 0.8 71 112 E 35 4.0 11.8 2.2 12.9 90 0.8 11 112 E 35 3.5 9.2 2.0 10.1 a1 3.4 7 105 SE 30 4.0 11.8 1.6 12.9 92 0.4 82 112 SE 36 3.0 5.5 1.8 93 1.5 72 99 ESE 30 4.0 11.8 1.6 12.9 94 1.0 64 88 SSE 30 4.0 11.8 1.6 12.9 95 2.0 17 105 SE 25 4.0 11.8 1.1 12.9 96 2.0 17 105 SE 25 3.0 6.8 0.9 7.7 97 1.1 11 105 NE 35 3.5 9.2 2.0 10.1 Table VII-11 PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON THE SILVER LAKE TRANSMISSION ROUTE 50-YEAR RETURN PERIOD Extreme Wind on Bare Wire T-Minute] Assoctated Wet Snow Icing 0.5 g cm-3 Rime Icing 0.4 g cm-3 Waxtmum 0.375" Dia. 0.783" Dia. WaxTmum 0.375" Dia. 0.783" Dia. ssoc tate Average | 5-Second Wind Transverse Shield Wire Conductor Transverse Shield Wire Conductor Segment Wind Gust Direction Storm Wind Storm Wind Number jLength Speed Speed Speed Dimension Speed Dimension Miles (mph) (mph) mph) Radial In. (mph) Radial In. 86 1.2 84 114 NE 35 4.0 87 2.9 84 114 NE 35 5.0 88 0.3 89 121 E 45 4.0 89 0.8 84 114 E 40 5.0 90 0.8 84 114 E 40 4.5 91 3.4 89 121 SE 36 5.0 92 0.4 89 121 SE 40 4.0 93 1.5 19 108 ESE 35 5.0 94 1.0 70 , 96 SSE 35 5.0 95 2.0 84 14 SE 30 5.0 96 2.0 84 114 SE 30 4.0 97 Ld 84 114 NE 40 4.5 Table VII-12 PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON THE SILVER LAKE TRANSMISSION ROUTE 75-YEAR RETURN PERIOD Cy Extreme Wind on Bare Wire Wet Snow Icing 0.5 g cm-3 Rime Icing 0.4 g cm-3 T-Hinute] AssocTate: issoctat WaxTmum 0.375" Dia. 0.783" Dia. Waxtmum 0.375" Dia. 0.783" Dia. Average | 5-Second Wind Transverse Shield Wire Conductor Transverse Shield Wire Conductor Segment Wind Gust Direction Storm Wind D b Storm Wind b Number |Length Speed Speed Speed Dimension Speed Dimension Miles)| (mph) _ (mph) (mph) Radial In. (mph) Radial In. 86 1.2 88 ng NE 40 4.5 14.8 3.3 3.4 87 2.9 88 ng NE 40 5.5 21.8 3.9 4.1 88 0.3 93 126 E . 50 4.5 89 0.8 88 1g — 45 5.5 21.8 5.0 5.2 90 0.8 88 119 — 45 5.0 18.2 4.6 4.7 91 3.4 93 126 SE 40 5.5 21.8 3.9 4.1 92 0.4 93 126 SE 45 4.5 93 1.5 84 114 ESE 40 5.5 21.8 3.9 4.1 94 1.0 73 100 SSE 40 5.5 21.8 3.9 4.1 95 2.0 88 119 SE 35 5.5 21.8 3.0 3.1 96 2.0 88 1g SE 35 4.5 14.8 2.5 2.6 97 1d 88 119 NE 45 5.0 18.2 4.6 4.7 Table VII-13 PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON THE SOLOMON GULCH ALTERNATE ROUTE 25-YEAR RETURN PERIOD Extreme Wind on Bare Wire Wet Snow Icing 0.5 g cm-3 Rime Icing 0.4 g cm-3 ssoctated | AssocTate: 5-Second Wind Gust Direction Speed HaxTmum ° a. Transverse Shield Wire Storm Wind b 0.783" Dia. , conductor WaxTmum Transverse Storm Wind 0.375" Dia. sauetd Wire 0.783" Dia. Conductor Speed Dimension Speed Dimension (mph) Radial In. Radial In. E 35 3.0 — 40 4.0 E 35 1.5 2.0 E 3.0 E 4.0 NE 45 1.5 5.0 Ss 40 2.5 4.0 Ss 25 2.5 |e ( an Table VII-14 PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON THE SOLOMON GULCH ALTERNATE ROUTE 50-YEAR RETURN PERIOD Extreme Wind on Bare Wire Wet Snow Icing 0.5 9 cm-3 Rime Icing 0.4 9 cm-3 issoctat ‘Waxtmum 0.375" Dia. 0.783" Dia. MaxTmum 0.375" Dia. 0.783" Dia. hield Wire Wind Transverse s Conductor Transverse Shield Wire Conductor Segment Direction Storm Wind b Storm Wind b Number jLength Speed Dimension |V ransverse Speed Dimension Miles (mph) Radial In. (mph) Radial In. . —E 40 4.0 3.0 2.7 c 45 5.0 4.7 0.1 (3 40 2.0 17 40 2.5 0.3 E 40 4.0 0.6 E 40 5.0 0.5 NE 50 2.0 2.6 50 6.0 0.1 s 45 3.0 3.0 45 5.0 6.3 $ 30 3.0 1.3 ~ ()< a i Table VII-15 PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON THE SOLOMON GULCH ALTERNATE ROUTE 75-YEAR RETURN PERIOD Extreme Wind on Bare Wire Wet Snow Icing 0.5 g cm-3 Rime Icing 0.4 9 cm-3 T-Minute] Assocfated | Assoctate MaxTmum 375" Dia. 0.783" Dia. ‘WaxTmum 0.375" Dia. 0.783" Dia. Average | 5-Second Wind Transverse Conductor Transverse Shield Wire Conductor Segment Wind Gust Direction Storm Wind b Storm Wind b Number jLength Speed Speed Speed Dimension Speed Dimension Miles)} (mph) (mph) (mph) Radial In. (mph) Radial In. 98 2.2 88 lig E 45 5.0 99 2.7 88 119 E 50 6.0 100 0.1 88 19 E 45 2.5 45 3.0 101 0.3 88 119 [3 45 5.0 102 0.6 88 119 FE 45 6.0 103 0.5 93 126 NE 55 2.5 55 7.0 104 0.1 88 119 s 50 3.5 50 6.0 105 6.3 88 119 s 35 3.5 eo aa Ss a) Table VII-16 PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON THE JACK BAY ALTERNATE ROUTE 25-YEAR RETURN PERIOD Extreme Wind on Bare Wire . Wet Snow Icing 0.5 g cm-3 Rime Icing 0.4 g cm-3 ssoctate laxTmum 0.375" Dia. 0.783" Dia. WaxTmum 0.375" Dia. 0.753" Dia. Wind Transverse Shield Wire Conductor Transverse Shield Wire Conductor Segment Direction Storm Wind D Storm Wind b Number jLength Speed Dimension Speed Dimension Miles (mph) Radial In. Radial In. 106 1.5 SE 25 3.5 9.2 1.0 10.1 1.1 107 3.4 SE 25 4.0 11.8 1. 12.9 1.2 108 0.5 e 40 4.0 11.8 2.9 12.9 3.0 109 0.5 E 40 3.5 9.2 2.6 10.1 2.7 110 1.5 E 30 3.0 6.8 1.2 7.7 1.3 Mn 0.2 NE 35 4.0 11.8 2.2 12.9 2.3 112 1.8 NE 35 2.5 4.9 1.4 5.6 1.5 113 5.8 ENE 35 2.0 3.2 1.2 3.8 1.3 Table VII-17 PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON THE JACK BAY ALTERNATE ROUTE 50-YEAR RETURN PERIOD Extreme Wind on Bare Wire Wet Snow Icing 0.5 g cm-3 Rime Icing 0.4 g cm-3 T-Minute| Assoctate issoctati Waxtimum 0.375" Dia. 0.783" Dia. “Max tmum 0.375" Dia. 0.783" Dia. Average | 5-Second Wind Transverse Shield Wire Conductor Transverse Shield Wire Conductor Segment Wind Gust Direction Storm Wind b Storm Wind b Number [Length Speed Speed Speed Dimension /|V Speed Dimension Miles (mph) (mph) (mph) Radial In. (mph) Radial In. 106 1.5 84 114 SE 30 4.0 11.8 12.9 7 107 3.4 84 114 SE 30 4.5 14.8 16.1 9 108 0.5 84 14 E 45 4.5 14.8 16.1 3 109 0.5 84 4 E 45 4.0 11.8 12.9 9 110 1.5 84 14 E 36 3.5 9.2 10.1 el 1 0.2 89 121 NE 40 4.5 14.8 16.1 4 112 1.8 19 108 NE 40 3.0 6.8 7.7 4 113 5.8 91 123 ENE 40 2.5 4.9 5.6 0 Table VII-18 PROBABLE MAXIMUM WIND AND ICE LOADING VALUES PER SEGMENT ON THE JACK BAY ALTERNATE ROUTE 75-YEAR RETURN PERIOD Extreme Wind on Bare Wire Wet Snow Icing 0.5 g cm-3 Rime Icing 0.4 g cm-3 xTmum 0.375" Dia. ~ 0.783" Dia. HaxTmum 0.375" Dia. 0.783" Dia. Wind Transverse shteld Wire Conductor Transverse aoe Wire Conductor Segment Direction Storm Wind Storm Wind Number jLength Speed Dimension |V Speed Dimension Miles (mph) Radial In. (mph) Radial In. 106 1.5 35 4.5 4.8 2.5 2.6 107 3.4 35 5.0 8.2 2.8 2.9 108 0.5 50 5.0 8.2 5.6 5.8 109 0.5 50 4.5 4.8 5.1 5.3 110 1.5 40 4.0 1.8 2.9 3.0 Mn 0.2 45 5.0 8.2 4.6 4.7 112 1.8 45 3.5 9.2 3.2 3.4 113 5.8 45 3.0 6.8 2.8 3.0 Figure VII-1. Bering River Coal Power Transmission Line Route - Segments 1-3. on Ce Si Me aT Wyn SAE I Figure VII-2. Bering River Coal’ Power Transmission Line Route - Segments 3-8. rosdiob ile aii aun: Basic ring River Coa Figure VII-3. Be arte at 2 AIRS 8 BARRA AE PIE hee so ME ep es Transm ission Line Route - S$ egment 8. Cy Figure VII-4. Bering River Coal Power Transmission Line Route - Segments 8-10. : Dy [dbs colle ee nt HN Si apt [Pre i ( DIM als sre , oe) : iy ’ si os Sa sat 3 anew HOMER GENS it ur TERRY 9 OT Figure VII-5. Bering River Coal Power Transmission Line Route - Segments 10-11. 8Y Figure VII-6. Bering River Coal Power Tra Be a5 1b nsmiss oF : x ey 4 Ns 37 We. 7 ADO at. ; wv ion Line Route - Segment 11. bith! ot Figure VII-7. Bering River Coal Power Transmission Line Route - Segment 11. os — Figure VII-8. Bering River Coal Power Transmission Line Route - Segments 11-15. 1s ; Lia: A ean et Figure VII-9. Intertie Route 3 - Segments 15-18. 59° Intertie Route 3 - Segment 18. Figure VII-10. Re Lik Jal ' oe, oe «fF a) we 1D. hes Figure VII-11. rntertis moute 3 - Sat 18. we," WN Pantie, My PTE d J. 8 t on 047 VN oe BEE adie treacle tet ech at aba HE RAR BS Figure VII-14. Intertie Route 3 - Segments 18-19. a Se at Figure VII-13. Intertie Route 3 - Segment 19. Intertie Route 3 - Segments 19-20. Figure VII-14. fis ernment geen fee eC . aS ig Niet 7 \ a9 = et hap hers Oe . Si pagle& Sep x re nye = % en i i AT. 7 x j to gt ASS S ; = : Be? E 1s Nas ES Bot! Fal aN 4 7 TZ Say 9° c aC : = - 6 iS " ‘ eS fee ; ae é = on ain M . f 13 EP OER x = Figure VII-15. Intertie Route 3. - Segments 20-21. 2 NSS SX .) Sar Rae DS Intertie Route 3 - Segments 21-22. Figure VII-16, Cy) Intertie Route 3 - Segment 22. Figure VII-17. ie ian Ze : RS St. a; bbe Figure VII-19. C) Intertie Route 3 - Segment 30. Figure VII-21. *OS-IE€ Squswbes - 2 ajnoy aLqsaquUT *2@2-1IA aunbL4 SL ot a RR En gRepb on ratte ai doe os OS ple Sat TER ap NCE B, hy EE See a ee ed) Pope bie Oe Gok 7 i / . <a Sh ter SS yy i i Yes : an yN = C = a ec a a en OREE wal | mA feet awe Le ees Ne hl sinessinibtlbuintdamea ree tsiiacaaitbabas. 4. “ete Figure VII-23. Intertie Route 2 - Segments 50-56 iA ea ae ae to PS . Le Figure VII-24. Intertie Route 2 - Segments 56-71. Figure VII-25. Intertie Route 2 - Segments 71-82. - oe Cy SASSER S Hy SpE S = Sas LenS = ; SSS Ss = aS xe eA (RS See AS E GPR FS Se SSG This eatiiat: be Pre ERNE AN bi Dh eae HM Z z z° \e = = s Ds fr a ae Bye Tee NA red POS WAGE ON INL eee AS LE OA WIG ete i od My Se Ss e oe LER WY Mite Sap OY ee — OD AT Lone AE oe CT He see SR ee E DS ee af ete A. 4 Intertie Route 2 - Segments 82-84. Figure VII-26. VALDEZ me Intertie Route 2 - Segment 85. Figure VII-27. Figure VII-28. Silver Lake Transmission Route - Segments 86-95. Figure VII-29. Silver Lake Transmission Route - Segments 95-97. oy ‘ aes el i We ‘ m§ Vie iy rin Ard . Hi SpE bie ee Wi QAAD. YS oO - VS ae a de < — resin gabad) NN Re es SEO. ‘ <hes [ (hae i a 4) Figure VII-30. Solomon Gulch Alternate Route - Segments 98-103, 105. SS : = a RO RE 6 ETE: erences * = rar Ne iy yn an ere KLM Aon d C gen WAG a ay a, Mo be ( va t Wd tm amas ¢ “ pr s . a ‘ ES i: x n rf \ + fh >" \ a e st ~» jy q % ts eo Ys. f ; A / Bs yi i y <4 ~ BYE ie if ae yi x New SY eT! t . 7 we ‘i Ve " ‘t. Z \ Mag "fs } ‘ | a t- “et! yy 7 ‘ y \ Figure VII-31. Solomon Gulch Alternate Route - Segments 103-105. le ead Me sb BSN TT H y; al ate od a rt aes N Sa- Lee id : 1 A S "i ; SEE sh © Solomon Gulch Alternate Route - Segment 105. Figure VII-32. Jack Bay Alternate Route - Segments 106-107. Figure VII-33. Figure VII-34. Jack Bay Alternate Route “Segments 107-113. ati oe The Cordova loadings were used to extrapolate to the entire six routes. Precipitation amount, winds, and temperature from other locations combined with elevation, MRI experience, and information from personal interviews were used to extrapolate to | the routes. The wet snow icing is assumed to have a density of 0.5 gm/cm3 and to be circular about the conductor and shield wire. Return period values for rime icing vertical loads were computed using the yearly maximum rime icing accumulation episode determined by the MRI rime icing model. Rime icing episodes were identified from the Cordova Mile 13 Airport (41 feet msl) hourly weather observations by the criteria of the occurrence of cloud ceilings less than or equal to 3000 feet with a temperature equal to or less than 41°F, but not lower than 23°F. The Cordova loadings were used to extrapolate to the aoe six routes. The rime icing is assumed to have a density of 0.4 g/cm3 and to be circular about the conductor and shield wire. A review of available weather records at Cordova Mile 13 Airport indicated occurrences of freezing drizzle and freezing rain for 33 hours for the entire period of 1956-1981. For most storms, durations were 1-2 hours, precipitation light, and winds calm. As a result, glaze icing is expected to be insignificant for the entire area. The transverse wind on ice loadings in Tables VII-1 through VII-18 were calculated by using the formula: . 0.0026 Dv2 TWL lbs/linear ft = ——~j>— (1) where D is the total diameter of ice plus conductor or shield wire in inches and V is the wind speed in miles per hour. The transverse wind on ice load- ings were computed using the respective return period ice plus conductor/ shield wire dimension with the estimated transverse wind. Ice dimensions and transverse winds used to compute the transverse wind on ice loads originated from the Cordova Mile 13 Airport hourly weather observations. The appropriate transverse storm wind was determined by computing the return period of Cordova transverse storm winds and then lifting the winds to 2000, 2500, and 3000 feet ms]. Winds at Cordova, measured at anemometer height, were lifted to the appropriate level through the power law as discussed in Section V-C. Then the Cordova lifted transverse winds were extrapolated to the entire six routes. A factor was then applied to the segment transverse storm wind, so that when combined with the respective ice plus conductor/shield wire return period dimension, the return period transverse wind on ice load was of the respective return period. A factor of 0.7 was generally used. VIII. OTHER WEATHER PHENOMENA One other phenomena offers threats to lines along the proposed routes. This is snow drifting. Significant snow drifting occurs when steady strong winds blow snow. Where objects such as trees, buildings, or raised road em- bankments exist in the path of steady strong winds, snow piles up behind (on leeward side) the objects. Areas susceptible to snow drifting for the proposed routes are the section of line through the Copper River Valley and segments 15, 16, 17, 31, and 32 around Cordova. Other areas include Marshall Pass, Heiden Canyon, Thompson Pass, and Keystone Canyon. Large snowdrifts of up to 50 feet have been observed on Round Island in the Copper River delta. 78 o IX. CONCLUSIONS The principal conclusions of the study are the following: The proposed transmission line routes will be susceptible to rime icing above 2000 feet msl and wet snow icing below 2000 feet msl. Highest wet snow vertical loads for a 50-year return period along the Bering River Coal Power Transmission Route are ex- pected to be 23.9 lbs/linear ft (conductor). Highest 50- year transverse wind on ice loads are expected to be 9.3 lbs/linear ft (conductor). Highest 50-year return period one-minute average wind on bare wire is expected to be 115 mph. The three heaviest loading values are expected to occur along that portion of line which crosses the Copper River delta. ; Highest wet snow vertical loads for a 50-year return period along Intertie Route 3 (Copper River) are expected to be 23.9 Ibs/linear ft (conductor) through the Copper River Valley. Highest 50-year return values for rime ice vertical loads is 16.0 1lbs/linear ft (conductor) in the Marshall Pass. Baird Canyon is expected to have the highest 50-year return period value for extreme wind on bare wire of 125 mph from the north. Baird Canyon will also have the highest 50-year transverse wind on ice load of 9.3 lbs/linear ft (conductor). Highest wet snow vertical loads for a 50-year return period along Intertie Route 2 (Prince William Sound) are expected to be 23.4 lbs/linear ft (conductor) where the line is normal to storm winds and between 500-2000 ft msl. Highest 50-year return period rime ice vertical loads are expected to be 22.0 lbs/linear ft (conductor) along the ridge line southwest of Meteorite Mountain. The ridge line near Meteorite Mountain is also expected to have the highest extreme 50-year return period value one-minute wind speed of 105 mph from the north- east. Highest 50-year return period transverse wind on ice loads are expected also along the ridge southwest of Meteorite Mountain. Transverse loads expected are 6.9 lbs/linear foot (conductor). Highest 50-year return period values of wet snow vertical loads are expected to be 19.6 lbs/linear foot (conductor) at elevations between 500-2000 feet ms] on the Silver Lake transmission line route. Ridge top rime vertical loads are expected to be 10.4 lbs/linear foot (conductor) for a 50-year return period. Highest transverse wind on ice loads are expected to be 3.9 lbs/linear foot (conductor) for a 50-year return period on the ridgeline north of Silver Lake. Highest extreme one-minute wind speeds are 89 mph from the eastern quadrant for a 50-year return period. Highest 50-year return period values of wet snow vertical loads are expected to be 19.6 lbs/linear foot (conductor) on the Solomon Gulch Alternate. Highest rime 50-year return period values are expected to be 22.0 lbs/linear foot (conductor) along the ridge top. Transverse wind on ice loads are expected to be highest along the ridge top with 6.7 lbs/linear ft (conductor). Extreme one-minute average winds for a 50-year return period are expected to be 89 mph from the northeast at the ridgeline. Highest 50-year return period wet snow vertical loading is expected to be 16.1 Ibs/linear ft (conductor) along the Jack Bay Alternate. Highest transverse wind on ice loads for a 50-year return period are expected to be 4.3 1lbs/linear ft (conductor). Extreme 50-year return period one-minute winds are expected to be 91 mph from the east-northeast. X. RECOMMENDATIONS A. Transmission Line Placement Due to Meteorological Factors 1. General An analysis of Cordova Mile 13 Airport hourly weather observations, as well as other data sources, as listed in Section III, indicate the heaviest wet snow vertical loading to occur between 500-2000 ft ms] for the Bering River Coal Power Line/Prince William Sound lines. Lower vertical wet snow loadings are expected below 500 ft msl. Rime ice vertical loadings are expected to be the heaviest above 2000 feet msl. Spruce forest stands will reduce wind speeds up to 20 percent in the lee of stands (Wegley, 1978). A comparable amount or greater (20 to 50 per- cent) could be used for winds within a dense forest stand. The effect of forest stands to reduce winds would reduce accumulations of wet snow. Up to 0.5 inches radial reduction of wet snow could be realized by the sheltering of forest stands. 2. Application of General Considerations to the Proposed Transmission Line Routes (a) Bering River Coal Power Transmission Line Route - Lowering Segments 4 and 6 to below 500 feet ms] could reduce radial accumulations by one inch. For Segments 11-15 accumulations and winds can be reduced by staying within forest stands. (b) Intertie Route 3 (Copper River Route) - For Segments 14-18, 21-22, 25-30 accumulations and winds can be reduced by staying within forest stands. (c) Intertie Route 2 (Prince William Sound Route) - For Segments 31-85 accumulations and winds can be re- duced by staying within forest stands. Wet snow vertical loads could be reduced along the entire route by staying below 500 ft msl. Accumulations could be reduced by 0.5-1.0 inch radial by staying below 500 ft msl. (d) Silver Lake Transmission Route - For Segments 86-97 accumulations and winds can be reduced by staying within forest stands. (e) Solomon Gulch Alternate Route - For Segments 98-105 accumulations and winds can be reduced by staying within forest stands. (f) Jack Bay Alternate Route - For Segments 106-113 accumulations and winds can be reduced by staying within forest stands. B. Supplemental Data Collection Additional data collection is needed for those areas of the proposed routes for which scant or no measured data exists. The areas expecting the greatest winds and vertical icing loads had little or no wind and/or ice accumulation measurements to correlate with Cordova Mile 13 Airport. Ice accumulation is very strongly a function of wind speed. Therefore, wind speed and direction measurements are recommended at the locations presented in Table X-1 to verify and adjust, if necessary, the estimated wind and icing loads in this report. Included in Table X-1 is the recommendation for passive icing spans to identify and quantify icing periods and accumulations. A passive icing span is a system composed of two poles with a conductor strung from the tops of the poles. During significant icing episodes the spans could be observed for accumulation amount and density. This data would be helpful in determining representativeness of weather stations to the passive span site. A measurement period of one year is recommended; however, measuring between Spetember through May would cover the period between which the strong- est winds and icing events occur. Field measured winds could be correlated with the Cordova Mile 13 airport winds to develop long term summaries for the remote areas. Table X-1 RECOMMENDATIONS FOR INSTRUMENTATION OF REMOTE AREAS Location system North End of Long Island WS/WD/temperature, Passive Span Baird Canyon WS/WD/temperature, Passive Span Marshall Pass WS/WD/temperature, Passive Span Wortmanns . WS/WD/temperature, Passive Span Silver Lake Ridge WS/WD/temperature, Passive Span Rude River mouth WS/WD/temperature, Passive Span Mavis Island, Eyak Lake, Cordova WS/WD/temperature, Passive Span WS = Wind Speed, WD = Wind Direction To measure wind speed/wind direction/temperature, MRI proposes to use their Weather Wizard™. The Weather Wizard™ is a meteorological field measurement and storage system composed of wind and temperature sensors, electronic processing and storage package, cables, batteries, and solar cell to charge the battery. Hourly-average wind speed and direction measurements would be made and recorded onto a cassette tape. The cassette tape would then be dumped onto hard copy for the correlation with Cordova Mile 13 airport hourly weather observations. REFERENCES Bourgsdorf, V. V., E. P. Nikiphorov, and A. S. Zelitchenko, 1968: Ice loads on overhead transmission lines. Int. Conf. on Large High Tension Electric Systems, Paris, 10-20 June 1968, Paper 23-05. Bowling, S. A., 1980: The weather and climate of Alaska. Weatherwise, 33, 5, Heldref Publications, pp 197-201. Boyd, D. W., 1965: Climatic information for building design in Canada, Supplement No. 1 to the National Building Code of Canada, National Research Council NRC No. 8329, Ottawa. Brook R. R. and K. T. Spillane, 1970: The variation of maximum wind gust with height. J. Appl. Meteor., 9 (No. 1), pp 72-78. Brower, W. A., et al, 1977: Climatic Atlas of the Outer Continental Shelf Waters and Coastal Regions of Alaska, Vol. 1, Gulf of Alaska. Environmental Data Services, National Climatic Center, Asheville, North Carolina. Bryson, R. A. and F. K. Hare, 1974: Climates of North America. Elsevier Scientific Publishing Company, New York, New York. Camp, D. W., 1968: Low level gust amplitude and duration study. NASA T™ X-53771, George C. Marshall Space Flight Center, Huntsville, Alabama. Court, A., 1953: Wind extremes as design factors. J. Franklin Inst., 256, (No. 1), pp 39-55. Davis, F. K. and H. Newstein, 1968: The variation of gust factors with mean wind speed and with height. J. Appl. Meteor., 7, (No. 3), pp 372-278. Deacon, E. L., 1955: Gust variation with height up to 150 meters. Quart. J. Roy. Meteor. Soc. (London), 81, p 563. DeMarris, G. A., 1959: Wind speed profiles at Brookhaven National Laboratory. J. Meteor., 16, (No. 2), pp 181-190. Dept. of Transport, Canada, 1968: Climatic normals, Vol. 5, Wind. Meteorological Office, 315 Bloor St., W., Toronto, p 95. Durst, C. S., 1960: Wind speeds over short periods of time. Meteor. Mag., 89 (No. 1056), pp 181-186. Ficht], G. H., J. W. Kaufman, and W. W. Vaughan, 1969: Character of atmos- pheric turbulence related to wind loads on tall structures. J. Spacecraft, 6 (No. 12), pp 1398-1403. References (Continued) Fisher, R. A. and L. H. C. Tippett, 1928: Limiting forms of the frequency distribution of the largest or smallest number of a sample. Proc. Cambridge Phil. Soc., 24, Pt. 2, pp 180-190. Grice, G. K. and A. L. Comiskey, 1976: Thunderstorm Climatology of Alaska. National Weather Service, Regional Headquarters, Anchorage, Alaska. NOAA Tech. Memo., NWS AR-14,. Griffing, K. L. and D. C. Leavengood, 1973: Transmission line failures, Part I. Meteorological phenomena - severe winds and icing. Paper No. 73 CHO816-9 PWR, July 5-14. ; Hallanger, N. L. and M. C. Richmond, 1972: A meteorological study of the 345 kv transmission line route from the Jim Bridger plant site to Borah, Kinport, and Goshen substations. Prepared for Pacific Power and Light Company, Portland, Oregon. Purchase Order No. 7970-973. Higuchi, H., 1973: Wet snow accretion in Japan. Paper presented at Ice Accretion Group Meeting, Toronto, Canada, 29 March. Higuchi, H., 1974: Snow accumulation prevention methods on transmission lines. Unpublished report Engineering Department. The Research Department, Hokkaido Electric Power Company, Japan. Johnson, 0., 1959: An examination of vertical wind profile in the lowest layers of the atmosphere. J. Meteor., 16 (No. 9), pp 144-148. Kravitz, R. A. and D. C. Leavengood, 1973: Analyze the weather for safer design. Electric Light and Power, T/D Edition, January. Kuroiwa, D., 1965: Icing and snow accretion on electric wires. U. S. Army Materiel Command, Research Rept. 123. Langmuir, I. and K. Blodgett, 1945: Mathematical investigations of water droplet trajectories. General Electric Research Lab., Schenectady, N.Y. Leibfried, W. and H. Mors, 1964: The bundled conductor experimental station at Hornisgrinde, Germany. Leavengood, D. C. and T. B. Smith, 1968: Studies of transmission line icing. Rept. by MRI to Southern California Edison Company, Los Angeles, CA, Contr. No. L-2127, MRI 68 FR-801. McKay, G. A. and H. A. Thompson, 1969: Estimating the hazard of ice accretion in Canada from climatological data. J. Appl. Meteor., 8, pp 927-935. Mitsuta, Y., 1962: Gust factor and analysis time of gust. J. Meteor. Soc. (Japan), 40 (No. 4) pp 242-244. References (Continued) Munn, R. E., 1966: Descriptive micrometeorology. Advances in Geophysics, Academic Press, New York and London. Richmond, M. C. and R. J. Boomer, 1974: The meteorological study of the April, 1973, ice storm near Pentecote River and the meteorological evaluation of the 735 kv transmission routes from Churchill Falls to Quebec. Prepared for Hydro-Quebec, Canada, Cont. No. H09538-260. Ruffner, J. A., 1980: Climates of the States. Gale Research Company, Detroit, Michigan. Volume 1, Second Edition. Searby, H. W., 1969: Coastal Weather and Marine Data Summary for Gulf of Alaska, Cape Spencer Westward to Kodiak Island. Essa Technical Memo. EDSTM 8. Environmental Data Service, Silver Spring, MD. Shellard, H. C., 1965: The estimation of design wind speeds. Wind Effects on Buildings and Structures. National Physics Laboratory Symposium (No. 16), pp 30-51. Shellard, H. C., 1968: Tables of surface wind speed and direction over the United Kingdom. Meteor. Office, 792, Her Majesty's Stationary Office, London. Sherlock, R. H., 1947: Gust factors for the design of buildings. Int. Assoc. for Bridge and Structural Engineering, Vol. 8, pp 207-235. P Sherlock, R. H., 1952: Variation of wind velocity and gusts with height. Paper No. 2553, Proc. Amer. Soc. Civil Eng., pp 463-508. Sissenwine, N., P. Tattleman, D. D. Granthan, and I. I. Gringorten, 1973: Extreme wind speeds, gustiness, and variations with height for MIL-STD 210B. Air Force Cambridge Research Laboratories. Tech. Report 73-0560, Aeronomy Laboratory, Project 8624, p 72. U. S. Department of Commerce, 1978: Summary of Synoptic Meteorological Observation. Environmental Data Service, National Climatic Center, Asheville, North Carolina. U. S. Department of Commerce: 1959-1981 Storm Data. Environmental Data and Information Service, National Climatic Center, Asheville, NC. U. S. Department of Commerce, National Bureau of Standards, 1953: Probability tables for the analysis of extreme-value data. Appl. Mathematics Series 22, July 6. U. S. Department of Commerce, 1970: U.S. Naval Weather Service World-Wide Airfield Summaries, Vol 8, Part 8. National Tech. Information Service, Springfield, VA, AD-704-607. References (Continued) U. S. Department of Commerce, 1978: Climate of Cordova, Alaska. Climatography of the United States., No. 20. National Climatic Center, Asheville, NC. U. S. Department of Commerce, 1971: Anchorage to Valdez Area, Climatic Summaries of Resort Areas. National Weather Service, No. 21-49-7. Wade, J. E., and E. W. Hewson, 1980: A Guide to Biological Wind Prospecting. Prepared for the United States Department of Energy, Dept. of Energy Division of Distributed Solar Technology Federal Wind Energy Program by the Department of Atmospheric Sciences, Oregon State Univ., Corvallis, OR. Weiss, L. L., 1955: A nomogram based on the theory of extreme values for determining values for various return periods. Mon. Wea. Rev., 83, pp 69-71. eee) eh eel Wegley, H. L., M. M. Orgill and R. L. Drake, 1978: A Siting Handbook for Small Wind Energy Conversion Systems. PNL-2521, Pacific Northwest Laboratory, Richland, WA. Williams, J. A., 1981: Charting heavy Alaskan weather. Offshore, June 5, pp 49-54. Willis, R. A. and G. K. Grice, 1976: The Wintertime Arctic Front and its Effects on Fairbanks. National Weather Service, Regional Headquarters, Anchorage, Alaska. NOAA Tech. Memo., NWS AR-13. Wise, J. L., et al., 1980: Wind Energy Resource Atlas, The Alaska Region. Prepared for the Pacific Northwest Laboratory, Report No. PNL-3195 WERA-10. Young, H. F. and J. P. Schell, 1971: Icing damage to transmission facilities in Newfoundland. Canadian Electrical Assn. Transmission Meeting, Quebec, P.Q., October 25-28. c~ ‘ 2 . | Technical Report METEOROLOGICAL EVALUATION OF THE PROPOSED PALMER TO GLENNALLEN TRANSMISSION LINE ROUTE MRI 82 FR-1868 Lm === Submitted to: Lemco Engineers, Inc. P. 0. Box 28549 West County Branch St. Louis, Missouri 63141 Purchase Order No. 11104 Date: 23 April 1982 By: S. C. Gouze M. C. Richmond Meteorology Research, Inc. Box 637, 464 West Woodbury Road Altadena, California 91001 Telephone (213)791-1901 Telex 67542) A Subsidiary of Cohu, Inc. TABLE OF CONTENTS ACKNOWLEDGEMENTS SUMMARY re INTRODUCTION Il. SCOPE OF STUDY III. DATA SOURCES A. Climatological Data B. Supplemental Data IV. REGIONAL METEOROLOGICAL CHARACTERISTICS Vv. WINDS A. General Considerations B. Wind Speed and Wind Gust Relationships C. Variation of Wind Speed with Height D. Wind Data Analysis E. Wind Speeds Span Factors VI. ICING ALONG THE PROPOSED ROUTES A. General Considerations B. Identification of Icing Areas Along the Proposed Routes Vite LOADING PROBABILITIES BY SEGMENT A. Division of the Route into Segments B. Ice and Wind Loadings by Segment VIII. CONCLUSIONS IX. RECOMMENDATIONS A. Transmission Line Placement Due to Meteorological Factors B. Supplemental Data Collection REFERENCES ii “ACKNOWLEDGEMENTS Meteorology Research, Inc. (MRI) wishes to acknowledge all those persons who have assisted in the assimilation of the data used in this report. In particular, Mr. Del LaRue of Dryden and LaRue Consulting Engineers for his insights into wind storm damage and ice accumulation on distribution lines in the Matanuska Valley, as well as providing a heli- coptor to fly and survey the proposed route. MRI also wishes to thank Mr. Jim Filinghame of Copper Valley Electric and Mr. Jim Cadden of Matanuska Electric for their insights into wind damage and ice accumulations on distribution systems in the Copper River Valley and Matanuska Valley, respectively. Jim Wise and Rich Becker of the Arctic Environmental Information and Data Center were helpful in locating and providing clima- tological records for this study. Special thanks go to Mr. Bob Hillestad and Ms. Sue Callander both meteorologists with MRI, for their persistence and patience in extracting weather data from voluminous quantities of micro- fiche and paper records. iii ‘y SUMMARY A meteorological study was conducted for the purpose of determining probable extreme values of wind, ice loading, and combined wind on ice load- ing to be experienced along the proposed transmission line route between Palmer and Glennallen, Alaska. The study consisted of three phases: a field survey, climatology survey, and analysis and application to the proposed route. The field survey consisted of one aerial survey by helicopter of the entire proposed route. Local variations in terrain were studied with regard to elevation and exposure. Evidence of strong windy areas were identified by the use of vegetative indicators such as tree flagging and blow down areas. In addition, interviews were conducted with personnel who live and work in the area of the proposed line and are familiar with the winds and storms which occur there. Also, weather records were secured from agencies in and near the route area. The climatology survey consisted of a review of all pertinent materials available in-house at Meteorology Research, Inc. (MRI), and summarized data from the National Climatic Center (NCC). In addition, weather records were secured in the study area from the University of Alaska, Arctic Environmental Information Data Center and the National Weather Service. In the analysis phase, the weather data collected from the reporting stations were processed and analyzed to develop probabilities of occurrence of extreme winds, vertical ice loads, and transverse wind on ice loads along the proposed route taking into account terrain and elevation effects. The proposed route will traverse through two climatic zones. The western portion will span the transition zone through the Matanuska Valley, and the eastern portion will span the continental zone through the Copper River Basin. Highest extreme winds of 85 mph from the east are expected for a 50- year return period value between PI-21 and PI-23 (Lions Head) in the Matanuska Valley. Significant accumulations of icing will occur along the route from glaze, rime, and hoar frost. Mixed icing (rime with hoar frost) is expected to be the highest along the eastern end of the line in the Copper River Basin with 50-year return period vetical loading values of 1.31 1bs/foot (conductor) and 0.66 1bs/foot (shield wire). Glaze icing is expected to be uniform along the entire route with 50- year return period vertical loadings of 0.41 Ibs/foot (conductor) and 0.06 lbs/foot (shield wire). iv The highest vertical ice loadings for a 50-year return period are ex- pected along the Sheep Mountain ridge with values of 2.28 1bs/foot (conductor) and 1.47 lbs/foot (shield wire). The portion of line spanning the eastern and southern slopes of Slide Mouuntain at the western side of the Copper River Basin are expected to have the highest transverse wind on ice loadings with 50-year return period values of 0.904 lbs/foot for the conductor. I. INTRODUCTION Lemco Engineers, Inc. is studying the technical feasibility of design and construction of a transmission line between Teeland Substation (near Palmer) and Glennallen, Alaska. Meteorology Research, Inc. (MRI) was com- missioned to conduct a study to determine the probable extreme values of wind loading, ice loading and wind on ice loading along the proposed route. This report presents the results of that study. The contents of the study contain the following sections. The scope of the study and data sources are outlined in Section II and III, respectively. The regional meteorological characteristics are discussed in Section IV, and the winds are analyzed in Section V. Analyzed in Section VI is icing, and loading values by line segment are tabulated in Section VII. Conclusions are “summarized in Section VIII. Finally, recommendations are discussed in Section IX. II. SCOPE OF STUDY This transmission line study consisted of three phases, as follows: S Field survey . Climatology survey . Analysis of data and application to the proposed route The field survey consisted of an aerial survey using a helicopter by one of the meteorologists who related the station data to the actual route. Local variations in terrain were studied with regard to elevation and exposure. Also, the distribution and density of forest cover were studied. Evidence of strong windy areas were identified by the use of vegetative indicators such as tree flagging and tree blow down areas. In addition, interviews were conducted with personnel who live and work in the area and are familiar with the winds and storms which occur there. Also, weather records pertaining to the route area were secured from local agencies. The climatology survey consisted of a review of all pertinent materials available in-house at MRI, as well as microfiche and paper copy records, and summarized data from the National Climatic Center (NCC) in Asheville, North Carolina. The NCC data included records of maximum wind speed tabulations and hourly weather observations. In addition, weather records were secured in the study area from the University of Alaska, Arctic Environmental Information Data Center, Anchorage; and the National Weather Service Office, Anchorage, Alaska and reviewed. In the analysis phase, the climatological data was processed and for each weather station return period probabilities were developed of maximum wind speeds, ice loads, and combined wind on ice loads. Then the return period probabilities developed in the analysis phase were utilized in combination with terrain effects to establish estimates of wind and ice loads to be expected along the proposed transmission line route. oe Ill. DATA SOURCES Data utilized in the preparation of this study consisted of climatolo- gical and supplemental data. A. Climatological Data Historical meteorological data from FAA and military stations in the form of hourly weather observations were obtained from the archives of the NCC. This data includes wind speed and direction, temperature, precipitation, and cloud conditions. Microfiche and paper copies of the hourly data were available for the stations listed below along with the period of record. Elmendorf AFB 1-01-46 through 10-31-53 4-01-56 through 12-31-80 Gulkana 7-01-48 through 12-31-73 Sheep Mountain 2-20-43 through 12-31-50 Additional data in the form of annual maximum hourly wind speed by direction summaries were obtained from the NCC for the weather stations listed below. The period for which the summaries were developed are also listed. Anchorage International Airport 1-1-54 through 12-31-77 Gulkana 1-1-49 through 12-31-64 In previous projects, the NCC has developed for MRI a computer program for summarizing maximum wind speeds, and this was used once again in this project. Additional meteorological data was obtained through the University of Alaska, Arctic Environmental Information and Data Center (AEIDC) in Anchorage, Alaska. These data include surface weather observations taken in a frequency from 3-15 times per day. The meteorological data was in the form of microfiche and the stations obtained along with the period of record are listed below. Gulkana 1-01-79 through 2-15-79 Palmer 1-01-73 through 12-31-80 Snowshoe Lake 1-01-73 through 12-31-80 Sutton 12-30-77 through 12-31-80 Tahneta Pass 3-12-78 through 12-31-80 The weather observations included wind speed and direction, temperature, preci- pitation, and cloud conditions. Additional climatological data from AEIDC were in the form of paper copy records of monthly average precipitation, monthly average snowfall and absolute maximum and minimum temperature. The data was available for the following stations. Included in the list below is the period of record for the parameter measured the longest time. Wasilla 2 NE 1965-1976 Wasilla 3 S 1951-1975 Snowshoe Lake 1963-1976 Matanuska Agricultural Experimental Station 1917-1975 Palmer 1N 1941-1970 Glennallen 1966-1976 Climatological data was also available in-house at MRI. Pertinent data included records of monthly storm data and unusual weather phenomena for the period 1959-1981 published by the U.S. Department of Commerce. Temperature and precipitation averages and extremes were available for Chickaloon, Eureka, and Glennallen from a U.S. Department of Commerce publi- caton, Climatic Summaries of Resort Areas. Monthly average precipitation tabulations were available for Matanuska Agricultural Experimental Station as well as normals, means, and extreme weather data for the Matanuska Agri- cultural Experimental Station and Gulkana. The data for Gulkana and the Matanuska Agricultural Experimental Station were contained in the NOAA publication entitled, "Climates of the States." Additional data available in-house also included climatological summaries for Palmer, Elmendorf AFB, and Gulkana from the U.S. Naval Weather Service World-Wide Airfield Summaries. Summaries included absolute maximum and minimum temperatures, mean monthly precipitation, mean snowfall, and mean number of days with thunderstorms. B. Supplemental Data At the time of the route and data acquisition survey in Anchorage, several people with first-hand experience with the winds and icing periods in the area of the proposed transmission line route were interviewed. Fore- casters with the National Weather Service in Anchorage were interviewed for the synoptic conditions conducive to extreme wind and icing events. A utility engineer and a former utility engineer with Matanuska Electric and the utility manager for Copper Valley Electric were interviewed for their observations of ice accumulations and wind damages to the local power lines. Meteorologists in-house at MRI were interviewed for their forecasting experience related to extreme weather events in the area of the proposed line. IV. REGIONAL METEOROLOGICAL CHARACTERISTICS The Palmer-Glennallen route traverses two climatic zones. The western portion of the route from Palmer through the Matanuska Valley spans the transition zone. The eastern portion of the route from Slide Mountain to Glennallen spans the continental zone. The transition zone is characterized by a mixture of cool, moist weather as found in mari- time climates and cold, dry weather found in continental climates. For the western portion of the line, absolute maximum tempera- tures could reach 90°F and absolute minimum temperatures as low as -40°F, as measured at Wasilla (see Tables IV-1 and IV-2). Precipitation would average around 16 inches with most falling in the summer months as rain (see Tables IV-3). Annual snowfall amounts average in the 50 inch category with most falling in the winter months (see Table IV-4). Thunderstorms occur with a low frequency of 1.3 days annually, mainly during the summer months (see Table IV-5 and Figure IV-1). The eastern portion of the line would probably experience absolute maximum temperatures of 90°F, as measured at Glennallen, with cooler maxi- mums of 85°F above 3000 feet mean sea level (msl), as measured at Eureka (see Table IV-1). Absolute minimum temperatures have reached -44°F at Eureka, above 3000 feet mean sea level, and -65°F at Gulkana in the Copper River basin. Precipitation would average around 10 inches in the Copper River basin along the eastern portion. Higher amounts would be expected adjacent to the Talkeetna Mountains near Eureka averaging 12 inches (see Table IV-3). Mean annual snowfall amounts average 50 inches in the Copper River basin with amounts doubling adjacent to the Talkeetna Mountains, as seen from Eureka measurements (see Table IV-4). Thunderstorm amounts increase eastward from the transition zone to the continental zone. The average number of thunderstorm days increases to four through the Matanuska Valley and reaches eight over the Copper River basin as shown in Figure IV-1. »s B | @ Table IV-1 ABSOLUTE MAXIMUM TEMPERATURE FOR VARIOUS ALASKA CLIMATOLOGICAL STATIONS ALONG THE PROPOSED LINE ROUTE Absolute Maximum Temperature Int'l] Merrill Elmendorf Wasilla Wasilla Matanuska Palmer Chickaloon Eureka Snowshoe Glennallen Gulkana Mo. | Airport Field AFB 3s 2 NE Lake Anchorage Anchorage Anchorage JAN 56 48 49 52 45 51 51 38 46 34 39 46 FEB 57 50 58 53 50 51 56 44 40 41 47 46 MAR 56 52 50 55 53 55 54 53 42 51 51 47 APR 63 62 63 68 65 67 68 57 50 53 60 67 MAY 82 82 80 80 80 81 84 82 75 73 77 85 JUN 86 86 84 90 87 89 90 86 85 85 90 89 JUL 83 83 83 85 84 85 85 86 79 79 88 91 AUG 82 80 81 83 84 87 81 89 79 80 83 85 SEP 73 72 74 716 71 75 eae 72 65 68 68 71 oct 63 62 62 67 65 64 66 64 51 57 65 57 NOV 60 53 57 55 50 54 55 50 44 44 45 48 DEC 53 47 53 51 48 50 51 35 37 39 42 44 Annual 86 86 84 90 87 89 90 89 85 85 90 91 Note: Differences in temperatures between two nearby locations due to varying periods of records and local variations. e l) Table IV-2 ABSOLUTE MINIMUM TEMPERATURE FOR VARIOUS ALASKA CLIMATOLOGICAL STATIONS ALONG THE PROPOSED LINE ROUTE Absolute Hintmum Temperature Int'] Merrill Elmendorf Wasilla Wasilla Matanuska Palmer Chickaloon Eureka Snowshoe Glennallen Gulkana Mo. | Airport Field AFB 3S 2 NE Lake Anchorage Anchorage Anchorage JAN -35 -35 -36 -40 -39 -40 -35 -39 -43 -55 -57 -60 FEB -38 -38 -43 -30 -26 -30 -33 -40 -44 -49 -60 -65 MAR -24 -20 -24 -30 -28 -30 -26 -30 -39 -53 -34 -48 APR -21 0 -20 -2 -4 -1 -17 -20 -14 -30 -11 -42 MAY 1 3 -1 2 20 15 3 14 -8 -10 12 9 JUN 31 32 33 31 30 30 33 25 18 24 25 28 JUL 35 38 34 31 32 34 38 29 30 27 27 30 AUG 31 31 29 22 29 28 29 29 26 17 17 20 SEP 19 20 20 v7 17 20 v7 13 19 3 0 7 oct -6 0 -6 -8 -9 -7 -6 0 -18 -29 -25 -23 NOV -21 -20 -20 -19 -19 -20 -18 -17 -32 -46 -44 -44 DEC -33 -33 -34 -30 -30 -37 -27 -33 -43 -63 -56 -53 Annual -38 -38 -43 -40 -39 -40 -35 -40 -44 -63 -60 -65 Note: Differences in temperatures between two nearby locations due to varying periods of records and local variations. Table IV-3 MONTHLY AND ANNUAL MEAN PRECIPITATION FOR VARIOUS ALASKA CLIMATOLOGICAL STATIONS ALONG THE PROPOSED LINE ROUTE Mean Precipitation (inches) Int'l Merrill Elmendorf Wasilla Wasilla Matanuska Palmer Chickaloon Eureka Snowshoe Glennallen Gulkana Mo. | Airport Field AFB 3s 2 NE Lake Anchorage Anchorage Anchorage JAN 0.80 1.18 1.08 0.83 0.51 0.79 0.98 0.86 0.76 0.33 0.29 0.63 FEB 0.71 0.59 0.96 0.96 0.50 0.63 0.71 0.93 0.85 0.54 0.77 0.45 MAR 0.51 0.58 0.67 0.79 0.62 0.52 0.56 1,22 0.67 0.38 0.23 0.32 APR 0.42 0.32 0.51 0.70 0.75 0.62 0.47 0.36 0.49 0.22 0.11 0.17 MAY 0.52 1.12 0.52 1.01 0.85 0.75 0.61 0.49 1.23 0.87 0.60 0.47 JUN 0.98 1.32 1.06 1.59 1.76 1.61 1.45 1.04 3.17 2.14 1.44 1.14 JUL 1.86 1.79 2.37 2.39 2.49 2.40 2.49 1.68 2.62 2.32 1.51 2.03 AUG 2.57 2.77 2.69 2.84 2.84 2.61 3.34 1.94 2.18 1,79 1.17 1.85 SEP 2.50 2.76 2.46 2.42 2.62 2.31 2.75 2.30 1.38 0.97 1.02 1.89 oct 1.87 1.68 1.51 1.88 1.60 1.39 1.50 1.32 0.85 0.74 0.57 0.87 NOV 1.03 1.03 1.22 0.97 0.83 0.93 0.92 0.96 0.83 0.69 0.57 0.87 DEC 0.94 1.01 1.46 1.12 0.98 0.93 0.80 0.90 0.98 0.70 0.63 0.86 Annual 14.71 16.15 16.51 17.50 16.35 15.49 16.58 14.00 16.01 11.69 8.91 11,55 Note: Large Differences between nearby stations likely due to local variations and varying periods of record. Table IV-4 MONTHLY AND ANNUAL MEAN SNOWFALL FOR VARIOUS ALASKA CLIMATOLOGICAL STATIONS ALONG THE PROPOSED LINE ROUTE Mean Snowfall (inches) Int'] Merrill Elmendorf Wasilla Wasilla Matanuska Palmer Chickaloon Eureka Snowshoe Glennallen Gulkana Mo. | Airport Field AFB aS 2 NE Lake Anchorage Anchorage Anchorage JAN 11.9 18.3 11.8 8.5 7.5 7.9 12.8 11.3 15.7 5.2 5.8 8.5 FEB 10.6 9.4 8.2 10.3 9.7 10.2 11.6 12.6 18.3 6.5 6.9 5.7 MAR 7.8 9.8 10.0 6.2 8.3 6.3 9.6 13.7 14.7 5.5 2.9 4.4 APR 4.1 2.9 6.1 1.6 5.1 2.7 3.0 2.2 7.9 3.2 1.6 1.3 MAY 0.5 0.8 0.4 0.2 0.6 0.1 0.6 0 2.3 2.7 0.3 0.5 JUN T 0 0 0 0 0 0 0 0.3 0.1 0 0 JUL 0 0 0 0 0 0 0 0 0.1 0 0 0 AUG 0 0 0 0 0 0 0 0 0.5 0.2 0 0.2 SEP 0.1 0 0.1 T 0.1 0.2 0.2 T 3.2 1.8 1.5 1.1 ocT 6.1 5.6 5.9 3.5 7.3 4.8 6.0 4.6 17.9 9.6 6.6 6.8 NOV 10.8 10.8 11.9 5.6 7.6 9.0 9.6 9.3 15.5 8.9 9.9 10.1 DEC 12.9 18.4 13.1 11.4 11.5 9.5 11.2 14.2 20.4 9.6 5.5 9.7 Annual 64.8 76.0 67.5 47.3 57.7 50.7 64.6 67.9 116.8 53.3 41.0 48.3 T = Trace Note: Large Differences between nearby stations likely due to local variations and varying periods of record. Table IV-5 THUNDERSTORM SUMMARY FOR VARIOUS STATIONS ALONG THE PROPOSED ROUTE Mean Number of Days With Thunderstorms Month International Airport fTemendort AFB Palmer Anchorage Anchorage JAN 0 0.1 0.1 FEB ) i) 0 MAR 0 0 0 APR 0 | |e 0 MAY 0.1 0 0 JUN 0.2 0.5 0.5 JUL 0.5 0.2 0.2 AUG 0.4 0.3 0.3 SEP 0.1 0.2 0.2 OCT 0 0 0 NOV 0 ) i) DEC 0 0 0 Annual 1.3 133 Les IT Figure IV-1. Isolines of Average Number of Thunderstorm Days from May 11 to August 31 for the 6-Year Period, 1969-1974. Line A-B is the Proposed Palmer- Glennallen Route. (Source: ‘NOAA, 1976) Vv. WINDS A. General Considerations Three types of meteorological conditions can result in strong winds over the area traversed by the proposed transmission line route. Summer and fall thunderstorms occur, but are of a significantly low frequency of occurrence. However, the winds associated with these thunderstorms can be strong and gusty, but are difficult to predict due to the localized nature of these storms. The second type of wind flow pattern producing strong winds occur in conjunction with storms associated with low pressure centers in the Gulf of Alaska. These moist winds are generally from the east to southeast and are associated with rain and/or snow storms that move through the area in the fall through spring months. The third type of strong wind occurs from a high pressure area build- ing in the interior of Alaska with an approaching low pressure center in the Gulf of Alaska during the winter months. These pressure gradient winds are extremely strong when accompanied by strong north to east winds aloft. At the surface these strong winds are accelerated through mountain passes, canyons, and long glacial tongues oriented in the same direction of the wind. B. Wind Speed and Wind Gust Relationships The actual duration of the sustained wind speed reported at a weather station depends greatly on the weather observer. The observer reads the value from dial or chart once each hour and records it in a log. Occasionally, if weather conditions (cloud cover or visibility) are changing rapidly, he may record special observations between the scheduled hourly observations. The hourly wind speeds recorded at these locations are one-minute average wind speeds occurring sometime during the ten minutes prior to the hour. In practice, the dial is probably observed for less than a minute. When the wind speed is fluctuating rapidly, the observer may record an average or most frequent value and a maximum (gust) speed occurring during the minute of observation. Wind speed data used in this study were derived from one-minute aver- ages from climatological station records. Gusts reported in the records were of unknown duration and it is doubtful that they were the peak gusts which occurred. Many studies of the relationship of gusts to the steady wind and their variation with speed, height, thermal stratification, and terrain have cul- minated in general agreement concerning the nature of these relationships (Sissenwine et al., 1973; Brook and Spillane, 1970; Ficht] et al., 1969; Camp, 1968; Davis and Newstein, 1968; Boyd, 1965; Shellard, 1965; Mitsuta, 1962; Durst, 1960; Deacon, 1955; Sherlock, 1947 and 1952;-and others). However, quantitative results have varied, depending on the analytical methods and data used. 12 Most studies of gustiness are from micrometeorological research. Because of refined anemometry, measurements obtained from such experiments are generally superior to operational data; however, such studies seldom provide data for the very high wind speeds important in design of trans- mission towers and conductors. Sissenwine, et al. (1973), analyzed a more meaningful spectrum of wind speeds and this work appears to be one of the better recent efforts in this field. Their study included the analysis of 548 wind observations taken at anemometer heights varying from 10 to 85 feet, with one-minute wind speeds varying from 20 to over 70 knots, and locations varying from tropical Pacific islands to Alaska and Greenland. Since recorder charts of steady winds greater than 70 knots were scarce (only 10 cases of the 548 studied), they also used 26 observations of gust factors for five-minute steady winds, ranging from 71 to 163 knots taken at Mt. Washington, New Hampshire, and four values derived from wind data taken during hurricanes that passed close to the Blue Hill Observatory near Boston, Massachusetts. Sissenwine, et al. (1973), found that a least-squares relationship (G.F. = 1 + 0.55 e79-0093V) best fit the median (50 percentile) two-second gusts related to five-minute steady speeds. Two-second gusts thus derived ranged from 1.46 times a five-minute steady speed of 25 knots (29 mph) to 1.22 times a five-minute steady speed of 100 knots (115 mph). In Table V-1 and Figure V-1, they show the relationship of other gust durations to five-minute steady speeds. One of the most widely used relationships for computing gust speeds was derived by Boyd (1965). His formula, G = 5.8 + 1.29 V, gives gust — vs speeds (G) in miles per hour based on hourly wind speeds (V) in miles per hour. At the time he derived this formula, the gust data used were thought to be of approximately three-second duration; however, in a recent telephone conversation, Mr. Boyd stated that he now believes the response time of the pressure tube anemometer and its. recorder, from which his data were collected, to be on the order of five to eight seconds. Another often referenced authority, Durst (1960), developed a statis- tical model based on samples taken with a high speed recorder. Although his empirical data were taken at speeds less than 42 miles per hour, he applied his model to class intervals of speed up to 80 mph. As Table V-2 shows, his probable gust factors for various duration gusts are nearly the same for all speed classes. If we combine the Durst relationships for hourly speeds to five- minute gusts (interpolated) with the Sissenwine, et al. (1973) relation of five-minute to two-second speeds, we find that the resulting gust factors for two-second gusts from hourly winds vary from 1.6 to 20 mph to 1.4 at 80 mph. This is nearly exactly what the Boyd formula of G = 5.8 + 1.29 V results in for five-second gusts. 12 ) Table V-1 GUST FACTORS VERSUS 5-MINUTE STEADY WIND SPEED (Sissenwine, 1973) 5-min Gust Factor (GF) Speed -sec O-sec -sec (knots) 20 1.120 1.172 1.4566 30 1.105 1.151 1.4160 40 1.094 1.134 1.3791 50 1.085 1.121 1.3454 60 1.077 1.111 1.3147 80 1.066 1.095 1.2613 100 1.057 1.081 1.2170 125 1.049 1.069 1.1719 150 1.042 1.059 1.1363 175 1.035 1.050 1.1080 200 1.028 1.040 1.0856 14 ) Figure V-l. iA 2 . GUST FACTOR us ue is Gust Factors Versus 5-Minute Steady Wind Speed (Sissenwine, 1973) 15 Table V-2 PROBABLE (50 PERCENT) GUST FACTORS FOR 20- TO 80-MPH AVERAGE HOURLY SPEEDS USING DURST's MODEL Mean Hourly Gust Factor (GF) Speed 600 sec 60 sec 30 sec 20 sec 10 sec sec (mph) 20 1.05 1.25 1.30 1.35 1.40 1.50 30 1.07 1.23 1.33 1.37 1.43 1.47 40 1.07 1.25 1.32 1.35 1.42 1.48 50 1.06 1.24 1.32 1.36 1.42 1.48 60 1.07 1.24 1.32 1.35 1.42 1.48 70 1.06 1.24 1.31 1.36 1.41 1.49 80 1.06 1.24 1.33 1.36 1.43 1.48 16 From the above discussion of the most frequently referenced sources currently, it is apparent that there are no hard and fast relationships to use in relating speeds of different averaging times. Wind near the earth's surface is very sensitive to the terrain; consequently, any particular location is likely to have its own gust characteristics. Since many of the data available for study are in the form of hourly wind speeds, we feel that Boyd's formula is still the most applicable. Based on his current understanding of the response time of the equipment used in the formation of his data base, we recommend that his formula be used for predicting five-second gust speeds from hourly-average wind speeds and two- second gust speeds from five-minute average wind speeds. The higher value of 6.4 + 1.43 V should be used for predicting two-second gust speeds from hourly average wind speeds. C. Variation of Wind Speed with Height In the extrapolation of station data to remote transmission line routes, it is necessary to take a number of factors into consideration. Among these are differences in elevation and exposure, type of terrain in the area, possible areas of channeling or funneling of gradient winds, and height above the terrain of the conductors. A height of 30 feet above the ground surface was chosen as the level to compute the wind speeds for this study. If a lower or higher effective height is desired, the wind speeds could be reduced or increased slightly, accordingly. There have been many studies undertaken and theories presented on the variations of ‘wind speed with height above the surface. There is general agreement that wind profiles tend to obey a power law (Munn, 1966; De Marrais, 1959; and Johnson, 1959). This relationship is normally used wheg neutral stability exists. The power law is of the form Vo/Vq = (Zo/ Z;) » Where V, is the wind speed at some known level, Z,, and Vo is the wind speed at the desired level, Zp. The exponent, P, is dependent on the atmospheric temperature lapse rate, wind speed, and ground roughness. There is less agreement as to what the value of P should be. It is larger under a stable vertical temperature gradient and smaller for neutral and unstable conditions; it decreases with increasing wind speeds and increases somewhat with terrain roughness (De Marrais, 1959). The typical value used for P is 1/7 or 0.143 (Sherlock, 1952). Even Sherlock recognized that this P value was applicable to steady or mean winds and that gusts were better described with a value of P = 0.0625. Shellard (1968), in the Table of Surface Wind Speed and Direction over the United Kingdom, used P values of 0.17 for mean hourly wind speeds and 0.085 for three-second gusts. The majority of studies of wind profiles are made under regimes of light-to-moderate wind speeds and P values resulting from such studies may not be applicable to high wind speeds. Sissenwine, et al. (1973), using high wind speed data collected at the Argonne National Laboratory instrumented tower in Argonne, Illinois, derived the empirical equation P = 0.077 + 1.56/ Vj, where the limiting P value approaches 0.077 as Vj becomes very large. 17 The Argonne National Summaries present a percentage frequency of P values versus the ten-minute average wind speeds. The data for the table contain about 35,000 observations. For wind speeds greater than 24 mph, the median P value is about 0.125. For computations in this study, we have used a P value of 0.125 for wind speed (Vj) values up to 50 knots (58 mph) and a P value of 0.080 for values of Vj over 50 knots. The anemometer heights during the periods of record of the five stations analyzed in this study are listed in Table V-3. D. Wind Data Analysis . The first step in the analysis was to rank all yearly extreme speeds for Anchorage International, Gulkana, Palmer, and Sheep Mountain in ascending order, compute the probability of occurrence of each speed, and plot the points on extreme probability paper of the Fisher-Tippett type I or Gumble distribution (Fisher and Tippett, 1928; U.S. Department of Commerce, 1953). This is a symmetric, extreme probability distribution cited by Court (1953) as particularly applicable to extreme surface winds and the distribution adopted by the Canadian Department of Transport (1968). Figures V-2 through V-5 show the plots for Anchorage International, Gulkana, Palmer, and Sheep Mountain. The mean and standard deviation of each stations extreme wind distri- bution was calculated and the characteristic line drawn using the relationship given by Weiss (1955). The line for each station is shown in Figures V-2 through V-5. (If the data points in a particular figure had a truly Gumble distribution, they would all fall on the line.) The speed to be equalled once in a given return period can be determined from these lines. The 25-, 50-, and 75-year return period wind speeds for 30 feet above the ground are summarized in Table V-4 for Anchorage International, Gulkana, Palmer, and Sheep Mountain. Included is the number of years of record and the probable direction of the extreme wind. As Table V-4 indicates the probable direction of the extreme wind is most likely to occur from the north-northeast through east-northeast for the four weather stations. However, Gulkana could have extreme winds from the south-southeast. The distribution of extreme winds by month and direction for Anchorage International, Gulkana, Palmer, Sheep Mountain, and Snowshoe Lake are given in Tables V-5 and V-6, respectively. An extreme probability analysis was not done for Snowshoe Lake due to an insignificant period of record of hourly wind observations. When in a particular year the annual extreme one-minute average wind speed occurred in more than one month and/or from more than one direction, each occurrence was counted. Thus, the totals for each station do not neces- sarily equal the years of data. For the majority of cases, as is shown in 18 & Table V-3 PERIODS OF RECORD AND ANEMOMETER HEIGHTS FOR THE STATIONS ANALYZED Height of Instrument Location Years of Record Above Ground ————— a Nea eae Anchorage Int'l 1-1-54 through 6-19-62 75 6-20-62 through 12-31-77 56 Elmendorf AFB 1-1-46 through 2-27-53 45 3-1-53 through 4-12-56 45 4-13-56 through 12-31-60 80 1-1-61 through 12-31-80 14 Gulkana 7-1-48 through 9-26-73 30 9-27-73 through 2-15-79 20 Palmer 1-1-73 through 12-31-80 18 Sheep Mountain 2-20-43 through 12-31-50 24 eee 19 02 WIND SPEED (mph) 1) EXTREME PROBABILITY PAPER RETURN HLH IOD (Yeors) 1001101 1h ta ta tens beenan one te 2 hos 20 900400 900 1000 Ron ates = | in} a | ' alee | tit i - | ot ‘ —-+— : ' ' | ' hee tito j i ‘ ' ! | i ' i = s t wie ll EEL Loniitiriitis Se tt ea eet betieenst bids a had -40 “4s Ao O89 o as se se ao as so as +o cd so as so os me REDUCED VARIATE ill il 5 oo ” enonaanity [19% Figure V-2. Maximum Wind Speed Probabilities for 30-foot Level at Anchorage International Airport, Alaska (Data Base 1954-1977) Lo WIND SPEED (mph) Ligiapiiipbirriiiis L scitpiltieen roi tistrisriata Hotisiittirieritibiriiiss ri bastitirii -10 “19 in til le hil i Figure V-3. wy EXTREME PROBABILITY PAPER RETURN FE KIO (Yeors) | dell il Eas lia ji reeRtrTy (2%, 3 10 “s 10 as so as 1 cay as so MEQUCED VARIATE Maximum Wind Speed Probabilities for 30-foot Level at Gulkana, Alaska (Data Base 1949-1964) as 70 ve WIND SPEED (mph) 90— . Loseorreratirrrirsiiliies eiiueignislasss tprobertrstopadoroass -20 “1s 0 08 o as Figure V-4. () EXTREME PROBABILITY PAPER AL TURN PEHIOO (Years) to ” . Hl [ Faia prosasiuity [2 %.,)) é i | All ro ” ” “e wr me i il! il | ' ! i cll | ! 10 ss 20 as se a so oe so a9 so REOQUCED VARIATE Maximum Wind Speed Probabilities for 30-foot Level at Palmer, Alaska. (Data Base 1973-1980) STaDEEaanaE iB i } \ ' t } at os ee ptotoappacatedertoriiid re te WIND SPEED (mph) + 2 “| 0 =a ee -20 ad se Od e a. Figure V-4. | ) EXTREME —— PAPER Mt Fut Ha MLOU iVee ies Daal ~ ” ” or or owe enoeasiuity [s5- in rl REQUCED VARIATE Maximum Wind Speed Probabilities for 30-foot Level] at Sheep Mountain, Alaska (Data Base 1943-1950) sages fe? ee lia (ie i. | EEL Ty ie: ae = Mel eee fe {con rat | j leh to: eels SS bi fo | i] 1 | PER PRBERE: Aittetanet dase rsars bisepsaeee besas acaba retasaas boned 40 as ae as se as 70 os se ae so as re & | Table V-4 RETURN PERIOD VALUES OF MAXIMUM ONE-MINUTE HOURLY WINDS FOR FOUR ALASKA STATIONS ALONG THE ROUTE Period Return Period Probable Location of Record 25 50 1 Direction (Years) Anchorage Int'l 24 51 56 58 NNE Gulkana 16 55 59 61 SSE, NNE Palmer* 8 67 74 78 NE Sheep Mountain** ; 8 63 69 72 ENE cm * Estimated using less than 24 observations per day ** Estimated based on 24 observations per day v 24 Table V-5 DISTRIBUTION OF EXTREME WINDS BY MONTH FOR PERIOD OF RECORD “Anchorage ~~~ ~~~ Sheep Snowshoe Int'l Gulkana Palmer* Mountain Lake* 1954-1977 1949-1964 1973-1980 1943-1950 1973-1980 JAN 8 3 S 3 A; FEB 5 2 a 2 0 MAR 0 2 2 2 z APR 3 3 0 0 0 MAY 0 3 0 0 2 JUN ft) 1 0 0 0 JUL 0 0 0 0 1 AUG 1 0 0 0 1 SEP 1 3 1 0 1 OCT 0 3 0 0 1 NOV i 2 1 1 1 DEC 7 2 0 4 2 * Based on less than 24 observations per day OB N NNE NE ENE E ESE SE SSE Ss SSW SW WSW W WNW NW NNW * Based on less than 24 observations per day Anchorage Int'] 1954-1977 5 oOo OO CO OWN WORK OOF Of nN Table V-6 DISTRIBUTION OF EXTREME WINDS BY DIRECTION FOR PERIOD OF RECORD Gulkana 1949-1964 z oo oooown Or FY OF wm ) Palmer* 1973-1980 26 0 ao OO CO COCO OCOOUNC NOOO OF PF eS Oo Sheep Mountain 1943-1950 0 oo o or NTO TO CO COON YO NY CO Snowshoe Lake* 1973-1980 1 rPoooeoroeFrPRrH OO CO CAO CO CO Table V-5, the extreme winds over the whole route area occur in the fall through spring months. The distribution of direction of the extreme wind speeds as seen in Table V-6 indicates northerly or southerly quadrants for Anchorage International, Gulkana and Snowshoe Lake and northeasterly quadrants for Palmer and Sheep Mountain. Channelling of winds are responsible for the extreme wind directions at Palmer and Sheep Mountain; whereas, in the more exposed areas of Anchorage International, Gulkana, and Snowshoe Lake the ex- treme wind directions occur from other quadrants as well. The distribution of wind directions indicates that the route will be affected significantly by channeling in the Matanuska Valley with the majority of extreme winds from the easterly quadrant. Where the terrain results in exposure from all directions, as in the Copper River Basin, extreme wind directions could occur from any direction. Weather records in the Matanuska Valley indicate that extreme winds occur during clear to partly cloudy skies associated with cold air drainage flowing from the interior of Alaska to the Gulf of Alaska. Copper River Basin data indicated extreme winds occurring mostly with cloudy and stormy weather with directions either south or north. Some slight channeling of extreme winds is evident in the Gulkana data by the Copper River Valley. The north-northeast and south-southeast winds are the result of valley channeling. ES Wind Speed Span Factors Span factors for transmission lines are a function of the scale of wind experienced by the cable. The scale of wind is dependent on the aver- aging period and terrain encountered. Wind gusts of five seconds are of small scale extent, covering perhaps 100 feet of span at one time. Steady winds upwards of one minute may engulf up to 1000 feet of span at one time. Steady winds produced by low pressure center storms can be steady for periods upwards of one to two days and engulf a large area of 100's of miles. How- ever, mountainous terrain can create very complex wind patterns and turbu- lence. Therefore, over mountainous terrain winds can be highly unsteady and unpredictable. ; 27 ) VI. ICING ALONG THE PROPOSED ROUTES A. General Considerations The basic theory of ice growth and the accretion of snow on cylinders (transmission lines) was developed by Langmuir and Blodgett (1945) from studies conducted on Mt. Washington. Additional studies of icing of trans- mission lines during various meteorological conditions have been conducted by the Japanese (Kuroiwa, 1965), the Germans (Leibfried and Mors, 1964), the Americans (Leavengood and Smith, 1968; Hallanger and Richmond, 1972; Richmond and Boomer, 1974; and Boomer and Richmond, 1975) the Russians (Bourgsdorf, et al., 1968), and the Canadians (McKay and Thompson, 1969; and Young and Schell, 1971). Basically, four types of frozen deposits will accumulate on trans- mission lines. These are classified according to the density of the ice accreted as: glaze, rime, wet snow, and hoar frost. 1. Glaze Glaze with a density of 0.9 to 0.92 g/em3 is equal to pure ice. Glaze grows under the conditions that the impingement rate is greater than the freezing rate. The deposited water drops cannot freeze unless the latent heat of fusion is transferred away by convection, evaporation or conduction. Because it is necessary for excess water to be present for glaze to form on exposed surfaces, often the excess water may freeze into icicles or other dis- tended shapes. In actual practice, glaze can be seen to form on conductors in a wide variety of shapes. They range from the classical, smooth cylindrical sheath, through crescents on the windward side and icicles hanging on the bottom, to large irregular protuberances spaced along the conductor. In most cases, glaze on structures develops as a fairly smooth layer on the windward surfaces, with icicles forming below horizontal members as the excess water flows to the bottom and drips off. The shape of the glaze is apparently dependent on a combination of factors, such as wind speed and variations in wind speed, the angle the wind flow makes with the line, the turbulence of the flow, movement of the conductor, the ability of the con- ductor to rotate, small variations in air temperature, and storm duration. Glaze is usually formed from freezing precipitation, rain or drizzle, or from clouds with large liquid water content and large drop sizes. oe Rime Rime has a density of 0.3 to 0.9 g/cm3, Soft rime, with density less than 0.6 g/cm3, grows in a granular structure that is white and opaque, with many air bubbles within the structure. It usually grows in a triangular or Pennant shape pointed into the wind. The granular structure results from the rate of freezing of the individual drops, each drop freezing completely be- fore another one impinges on the surface. Hard rime, with density from 0.6 to 0.9 g/cm, tends to grow in a layered structure with clear ice mixed with ice containing air bubbles. In this case, the freezing rate of the droplets is equal to the impingement rate of the droplets. 28 In general, for rime to form, it is necessary to have supercooled water droplets (cloud or fog) impinge on a surface. Large supercooled cloud droplets in the temperature range from -1°C to -5°C will partially freeze on impact, resulting in hard rime. Small cloud droplets in the temperature range from about -5°C to -15°C will freeze on impact, result- ing in soft rime (Kravitz and Leavengood, 1973; and Griffing and Leavengood, 1973). Large concentrations of supercooled droplets are not common in ambient temperatures below -15°C. At lower temperatures, ice crystals are likely to form. These grow at the expense of the supercooled water and largely remove the icing condition. ae Wet Snow A density of 0.3 to 0.8 g/cm? is usually defined as snow which falls with temperatures 231° F (-0.5°C). Under these conditions the snow is sticky enough to adhere to surfaces easily and accumulate rapidly. Wet snow tends to build on tops and windward surfaces of structures and in cylindrical layers around conductors. At temperatures colder than about -2°C, snow particles are usually too dry to adhere to surfaces in appreciable quantities. It has previously been believed that damaging wet snow accumulations occurred in conjunction with light winds (Kuroiwa, 1965). However, recent experiences and studies indicate that wet snow will accumulate on conductors with wind speeds up to 45 mph and temperatures up to near +2°C. Cases of cohesive wet snow building up to a symmetrical thickness of four inches radially have been documented (Higuchi, 1973). Investigations in Japan (Higuchi, 1974), have indicated that exten- sive damage has occurred with what is referred to as the Hokkaido Type snow storm. This type is characterized by temperatures at gr Slightly above 32° F and wet snow with densities as high as 0.6 to 0.8 g/cm? which may not be blown off conductors even when the wind exceeds 25 mph (11 m/s). The damaging storms in southern Alberta and southwestern Saskatchewan in April and May, 1974, are recent examples of this in Canada. In these cases, heavy, wet snow was ac- companied by wind speeds over 40 mph (18 m/s). 4, Hoar Frost Hoar frost has a density of less than 0.3 g/cm? and is a deposit of interlocking ice crystals formed by direct sublimation of water vapor in the air onto objects. The deposition of hoar frost is similar to the process by which dew is formed, except the temperature of the frosted object must be below freezing. It forms when air with a dew point below freezing is brought to saturation by cooling. Hoar frost is feathery in appearance and will occasionally build to large diameters with very little weight. 29 B. Identification of Icing Areas Along the Proposed Route 1. Matanuska Valley Significant ice accumulations are expected from mixed icing (rime and hoar frost) at elevations below 2000 feet. Mixed ice accumulations are the result of light winds with dense fog. en Copper River Basin Significant rime ice accumulations are expected at elevations above 3300 feet. The route portion over the Sheep Mountain ridge reaches ele- vations of 3500 feet, therefore would be susceptible to significant rime ice accumulations. Significant mixed ice accumulations are expected along the route below 2500 feet from Tolsona into Glennallen. an 'p VII. LOADING PROBABILITIES BY SEGMENT A. Division of the Route into Segments The proposed Palmer to Glennallen transmission system was divided into a total of 24 segments. The segments were selected based on elevation and exposure. These are described below and comments are included as to the exposure of each. Each of the segments are bounded by the PI location. Teeland Substation to PI-8 (36 miles). Elevations range 200-800 feet. Exposed to winds from northeast through east-northeast and southwest through west. Sheltered to winds from the north by the Talkeetna Mountains and from the east through south by the Chugach Mountains. PI-8 to PI-10 (6 miles). Elevations range 600-1300 feet. Exposed to winds from the northeast and southwest. Sheltered to winds from the north and south by the Talkeetna and Chugach Mountains, respectively. PI-10 to PI-11 (3.5 miles). Elevations range 1100-1500 feet. Exposed to winds from the east-northeast and southwest. Sheltered to winds from the north and south by the Talkeetna and Chugach Mountains, respectively. Route proceeds along a ridge top between the Chickaloon Trail and Matanuska River. PI-11 to PI-12 (4 miles). Elevations range 800-1500 feet. Exposed to winds from the northeast and southwest. Sheltered to winds from the north and south by the Talkeetna and Chugach Mountains, respectively. PI-12 to PI-13 (3.5 miles). Elevations range 900-1300 feet. Exposed to winds from the north-northeast, east, and southwest. Sheltered to winds from the south by the Chugach Mountains. Exposed to downslope winds from the north-northeast flowing out of the Chickaloon River Canyon. PI-13 to PI-14 (6 miles). Elevations range 1300-2500 feet. Exposed to winds from the east-northeast and west-southwest. Sheltered to winds from the north and south by the Talkeetna and Chugach Mountains, respectively. Ridge to the south also shelters winds from the south. PI-14 to PI-16 (8 miles). Elevations range 1800-2900 feet. Exposed to winds from the east-southeast and west-southwest. Sheltered to winds from the north and south by the Talkeetna and Chugach Mountains, respectively. PI-16 to PI-18 (1.8 miles). Elevations range 1700-2100 feet. Exposed to winds from the east and west. Sheltered to winds from the north and south by the Talkeetna and Chugach Mountains, respectively. Some slight sheltering to winds from the east by Fortress Ridge. PI-18 to PI-19 (1.5 miles). Elevations range 1500-2100 feet. Exposed to winds especially from the east and west through the ridge gaps. Sheltered to winds from the north and south by the Talkeetna and Chugach Mountains, respectively. 21 ~~ PI-19 to PI-20 (2 miles). Elevations range from 1600-1800 feet. Exposed to to winds from the east and west. Sheltered to winds from the north and south by the Talkeetna and Chugach Mountains, respectively. PI-20 to PI-21 (5 miles). Elevations range from 1500-1900 feet. Exposed to winds from the east and west. Sheltered to winds from the north and south by the Talkeetna and Chugach Mountains, respectively. PI-21 to PI-23 (1.5 miles). Elevations range from 1800-2400 feet. Exposed to winds from the east and west especially over Lions Head ridge. Sheltered to winds from the north and south by the Talkeetna and Chugach Mountains, respectively. PI-23 to PI-24 (0.5 mile). Elevations range from 2400-2500 feet. Exposed to winds from the east and west. Sheltered to winds from the north by the Talkeetna Mountains and from the south by’ a ridge and the Chugach Mountains. PI-24 to PI-26 (2.7 miles). Elevations range from 2100-2500 feet. Exposed to winds from the west and east. Sheltered to winds from the north and south by the Talkeetna and Chugach Mountains, respectively. PI-26 to PI-27 (4.5 miles). Elevations range from 2500-2900 feet. Exposed to a winds from the east-northeast and west-southwest. Sheltered to winds from \ the north and south by the Talkeetna and Chugach Mountains, respectively. PI-27 to PI-28 (2.2 miles). Elevations range from 2800-3000 feet. Exposed to winds from the northeast and southwest. Sheltered to winds from the north by Gunsight Mountain and from the south by the Chugach Mountains. PI-28 to PI-30 (3.5 miles). Elevations range from 3000-3500 feet. Exposed to winds from the north and south through the ridge gap and from the northeast at the north and south ends of the segment. PI-30 to PI-34 (18 miles). Elevations range from 2600-3300 feet. Exposed to winds from the northeast, east, and southwest. Sheltered to winds from the west through north by the Talkeetna Mountains and from the south by the Chugach Mountains. PI-34 to PI-36 (6 miles). Elevations range from 2500-2700 feet. Exposed to winds from the east and southwest. Sheltered to winds from the north by Slide Mountain, from the west by the Talkeetna Mountains and from the south by the Chugach Mountains. PI-36 to PI-37 (3.5 miles). Elevations range from 2500-2700 feet. Exposed to winds from the north through south-southeast. Sheltered to winds from all other directions by Slide Mountain. PI-37 to PI-40 (12 miles). Elevations range from 2200-2600 feet. Exposed to winds from the northwest through north, and from the east through south. J Sheltered to winds from the north-northeast through east-northeast by a — ridge and from the west by Slide Mountain. 29 PI-40 to PI-42 (6 miles). Elevations range from 2500-2600 feet. Exposed to winds from the east through west. Sheltered to winds from the west- northwest through east-northeast by a ridge. PI-42 to PI-45 (8 miles). Elevations range from 2000-2600 feet. Exposed to winds from all directions. Some sheltering to winds from the northwest along the western portion of the segment. PI-45 to PI-46 (13 miles). Elevations range from 1400-2100 feet. Exposed to winds from all directions. Some slight channeling of winds from the north-northeast and south-southeast by the Copper River Valley. B. Ice_and Wind Loadings by Segment The probable extreme wind, vertical ice, and transverse wind on ice loadings in the form of 25-, 50-, and 75-year return period values are listed in Tables VII-1 through VII-3. These section values computed for 30 feet above ground are based on weather station values modified for altitude and exposure. Also taken into consideration were comments from personnel who live and work in the area and are familiar with wind or icing problems that May have occurred. The probable maximum wind speed and direction per 25-, 50-, and 75- year return period are one-minute averages. Wind gusts (G) are five second in duration and are calculated from the maximum wind speeds (V) by the formula G = 5.8 + 1.29 V. Hourly weather observations from Elmendorf AFB, Sheep Mountain, and Gulkana were used to identify the significant icing types along the proposed route. Icing types identified as significant were mixed (rime with hoar frost), glaze, and rime icing. Wet snow occurrences were of insignificant duration to produce significant accumulations from this icing type. The return period values for mixed icing, glaze, and rime icing are indicated in Tables VII-1 through VII-3. Return period values for mixed icing were computed using the yearly maximum mixed icing accumulation episode determined by the MRI ae model. Mixed ice accumulations are assumed to have a density of 0.4 gm/cms and to be circular about the conductor and shield wire. Mixed icing episodes were identified in the hourly weather observations by the occurrence of tempera- tures less than or equal to 32°F along with visibilities equal to or less than five-eights of a mile. Most of these occurrences are associated with light winds, therefore result in hoar frost and light rime buildups. Winds associated with mixed icing cases were mostly calm with highest values of 10 mph. Elmendorf AFB hourly observations were used to quantify mixed icing episodes for the western portion of the proposed line. Sheep Mountain and Gulkana hourly weather observations were used to quantify mixed icing episodes for the eastern portion of the proposed line. 33 Table VII-1 25-YEAR RETURN PERIOD VALUES FOR EXTREME WIND, VERTICAL ICE**, AND WIND ON ICE LOADS GLATE_ ICING “AIRE TCTNG 0.9 gm cm-3 | Weight (Ibs/ft)| TL (Ibs/ft) [0.4 gmcm-3 | Weight (Ibs/ft)| Tw (Ibs/ft) DimensTon |Conductor|Shteld |Conductor| Dimenston |Conductor|Shteld |Conductor|Shietd| WIND HIKED ICING (RIME & WOAR FROST) 0.4 gmcm-3 | Weight (Ibs/ft)] TW (Ibs/ft) Segment One-Min| 5-Second rom 0 Length Avera: Gust Direction | Dimenston [Conductor] She! miles mph radial in. Wire radial in. Wire radial in. Wire Wire TeeTand Sub 8 36 67 ENE 0.60 0.55 0.32 -008 0.15 0.23 0.10 -031 8 10 6 67 NE 0.60 0.55 0.32 008 0.15 0.23 0.10 031 10 ll 3.5 67 ENE 0.60 0.55 0.32 -008 0.15 0.23 0.10 031 WM 12 4 67 NE 0.60 0.55 0.32 -008 0.15 0.23 0.10 031 12 13 3.5 67 E,NNE 0.60 0.55 0.32 008 0.15 0.23 0.10 031 13 “4 6 s7 ENE 0.40 0.33 0.17 -004 0.15 0.23 0.10 020 “4 16 8 67 ESE 0.40 0.33 0.17 007 0.15 0.23 0.10 020 16 18 1.8 57 — 0.60 0.55 0.32 2005 0.15 0.23 0.10 020 18 19 1.5 13 E 0.40 0.33 0.17 020 0.15 0.23 0.10 -020 19 20 . 67 E 0.60 0.55 0.32 008 0.15 0.23 0.10 +020 20 2 5 63 E 0.60 0.55 0.32 -008 0.15 0.23 0.10 031 21 23 1.5 78 — 0.40 0.33 0.17 026 0.15 0.23 0.10 069 0.25 0.18 209 0.31 0.17 23 24 0.5 63 E 0.40 0.33 0.17 007 0.15 0.23 0.10 069 0.25 0.18 209 0.31 0.17 24 26 2.7 13 — 0.40 0.33 0.17 015 0.15 0.23 0.10 -020 26 27 4.5 67 ENE 0.40 0.33 0.17 007 0.15 0.23 0.10 031 2 28 2.2 63 NE 0.40 0.33 0.17 004 0.15 0.23 0.10 031 28 30 3.5 58 NE 0.40 0.33 0.17 ~004 0.15 0.23 0.10 020 1.00 1.14 75 0.27 0.21 30 4 18 63 NE 0.40 0.33 0.17 007 0.15 0.23 0.10 031 4 36 6 60 € 0.40 0.33 0.17 004 0.15 0.23 0.10 031 0.50 0.43 24 0.41 0.27 36 Ey] 3.5 60 SE 0.40 0.33 0.17 004 0.15 0.23 0.10 031 0.50 0.43 224 0.41 0.27 37 40° 12 60 SSE 0.60 0.55 0.32 013 0.15 0.23 0.10 031 40° 42¢ 6 $5 — 0.60 0.55 0.32 013 0.15 0.23 0.10 2031 42 ase 8 55 NE 0.75 0.75 0.46 036 0.15 0.23 0.10 031 45¢ 46* 13 55 NNE 0.75 0.75 0.46 2036 0.15 0.23 0.10 2031 * P1-39 through PI-46 add 20 percent to wind speed for unforested areas ** Wet snow loading insignificant Note: Conductor diameter = 1.108", Shield Wire diameter = 0.38" Weight for ice only (does not include wire weight) Table VII-2 50-YEAR RETURN PERIOD VALUES FOR EXTREME WIND, VERTICAL ICE**, AND WIND ON ICE LOADS TRIKE TCT 0.4 gmcm-3 | Weight (Ibs/ft)| Twi (Ibs/ft) 0.9 gm can3 | Weight (Ibs/ft)| Tw (Ibs/ft) ‘One-Min| 5-Second rom 0 Length Direction DinensTon e Dinens ton miles radial in. Wire radial in, TeeTand Sub 8 36 ENE 0.25 0.06 8 10 6 NE 0.25 0.06 10 i 3.5 ENE 0.25 0.06 ul 12 4 NE 0.25 0.06 12 13 3.5 E,NNE 0.25 0.06 13 “4 6 ENE 0.25 0.06 “4 16 8 ESE 0.25 0.06 16 18 1.8 — 0.25 0.06 18 19 1.5 E 0.25 0.06 19 20 2 E 0.25 0.06 20 2 5 E 0.25 0.06 21 23 1.5 Ee 0.25 0.06 0.50 23 24 0.5 — 0.25 0.06 0.50 24 26 2.7 e 0.25 0.06 26 27 45 ENE 0.25 0.06 2) 28 2.2 WE 0.25 0.06 28 30 3.5 NNE 0.25 0.06 1.50 30 u 18 NE 0.25 0.06 u 36 6 0.25 0.06 0.75 36 vu 3.5 SE 0.25 0.06 0.75 cy 40° 12 SSE 0.25 0.06 40° 42 6 0.25 0.06 42° 45* 8 NE 0.25 0.06 45° 46° 13 *__NNE 0.25 0.06 * PI-39 through PI-46 add 20 percent to wind speed for unforested areas ** Wet snow loading Jos tent icons Mote: Conductor diameter = 1.108", Shield Wire diameter = 0.36" Weight for ice only (does not include wire weight) Table VII-3 75-YEAR RETURN PERIOD VALUES FOR EXTREME WIND, VERTICAL ICE**, AND WIND ON ICE LOADS ~ GLAZE ICING RIRE_ ICING 0.9 gm cm-3 | Weight (Ibs/ft)] TWL (Ibs/ft) |0.4 gmcm-3 | Wetght (Ibs/ft)] Tw (Ibs/ft) Segment One-Min| 5-Second Tom fo Length |Average| Gust |Direction | Dimenston [Conductor ‘onductor, Dimenston |Conductor Conductor Dimenston |Conductor|Shteld |Conductor|Shteld miles mph radial in. radial in. radial in. Wire TeeTand Sub 8 36 78 ENE 1.00 1.14 +033 0.30 0.51 148 8 10 6 78 NE 1.00 1.14 033 0.30 0.51 2148 10 iu 3.5 78 ENE 1,00 1.14 +033 0.30 0.51 148 i 12 4 78 NE 1,00 1.14 033 0.30 0.51 148 12 13 3.5 78 E,NNE 1.00 14 2033 0.30 0.51 2148 13 “4 6 68 ENE 0.75 0.75 020 0.30 0.51 2083 4 16 8 718 ESE 0.75 0.75 2028 0.30 0.51 -083 16 18 1.8 68 € 1,00 1.14 024 0.30 0.51 2083 18 19 1.5 84 € 0.75 0.75 057 0.30 0.51 083 19 20 2 78 e 1.00 1.14 033 0.30 0.51 2083 20 2 5 4 — 1.00 1.14 2033 0.30 0.51 148 ra 23 1.5 89 £ 0.75 0.75 081 le 0.51 0196 0.75 0.75 0.46 1.41 23 24 0.5 4 e 0.75 0.75 028 0.30 0.51 +196 0.75 0.75 0.46 141 24 26 2.7 84 - 0.75 0.75 2057 0.30 0.51 083 26 27 4.5 78 ENE 0.75 0.75 028 0.30 0.51 2120 27 28 2.2 72 NE 0.75 0.75 +020 0.30 0.51 148 28 30 3.5 67 NNE 0.75 0.75 020 2015 0.30 0.51 083 1.75 2.71 2.02 1.60 30 4 18 72 NE 0.75 0.75 028 020 0.30 0.51 148 4 36 6 66 — 0.75 0.75 020 2015 0.30 0.51 148 1,00 1.4 0.75 1.68 36 ” 3.5 66 SE 0.75 0.75 020 2015 0.30 0.51 2148 1.00 1.14 0.75 1.68 cy 40° 12 66 SSE 1,00 1.14 2043 2033 0.30 0.51 148 40* 42 6 61 — 1.00 1.14 043 +033 0.30 0.51 148 42 4s 8 61 NE 1.50 2.12 128 105 0.30 0.51 148 4s* 46* 3 61 NNE 1.50 2.12 2128 2105 0.30 0.51 2148 * PI-39 through PI-46 add 20 percent to wind speed for unforested areas Wet snow loading ington! Cheat Wote: Conductor diameter = 1.108", Shield Wire diameter = 0.38" Weight for ice only (does not include wire weight) Return period values for glaze icing were computed using the yearly maximum glaze icing accumulation episode determined by the MRI icing model. Glaze icing is assumed to have a density of 0.9 gm/cm? and to be circular about the conductor and shield wire. Glaze icing episodes were identified in the hourly observations by the occurrences of freezing rain and freezing drizzle. Elmendorf AFB hourly observations were used to identify glaze epi- sodes for application to the western portion of the proposed route. Sheep Mountain and Gulkana hourly weather observations were used to identify glaze episodes for application to the eastern portion of the proposed route. The majority of freezing rain and drizzle cases were associated with anywhere from trace to light amounts of precipitation. Winds associated with glaze episodes were mostly under 10 mph with maximum speeds of 20 mph. As a result of light precipitation amounts glaze accumulations are expected to be light over the whole route. Return period values for rime icing were computed using the yearly maximum rime icing accumulation episode determined by the MRI icing model. Rime ice accumulations are assumed to have a density of 0.4 gm/cm3 and to be circular about the conductor and shield wire. Rime icing episodes were identified in the hourly observations by the occurrences of cloud ceilings between 100 to 3000 feet along with appropriate surface temperatures such that the extrapolated cloud level temperatures were below 32°F. Elmendorf AFB hourly observations were used to identify rime episodes for application to the western portion of the proposed route. Sheep Mountain and Gulkana hourly weather observations were used to identify rime episodes for appli- cation to the eastern portion of the proposed route. Surface winds associated with rime events typically were 20-30 mph. The transverse wind on ice loadings in Tables VII-1 through VII-3 were calculated by using the formula: 0.0026 Dv2 TWL [lbs/linear ft] = 2 where D is the total diameter of ice plus conductor or shield wire in inches and V is the wind speed in miles per hour. The transverse wind on ice load- ings were computed using the return period ice dimension along with the transverse storm wind. The transverse storm wind used was the average of episode speeds measured during and 12 hours after the respective icing type. For glaze and mixed icing transverse winds, Elmendorf AFB winds were applied to the western portion of the route. Sheep Mountain and Gulkana glaze and mixed icing transverse winds were applied for the middle and eastern portion of the route, respectively. Sheep Mountain rime transverse winds were applied to the Lion's Head portion and Sheep Mountain ridge portion. Winds at Sheep Mountain measured at anemometer height were lifted to the 500 and 1000 foot, above ground level, by the power law as discussed in Section V-C. Then, the lifted winds were extrapolated to the ridge portion taking into account the exposure and elevation. 37 For the majority of the transmission line route through the Matanuska Valley transverse winds during icing cases were found to be low, because the line is in most cases parallel to storm winds. Where the transmission line is exposed in all directions to storm winds, as in the Copper River Basin, storm winds were found to be low according to the weather observations. 38 VIII. CONCLUSIONS The principal conclusions of the study are the following: The proposed transmission line route will traverse the transition climatic zone through the Matanuska Valley and the continental climatic zone through the Copper River Basin. Measured absolute maximum temperatures have ranged from 84-90°F along the entire route. Measured absolute minimum temperatures along the route have been as low as -40°F in the Matanuska Valley and -65°F in the Copper River Valley. Average number of thunderstorm days per year range from less than two in the Matanuska Valley up to eight in the Copper River Valley. Extreme winds through the Matanuska Valley will be channeled by the terrain, generally east or west, whereas, the Copper River Basin will be generally exposed to winds from all directions. Highest 50-year return period values of wind speed are expected by terrain channeling between PI-21 and PI-23 (Lions Head) in the Matanuska Valley of 85 mph from the east. Significant accumlations of mixed (rime with hoar frost), glaze, and rime icing are expected along the proposed transmission line route. Wet snow icing is expected to be insignificant along the entire route. Highest 50-year return period values for mixed ice vertical loading (rime with hoar frost) of 1.31 1bs/foot (conductor) and 0.66 lbs/foot (shield wire) are expected along the eastern end of the proposed line in the Copper River Basin. 50-year return period values for glaze ice vertical loading of 0.41 lbs/foot (conductor) and 0.06 1bs/foot (shield wire) are expected along the entire route. Highest 50-year return period values for rime ice vertical loading of 2.28 lbs/foot (conductor) and 1.47 1bs/foot “ (shield wire) are expected for that portion of the route crossing over the Sheep Mountain ridge. Highest 50-year return period values for transverse wind on ice loading of 0.904 lbs/foot (conductor) are expected along the eastern and southern slopes of Slide Mountain. 39 mm IX. RECOMMENDATIONS A. Transmission Line Placement Due to Meteorological Factors 1. General An analysis of Sheep Mountain and Gulkana hourly weather observations, as well as other data sources, as listed in Section III, indicate the heaviest icing to occur from rime above 3300 feet. Spruce forest stands will reduce wind speeds up to 20 percent in the lee of stands (Wegley, 1978). A comparable amount or greater (20 to 50 percent) could be used for winds within a dense forest stand. The smaller percentage should be used where the cleared transmission line corridor is parallel to the extreme winds. The effect of forest stands to reduce winds should not significantly affect accumulations of ice from mixed and glaze icing, since these icing types occur mostly during light winds. Since timberline is generally 2000- 3000 feet along the route, winds are not expected to be affected by forest stands where rime is significant. 2. Application of General Considerations to the Proposed Transmission Line Route (a) For the entire route, remain in the forest to take advantage of the sheltering by the spruce and cottonwood trees. (b) Some additional sheltering of winds from the east by a ridge line could be realized between PI-10 through PI-13 by moving PI-10, 11 and 12 to the following locations. + Move PI-10 0.2 mile due north to the 1000 foot contour line. * Move PI-11 0.8 mile north-northwest to the 1300 foot contour line. Locate at inter- section of 1300 foot contour line and boundary line between sections 31 and 32. * Move PI-12 0.7 mile due north along the boundary line between sections 25 and 26. (c) Additional sheltering of winds from the east by a ridge line could be realized between PI-17 through PI-20 by moving PI-18 and PI-19 to the following locations. 40 (d) (e) * Move PI-18 0.7 mile south-southwest to the 1550 foot contour line. The point would be 0.2 mile northeast of the Watchtower Inn. * Move PI-19 0.8 mile due north. Result of change of PI locations would be to increase 50-year return period mixed ice vertical loads to 0.75 Ilbs/linear ft (conductor) and 0.40 Ibs/linear ft (shield wire) for segment PI-16 through PI-20. However, extreme one-minute average winds could drop to 74 mph for a 50-year return period between PI-18 through PI-20. Additonal sheltering and reduction in transverse winds could be realized between PI-20 through PI-23 by moving PI-21 and PI-22 to the following locations. * Move PI-21 to 1.1 mile east of PI-20 along existing route. * Move PI-22 0.75 mile northwest to the saddle point along the Lions Head ridge. Elevation of point in saddle is 2300 feet. Result of change of PI locations would reduce 50- year extreme one-minute average winds from 85 mph to 74 mph between PI-21 through PI-23. Reduction in vertical ice loads from rime icing could be realized between PI-28 through PI-31 by moving PI-29 and PI-30 to the following locations. * Move PI-29 1.50 miles due east to approximately the 3100 foot contour. * Move PI-30 1.45 miles east-southeast to the dashed line just west of the building on Lake Leila. Result of change of PI locations would eliminate rime vertical and transverse wind on ice loads between PI-28 through PI-30. However, extreme one-minute average winds would increase from 64 to 69 mph from the northeast for a 50-year return period. Al () B. Supplemental Data Collection Additional data collection is needed for those areas of the proposed route for which scant or no measured data exists. For the proposed Palmer to Glennallen line the areas expecting the greatest winds had little or no wind Measurements. Therefore, MRI recommends that field measurements of wind speed, wind direction, and temperature be taken at Lions Head ridge and a location between PI-1 and PI-2, designated P. A third instrument would be placed at Sheep Mountain Airport to correlate with the Lions Head and P sites. Once a correlation is made, long term wind summaries could be developed for the Lions Head and P site areas from Sheep Mountain long term data. To measure wind speed/wind direction/temperature, MRI proposes to use their Weather Wizard". The Weather Wizard™ is a meteorological field measure- ment and storage system composed of wind and temperature sensors, electronic Processing and storage package, cables, batteries, and solar cell to charge the battery. Hourly-average wind speed and direction measurements would be made and recorded onto a cassette tape. The cassette tape would then be dumped onto hard copy for the correlation with the Sheep Mountain Airport site. 42 cH _ REFERENCES Boomer, R.J., and M.C. Richmond, 1975: The meteorological study of the January 1975 ice storm along the number three Midway-Vincent 500 kV transmission line route at the Tejon Ranch Summit, MRI 75 R-1313, prepared for Southern California Edison Co., Rosemead, CA, Contract No. U703901. Bourgsdorf, V. V., E. P. Nikiphorov, and A. S. Zelitchenko, 1968: Ice loads on overhead transmission lines. Int. Conf. on Large High Tension Electric Systems, Paris, 10-20 June 1968, Paper Bowling, S. A., 1980: The weather and climate of Alaska. Weatherwise, 33, 5, Heldref Publications, pp 197-201. Boyd, D. W., 1965: Climatic information for building design in Canada, Supplement No. 1 to the National Building Code of Canada, National Research Council NRC No. 8329, Ottawa. Brook R. R. and K. T. Spillane, 1970: The variation of maximum wind gust with height. J. Appl. Meteor., 9 (No. 1), pp 72-78. Brower, W. A., et al, 1977: Climatic Atlas of the Outer Continental Shelf Waters and Coastal Regions of Alaska, Vol. 1, Gulf of Alaska. Environmental Data Services, National Climatic Center, Asheville, North Carolina. * Bryson, R. A. and F. K. Hare, 1974: Climates of North America. Elsevier Scientific Publishing Company, New York, New York. Camp, D. W., 1968: Low level gust amplitude and duration study. NASA _TM X-53771, George C. Marshall Space Flight Center, Huntsville, Alabama. Court, A., 1953: Wind extremes as design factors. J. Franklin Inst., 256, (No. 1), pp 39-55. Davis, F. K. and H. Newstein, 1968: The variation of gust factors with mean wind speed and with height. J. Appl. Meteor., 7, (No. 3), pp 372-278. Deacon, E. L., 1955: Gust variation with height up to 150 meters. Quart. J. Roy. Meteor. Soc. (London), 81, p 563. DeMarris, G. A., 1959: Wind speed profiles at Brookhaven National Laboratory. J. Meteor., 16, (No. 2), pp 181-190. Dept. of Transport, Canada, 1968: Climatic normals, Vol. 5, Wind. Meteorological Office, 315 Bloor St., W., Toronto, p 95. Durst, C. S., 1960: Wind speeds over short periods of time. Meteor. Mag., 89 (No. 1056), pp 181-186. 43 References (Continued) Fichtl, G. H., J. W. Kaufman, and W. W. Vaughan, 1969: Character of atmos- pheric turbulence related to wind loads on tall structures. J. Spacecraft, 6 (No. 12), pp 1398-1403. Fisher, R. A. and L. H. C. Tippett, 1928: Limiting forms of the frequency distribution of the largest or smallest number of a sample. Proc. Cambridge Phil. Soc., 24, Pt. 2, pp 180-190. Grice, G. K. and A. L. Comiskey, 1976: Thunderstorm Climatology of Alaska. National Weather Service, Regional Headquarters, Anchorage, Alaska. NOAA Tech. Memo., NWS AR-14. Griffing, K. L.,and D. C. Leavengood, 1973: Transmission line failures, Part I. Meteorological phenomena - severe winds and icing. Paper No. 73 CHO816-9 PWR, July 5-14. Hallanger, N. L. and M. C. Richmond, 1972: A meteorological study of the 345 kv transmission line route from the Jim Bridger plant site to Borah, Kinport, and Goshen substations. Prepared for Pacific Power and Light Company, Portland, Oregon. Purchase Order No. 7970-973. Higuchi, H., 1973: Wet snow accretion in Japan. Paper presented at Ice Accretion Group Meeting, Toronto, Canada, 29 March. Higuchi, H., 1974: Snow accumulation prevention methods on transmission lines. Unpublished report Engineering Department. The Research Department, Hokkaido Electric Power Company, Japan. Johnson, 0., 1959: An examination of vertical wind profile in the lowest layers of the atmosphere. J. Meteor., 16 (No. 9), pp 144-148. Kilday, G.D., 1970: Taku Winds at. Juneau, Alaska. U.S. Department of Commerce, National Weather Service, Anchorage, Alaska, unpublished. Kravitz, R. A. and D. C. Leavengood, 1973: Analyze the weather for safer design. Electric Light and Power, T/D Edition, January. Kuroiwa, D., 1965: Icing and snow accretion on electric wires. U. S. Army Materiel Command, Research Rept. 123. Langmuir, I. and K. Blodgett, 1945: Mathematical investigations of water droplet trajectories. General Electric Research Lab., Schenectady, N.Y. Leibfried, W. and H. Mors, 1964: The bundled conductor experimental station at Hornisgrinde, Germany. Leavengood, D. C. and T. B. Smith, 1968: Studies of transmission line icing. Rept. by MRI to Southern California Edison Company, Los Angeles, CA, Contr. No. L-2127, MRI 68 FR-801. 44 References (Continued) McKay, G. A. and H. A. Thompson, 1969: Estimating the hazard of ice accretion in Canada from climatological data. J. Appl. Meteor., 8, pp 927-935. Mitsuta, Y., 1962: Gust factor and analysis time of gust. J. Meteor. Soc. (Japan), 40 (No. 4) pp 242-244, Munn, R. E., 1966: Descriptive micrometeorology. Advances in Geophysics, Academic Press, New York and London. Pacific Northwest Laboratory, 1980: Preliminary evaluation of wind energy potential - Cook Inlet area, Alaska. Prepared for the Alaska Power Administration. Contract No. DE-ACO6-76RLO 1830. Richmond, M. C. and R. J. Boomer, 1974: The meteorological study of the April, 1973, ice storm near Pentecote River and the meteorological evaluation of the 735 kv transmission routes from Churchill] Falls to Quebec. Prepared for Hydro-Quebec, Canada, Cont. No. H09538-260. Ruffner, J. A., 1980: Climates of the States. Gale Research Company, Detroit, Michigan. Volume 1, Second Edition. Searby, H. W., 1969: Coastal Weather and Marine Data Summary for Gulf of Alaska, Cape Spencer Westward to Kodiak Island. Essa Technical Memo. EDSTM 8. Environmental Data Service, Silver Spring, MD. Shellard, H. C., 1965: The estimation of design wind speeds. Wind Effects on Buildings and Structures. National Physics Laboratory Symposium (No. 16), pp 30-51. Shellard, H. C., 1968: Tables of surface wind speed and direction over the United Kingdom. Meteor. Office, 792, Her Majesty's Stationary Office, London. Sherlock, R. H., 1947: Gust factors for the design of buildings. Int. Assoc. for Bridge and Structural Engineering, Vol. 8, pp 207-235. Sherlock, R. H., 1952: Variation of wind velocity and gusts with height. Paper No. 2553, Proc. Amer. Soc. Civil Eng., pp 463-508. Sissenwine, N., P. Tattleman, D. D. Granthan, and I. I. Gringorten, 1973: Extreme wind speeds, gustiness, and variations with height for MIL-STD 210B. Air Force Cambridge Research Laboratories. Tech. Report 73-0560, Aeronomy Laboratory, Project 8624, p 72. U. S. Department of Commerce, 1978: Summary of Synoptic Meteorological Observation. Environmental Data Service, National Climatic Center, Asheville, North Carolina. U. S. Department of Commerce: 1959-1981 Storm Data. Environmental Data and Information Service, National Climatic Center, Asheville, NC. 45 ( References (Continued) U. S. Department of Commerce, National Bureau of Standards, 1953: Probability tables for the analysis of extreme-value data. Appl. Mathematics Series 22, July 6. U. S. Department of Commerce, 1970: U. S. Naval Weather Service World-Wide Airfield Summaries, Vol 8, Part 8. National Tech. Information Service, Springfield, VA, AD-704-607. U. S. Department of Commerce, 1978: Climate of Matanuska, Alaska. Climatography of the United States., No. 20. National Climatic Center, Asheville, NC. U. S. Department of Commerce, 1971: Anchorage to Valdez Area, Climatic Summaries of Resort Areas. National Weather Service, No. 21-49-7. Wade, J. E., and E. W. Hewson, 1980: A Guide to Biological Wind Prospecting. Prepared for the United States Department of Energy, Dept. of Energy Division of Distributed Solar Technology Federal Wind Energy Program by the Department of Atmospheric Sciences, Oregon State Univ., Corvallis, OR. Weiss, L. L., 1955: A nomogram based on the theory of extreme values for determining values for various return periods. Mon. Wea. Rev., 83, pp 69-71. Wegley, H. L., Me M. Orgill and R. L. Drake, 1978: A Siting Handbook for Small Wind Energy Conversion Systems. PNL-2521, Pacific Northwest Laboratory, Richland, WA. Williams, J. A., 1981: Charting heavy Alaskan weather. Offshore, June 5, pp 49-54. Willis, R. A. and G. K. Grice, 1976: The Wintertime Arctic Front and its Effects on Fairbanks. National Weather Service, Regional Headquarters, Anchorage, Alaska. NOAA Tech. Memo., NWS AR-13. Wise, J. L., et al., 1980: Wind Energy Resource Atlas, The Alaska Region. Prepared for the Pacific Northwest Laboratory, Report No. PNL-3195 WERA-10. Young, H. F. and J. P. Schell, 1971: Icing damage to transmission facilities in Newfoundland. Canadian Electrical Assn. Transmission Meeting, Quebec, P.Q., October 25-28. 46