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HomeMy WebLinkAboutRivers and Harbors in AK Sitka and Petersburg-Wrangell Study Areas 1979SOE 008 RIVERS AND HARBORS IN ALASKA SITKA AND PETERSBURG/WRANGELL STUDY AREAS STUDY DOCUMENTATION AlasKa . District~ Corp~ Q~ ~ngineers Anchorage.. M:.a$ka.-,. March 1979 1 I - I I l 1. I lU•U H.LIIUIHGIH OJ. Olln881 800 ~r;s liJ.VO _I I I I ' I I ' I RIVERS AND HARBORS IN ALASKA PETERSBURG/WRANGELL AREA STAGE II ANALYSIS OF HYDROELECTRIC DEVELOPMENT This information is the result of studies conducted as part of Rivers and Harbors in Alaska, Southeast Alaska Hydropower Study. The analysis represents Stage II level of detail. The study did not pro- ceed further due to local action which eliminated the need for addi- tional hydropower development. The results of the study are summarized in the Main Report of Rivers and Harbors in Alaska. Item HYDROLOGY FOUNDATION AND MATERIALS REGIONAL ECONOMY TABLE OF CONTENTS PROJECT DESCRIPTION AND COST ESTIMATES POWER STUDIES AND ECONOMICS ENVIRONMENTAL ASSESSMENT CORRESPONDENCE Item Thomas Bay and Tyee Lake Thomas Bay Site Plan List of Plates Thomas Bay Project Details Tyee Lake Plan and Sections Tyee Lake Profile and Sections Tyee Lake Project Details Section A 8 c D E F G Number 1 2 3 4 5 6 SECTION A HYDROLOGY PETERSBURG/WRANGELL HYDROPOWER STUDY GENERAL BASIN DESCRIPTION Both Thomas Bay and Tyee Lake project sites are located on the mainland in southeastern Alaska as shown on the location map, Plate 1. Thomas Bay is approximately 40 air miles (67 km} northeast of Wrangell; Tyee Lake is 38 air miles (63 km) southeast of Wrangell. In addition to the above two alternative sites, 12 other potential hydropower sites in the Petersburg/Wrangell area were screened as candidates for develop- ment and are shown on Plate 1. All of the alternate sites, including Tyee and Thomas Bay sites, are at comparatively low elevation (below 2,000 feet). The Tyee Creek watershed ranges in elevation from 1,387 feet at the lake up to approxi- mately 5,000 feet. Thomas Bay watershed extends from an elevation of 1 ,514 feet at Swan Lake up to 6,300 feet. Neither watershed has an extensive drainage area above the 4,500-foot level. Thick stands of coastal coniferous forest occupy both the Tyee and Thomas Bay watersheds from tidewater to approximately 2,750 feet. The only exceptions are the steep, rocky, canyon walls as well as a few scattered bogs and poorly drained meadows where tree growth is either absent or stunted. Tree growth becomes increasingly dwarfed and scat- tered above the 2,000-foot elevation. At higher altitudes, low, scat- tered shrubs and subalpine herbaceous cover prevails, along with extensive areas of barren rock slides. Tyee Creek drainage contains three small glaciers with an area less than 0.4 of a square mile, with no permanent snowfields. The Cascade Creek drainage has extensive glacier and snowfield coverage. Of the total 17.3 square miles, approximately 4 square miles on the south side of the watershed are occupied by permanent snowfields and glaciers. The terrain in both watersheds is mountainous and extremely rugged. The stream channels from lakes to tidewater are exceedingly steep with frequent cascades flowing through occasional, deep rock gorges. STREAMFLOWS Tyee and Cascade Creek drainages are both comparatively small water- sheds with the exceptionally high runoff yield per square mile typical of southeastern Alaska streams. For Tyee Creek, the average runoff is 12.8 cubic feet per second (cfs) per square mile. Cascade Creek average is 11.9 cfs per square mile. The highest discharge each year on both streams normally occurs in June, primarily the result of snowmelt. The highest recorded peak flows, however, have occurred in the months of September and October. The onset of winter storm systems from the eastern Pacific bring heavy precipitation to southeastern Alaska in the form of rain. The greater portion of the annual runoff on both streams occurs in the warm season from May through October. With the onset of freezing temperatures in November, the streamflows decline rapidly to a winter base flow, which is about 10 percent of the summer flow. Because of A-2 the predominantly granitic nature of the substrata in these two water- sheds, there is only meager ground water inflow after winter freezeup. The average seasonal runoff for Tyee and Cascade Creeks is as follows: Discharge Tyee Creek near Mouth October 288 November 117 December 48 January 27 February 27 March 45 April 46 May 253 June 403 July 297 August 233 September 327 Annual 175 Record Minimum Month 11 (Mar 69) Record Maximum Month 494 (Jun 67) in cfs Cascade Creek near Thomas Bay 310 184 100 60 54 50 73 266 547 490 445 505 251 16 {Feb 69) 722 (Jun 67) Despite the low average streamflows indicated for November through March, the occurrence of occasional warm storms, even in midwinter, in southeastern Alaska cause heavy runoff for brief periods. As an example, on 23 January 1968, the discharge at Thomas Bay went from 40 cfs to 450 cfs in 48 hours. A-3 CLIMATE OF THE AREA GENERAL DESCRIPTION Tyee and Thomas Bay drainages lie in comparatively temperate portions of southeastern Alaska and experience the high precipitation character- istic of that part of the state. Tyee Creek is located at approximately latitude 56° N; Thomas Bay is at latitude 57° N. This is approximately the same as Edinburgh, Scotland and Copenhagen, Denmark. Southeastern Alaska is classed as a "Maritime" climate. The dominating influence of the comparatively warm North Pacific Ocean is evident in all seasons. In addition to the proximity of the ocean, the configuration of the southeast Alaska coastline is one of numerous fjords, bays, and inlets, such that water surfaces are everywhere interspersed with land surfaces. This also contributes to the moderate climate. During the winter season, moisture-laden air masses move from the North Pacific across the study area in regional-scale storm systems, dropping precipitation in heavy amounts. Occasionally, stationary cold inversions of air, which build up over the interior plateaus of Canada, migrate southward bringing dry, northerly winds and lowering temperatures in southeastern Alaska. Nearly all the climatic data for southeastern Alaska is gathered at stations near sea level. Therefore, the climatic records do not present an accurate picture of conditions for Tyee and Thomas Bay A-4 watersheds. Both have extensive portions of area above the 2,000-foot level. For Thomas Bay, its close proximity to the major icefield in the coast mountain range along the U.S.-Canada border accounts for substantial climatic effects, such as cold drainage winds which are not as pronounced to the west of the island archipelago. In addition, the incidence of low clouds and fog at the higher altitude are more frequent at both Tyee and Thomas Bay drainage than at adjacent lowland stations. TEMPERATURE The climatic average temperatures near sea level at Petersburg and Wrangell illustrates the mild winters and modest annual fluctuations: Mean Dailt TemQeratures OF Petersburg Wrangell Maximum Minimum Maximum Minimum January 34 23 35 25 February 36 25 37 26 March 41 28 43 31 Apri 1 49 33 50 35 May 56 39 58 41 June 62 45 64 47 July 64 48 65 50 August 63 47 65 49 September 58 43 59 45 October 49 38 51 39 November 41 31 43 32 December 36 27 37 27 There are few climatic stations in southeastern Alaska at elevations above sea level. Records from Perseverance Camp near Juneau, at ele- vation 1 ,400 feet, indicate that summer temperatures at high elevations A-5 are about 4° F less than sea level readings. In winter the difference is considerably greater, with temperatures about yo F lower than at sea level. Mean Monthly Temperature o F January February March Apri 1 May June July August September October November December Perseverance Camp (elev. 1,400 ft) 20.9 26.3 25.8 37.8 42.2 48.8 53.5 53.5 50.4 37.6 31.3 22.3 Juneau { e 1 ev. 72 ft) 28.5 29.9 34.3 34.3 48.3 54.8 56.9 56.2 51.3 43.9 36.3 30.3 The data from Perseverance Camp is typical of Tyee and Swan Lakes. Both are near the 1,400-foot elevation. The lowest temperature on record for Petersburg and Wrangell are -19° and -10° F, respectively. Whereas at Perseverance Camp the recorded minimum over 4 years was -23° F. The highest temperatures recorded at all three locations are 84°, 92°, and 81° F, respectively. The seasonal temperature regimes between sea level at Petersburg and high lake levels in the project area are significantly different. Winter daytime temperatures normally exceed 32° F nearly every day at sea level, however, there are long periods of continuous freezing tern- peratures at lake level during the winter. A-6 PRECIPITATION Precipitation is heaviest during the fall months and generally declines in the spring to a minimum in June. During early summer, the North Pacific storm systems, which are the primary precipitation producing mechanism in southeastern Alaska, are relatively weak and few in number. The seasonal distribution of precipitation at Tyee and Thomas Bay are reflected in the data for Petersburg and Wrangell. Mean Monthly Precipitation (inches) January February March April May June July August September October November December Total Petersburg 8.93 7.49 7.10 6.85 5.95 4.59 5.23 7.67 10.97 17.22 12.14 11 .06 105.20 Wrangell 7.27 5.89 5.43 5.05 4.13 3.96 5.25 6. 31 8.27 12.61 9.90 8.33 82.40 Very little of the precipitation occurs in convective-type showers. Even with the substantial quantities of precipitation, the intensity is comparatively low. Thundershowers are rare in the study area, aver- aging only about one per year. Although precipitation data is not available from either Tyee or Thomas Bay areas, ample evidence exists that precipitation on the A-7 watersheds greatly exceeds the sea level figures at Petersburg and Wrangell. The measured depth of runoff from Tyee Creek, for example, is 172 inches annually or 172 percent of the nearest sea level station at Bell Island. A similar relationship is characteristic of high elevation watersheds in all southeastern Alaska. It is due to the orographic effect of the coast mountain ranges which cause rapid uplift of maritime air masses forcing heavy release of precipitation. For the Thomas Bay watershed, the percentage increase is 171 percent over sea level percipitation. As in all of southeastern Alaska, the total amount of annual pre- cipitation in the Petersburg-Wrangell area is very dependable. During the 56-year record at Petersburg, the longest period of low precipitation occurred between 1950 and 1951. The 24-month total precipitation was 73 percent below normal. The driest year on record had 71.31 inches; rarely does the annual total precipitation produce less than 90 inches. The minimum month recorded was June 1924, when only 0.78 inches were recorded at Petersburg. Rarely is the monthly total precipitation less than 2 inches. SNOW Annual snowfall is a modest amount near sea level at the project area. The annual average at Petersburg is 97 inches, for Wrangell it is 61 inches. This represents about 8 percent of the total annual pre- cipitation. Snowfall data is unavailable at the elevation of Tyee and Swan Lake. However, in the record from Jumbo Mine at 1,500 feet in the A-8 Ketchikan area snowfall constitutes about 25 percent of the annual precipitation. Using this proportion, the annual snowfall at Tyee and Swan Lake would be approximately 340 inches. No snow courses are located in the immediate project watersheds. However, the following courses are representative of this portion of southeastern Alaska: Course Harriet Top Hunt Saddle Lake Shore WINDS Snow Course Data Average Water Content (Inches) Elevation (ft} 2,000 1,500 660 February 1 37.2 29.4 16.2 March 53.1 40.9 28.2 April 1 65.3 55.4 34.7 The only available wind measurements near the study area are at Petersburg. The prevailing directions are south and southeast. Approxi- mately 50 percent of the time wind speeds are below 8 mph. Wind speeds over 25 miles occur only about 1 percent of the time. The highest hourly average over a 4-year period on record at Petersburg was 46 mph. Because of the orientation of the Bradfield Canal near Tyee Lake. occasionally strong gravity winds originating over the interior ice- fields blows through the terrain channel toward the ocean. This flow of cold air is strengthened during winter by the steep pressure gradient between the coast and the interior. Hourly average wind speeds from the east in excess of 35 mph have been measured occasionally at Peters- burg during the winter months. These gravity winds need to be considered in transmission line design. A-9 EVAPOTRANSPIRATION For both projects the proposed reservoir site is at an already existing lake. Because of the cool, cloudy climate in the study area, the additional evaporation from the reservoir surface, as compared to the present site loss (from the surface and existing vegetation), will be negligible. For this reason no adjustment for reservoir evaporation was made in the power studies. Following project completion, the monthly operating records for the lake should be adjusted to estimate the full natural flow. This can be accomplished by adding to the calculated lake inflow the difference between the lake evaporation at natural level and that for the operating level for the given month. This value in any given month may be negative or positive, since the actual lake surface area may be greater or less than the existing natural lake surface area. Evaporation records should not be used from another part of southeast Alaska, because the differences may be large. An evaporation pan should be maintained along with the project weather station. A-10 STREAMFLOW RECORDS AVAILABLE RECORDS Stream gaging data are available on both Tyee and Cascade Creeks. Records of average monthly discharge are fragmentary for Tyee Creek and much more extensive for Cascade Creek. Stream Gaging Records Station Years Period of Record Cascade Creek 38 Water Years 1918 -1928 1947 -1973 Tyee Creek 12 Water Years 1922 -1927 1964 -1969 For the earlier period of record at Tyee Creek the gage was located 1 mile further upstream from the gage location in the 1960's. The measured average monthly runoff for both stations is given in Tables A-1 and A-2. The U.S. Geological Survey has determined the pH and specific conductance for Tyee and Cascade Creeks. The U.S. Fish and Wildlife Service has measured dissolved oxygen and temperature in Tyee Lake. For the discharge on both creeks, there are several days each year with no gage-height records. For this reason, and also because of the scarcity of good field hydrographic measurements, the records for Tyee and Cascade Creeks are rated as 11 fair 11 by the U.S. Geological Survey. A-ll EXTENSION OF STREAMFLOW RECORDS In order to develop a complete 50 years of streamflow data, the records for the above gages were correlated with those from other streams in southeastern Alaska having long historical records. Because of its comparatively longer record, the Cascade Creek gage was initially used in a series of correlations with three streams which were similar in drainage area, watershed aspect, and elevation. After determining the best correlation for Cascade Creek and calculating the years of missing record, (1929-1946) and (1974-1976), the Cascade Creek record was then correlated with the shorter record for Tyee Creek and an entire 50 years of streamflow data calculated for Tyee Creek. The early record (1922-1927) for Tyee Creek was not used in the correlation analysis. The three streamflow records considered in the initial correlation analysis for Cascade Creek are listed below: Streamflow Records for Correlation Analysis Station Dorothy Creek near Juneau Fish Creek near Ketchikan Sawmill Creek near Sitka Drainage Area in Square Miles 15.2 32.1 39.0 Period of Record 1930-1967 1916-1978 1920-1922, 1928-1942, & 1945-1957 Because the record for Sawmill Creek contained so many gaps, it was not considered further in the correlation analysis. Of the two remain- ing streamflow records, Dorothy Creek appeared to give the best fit data as a predictor of Cascade Creek. However, since Dorothy Creek A-12 records were not available for 1929 and parts of 1942 and 1944, the Fish Creek records had to be used to fill in the missing records for those years. The best relationship was found by dividing the monthly streamflow into winter and summer portions. The resulting equations are as follow: (May-Oct) Qc = 1.41 Qd + 68 (Nov-Apr) Qc = 1.89 Qd + 4 Where: Qc = Cascade Creek near Thomas Bay monthly discharge in cfs. Qd = Dorothy Creek near Juneau monthly discharge in cfs. For Tyee Creek the correlation equations were as follow: (May-Oct) Qt = 0.740 Qc (Nov-Apr) Qt = 0.700 Qc Where: Qt = Tyee Creek near mouth monthly discharge in cfs. Qc = Cascade Creek near Thomas Bay Although the above equations provide an acceptably good fit, it is likely that in a more detailed study, precipitation records could be used to improve the predictions considerably. Precipitation records at Petersburg are only 30 air miles from Cascade Creek as compared to 95 air miles to Dorothy Creek. For Tyee Creek, there are precipitation records at Wrangell and Bell Island, 30 air miles south. A-13 ESTIMATED OAMSITE STREAMFLOWS The streamflow records at the two proposed damsites (Swan Lake on Cascade Creek, and Tyee Lake on Tyee Creek) were developed using the assumpticr that a direct linear relationship exists between drainage: area and streamflow. Since no gaging records exist at the propo~~d damsites, there is no way to verify this assumption. However, because precipitation generally increases with altitude, it is probable that the true runoff at Tyee and Swan Lakes is higher than that estimated by using the proportional drainage area relationship. In addition, the streamflow at Swan Lake likely includes a substantial volume of glacial melt which would not be equal at all elevations on the water- shed. Therefore, this cannot be estimated accurately by the propor- tional drainage area method. For both Tyee and Swan Lakes, the actual winter flows are likely lower and the summer flows higher than the figure derived by the pro- portional drainage area method. This is because the areas contributing inflow to the gaging sites receive more precipitation in the form of rain throughout the winter than do the lake watersheds. In summer, the lake watersheds have a greater proportion of their runoff from snowmelt than is the case for the watersheds at the gaging sites. The following relationships were used to estimate the damsite streamfl ows: .IJ.-14 (May-Oct) Qs = 1.06 Qd + 51 (Nov-Apr) Qs = 1.42 Qd + 33 (May-Oct) Qtl = 0.653 Qc (Nov-Apr) Qtl = 0.617 Qc Where: Qs = Cascade Creek at Swan Lake monthly discharge in cfs Qd = Dorothy Creek near Juneau Qtl = Tyee Lake monthly discharge in cfs Qc = Cascade Creek near Thomas Bay The drainage areas used in the calculation are as follow: Location Cascade Creek near Thomas Bay Cascade Creek at Swan Lake Tyee Creek near Mouth Tyee Creek at Tyee Lake A-15 Drainage Area Square Miles 23.0 17.3 16. 1 14.2 STREAMFLOW CHARACTERISTICS FLOW DURATION Because the duration of streamflow levels is critical in power production~ the respective flow duration curves for mean daily discharge for both Tyee and Cascade Creeks is presented in Figure A-1. For Cascade Creek, the lowest daily flow of record is 14 cfs; the curve illustrates that rarely does the flow drop below 20 cfs. Tyee Creek has experienced a minimum daily flow of 7 cfs and rarely falls below 10 cfs. For 25 percent of the time, Tyee Creek is below a 25 cfs, whereas Cascade Creek drops below 25 cfs only about 5 percent of the time. Tyee Creek has a median daily flow of 105 cfs as compared to a mean daily discharge of 175 cfs. For Cascade Creek, the respective values are 155 and 251 cfs. This wide disparity between mean and median daily indicates the uneven nature of the flows on both streams, and illustrates the need for storage control on a seasonal basis in order to capture and use effectively the comparatively infrequent high flows. Despite its very short period of record, Tyee Creek has experienced a maximum daily flow of 1,950 cfs which exceeds that of Cascade Creek (1,870 cfs). The flow duration curve indicates the extreme rarity of high flows on either watershed. Discharge in excess of 1,000 cfs occur less than 5 percent of the time. A-16 )• · DAILY FLm~ DURATION CURVES 3000 2000 1000 PERIOD OF.RECORD Cascade Creek 1918-1928 & 1947-1973 Ul 500 Tyee Creek 1964-1969 4-u OJ O"l &.. "' .J:.: u Ul ,.... 200 Cl >, r-~ .,.... q/; as I:: 100 8q "' (}' G.J :E 0 10 20 30 40 50 60 70 80 90 100 Percent of Time Daily Flow Exceeds Indicated Value A-17 FIG. A-1 It should be kept in mind that these flows are at the respective gaging sites and that the minimum flows at the proposed damsite would be somewhat lower. The sharp drop in the curve for Tyee Creek above the 60 percentile level is noteworthy. This indicates that low flows on Tyee Creek do not sustain as well as on Cascade Creek. It should be kept in mind that these flows are at the respective gaging sites and that the minimum flows at the proposed damsites would be somewhat lower. LOW FLOW FREQUENCY ANALYSIS Although the seasonal fluctuations in streamflow from summer to winter are extreme on both Tyee and Cascade Creeks, the reliability of the total runoff from year to year is exceptionally high. The low flow frequency curve for mean annual discharge at Cascade Creek is presented in Figure A-2. The clustering of points about the median value (248 cfs) is an indication of the high reliability of the flow. The 100-year expected low flow can be derived by extrapolation, using the straight line assumption. This value is 165 cfs or 67 percent of the median annual flow. Also, noteworthy is the 20-year low flow which is 202 cfs, or 81 percent of the median annual flow. From the low frequency curve it can be inferred that prolonged periods of low runoff are not a problem in the study area. On the upper end of the curve, it is apparent that the expected high annual average flows are not greatly in excess of the median. For the 100-year and 20-year return periods, the respective annual A-18 (/) 4-u <!) 01 s... """ -. . ,.... Cl <U :::l c c cJ:: LOW EXCEEOANCE FREQUENCY PER HUNDRED YEARS 95 90 8!) 70 60 50 4-0 30 2.0 ) JO l i i I . I I 400 _ 1 1. ANNUAL .L01ILfw ~REQ~ENC~ I CAsc;DECREEK! nrl THC~fS r I f j 300 200 100 I -----· ----t :-I ! l I I ! -·-i -- ·I ---- ! ·I ' I .l I I I· I I I I : ! ... 0! ! i . :· l I I . I I I . ·--1 -. '!' . 1 I I ! I I ' l j I I eri od ofi Rec'ord i38 years) I I l I I I ! I , I I 2 5 10 20 ' RETURN PERIOD YEARS A-19 2 1 i i I r I . I I ~ I I r I I : I l 50 100 FIG. A-2 flows are 322 cfs and 302 cfs. These flows are respectively 130 and 122 percent of the median annual flow. It would, therefore, be unnec- essary at Cascade Creek to construct a reservoir for the purpose of storing large volumes of water in the years of high streamflow to be used in subsequent years. The main use of the storage would be to even the flow on a seasonal basis. The record for Tyee Creek is not of sufficient length to permit the construction of a useful frequency curve. However, such a curve for Tyee Creek should be comparable to that for Cascade Creek. The 50-year calculated streamflow records for both Tyee and Cascade Creeks at the damsites include low flow periods which are significant in evaluating the hydropower potential of the streams. The following table presents a listing of lowest single-year and lowest consecutive 2 years. Low Streamflow Periods of the 50-Yr Calculated Record (cfs) Mean Annual Stream 1-Yr 2-Yr Discharge Cascade Creek at Swan Lake 151 ( l 951 ) 178 (1932-33) 190 Tyee Creek at Tyee Lake 126 (1935) 135 (1951-52) 164 It is significant that the lowest years are over 75 percent of average, from a 50-year calculated period of record. The critical period for power production depends on the project design as well as the natural streamflow. The critical period is described in Appendix E under Hydropower Analysis. A-20 FLOOD CHARACTERISTICS Floodflows on both Tyee and Cascade Creeks are generally confined to the summer and fall months (Jun -Nov) and are mainly the result of heavy, coastal orographic rainfall. Snowmelt flows also are high but rarely approach the level of rain flood discharges, primarily because solar energy is limited by the high incidence of cloud cover. The rain flood peaks on both watersheds are accentuated by the comparative lack of vegetative cover, and the exceedingly rugged topography. The relatively larger area of snowfield and glacial coverage on Cascade Creek would tend to attenuate the rain flood peaks on that watershed. Although the majority of flood discharges are related to rainfall, flood events are not necessarily characterized by a sharply rising storm hydrograph with a high peak of short duration. The fairly steady region-wide rainfall from a succession of North Pacific storm systems usually results in a slowly rising flood hydrograph which may remain high for 3 or 4 days. PAST FLOODS Although the streamflow records for purposes of floodflow analysis are short for Cascade and Tyee Creeks, the following tabulation illu- strates the order of magnitude during peak flows. A-21 Flood Discharges of Record (cfs) Cascade Creek Tyee Creek near Thomas Bay near Mouth Momentary Daily Momentary Daily Date Peak Mean Date Peak Mean 09/ll/47 3,280 10/23/65 2,440 1,950 10/03/61 2,480 1 ,870 09/24/68 2,200 937 09/30/57 2,350 2,040 09/04/66 1 ,620 1 ,320 09/30/72 1 '960 1 '780 10/19/64 1,490 1 '390 10/01/72 1,850 1 '380 10/10/67 1,420 1 ,280 07/08/52 1,800 1 '580 10/06/65 1 ,200 859 10/15/61 1 '760 1 ,320 07/11/69 1 '120 1 ,010 10/02/58 1 '740 1 '560 10/16/63 960 808 09/04/66 1 ,650 1,460 09/11/68 917 788 All of the above flood peaks of record are rain events. It should be noted that the tabulation includes only the single historical peak flows for each individual year. The peak flows for the entire period of record would include many additional high flows. FLOOD FREQUENCIES The frequency curve of annual peak discharges at Thomas Bay is presented in Figure A-3. The curve was developed using the procedure as outlined in Beard, Statistical Methods in Hydrology (1962). Using the values from the curve in Figure A-3, the flood peaks for various return periods can be estimated: A-22 - 99 98 4000 3000 .,.. c 2000 1000 EXCEEDANCE FREQUENCY PER HUNDRED YEA~S eo BO 10 60 50 4C 30 2() I I I PEAK:DISCHARGE FREQUENCY I I 1 I I CASCADE C EEK;nr THOMAS BAY i ,. ' I 1 I I I I , I I I. I \ ' I I I ·.'I ·; 1 ' I I . , 'I I I l I I I I ! I I . t -I I I I l' I I ; I i I I I I I I . I I I I I I ' I i ' I I . ! ' I i I (Peri~d o~ Re~ord!!l947, : ! ! I I ! 1f51-lr73) , I ! IO , I I 5 2 5 I 10 20 RETURN PERIOD YEARS A-23 1• l 2 1 100 FIG. A-3 Peak Discharge Frequency Cascade Creek near Thomas Bav Return Period {Years) 2 5 10 25 50 100 Discharge (cfs) 1,540 1 ,880 2,175 2,750 3,525 3,950 The historical record for Tyee Creek was not adequate to provide a representative distribution. PROBABLE MAXIMUM FLOOD The probable maximum precipitation (PMP) for southeastern Alaska was calculated by the Hydrometeorological Branch of the National Weather Service for six locations. These sites include Cascade Creek and because of the topographic similarity and geographic proximity the same PMP was also used for Tyee Creek. The National Weather Service PMP values were estimated using a generalized elevation-precipitation curve and observed 3-day storm events in the project area. A high and low range value were given for each location of interest. In deriving the probable maximum flood (PMF) for Tyee and Cascade Creeks, the low range PMP was used. The depth in inches for various durations is as follows: A-24 Probable Maximum Precipitation Cascade and Tyee Creeks Duration (hours} 6 18 24 30 48 72 Depth 8.50 15.25 17.50 19.50 24.25 29.75 Source: National Weather Service -Memorandum of 6 May 1977. The hourly precipitation totals were then derived for a theoretical 72-hour storm using the method outlined by the National Weather Service in the same 6 May 1977 memorandum. The hourly values were then used to simulate a flood hydrograph for each watershed using the computer program HEC-1, 11 Flood Hydrograph Package ... The PMF so derived is appropriate only for the months of August through November. For the snowmelt season (May -July), the values of PMF are about 30 percent lower than the tabular values. Location Cascade Creek at Swan Lake Tyee Creek at Tyee Lake Probable Maximum Flood ( cfs) Spring Probable Maximum Flood 5,040 4,270 A-25 Summer Probable Maximum Flood 7,200 6,100 The above estimated flood discharges are appropriate only for Swan Lake and Tyee Lake and not for the respective gaging sites. They are the inflow hydrograph peaks for each lake. In the second stage of the project, a bin-wall dam is proposed at Tyee Lake. A standard project flood {SPF) equal to one half the PMF was routed through the reservoir using assumed spillway widths of 100, 150, and 200 feet. The corres- oondino oeak outflows for the summer SPF at Tvee Lake were respectively: 1,470, 1,640, and 1,850 cfs. A-26 WATER QUALITY SEDIMENTATION Both the Tyee and Cascade Creeks drainage basins are composed of consolidated igneous bedrock with little soil mantle. The only excep- tions are the muskeg areas which rarely contribute sediment load to the streams because they are poorly drained. The only significant glacial coverage is on Cascade Creek (4 square miles). Tyee Creek drainage has only about 0.4 square mile in glaciers and permanent snowfields. During a reconnaissance field trip to Tyee Lake in June 1978, the creek inflowing at the head of the lake was clear with no apparent glacial flour or other sediment. For the above reasons, the sedimen- tation rate for Tyee Lake is expected to be negligible for an assumed 100-year life of the project. A rational method for estimating sediment yield was developed by Elliott Flaxman in the Proceedings of the American Society of Civil Engineers, Hydraulics Journal, December 1972. His formula is appli- cable only for nonglacial streams and is of the form: Log (S+lOO) = 6.21 -2.19 log + • 06 1 og .016 log (Xl + 100) (X2 + 100) (X3 + 100) Where: S = Annual sediment yield in acre-feet per square mile = Annual precipitation + mean annual temperature (inches and oF) A-27 x2 = Watershed percent slope X3 = Percent coverage of soil particles with diameter 1. 0 mm x4 = Soil aggregation index (negligible for Tyee Creek) The value of S calculated for Tyee Creek drainage using the above formula was less than zero. This supports the conclusion that sedi- mentation in Tyee Lake is negligible over a 100-year time span. Because there is a large talus cone on the south side of Tyee Lake, it is likely that falling rock debris from this source through time would tend to reduce the active lake storage. It would be difficult to estimate the frequency of rock debris slides into the lake. For Swan Lake on Cascade Creek, the 100-year sedimentation rate was calculated by the Bureau of Reclamation in a 1965 hydropower study. That estimate was 3,000 acre-feet of the active storage capacity of the lake. The calculation was based on sediment yield data from small glacial streams both in Europe and North America. The 3,000 acre-feet would be less than 5 percent of the planned active storage capacity of 72,000 acre-feet. The 3,000 acre-feet estimate can be added to the inactive storage in the elevation area capacity curve for Swan Lake. WATER QUALITY SAMPLING Stream water quality data are not regularly measured on either Tyee or Cascade Creek. Measurements of temperature and dissolved solids for both streams were published in the 1967 records of the U.S. Geological A-28 Survey. Because the data are 1-day samples, they cannot be used to define the water quality conditions on the two streams. Water Quality Samples Station Date Cascade Creek near Thomas Bay 9 Apr 67 Tyee Creek near Mouth 10 Apr 67 Specific Conductance Discharge (cfs) (Micromhos) 35.3 25 13.8 12 7.2 6.7 A brief study of Swan Lake on Cascade Creek was conducted by the Alaska Department and Fish and Game in July and September 1974. Thermal stratification was not well developed in the lake, either in July or September. The thermocline extended to a depth of 80 feet in September, where the temperature was 39° F. The lake surface temperature was 42° F in July and 46° F in September. High values of chlorophyll and organic carbon were found in Swan Lake during the 1974 sampling. Most of the water quality parameters sampled changed little from July to September, except for the calcium to magnesium ratio which showed a marked decline. The Department of Fish and Game attributed the decline to changes in concentration of dissolved minerals in the surface runoff which comes in greater contact with exposed bedrock in the summertime. They appeared to have over- looked the fact that a greater proportion of the water in late summer would be of glacial origin. A-29 The water quality sampling data for Swan Lake from the 1974 study are given in the following tabulation: Water Quality Data, Swan Lake near Thomas Bay July and September 1974 7 July 9 September Location Outlet West End Outlet Center Sample Depth s1o2 Fe Mn Ca Mg Na K pH (ft) 3 (mg/1 ) 2. 1 (ug/1) 30 { ug/1) 0 (mg/1) 3. 0 (mg/1) 0.2 (mg/1) 0.5 {mg/1) 0. 3 Color (Cobalt Units) Total Nitrogen {mg/1) 6.7 2 0.17 Tota 1 Nitrite plus Nitrate Ammonia Phosphorus HC03 C02 so 4 sl F Total Dissolved Solids Hardness as Caco 3 (mg/1) (mg/1) (mg/1) (mg/1) (mg/1) (mg/1) (mg/1) (mg/1) 0.08 0 0 12 8.6 1.6 0.6 0 (mg/1) 15 (mg/1) 11 3 2.0 40 0 3.7 0.2 1.0 0.4 6.6 2 0.14 0.04 0 0 i2 9.3 1.5 0.7 0 16 10 2 1.4 10 10 1.7 1.6 1.9 0. 1 6.5 3 o. 19 0.01 0.02 o. 01 9 4.5 0. 1 0 16 11 Source: U.S. Geological Survey, Limnologica1 Investigations ... in Southeast Alaska 1977. 12 1.3 200 40 2.0 1.5 1.8 0 6.3 5 0.17 0.07 0. 01 0. 01 9 4.5 0. 1 0 16 11 The turnover rate for both Tyee and Swan Lakes is fairly high. Tyee Lake waters are replaced on an average every 9 months; Swan Lake waters are replaced about once each year. There are no extensive water quality data for Tyee Lake. During a field visit on 8 June 1978, the U.S. Fish and Wildlife Service found the lake temperature to be 54° F (10° C) at a depth of 50 feet. Dissolved oxygen was measured at 12 parts per mi 11 ion. A.-30 TABLE A-1 TYEE CREEK NEAR WRANGELL Recorded Monthly Discharge in Cubic Feet Per Second Drainage Area {1922-1927) 14 Square Miles {1964-1969) 16.1 Square Miles WATER YR OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP ANNUAL 1922 172 158 371 268 185 278 1923 238 263 1924 410 337 245 1925 288 340 343 205 154 1926 128 179 280 240 77 117 146 210 270 256 199 140 188 1927 313 140 112 67 30 35 50 167 380 299 191 226 168 ):::> 1964 333 65 114 67 49 27 59 150 337 340 312 197 180 I w 1965 355 106 79 90 46 42 77 155 362 313 161 108 159 __. 1966 435 60 50 26 19 48 75 211 374 307 265 312 183 1967 222 128 50 36 26 20 23 270 494 305 240 403 185 1968 272 155 55 31 51 100 43 245 317 290 181 435 181 1969 223 126 38 14 13 11 72 284 426 285 244 156 158 TABLE A-2 CASCADE CREEK NEAR THOMAS BAY Recorded Monthly Discharge in Cubic Feet Per Second Drainage Area 23.0 Square Miles WAfER YR OCT NOV OEC JAN --Frn-MAR APR MAY JUN JUL AUG SEP ANNUAL 1918 589 657 74 66 27 20 51 195 482 532 656 400 314 1919 376 185 91 161 27 27 75 155 322 476 571 487 248 1920 334 102 73 78 60 33 34 99 441 549 676 332 235 1921 158 128 35 33 41 40 35 200 510 432 370 403 199 1922 566 124 147 50 25 20 65 181 310 473 502 395 240 1923 252 253 64 28 41 55 90 248 511 450 507 555 255 ::z:.., 1924 385 238 78 37 25 45 65 292 594 529 517 684 291 I 1925 357 204 85 19 334 488 623 451 315 248 w 20 25 33 N 1926 210 184 346 405 74 139 272 288 410 412 326 231 276 1927 389 162 135 54 20 31 33 165 551 481 420 530 249 1928 299 85 32 141 49 66 72 365 571 588 442 424 262 1947 189 227 38 43 41 187 164 327 510 389 369 527 251 1948 188 160 72 86 40 27 25 349 496 403 357 484 224 1949 217 146 48 45 25 35 61 290 445 495 460 455 228 1950 376 372 62 25 20 23 27 164 518 504 388 428 243 1951 140 86 49 42 26 29 45 291 584 487 332 285 200 1952 244 112 67 33 33 30 47 258 438 615 465 522 239 1953 473 159 63 33 30 30 43 350 458 389 412 385 236 1954 393 133 77 51 199 34 30 196 456 390 281 331 214 1955 258 223 149 67 46 36 50 136 424 554 549 438 245 1956 215 137 40 23 20 16 35 360 423 542 662 301 232 1957 233 205 194 69 42 34 52 302 491 444 353 481 243 TABLE A-2 (cont) CASCADE CREEK NEAR THOMAS BAY WATER YR OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP ANNUAL 1958 270 253 87 101 39 43 90 301 485 421 434 208 229 1959 566 142 105 48 56 43 60 265 515 660 476 273 261 1960 407 146 200 69 51 51 129 311 438 565 503 423 275 1961 613 196 176 80 87 35 111 299 578 536 640 403 315 1962 562 163 55 139 125 42 58 203 526 616 479 514 291 1963 289 244 291 178 196 77 62 261 400 445 351 633 286 1964 333 86 120 87 65 41 58 144 592 615 463 259 239 1965 342 153 103 154 59 63 70 158 423 407 327 255 211 1966 474 96 64 55 42 52 88 227 502 485 475 462 253 )> 1967 330 167 66 55 33 32 48 299 722 477 507 599 279 I 1968 291 215 76 96 96 138 72 290 368 518 320 611 258 w w 1969 235 150 62 20 16 19 39 287 589 508 450 317 225 1970 219 393 234 72 83 56 51 229 554 463 472 535 281 1971 326 177 45 53 34 31 43 217 528 502 541 342 238 1972 240 107 56 38 60 95 40 250 505 651 626 471 262 1973 433 153 54 49 52 42 71 238 488 563 612 715 290 TABLE A-3 TYEE LAKE DAMSITE Unregulated Monthly Flow in Cubic Feet Per Second Drainage Area 14.2 Square Miles WATER YR OCT NOV DEC JAN-FEB MAR APR MAY JUN JUL AUG SEP .ANNUAL 1927 254 100 83 33 12 19 20 108 360 314 274 396 165 1928 195 52 20 87 30 41 44 238 373 384 289 277 171 1929 188 87 32 53 11 39 22 127 308 326 360 194 147 1930 359 180 77 16 17 27 58 114 226 348 387 305 177 1931 224 228 119 48 85 28 42 152 347 331 379 320 192 1932 237 77 22 24 19 17 34 109 274 311 303 296 144 J> 1933 241 52 28 25 21 16 27 124 182 275 292 214 126 I 1934 200 186 39 14 16 20 25 100 274 299 418 274 156 w -+::> 1935 242 99 66 22 14 24 25 94 195 409 324 230 147 1936 230 70 99 24 17 25 38 145 336 319 294 372 177 1937 463 333 134 32 20 30 33 105 319 274 320 357 203 1938 398 103 60 52 47 82 27 160 233 301 270 404 179 1939 258 90 66 39 30 22 30 111 252 359 445 281 166 1940 281 166 90 34 41 22 46 150 243 339 415 335 181 1941 249 84 39 22 30 30 66 132 275 341 244 181 142 1942 232 143 44 101 21 34 51 148 293 280 253 308 160 1943 276 64 39 46 25 49 75 132 253 397 355 397 177 1944 407 186 130 62 22 45 46 144 353 317 311 240 190 1945 339 166 100 25 19 32 34 152 268 348 286 330 187 1946 411 57 25 20 20 22 25 173 304 289 350 257 164 1947 123 140 23 27 25 122 107 214 333 254 241 344 163 1948 123 99 45 53 25 17 16 228 324 263 233 316 146 TABLE A-3 (cont) TYEE LAKE DAMSITE WATER YR OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP ANNUAL 1949 141 91 30 28 16 22 38 189 291 323 300 297 148 1950 246 231 38 16 12 14 17 107 338 329 253 279 157 1951 91 53 30 26 16 18 28 190 381 318 217 186 130 1952 159 69 42 20 20 19 29 168 286 402 304 341 156 1953 309 99 39 20 19 19 27 229 299 254 269 251 154 1954 257 82 48 32 123 22 19 128 298 255 183 271 143 1955 168 138 92 42 29 22 31 89 277 362 358 286 159 1956 140 85 25 14 12 10 22 235 276 354 432 197 151 1957 152 127 120 43 26 21 32 177 321 290 231 314 155 ·;p. 1958 176 157 54 66 24 27 56 197 317 275 283 136 148 I 1959 304 w 88 65 30 35 27 37 173 336 431 311 178 169 U1 1960 266 91 124 43 32 32 80 203 286 369 378 276 183 1961 400 122 109 50 54 22 69 195 377 350 418 263 204 1962 367 101 34 86 78 26 36 133 343 402 313 336 189 1963 189 151 180 110 122 48 38 170 261 291 229 413 184 1964 217 53 74 54 40 25 36 94 387 402 302 169 155 1965 223 95 64 95 37 39 43 103 276 266 214 167 136 1966 310 60 40 34 26 32 55 148 328 317 310 302 164 1967 215 104 41 34 20 20 30 195 471 311 331 391 181 1968 190 133 47 60 60 86 45 189 240 338 209 399 167 1969 153 93 38 12 10 12 24 187 385 332 294 207 146 1970 143 244 145 45 51 35 32 150 362 302 308 349 181 1971 213 110 28 33 21 19 27 142 345 328 353 223 154 1972 157 66 35 24 37 59 25 163 330 425 409 308 171 1973 283 95 33 30 32 26 44 155 319 368 400 467 188 1974 213 21 35 5 14 15 43 203 336 365 293 222 148 1975 328 130 90 36 16 18 29 157 328 361 297 252 171 1976 188 71 89 88 25 26 32 151 325 407 338 306 172 TABLE A-4 CASCADE CREEK AT SWAN LAKE Unregulated Monthly Flow in Cubic Feet Per Second Drainage Area-17.3 Square Miles WATER YR OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP ANNUAL 1927 293 122 102 41 15 23 25 124 414 362 316 399 187 1928 225 64 24 106 37 50 54 274 429 442 332 319 197 1929 217 106 39 65 13 47 27 146 355 376 415 224 170 1930 414 219 94 19 21 33 71 131 260 401 446 351 206 1931 258 278 145 59 104 34 51 175 400 381 437 369 225 1932 273 94 27 29 23 21 41 126 316 358 349 341 167 :Po 1933 278 64 34 30 26 19 34 143 210 317 336 246 150 I 1934 230 227 48 17 20 24 31 115 316 345 481 316 182 w ()) 1935 279 121 80 27 17 29 30 108 225 . 471 373 265 170 1936 265 85 121 29 21 30 46 167 387 368 339 429 191 1937 533 406 163 39 24 36 40 121 367 316 369 411 236 1938 458 125 73 64 57 100 33 184 268 347 311 465 208 1939 297 110 81 48 37 27 36 128 290 414 513 324 193 1940 324 202 110 41 50 27 56 173 280 390 478 386 211 1941 287 102 48 27 36 36 80 152 317 393 281 208 165 1942 267 174 54 123 26 41 62 171 338 323 292 355 186 1943 318 78 47 56 31 60 91 152 291 457 409 457 205 1944 469 227 159 76 27 55 56 166 407 365 358 277 222 1945 390 202 122 31 23 39 41 175 309 401 329 380 205 1946 473 70 31 24 24 27 30 199 350 333 403 296 190 1947 142 171 29 32 31 140 123 246 384 293 277 396 189 1948 141 120 54 65 30 20 19 262 373 303 268 364 168 TABLE A-4 (cont) CASCADE CREEK AT SWAN LAKE WATER YR OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP ANNUAL 1949 163 110 36 34 19 26 46 218 335 372 346 342 171 1950 283 280 47 19 15 17 20 123 390 379 292 322 183 1951 105 65 37 32 20 22 34 219 439 366 250 214 150 1952 183 84 50 25 25 23 35 194 329 462 350 393 180 1953 356 120 47 25 23 23 32 263 344 293 310 290 177 1954 296 100 58 38 150 26 23 147 343 293 211 249 161 1955 194 168 112 50 35 27 38 102 319 417 413 329 184 1956 162 103 30 17 15 12 26 271 318 408 498 226 174 1957 175 154 146 52 32 26 39 227 369 334 265 362 183 1958 203 190 65 76 29 32 68 226 365 317 326 156 172 )> 1959 350 107 79 36 42 32 45 199 387 496 358 205 196 I w '-I 1960 306 110 150 52 38 38 97 234 329 424 378 318 207 1961 461 147 120 60 65 26 83 225 435 403 481 303 237 1962 423 123 41 105 94 32 44 153 396 463 360 387 219 1963 217 183 219 134 147 58 47 196 301 335 264 476 215 1964 250 65 90 65 49 31 45 108 445 462 348 195 180 1965 257 115 77 116 44 47 53 119 318 306 246 192 159 1966 356 72 48 41 32 39 66 171 378 365 357 347 190 1967 248 126 50 41 25 24 36 225 543 359 381 450 210 1968 219 162 57 72 72 104 54 218 277 390 241 459 194 1969 177 113 47 15 12 14 29 216 443 382 338 238 169 1970 165 296 176 54 62 42 38 172 417 348 355 402 211 1971 245 133 34 40 26 23 32 163 397 378 407 257 179 1972 180 80 42 29 45 71 30 188 380 490 471 354 197 1973 326 115 41 37 39 32 53 179 367 423 460 538 218 1974 245 26 43 6 17 18 53 234 387 420 338 256 172 1975 378 159 110 44 20 22 35 181 378 416 343 290 199 1976 217 86 109 107 30 32 39 174 374 469 389 352 199 SECTION B FOUNDATION AND MATERIALS THOMAS BAY GEOLOGY The dominant geological features of the region are: (1) the coast range batholith and (2) the metamorphic zone immediately to the west. The western part of the batholith is characterized by bands of gneiss in various stages of assimilation. Swan Lake is some 32 kilometers north, northeast of Petersburg at (57° 02' N, 132° 45' W). Access to the area is best made by helicopter. Although a floatplane can get into the lake there is no accessible landing along Cascade Creek flowing out of Swan Lake. Swan Lake is a perched lake, bypical of many lakes in the southeastern Alaska. Swan Lake is located between high, steep valley walls some 4 kilometers from the tidewater at Thomas Bay. Cascade Creek drops over 1,500 feet in roughly 4 kilometer, flowing through Falls Lake, a long narrow lake, about one-third of the way down from Swan Lake at elevation 1,197 feet. The creek below Falls Lake is entranced by a very steep walled canyon. GENERAL GEOLOGY Swan Lake lies within the crystaline rocks of the Great Coast Range batholith. Immediately to the west is the broad belt of meta- morphic rock which parallels the western edge of the crystaline rocks. A layered sequence of rocks is exposed at tidewater near the mouth of Cascade Creek where it empties into Thomas Bay. These rocks are of argillite texture and appear to be quite durable and resistant to weathering and sea erosion. The crystaline rocks that surround the 8-1 lake outlet ranges from quartz diorite to banded gneisses. The gneissic banding appears to be more prevelant as one goes downstream towards Thomas Bay. The rock is very hard and dense with small to medium grained crystals. JOINT AND LINEAMENTS The dominant structures and lineaments which trend N 10° E, dipping nearly vertical. While other joints persist, they are not well defined. Onion skin jointing is quite pronounced in several areas. Other joints probably trending in a NW direction were observed in the lake outlet area and along Cascade Creek. The major indication of the NW joints appear as a cliff above Falls Lake. The trend of this resistant rock mass is N 50° w. Elsewhere topographic features indicate structure trending NW. A strong surface expression is reflected by the valley in which Cascade Creek flows. This lineament strikes N 50° E. Three different places along the valley, (1) at the damsite, (2) halfway to Falls lake, and (3) at Falls Lake, reveiled no evidence of either jointing or faulting. However, when traversing the shoreline on the way to the powerhouse site a shear zone some 15 to 20 feet wide exists. The exact location of shear zone at tidewater is not known, but it is approximately halfway to the powerhouse site. If the location is true, then it alines well with Cascade Creek lineament and confirms that Cascade Creek is flowing in a fault controlled valley. B-2 LAKE OUTLET The valley geometry at the outlet of the lake is very favorable for most any kind of structure, bt it a low wier or a higher structure. The narrow canyon has steep walls which rise several hundred feet above the lake and are not unduly fractured. Onion skin jointing exists on the south wall, the north wall is covered with vegetation preventing terrain observation. Large boulders filled the bottom of the stream at the outlet of the lake. TAP AREA The area selected for the lake tap is in a massive rock formation that doesn•t have a large number of joints or lineaments passing through it. The bathymetry is fairly steep with no shelves or breaks in the slope where silt could build up. The rocks above the lake are covered over with vegetation. Special attention will be given to this vegeta- tion cover above the tap area. It is quite probable the vegetative cover will require removing to insure that it will not slide into the lake and endanger the tap. PRESSURE TUNNEL In the scheme where two short tunnels are utilized, the upper tunnel is expected to be unlined except for the rock trap and gate area. The lower tunnel is the pressure tunnel and/or penstock which enters the powerhouse. From limited observations in the field and from topographic maps there doesn•t appear to be any major lineaments which would cross the tunnel area. However, it is quite safe to expect some B-3 such structure crossing the tunnel. The selected scheme, which has the long power tunnel shows numerous lineaments, of which some crossings will require remedial treatment. Disposal of excavated rock from the tunnel(s) is best utilized to make a level area for camp and other auxiliary features associated with the tidewater facilities. POWERHOUSE The powerhouse locations for the two-tunnel scheme is in a small basin at roughly 550 feet elevation. The present design consideration is to have an above ground powerhouse. The tailrace would follow an intermittent stream to Cascade Creek, thence to tidewater. No major geologic problems are anticipated for the powerhouse or tailrace. The powerhouse location for the long tunnel is located above ground several hundred meters NW of the mouth of Cascade Creek, the exact location has not been determined. The rock rises quite rapidly from tidewater, thus providing an excellent site for an underground powerhouse. No obvious geologic problems were observed from a traverse of some 2 kilo- meters along the shoreline. B-4 TYEE LAKE GEOLOGY Tyee Lake is about 45 kilometers SE of Wrangell on the Bradfield Canal at (56° 12' N, 131° 30' W). Access to the area is made either by helicopter or floatplane. Tyee Lake is a high perched lake at elevation 1,370 MSL. The lake is nearly 4 kilometers long and 600 meters wide. The valley walls rise on either side of the lake to elevations 7,600 meters. Tyee Creek leaves the lake through a very narrow defile in the rockwall and forms a series of cascades over the first 300 meters before leveling off to a gradual decline in tidewater at the head of Bradfield Canal. GENERAL GEOLOGY Tyee Lake is within a matamorphic band which trends somewhat to the north, northwest. The rocks at the lake are contorted gneiss with some pegnatite stringers. Because of the heavily forested countryside joints and other rock discontinueties were not observed. JOINTS AND LINEAMENTS The topographic experssion in the area leads to the interpretation of at least two major lineaments trending N 60° Wand at least two minor lineaments trending NS. Elsewhere throughout the area are numerous lineaments which trend N 60° W. This appears to be the major structural trend of the area. Only one of the N 60° W trending linea- ments would affect the pressure tunnel. The width is estimated to be over 6 meters thick of closely broken rock. This observation was made from a 1ow flying helicopter while flying over Tyee Creek. B-5 TYEE DAMSITE The location for a dam is between two shear walls of the outlet of the lake. When observed the rock appeared normally jointed, i.e., 1 to 3 meters apart. The outlet is chocked with larger diameter water logged trees devoid of their limbs. Also, large boulders prevailed through the outlet channel. A fracture is presumed to pass through the outlet channel. The attitude of the fracture is not known but it must dip to one side or the other to where the outlet stream has encountered more resistance to erosion. When observing the cascading water below the outlet there is no obvious evidence of a fracture passing through the portion of the rock. TAP AND PRESSURE TUNNEL The tap area is located near the outlet on the NE side of the lake. The rock, while well covered with trees, is quite steep. Fractures could not be observed due to the vegetation. Topographically it appears as if the tap area is between two lineaments which trend N 60° W some 600 meters apart. It can be presumed that unusually close spaced jointing would not occur within this mass of rock. However, investigation for onion skin jointing is quite necessary. This type of jointing was not seen elsewhere in the area. The pressure tunnel will cross at least one NW trending lineament which is described above. POWERHOUSE The powerhouse is to be located very close to where Tyee Creek enters tidewater at the head of Bradfield Canal. The present scheme B-6 is for an above ground facility. There was no obvious rock defects which would be a problem with foundations for the powerhouse. SEISMICITY All of coastal southeastern Alaska is in a moderately active seismic zone which has been classified Zone 3 by the Corps of Engineers. In Zone 3, earthquakes of magnitude 6.0 and greater can be expected. While there are no recorded earthquake epicenters in the immediate project area, the Fairweather-Queen Charlotte Fault systems are well defined and lie approximately 80 to 90 miles to the west of the project. Swarms of microseisms have been recorded in recent years in south- eastern Alaska, but it is not clear whether these events are related to faulting, glacial movement, or glacial unloading. However, as there are only two recorded epicenters of earthquakes within 100 miles (both magnitude less than 5.0) and the nearest epicenter for any earthquake of magnitude 6.0 or greater is 135 miles northwest of Wrangell, the immediate project area appears to be relatively inactive to the extent of available records. B-7 SECTION C REGIONAL ECONOMY ECONOMY OF THE AREA GENERAL The area that comprises Petersburg and Wrangell is shown on the records of the State as the Wrangell, Petersburg Census Division. In addition to these major communities, the area includes the village of Kake (west of Petersburg) and the fish processing center known as Scow Bay. For the purposes of this report, the human and natural resources closely related to Petersbury and Wrangell will be treated. The popu- lations of these two centers are about the same, and while there is some difference in the degree to which major resources are being developed at each community, they have the same five basic resources in common. POPULATION (HUMAN RESOURCES) Early in the century these two communities were active in the fishing and mining industries as their main economic base, while they were each involved as a way station for equipment and supplies for those who were traveling to Juneau, Skagway, and beyond. Beginning in the 1960's the area economy took on an atmosphere of diversification, which set the stage for the present economy and the development that can logically be projected to the future. Since 1960 the area economy has been based on wood processing activities, fish processing, institutional services, tourism, and basic transpor- taion. The labor force associated with activity in these resources C-1 sets the stage for overall population trends for both areas. Popu- lation trends stayed steady for the overall election district prior to the 1960 with extreme seasonal fluctuations based on high employ- ment during summer months and extreme unemployment during winter months. With industrial diversification, population trends showed a steady growth pattern until recent years when a slight reduction based on cutbacks in the wood processing industry has developed. The following table shows population trends for Wrangell and Petersburg individually and combined, and also the population trend of the Census Division, which takes into account the areas just beyond the city limits plus Kake and Scow Bay. Projections to 2000 are shown as 3 and 5 percent annual growth rate suggesting that a number of favorable developments will occur. Population Trends for Petersburg, Wrangell, and the Census Division l! 2000 Area 1960 1970 1975 1977 3% 50! ,-'Q Petersburg 1 ,502 2,042 2,300 2,200 4,342 6,757 Wrangell 1 '315 2,029 2,300 2,250 4,440 6,910 Total 2,817 4,071 4,600 4,250 8,782 13,667 Census Div. 3,400 4,913 5,700 5,600 11 ,052 17,200 ll State Department of Commerce and Community Profiles. LABOR FORCE The following table shows the most recent breakdown of the labor force by employment categories. The low employment period, the midyear C-2 period, and the yearly average are shown for the Census Division as reported by the State Department of Labor. Civilian Labor Force (1977) January ~ August Annual Aug Total 1,966 2,345 2,643 2 '131 Unemployed 555 (28%) 178 (7.6%) 286 ( 10.8%) 327 Employed 1 ,411 2 '167 2,357 1,804 Insured Employment by Category Total 1,618 2,444 2,675 2,051 Mining * * * * Construction 54 192 211 146 Manufacturing 440 781 923 611 Transportation and Public Utilities 192 237 287 233 Wholesale Trade * * * * Retail Trade 241 316 305 266 Finance 28 28 30 27 Service 143 146 150 145 Miscellaneous 31 169 204 * Government 467 547 537 506 Federal 81 146 143 116 State 386 401 393 389 * Withheld to honor disclosure regulation. Future employment patterns are not expected to differ greatly between now and the year 2000. If the basic plan for roads developed to the interior, hydropower development, bottom fish development, and increased tourism become a reality, there could be a slight change in the ratio of population to the labor force. These conditions result as an economy becomes diversified and mature. C-3 (15.3%) NATURAL RESOURCES Wood Processing The wood products industry is Wrangell's leading industrial activity. The two mills of the area produce 40 percent of Alaska's lumber exports and in 1978 employed 125 people at the mill sites. In 1977 the lumber mills of the area exported approximately 70 million board-feet of lumber to the Japanese market. Sitka Spruce cuts accounted for the bulk of the production with lesser amounts of Western Hemlock and cedar logs. For years the mills operated two shifts per day, but since 1976 production has been reduced to one shift per day and about 60 employees. The forest inventory of the Petersburg/Wrangell area is shown in the following table. Timber Inventory Acres in National Forest Annual Allowable Cut (mill board-feet) Sustained Yield Capacity (mill board-feet) 3,286,000 201 ,000 358,000 Some forecasts have suggest as many as 475 people employed in the lumber industry by 1978. Present D-2 legislation before Congress, spiraling costs, and a weak foreign market have created a serious concern about the future of the industry. Fisheries Fishing activity has been the main industry of Petersburg with forest products second by comparison. While salmon processing has long been the most important fish resource, there is a growing interest C-4 and involvement in the bottom fish industry and the newly established fish hatchery experiments. The Crystal Lake Hatcher, 17.5 miles south of Petersburg was funded by a 2.3 mill bond issue and has a capacity of 6 million eggs, 4 million alevins, 2 million fingerlings, or 1 million smolt. The natural stream production of southeatern Alaska can be supported and sustained and kept at a more uniform level through the output of this plant. Employment in the fishing industry is expected to be more constant than in the past and in general the fish- ing industry of the Wrangell/Petersburg area is projected to have a bright future. Tourism The tourist industry has become a major factor in the economy of southeastern Alaska. Each city along the Inside Passage route holds some special attraction and provides local guided tours and festivities designed to promote tourism. The Petersburg/Wrangell area has many local attractions such that the Stikine River and the migratory water fowl nesting areas of Dry Straits. Future development plans call for a highway from Wrangell to the town of Stewart in British Columbia. This will allow tourists from British Columbia to travel to Wrangell and Petersburg by ferry and return via the Aarons Creek highway. Tourism through southeastern Alaska amounted to over 500,000 people who spent an estimated $369 million within the State and for trans- portation. In recent years tourists have accounted for 70 percent of C-5 the total revenues of the State ferry system and have been the main reason for the 20 percent annual growth rate in that system since it started in 1963. In addition to the ferry system it is estimated that 13~000 cruise ship passengers will visit Petersburg and Wrangell during 1978. If present plans for the future are followed, tourism will play an ever increasing role in the economy of the Wrangell/Petersburg area. Mining The Petersburg/Wrangell area has played a supportive role as an outfitting point for mineral research conducted along the Stikine River. Copper deposits in the Scud River area of Canada have been researched extensively by crews and equipment from Wrangell and Petersburg. The impact that the mining industry will have on future development of the area will remain unknown until questions involving land use have been settled at the national and State level. Transportation Employment associated with transportation is estimated at 90 workers in the lumber loading and longshoring categories. Freight arrives by barge from Seattle and British Columbia ports and by the ferry boats moving between Seattle and Skagway. Future changes will be consider- able if mineral deposits along the Stikine are developed or if the Petersburg/Wrangell area is chosen for a mineral processing plant. Lumber mills in the area are supplied by log tows, which involves a minimum of highway transportation. The Wrangell Narrows inland passage is the main route for general freight and tourist passengers moving C-6 in southeastern Alaska by a wide variety of carriers. During 1976, 827,347 tons of freight and 17,000 passengers moved through the port of Wrangell, which involved log tows coming to the Wrangell mills and shipments of logs to Japanese markets. During 1976 the port of Petersbury handled 55,000 tons of general freight and 31,496 passengers mostly tourists travely the Inside Passage. As with mining and other waterborne commerce, the future of the transportation industry lies with decisions yet to be made in the future land use of the region. C-7 SECTION 0 PROJECT DESCRIPTIONS AND COST ESTIMATES Reservoir PERTINENT DATA THOMAS BAY Maximum Elevation, feet msl Average Elevation, feet msl Minimum Elevation, feet msl Tailwater Elevation, feet msl Surface Area at Maximum Elevation of Reservoir, acres Usable Storage, acre-feet Hydrology Drainage Area, square miles Annual Runoff, acre-feet Average Annual, cfs Maximum Annual, cfs Minimum Annual, cfs Power Tunnel Tunnel Size, feet Tunnel Length, feet Tunnel Grade, percent Gate Chamber and Adit Gate Chamber (underground) Gates, Hydraulic Slide Gates Ad it Tunnel Size, feet Tunnel Length, feet Tunnel Grade, percent Surge Chamber (excavated in rock) Diameter, feet Length, feet Penstock Type Diameter, feet Length, feet Shell Thickness Maximum, inches Minimum, inches Support Spacing, feet Type l ,525 1 ,490 1,345 45 570 70,500 17.3 137,560 190 236 151 8 (horseshoe) 12,030 0.5 2 10 (horseshoe) 490 0.5 10 361 Steel -ASTM A537 Grade "A 11 6 2,970 2 3/4 40 Concrete Powerplant (Stage II) Number of Units (total) Type of Turbine Installed Capacity, kW Plant Factor, percent Net Hed Maximum, feet Average, feet Minimum, feet Generator Rating, kW Power Factor, percent Voltage, kV Powerhouse Transmission line Voltage, kV Type PERTINENT DATA THOMAS BAY (cant) Length, miles (Wooden H-pole) Length, miles (Submarine Cable) Transmission Losses, percent (energy) System Characteristices (Stage II, at site) Dependable Capacity, kW Primary Energy, MWH Average Annual Energy, MWH 4 Impluse 34 50 l ,470 1,445 1,300 8,500 90 13.8 Steel Structure on Concrete Foundation 100 Wooden H-pole and Submarine Cable 43 16 2 15' 400 170,200 191 ,500 Reservoir PERTINENT DATA TYEE LAKE Maximum Elevation, feet msl (Stage II} Average Elevation, feet msl (Stage II} Minimum Elevation, feet msl Tailwater Elevation, feet msl Surface Area at Maximum Elevation of Reservoir, acres Usable Storage, acre-feet (Stage II) Hydrology Drainage Area, square miles Annual Runoff, acre-feet Average Annual, cfs Maximum Annual, cfs Minimum Annual, cfs Dam -Steel Bin Wall Height, feet Top Elevation, feet msl Spillway Crest Elevation, feet msl Power Tunnel Tunnel Size, feet Tunnel Length, feet Tunnel Grade, percent Gate Chamber and Adit Gate Chamber (underground) Gates, Hydraulic Slide Gates Adit Tunnel Size, feet Tunnel Length, feet Tunnel Grade, percent Surge Chamber (excavated in rock) Diameter, feet Length, feet 1,420 1 '395 1,240 30 573 126,700 14.2 118,730 164 204 126 48 1 ,421 1,420 8 (horseshoe) 4,900 0.5 2 10 (horseshoe) 490 0.5 10 361 Penstock Type Diameter, feet Length, feet She 11 Thickness Maximum, inches Minimum, inches Support Spacing, feet Type Powerp1ant (Stage II) Number of Units (total) Type of Turbine Installed Capacity, kW Plant Factor, percent Net Head (Stage II) Maximum, feet Average, feet Minimum, feet Generator Rating, kW Power Factor, percent Voltage, kV Powerhouse Transmission Line Voltage, kV Type PERTINENT DATA TYEE LAKE {cant) Length, miles (Wooden H-pole) Length, miles (Submarine Cable) Transmission Losses, percent (energy) System Characteristices (Stage II, at site) Dependable Capacity, kW Primary Energy, MWH Average Annual Energy, MWH Steel -ASTM A537 Grade "A 11 6 2,300 2 3/4 40 Concrete 4 Impluse 32.8 50 1 ,390 1 ,365 1 '21 0 8,200 90 13.8 Steel Structure on Concrete Foundation 100 Wooden H-pole and Submarine Cable 79 12 3 11 '1 00 126,500 138,800 GENERAL A screening study was performed to determine the most feasible hydropower sites in the Petersburg-Wrangell area. The following sites were investigated in detail: Tyee Lake, Swan Lake, Swan-Falls Lakes, Anita-Kunk Lakes, Goat Creek, Sunrise Lake, Scenery Lake, Virginia Lake, and Olive Lake. The Aaron Creek, Crittenden Creek, Thomas Lake, Ruth Lake, and Wilkes Range projects were eliminated in a preliminary screening. A construction cost estimate was derived for each site that was investigated in detail. Tyee Lake and Swan Lake possess the most potential for meeting both short and long term power requirements based on power capacity and construction costs, therefore, these two projects will be discussed here. Swan Lake is located on Thomas Bay, 17 air miles north of Petersburg. Tyee Lake is located on the Bradfield Canal, 47 air miles southeast of Wrangell. A 100 kV single conductor ground return submarine cable transmission system was studied for the two selected plans. Initial cost estimates indicated this type of system would be more economical than a conventional one. The conventional system will be presented in this study based upon its known reliability over a single conductor system. Should these projects be investigated at a more detailed level, the DC Submarine Cable will be studied at greater length as an alternate transmission system. D-1 ANITA -KUNK LAKES Two rockfilled concrete faced dams and two powerhouses would be required in this scheme. A 60-foot-high dam would be constructed at Anita Lake. A 2.5-foot diameter steel penstock 6,300 feet long would be required. A diversion dam and ditch would be required to divert Anita Creek into Kunk Lake reservoir. A 110-foot-high dam would be constructed near the outlet of Kunk Lake. The waterway would consist of an 8-foot diameter power tunnel 1,600 feet long and a 4-foot diameter penstock, 1,150 feet long. A diversion dam and ditch is required to divert runoff from an unnamed creek into Kunk Lake. An access road 5 miles long would be constructed. The transmission line would consist of 17 miles of wooden H-pole and 1.1 miles of submarine cable. Power from this project would be deliv- ered to Wrangell. The installed capacity for this plan is 6,800 kW which would pro- duce 29,770 MWH of average annual energy. 0-2 TABLE SUMMARY COST ESTIMATE JANUARY 1979 PRICE LEVEL ANITA-KUNK LAKES HYDROPOWER PROJECT CONCRETE FACED, ROCKFILL DAM, UNGATED Feature Account Cost Number Item ( 1 '000) MOBILIZATION AND PREPARATORY WORK 4,000 01 LANDS AND DAMAGES 264 03 RESERVOIRS 360 04 DAMS 24,242 07 POWER PLANTS 9,489 08 ROADS AND BRIDGES 3,000 19 BUILDINGS, GROUNDS, AND UTILITIES 1,000 SUBTOTAL 42,355 20% CONTINGENCIES 8,471 CONTRACT COST 50,826 30 ENGINEERING AND DESIGN 4,066 31 SUPERVISION AND ADMINISTRATION 4,391 TOTAL PROJECT COST 59,283 D-3 GOAT CREEK This project would have a rockfill dam with a reinforced concrete upstream face. It would be 950 feet long and 85 feet high at its deepest section. It would impound a reservoir of 94,900 acre-feet. A 100-foot wide by 700-foot long, side channel spillway excavated out of rock would be located in the right bank. An intake structure would house two 8-foot by 8-foot caterpillar gates and a trashrack. The power tunnel intake invert would be approximately the same elevation at the existing lake water surface. An 8-by 8-foot concrete lined horseshoe power tunnel would extend to a surge chamber 7,500 feet downstream. The surge chamber would be 18 feet in diameter and 180 feet deep excavated in rock. Two 30-inch steel penstocks, each 1,000 feet long. would convey the water from the surge tank to the powerhouse. The powerhouse would contain two power units which would have a com- bined capacity of 15,950 kW. This would produce 69,870 MWH of average annual energy. An access road 30 miles long would run along the Stikine River and would connect the powerhouse with a dock located on the Eastern Passage near Wrangell. The 69 kV transmission line to Wrangell would run along portions of the access road and would consist of 31 miles of H-pole construction and 2.7 miles of submarine cable. Power from this porject would be delivered to Wrangell. ~4 TABLE SUMMARY COST ESTIMATE JANUARY 1979 PRICE LEVEL GOAT CREEK HYDROPOWER PROJECT CONCRETE FACED, ROCKFILL DAM, UNGATED Feature Account Cost Number Item (1,000) MOBILIZATION AND PREPARATORY WORK 5,000 01 LANDS AND DAMAGES 732 03 RESERVOIRS 232 04 DAMS 24,080 07 POWERPLANTS 18,120 08 ROADS AND BRIDGES 12,400 19 BUILDINGS, GROUNDS, AND UTILITfES 1,000 SUBTOTAL 61 ,564 20% CONTINGENCIES 12,313 CONTRACT COST 73,877 30 ENGINEERING AND DESIGN 5,910 31 ~UPERVISION AND ADMINISTRATION 6,383 TOTAL PROJECT COST 86,170 D-5 OLIVE CREEK A 30-foot-high rockfilled concrete faced dam would be required in this scheme to create a reservoir on Olive Lake. The crest of the dam would be at elevation 460 feet. A storage capacity of 5,000 acre-feet would be created. The waterway would consist of a 4-foot diameter penstock 7,150 feet long. The access road would be 3 miles long. The transmission line would require 25 miles of overhead line supported by wooden H-poles and a 0.4 mile section supported by steel towers for crossing the Zimovia Strait. The 3,260 kW of installed capacity would produce some 28,560 MWH of energy which would be transmitted to Wrangell. D-6 TABLE SUMMARY COST ESTIMATE JANUARY 1979 PRICE LEVEL OLIVE LAKE HYDROPOWER PROJECT CONCRETE FACED, ROCKFILL DAM, UNGATED Feature Account Cost Number Item (1,000) MOBILIZATION AND PREPARATORY WORK 2,000 01 LANDS AND DAMAGES 336 03 RESERVOIRS 40 04 DAMS 6,580 07 POWERPLANTS 8,571 08 ROADS AND BRIDGES 1,500 19 BUILDINGS, GROUNDS, AND UTILITIES 1 ,000 SUBTOTAL 20,027 20% CONTINGENCIES 4,005 CONTRACT COST 24,032 30 ENGINEERING AND DESIGN 1,923 31 SUPERVISION AND ADMINISTRATION 2,076 TOTAL PROJECT COST 28,031 D-7 SCENERY LAKE A 160-foot-high concrete arch dam would be required in this scheme to create a reservoir on Scenery Lake. The crest of the dam would be at elevation 1,040 feet. A lake tap at elevation 825 feet would utilize a storage capacity of 135,000 acre-feet. An 8-foot concrete lined horseshoe tunnel 13,900 feet long would connect with a 2,100-foot above ground steel penstock. A 282-foot surge tank in unlined rock would be constructed at the juncture of the power tunnel and penstock. A 1,400-foot adit would provide access to the underground gate control structure. An access road 3 miles long would be required. A tramway from the end of the access road to the damsite would be required. A transmission line consisting of 23 miles of wooden H-pole overhead line and 3.6 miles of submarine cable would delvier power to Petersburg. This project would produce some 127,900 MWH of average annual energy based upon an installed capacity of 29,200 kW. 0-8 TABLE SUMMARY COST ESTIMATE JANUARY 1979 PRICE LEVEL SCENERY LAKE HYDROPOWER PROJECT CONCRETE FACED, ROCKFILL DAM, UNGATED Feature Account Cost Number Item (1,000) MOBILIZATION AND PREPARATORY WORK 6,000 01 LANDS AND DAMAGES 312 03 RESERVOIRS 384 04 DAMS 34,772 07 POWERPLANTS 19 '140 08 ROADS AND BRIDGES 1 ,500 19 BUILDINGS, GROUNDS, AND UTILITIES 3,500 SUBTOTAL 65,608 20% CONTINGENCIES 13 '122 CONTRACT COST 78,730 30 ENGINEERING AND DESIGN 6,298 31 SUPERVISION AND ADMINISTRATION 6,802 TOTAL PROJECT COST 91,830 D-9 SUNRISE LAKE This scheme would require a concrete faced rockfill dam 45 feet high. The damsite dewatering during construction would be accomplished by a gated diversion tunnel. The diversion tunnel would be 10 feet square and 595 feet long. After dam and spillway construction, an 18 inch diameter steel penstock would be placed in the diversion tunnel and connected to the gate structure. The 4,040-foot steel penstock would connect to the powerhouse at elevation 300 feet. The powerhouse would have one 3,300 kW unit which would produce approximately 14,330 MWH of average annual energy. A dock and 2.5 miles of access road would be required. A transmission line consisting of 8 miles of wooden H-pole overhead line and 2.1 miles of submarine cable would deliver power to Wrangell. D-10 TABLE SUMMARY COST ESTIMATE JANUARY 1979 PRICE LEVEL SUNRISE LAKE HYDROPOWER PROJECT CONCRETE FACED, ROCKFILL DAM, UNGATED Feature Account Cost Number Item (LOOO) MOBILIZATION AND PREPARATORY WORK 1,000 01 LANDS AND DAMAGES 126 03 RESERVOIRS 40 04 DAMS 3,097 07 POWERPLANTS 4,761 08 ROADS AND BRIDGES 330 19 BUILDINGS, GROUNDS, AND UTILITIES 1,000 SUBTOTAL 10,354 20% CONTINGENCIES 2,071 CONTRACT COST 12,425 30 ENGINEERING AND DESIGN 994 31 SUPERVISION AND ADMINISTRATION 1 ,074 TOTAL PROJECT COST 14,493 D-11 SWAN -FALLS LAKES SCHEME This scheme would consist of a lake tap, two gated tunnels, dam, powerhouse, transmission system, access road, living quarters, dock, and seaplane float. A lake tap would enter Swan Lake approximately 170 feet below the existing lake surface. It would connect to a 2,000-foot-long unlined tunnel and discharge into Cascade Creek 0.4 mile above Falls Lake. It would be controlled with hydraulic lift gates located near the outlet. There would be a wier 30 feet high located at the Falls Lake out- let. A lined 1,900-foot long power tunnel 8 feet in diameter would contain two vertical lift slide gates and a trashrack. The powerhouse would contain two units having a combined coapacity of 14,400 kW. This scheme would produce some 63,000 MWH of average annual energy. The powerhouse would discharge back into Cascade Creek 0.5 mile above the mouth. An access road, 1.4 miles long, would connect the powerhouse with the dock area. The powerplant would be controlled from Petersburg by a carrier communications system. A 69 kV transmission line would connect the powerhouse with Petersburg. A transmission line would also connect Petersburg with Wrangell. Between the power project and Petersburg there would be 18.9 miles of overhead line constructed with H-poles and 3.6 miles of submarine cable. Between Petersburg and Wrangell there would be 26.5 miles of H-pole line and 11.5 miles of submarine cable. 0-12 TABLE SUMMARY COST ESTIMATE JANUARY 1979 PRICE LEVEL SWAN-FALLS LAKES HYDROPOWER PROJECT LAKE TAP, BIN WALL DAM Feature Account Cost Number Item (1 ,000) MOBILIZATION AND PREPARATORY WORK 3,000 01 LANDS AND DAMAGES 562 03 RESERVOIRS 72 04 DAMS 11 ,397 07 POWERPLANTS 15,230 08 ROADS AND BRIDGES 1,100 19 BUILDINGS, GROUNDS, AND UTILITIES 775 SUBTOTAL 32,136 20% CONTINGENCIES 6,427 CONTRACT COST 38,563 30 ENGINEERING AND DESIGN 3,085 31 SUPERVISION AND ADMINISTRATION 3,332 TOTAL PROJECT COST 44,980 D-13 VIRGINIA LAKE This scheme would require a concrete faced rockfill dam 130 feet high. The dam crest would be at elevation 220 feet. An active storage of 91,700 acre-feet would be used. Diversion during construction would be accomplished by a portion of the steel penstock. A 9-foot diameter aboveground penstock 4,000 feet long would connect to the powerhouse at elevation 10 feet. An aboveground steel surge tank 130 feet high, 24 feet in diameter would be required. An access road 0.9 mile long would be constructed. The transmission line would consist of 6.8 miles of wooden H-pole and 2.7 miles of submarine cable. The 40,080 MWH of average annual energy based upon an installed capacity of 9,150 kW would be transmitted to Wrangell. 0-14 TABLE SUMMARY COST ESTIMATE JANUARY 1979 PRICE LEVEL VIRGINIA LAKE HYDROPOWER PROJECT LAKE TAP, BIN WALL DAM Feature Account Cost Number Item ( 1 ,000) MOBILIZATION AND PREPARATORY WORK 3,000 01 LANDS AND DAMAGES 92 03 RESERVOIRS 632 04 DAMS 23,997 07 POWERPLANTS 6,926 08 ROADS AND BRIDGES 90 19 BUILDINGS, GROUNDS, AND UTILITIES 1,075 SUBTOTAL 35,812 20% CONTINGENCIES 7.162 CONTRACT COST 42,974 30 ENGINEERING AND DESIGN 3,438 31 SUPERVISION AND ADMINISTRATION 3,713 TOTAL PROJECT COST 50,125 D-15 THOMAS BAY HYDROPOWER PROJECT This study investigated a lake tap without a dam as the scheme to develop the hydropower potential of Swan Lake. One and two stage con- struction sequences were considered with the latter delaying expansion of the powerhouse until the Petersburg-Wrangell area power load projec- tions indicated the need. Total project design power production would be 34 MW. SELECTED PLAN The selected plan is a lake tap without dam that would be constructed in two phases. See Plates 2 and 3. The first phase includes construc- tion of a lake tap, power tunnel, underground gate chamber and adit, underground surge chamber, an aboveground steel penstock, and an above- ground powerhouse with two 8.5 MW power units. Other features include a switchyard and transmission line through Petersburg to Wrangell, reservoir clearing, dock and seaplane float on Thomas Bay, living accommodations for the operating crew, and an access road connecting the dock area, living complex, powerhouse, and the power tunnel portal. The second phase consisting of expanding the powerhouse and installing two additional 8.5 MW power units would be constructed when power load projections indicated the need. Access to the project site during con- struction would be by water up Frederick Sound, by seaplane or helicopter. Access to the gate chamber adit would be by helicopter. D-16 LAKE TAP The lake tap would be made directly from the power tunnel with the invert at elevation 1,345 feet above mean sea level, approximately 170 feet below existing lake surface. A rock trap would provide space to catch and permanently store approximately 97 percent of the rock from the final blast. The power tunnel branches off from the side of the rock trap above the floor level so that rock from the blast would not be diverted into the power tunnel itself. LAKE TAP TRASHRACK The lake tap entrance would be covered by a steel trashrack to prevent debris from entering the power tunnel and reaching the turbines. Divers would place the trashrack in 170 feet of water. The trashrack would be anchored to the rock with rock bolts. POWER TUNNEL The power tunnel would be an 8-foot horseshoe shaped conduit, approximately 12,030 feet long. Excavation for the power tunnel would begin at a portal on the Thomas Bay side of the mountain. The excavated material would be disposed of north of the portal to not interfere with the penstock construction. For this study it was assumed that 1,790 feet of the tunnel would be lined with reinforced concrete 1 foot thick and 1,014 feet of tunnel would be rock bolted. During construction of the tunnel onsite conditions will determine the required amount of concrete lining and rock bolting. An alternate power tunnel alinement was studied, but it did not provide sufficient rock cover in the area of the gate chamber. D-17 GATE CHAMBER The gate chamber would house two 6-by 10-foot hydraulically operated slide gates. The chamber would be dry and located underground, approximately 3,000 feet from the lake tap. A 12 inch diameter pipe with manually operated gate valve would be located in the gate chamber. This pipe would provide minimum streamflow when the lake was not dis- charging at its natural outlet. Access to the gate chamber would be by a 10-foot horseshoe adit 490 feet long and a vertical shaft 54 feet deep. The gate chamber and adit would be constructed with helicopter access and maintained by helicopter. For this study, it was assumed that 74 feet of the adit would be lined with reinforced concrete 1 foot think and 42 feet of adit would be rock bolted. During construction of the adit, a field investigation would be made to determine the required amount of lining and rock bolting. SURGE CHAMBER The underground surge chamber would be located approximately 11,550 feet downstream from the lake tap with an invert elevation of 1,262 feet. The surge chamber would be 10 feet in diameter, rising approxi- mately 361 feet above the power tunnel and would open vertically to the ground surface. A horizontal tunnel or drift would connect the surge chamber to the power tunnel. It was assumed that 150 feet of the surge chamber would be rock bolted. During construction onsite conditions will determine the required amount of rock bolting. D-18 PENSTOCK The penstock would emerge from a concrete plub in the power tunnel through a steel chamber. The penstock would be a 6-foot diameter, 2,970-foot-long, all welded structure supported on concrete piers. The penstock would extend approximately 90 feet from the power tunnel plug through an open tunnel on a 1 percent slope to the portal, and then continue on the remaining 2,880 feet to the aboveground powerhouse. The portion that lies between the tunnel portal and powerhouse will be constructed on a steep hillside. POWERHOUSE The Thomas Bay powerhouse would be located approximately 0.5 mile from the mouth of Cascade Creek. The powerhouse design would be for eventual installation of four 8,500 kilowatt three-phase generators. Each generator would be driven by a 11,600 horsepower nozzle impulse turbine with a rotational speed of 400 RPM at a design head of 1 ,300 feet. During Phase I, only two 8.5 MW units would be installed in the powerhouse which will initially be constructed for these two units. The powerhouse would be of steel frame construction and would be designed and located so that future expansion could be accomplished. The powerhouse structure would contain the generators, turbines, a 30-ton bridge crane, and all other equipment required for operation and maintenance. D-19 SWITCHYARD AND TRANSMISSION SYSTEM The Thomas Bay switchyard would be located southeast of the power- house. It would initially contain one three-phase transformer with a second to be installed when the powerhouse is expanded. The transmission line would begin at the Thomas Bay powerhouse and run 59 miles through Petersburg to Wrangell. The transmission system voltage would be 100 kilovolts. The transmission line would consist of 43 miles of wood-pole H-frames and 16 miles of submarine cable. A total of three submarine cable crossings would be required. The Frederick Sound north of Petersburg and the Stikine Strait would be crossed by 12 miles of sub- marine cable. The 16.5 miles of wood-pole H-frame transmission line north of Petersburg would be constructed and maintained by helicopter. The 26.4 miles of wood-pole H-frame transmission line on Mitkof Island would be constructed and maintained using the existing road. Two new substations would be constructed, one at Petersburg and one at Wrangell. ACCESS ROAD A 3.5 mile access road would be constructed from the powerhouse to the power tunnel portal. Access to the gate chamber adit would be by helicopter. BUILDINGS, GROUNDS, AND UTILITIES The camp would provide quarters and offices during construction and permanent maintenance facilities during operation of the projects. It would consist of the dock, seaplane float, dormitory for eight men, residence for one family, warehouse, garage, and sewer and water systems. D-20 POWERHOUSE (PHASE II) During Phase II, the powerhouse would be expanded and two additional 8.5 MW power units would be installed. This construction would bring the powerhouse to its design capacity of 34 MW. D-21 DETAILED COST ESTIMATE THOMAS BAY HYDROPOWER PROJECT LAKE TAP WITHOUT DAM Cost Unit Total Account Cost Cost 1/ Number Descri~tion or Item Unit Quant ill_ (1 ,OOOT MOB AND PREP WORK LS 5,000 01 LANDS AND DAMAGES Reservoir Area Public Domain AC 33 (50) Private AC 7 0 Transmission Line Public Domain AC 284 (256) Private AC 131 118 Government Admin Cost 20 TOTAL -LANDS AND DAMAGES (444) 04 DAM 04.1 POWER TUNNEL Rock Excavation CY 25,707 180 4,627 Concrete CY l '979 500 990 Cement CWT 11 '162 12 134 Reinforcement TON 50 1,500 75 Rock Bolts Grouted 1'' 0 X 10'-0'' EA 732 275 201 Lake Tap LS 1 500 Trashrack TON 10 7,500 75 TOTAL -POWER TUNNEL 6,602 04.2 GATE CHAMBER Rock Excavation CY 1 '586 175 278 Concrete CY 736 600 442 Cement CWT 4' 151 12 50 Reinforcement TON 18.4 1 '500 28 Slide Gates w/hoist TON 60 5,000 300 Minimum Streamflow Pipe w/valve TON 13.75 2,500 34 Rock Bolts Grouted 111 0 X 10'-011 EA 32 275 TOTAL -GATE CHAMBER 1 • 141 D-22 THOMAS BAY HYDROPOWER PROJECT LAKE TAP WITHOUT DAM (cant) Cost Unit Total Account Cost Cost 1 I Number Description or Item Unit Quant ilL (l,OOOT 04.3 ADIT Rock Excavation CY 1 ,605 170 273 Concrete CY 100 500 50 Cement CWT 564 12 7 Reinforcement TON 2.5 1 ,500 4 Rock Bolts Grouted 1"0 X 10•-o" EA 10 275 3 TOTAL -ADIT 337 04.4 SURGE CHAMBER Rock Excavation CY 1,094 200 219 Concrete CY 29 1,000 29 Cement CWT 164 12 2 Reinforcement TON .75 1 ,500 1 Rock Bolts Grouted 111 0 X 10•-o" EA 300 225 68 TOTAL -SURGE CHAMBER 319 04.5 PENSTOCK 6'0 Pipe TON 1, 524 4,500 6,858 Stiffeners, Anchors TON 107 4,500 482 Concrete Anchor Blocks Concrete CY 306 500 153 Cement CWT 1 '726 12 21 Reinforcement TON 7.7 1 ,500 12 Concrete Piers Concrete CY 89 600 53 Cement CWT 502 12 6 Reinforcement TON 2.2 1 '500 33 Clearing AC 7 6,000 42 TOTAL -PENSTOCK 7,660 TOTAL DAM 16,059 0-23 THOMAS BAY HYDROPOWER PROJECT Cost Unit Total Account Cost Cost l/ Number Description or Item Unit Quant ilL (1 ,oooi 07 POWER PLANT 07.1 POWERHOUSE LS 1 7,200 07.2 SUBSTATIONS Petersburg EA 1 400 Wrange 11 EA 1 2,500 07.3 TRANSMISSION LINES Wood Pole by Road MI 26.4 150,000 3,960 Wood Pole by Helicopter MI 16.5 300,000 4,950 07.4 SUBMARINE CABLE Conductors MI 16 600,000 9,600 Terminals EA 6 10,000 60 TOTAL -POWERPLANT 28,670 08 ROADS AND BRIDGES Clearing AC 31.4 4,000 126 Rock Excavation CY 170,197 15 2 '553 Common Excavation CY 6,627 5 33 Embankment CY 14,889 2 30 Gravel CY 7,307 7 51 Culverts 18 11 ~ LF 200 25 5 Bridge (100 1 .f.) EA 1 300 TOTAL -ROADS AND BRIDGES 3,098 19 BUILDINGS, GROUNDS, AND UTILITIES Dock LS 1 500 Sea p 1 a ne F 1 oa t LS 1 100 Camp Facilities LS 1 2,750 TOTAL -BUILDINGS, GROUNDS, AND UTILITIES 3,350 SUBTOTAL -CONSTRUCTION COST 56,177 CONTINGENCIES 20% 11 '235 TOTAL -CONSTRUCTION COST 67,412 D-24 Cost Account Number THOMAS BAY HYDROPOWER PROJECT LAKE TAP WITHOUT DAM {cont) Description or Item Unit Quant ENGINEERING AND DESIGN 8% SUPERVISION AND ADMINISTRATION 8% TOTAL -PROJECT COST PHASE I INTEREST DURING CONSTRUCTION PHASE I INVESTMENT COST D-25 Unit Cost ill_ Total Cost 1/ (1 ,oooT 5,393 5,824 78,630 10,812 89,442 Cost Account Number DETAILED COST ESTIMATE THOMAS BAY HYDROPOWER PROJECT PHASE II EXPAND POWERHOUSE Description or Item Unit Quant MOB AND PREP WORK LS 07 POWERHOUSE 07.1 POWERHOUSE EXPANSION LS SUBTOTAL -CONSTRUCTION COST CONTINGENCIES 20% TOTAL CONSTRUCTION COST ENGINEERING AND DESIGN 8% SUPERVISION AND ADMINISTRATION 8% TOTAL -PROJECT COST PHASE II INTEREST DURING CONSTRUCTION PHASE II INVESTMENT COST TOTAL INVESTMENT COST AVERAGE ANNUAL COST OPERATION, MAINTENANCE, AND REPLACEMENT TOTAL AVERAGE ANNUAL COST D-26 Unit Cost ill_ Total Cost 1/ (l,OOOT 1 ,350 9,000 10,350 2,070 12,420 994 l ,073 14,487 996 6,972 96,414 6,637 450 7,087 TYEE LAKE HYDROPOWER PROJECT This study investigated two types of dams located at the outlet of Tyee Lake and one scheme for lake entry. Studies were made using different spillway crest elevations and lake entry elevations. One and two stage construction sequences were considered with the latter delaying construction of the dam until the Petersburg-Wrangell area power load projections indicated the need. This latter scheme would eliminate the need for diversion structures during dam construction. A lake tap was studied as the method of lake entry. The dam types studied were a double curvature thin-arch with concrete gravity spillway section and a steel bin wall with rockfill. Water would spill over the entire length of the bin wall dam during periods of high flow. Total project design power production would be 32.8 MW. SELECTED PLAN The selected plan is the steel bin wall dam scheme with two con- struction phases. See Plates 4,5, and 6. The first phase would include construction of a lake tap~ power tunnel, underground gate chamber and adit, underground surge chamber, an aboveground steel penstock, and the powerhouse containing two 8.2 MW units. Other features include a switchyard and transmission line through Wrangell to Petersburg, dock facility, upgrading the existing airstrip, living accommodations for the operating crews, and reservoir clearing. The second phase consist- ing of building a bin wall dam at the outlet of Tyee Lake and installing two additional power units in the powerhouse would be constructed when D-27 power load projections indicated the need. Access to the project site during construction and operation would be by water up the Bradfield Canal and by airplane or helicopter. Access to the tunnel protals and the damsite would be by helicopter as road access was found to be too costly. LAKE TAP The lake tap would be made directly from the power tunnel with the invert at elevation 1,240 feet above mean sea level which is approxi- mately 150 feet below existing lake surface. The rock trap would provide space to catch and permanently store approximately 97 percent of the rock from the final blast. The power tunnel branches off from the side of the rock trap above the floor level so that rock from the blast would not be diverted into the power tunnel itself. LAKE TAP TRASHRACK The lake tap entrance would be covered by a steel trashrack to Prevent debris from entering the power tunnel and reaching the turbines. Divers would place the trashrack in 150 feet of water. The trashrack would be anchored to the rock with rock bolts. POWER TUNNEL The power tunnel would be an 8-foot horseshoe shaped conduit approxi- mately 4,900 feet long. Excavation for the power tunnel would begin at a portal on the Bradfield Canal side of the mountain. The excavated material would be disposed of east of the portal so disposal would not interfere with penstock construction. For study purposes it was assumed that 735 feet of the tunnel would be lined with reinforced concrete l D-28 foot thick and 415 feet of tunnel would be rock bolted. The actual amount of concrete lining and rock bolting will be determined by onsite conditions during tunnel construction. GATE CHAMBER The gate chamber would house two 6-by 10-foot hydraulically operated slide gates. The chamber would be dry and located underground approxi- mately 3,000 feet from the lake tap. A 12-inch diameter pipe with manually operated gate valve would be located in the gate chamber to provide minimum streamflow when the lake was not discharging at its natural outlet. Access to the gate chamber would be by a 10-foot horse- shoe adit 850 feet long. For this study, it was assumed that 128 feet of the adit would be lined with reinforced concrete 1 foot thick and 72 feet of the adit would be rock bolted. The actual amount of lining and rock bolting would be determined by onsite conditions during tunnel construction. SURGE CHAMBER The underground surge chamber would be located approximately 4,500 feet from the lake tap with an invert elevation of 1,215 feet. The surge chamber would be 10 feet in diameter, rising approximately 275 feet above the power tunnel and would open vertically to the ground surface. A horizontal tunnel or drift would connect the surge chamber to the power tunnel. It was assumed that 100 feet of the surge chamber would be rock bolted. During construction onsite conditions would determine the required amount of rock bolting. D-29 PENSTOCK The penstock would emerge from a concrete plug in the power tunnel through a steel reducer. The penstock would be a 6-foot-diameter 2,300- foot-long, all welded structure supported on concrete piers. The pen- stock would extend approximately 200 feet from the power tunnel plug through an open tunnel on a 1 percent slope to the portal, and then con- tinue on the remaining 2,100 feet to the aboveground powerhouse. The portion that lies between the tunnel portal and powerhouse will be con- structed on a steep hillside. POWERHOUSE The Tyee Lake powerhouse would be located on the Bradfield Canal approximately 500 feet from the mouth of Tyee Creek. The aboveground powerhouse design would be for eventual installation of four 8,200- kilowatt three-phase generators. Each generator would be driven by a 11,200-horsepower impulse turbine, with a rotational speed of 450 RPM at a design head of 1,380 feet. During Phase I, two 8.2 ~1W units would be installed in the powerhouse which would be sized for two units. The powerhouse would be of steel frame construction and would be designed and located so that future expansion could be accomplished. The power- house structure would contain the generators, turbines, a 30-ton bridge crane, and all other equipment required for operation and maintenance. The area for the powerhouse site is presently being used by a logging company as a permanent base camp in which living accommodations and maintenance facilities have been erected. A crude docking facility 0-30 has already been constructed. A short service road would provide access from the dock to the powerhouse. SWITCHYARD AND TRANSMISSION SYSTEM The Tyee Lake switchyard would be located adjacent to the west side of the powerhouse. It would initially contain one three-phase trans- former with a second to be installed when the powerhouse is expanded. The transmission line would begin at the Tyee Lake powerhouse on the Bradfield Canal and run 92.2 miles through ~/rangell to Petersburg. The transmission system voltage would be 100 kilovolts. The line would consist of 79 miles of wood-pole H-frames and 12 miles of submarine cable. There would be three major overhead crossings of water obstacles. One 0.54-mile span across the Bradfield Canal, and two spans across the Blake Channel (0.33 mile and 0.26 mile). Six steel self-supporting towers would be required for the overhead crossings. The overhead con- ductors would be 397.5 MCM ACSR without overhead ground wires. The portion of the transmission line from Tyee powerhouse to Wrangell Island (21 miles with three overhead crossings of water) would be con- structed and maintained by helicopter. Nineteen of the 33 miles of transmission line on Wrangell Island would be build using the existing improved road on the northwest tip of the island. There are also several miles of unimproved logging roads on Wrangell Island that would be used to construct and maintain a portion of the transmission line. The Forest Service has indicated that the logging roads would eventually be extended toward the southern portion of the island and portions of 0-31 the island and portions of these might be avialable for construction use. The portion of the transmission line not paralleling the unim- proved logging roads would be constructed and maintained by helicopter. A more detailed routing study would be made during final design. The 12 miles of submarine cable would connect Wrangell Island and Mitkof Island. The 26 miles of transmission line on Mitkof Island would be constructed and maintained using the existing improved road on the west side of the island. Two new substations would be constructed, one at Petersburg and one at Wrangell. ACCESS ROAD Road construction was considered too expensive because of the steep rocky terrain. A service road less than 1 mile long will connect the dock, airstrip, powerhouse, switchyard, and camp facilities. A tug and shallow draft barge will be required to transport supplies and equipment from vessels anchored in deep water in the Bradfield Canal. BUILDINGS, GROUNDS, AND UTILITIES The camp would provide quarters and offices during construction and permanent maintenance facilities during operation of the project. It would consist of the dock, airstrip, dormitory for eight men, residence for one family, warehouse, garage, and sewer and water systems. RESERVOIR CLEARING The reservoir clearing operation would remove all timber to an elevation of 5 feet above maximum flood water elevation. Merchantable timber will be sold and the remainder would be stacked and burned. Downed timber currently floating in the lake near the damsite would be removed. D-32 BIN WALL DAM (PHASE II) The selected plan includes a 48-foot-high dam constructed of heavy steel gage bin wall cells (used conventially for retaining walls). The cells would be tied together and filled with rock. The top layer would contain heavy riprap to prevent rock movement during peak runoff periods. The cells would be keyed into the rock sidewalls of the channel and a concrete cutoff wall would be placed at the heel. The upstream face would have a welded steel membrane. A 40-foot wide section would be set 1 foot lower than the adjacent sections to confine streamflow to the center of the dam. During high runoff periods, flow would be over the dam's entire length. The bin wall type dam was selected because it utilizes the surrounding material and would require a minimum of heavy equipment for construction. Rockfill would be obtained from a quarry site near the dam outlet. An alternate quarry site at the south end of the lake was considered too costly. POWERHOUSE (PHASE II) During Phase II, the powerhouse would be expanded and two additional 8.2 MW power units would be installed. This construction would bring the powerhouse to its design capacity of 32.8 MW. ALTERNATIVE TYPE OF DAM CONSIDERED FOR SELECTED SITE -THIN ARCH DOUBLE CURVATURE DAM WITH LAKE TAP The dam would be approximately 375 feet long measured along the dam crest and 100 feet high. Top of the dam would be a televation 1,467 feet. The spillway would be 80 feet long with a crest elevation of D-33 1,447 feet. The spillway would be a concrete gravity section. The lake tap would be at elevation 1,350 feet. The remainder of the project would be the same as for the selected plan. 0-34 DETAILED COST ESTIMATE TYEE LAKE HYDROPOWER PROJECT PHASE I LAKE TAP WITHOUT DAM Cost Unit Total Account Cost Cost 1 I Number Description or Item Unit Quant _w_ ( 1 ,oooi MOB AND PREP WORK LS 5,000 01 LANDS AND DAMAGES Transmission Line Public Domain AC 649 (876) Private AC 116 157 Government Admin Cost 20 TOTAL -LANDS AND DAMAGES (1,053) 03 RESERVOIR Clearing AC 22 4,000 88 Downed Trees LS 30 TOTAL -RESERVOIR 111 04 DAM 04.1 POWER TUNNEL Rock Excavation CY 10,450 180 1 ,881 Concrete CY 813 500 407 Cement CWT 4,585 12 55 Reinforcement TON 21 1 '500 32 Rock Bolts Grouted 111 0 X 1 o• -0 11 EA 303 275 83 Lake Tap LS 1 500 Trashrack TON 10 7,500 75 TOTAL -POWER TUNNEL 3,033 04.2 GATE CHAMBER Rock Excavation CY 1,950 175 341 Concrete CY 580 600 348 Cement CWT 3,270 12 39 Reinforcement TON 15 1,500 23 Slide Gates w/hoist TON 60 5,000 300 Minimum Streamflow Pipe w/va1ve TON 21.25 2,500 53 Rock Bolts Grouted 111 0 X 1 0' -0 11 EA 40 275 11 TOTAL -GATE CHAMBER 1 '115 D-35 TYEE LAKE HYDROPOWER PROJECT PHASE I LAKE TAP WITHOUT DAM (cant) Cost Unit Total Account Cost Cost 1/ Number Description or Item Unit Quant ill_ (1 ,oooT 04.3 ADIT Rock Excavation CY 6,117 170 1 ,040 Concrete CY 173 500 87 Cement CWT 976 12 12 Reinforcement TON 4.5 1 '500 7 Rock Bolts Grouted 111 0 X 10 '-0 11 EA 28 275 8 TOTAL -ADIT 1 '154 04.4 SURGE CHAMBER Rock Excavation CY 810 200 162 Concrete CY 20 1 ,000 20 Cement CWT 113 12 2 Reinforcement TON 0.5 1,500 1 Rock Bolts Grouted 111 0 X 10'-0 11 EA 200 225 45 TOTAL -SURGE CHAMBER 230 04.5 PENSTOCK 6'0 Pipe TON 1 ,259 4,500 5,666 Stiffeners, Anchors TON 88 4,500 396 Concrete Anchor Blocks Concrete CY 204 500 102 Cement CWT 1 '150 12 14 Reinforcement TON 3 1,500 5 Concrete Piers Concrete CY 63 600 38 Cement CWT 355 12 4 Reinforcement TON 1 1 ,500 2 Clearing AC 7 6,000 30 TOTAL -PENSTOCK 6,257 TOTAL DAM 11 '789 D-36 TYEE LAKE HYDROPOWER PROJECT PHASE I LAKE TAP WITHOUT DAM (cont) Cost Unit Total Account Cost Cost 1/ Number Descri~tion or Item Unit Quant ill_ (1 ,oooi 07 POWERPLANT 07. 1 POWERHOUSE LS 1 7,000 07.2 SUBSTATIONS Petersburg EA 1 400 Wrangell EA 1 2,500 07.3 TRANSMISSION LINES Wood Pole by Road MI 45 150,000 6,750 Wood Pole by Helicopter MI 35 300,000 10,500 Steel Self-Support Towers EA 6 75,000 450 07.4 SUBMARINE CABLE Conductors MI 12 600,000 7,200 TOTAL -POWERPLANT 34,800 19 BUILDINGS, GROUNDS, AND UTILITIES Dock LS 1 500 Inprove Existing Airstrip LS 1 200 Camp Facilities LS 1 2,750 TOTAL -BUILDINGS, GROUNDS, AND UTILITIES 3,450 SUBTOTAL -CONSTRUCTION COST 56,210 CONTINGENCIES 20% 11 ,242 TOTAL -CONSTRUCTION COST 67,452 ENGINEERING AND DESIGN 8% 5,396 SUPERVISION AND ADMINISTRATION 8% 5,828 TOTAL -PROJECT COST PHASE I 78,676 INTEREST DURING CONSTRUCTION 10,818 PHASE I INVESTMENT COST 89,494 D-37 DETAILED COST ESTIMATE TYEE LAKE HYDROPOWER PROJECT PHASE II BINWALL DAM Cost Unit Total Account Cost Cost Number Descri~tion or Item Unit Quant ilL (1 ,000) MOB AND PREP WORK LS 2,000 01 LANDS AND DAMAGES Reservoir Areas Public Domain AC 36 (54) Private AC 0 0 TOTAL -LANDS AND DAMAGES 04 DAM 04.1 BIN WALL Clearing AC 1 6,000 6 Rock Excavation CY 8,000 50 400 Overburden Excavation CY 5,500 35 194 Steel Bins TON 243 3,000 729 Rockfi11 for Bins CY 17,877 50 894 Rockfi 11 at Heel CY 367 50 18 Steel Plate on Face of Dam TON 50 2,500 125 Concrete Cutoff Wall Concrete CY 75 500 38 Cement CWT 423 12 5 Reinforcement TON 0.5 2,000 1 TOTAL -BIN WALL DAM 2,410 07 POWERHOUSE 07.1 POWERHOUSE EXPANSION LS 8,750 SUBTOTAL -CONSTRUCTION COST 13,214 CONTINGENCIES 20% 2,643 TOTAL CONSTRUCTION COST 15,857 ENGINEERING AND DESIGN 8% 1 ,269 SUPERVISION AND ADMINISTRATION 8~~ 1 '370 D-38 Cost Account Number DETAILED COST ESTIMATE TYEE LAKE HYDROPOHER PROJECT PHASE II BINWALL DAM Description or Item Unit Quant TOTAL -PROJECT COST PHASE II INTEREST DURING CONSTRUCTION PHASE II INVESTMENT COST (1990 Present Worth) TOTAL INVESTMENT COST AVERAGE ANNUAL COST OPERATION, MAINTENANCE, AND REPLACEMENT TOTAL AVERAGE ANNUAL COST D-39 Unit Total Cost Cost .ill_ ( 1 ,000) 18,496 1 ,272 11 '613 101,107 6,960 450 7,410 SECTION E POWER STUDIES AND ECONOMICS METHOD OF ANALYSIS Initial Screening HYDROPOWER ANALYSIS The first step in the analysis was to select a series of project sites which were close enough to the Petersburg-Wrangell service area, such that transmission line distances were minimized. A total of 14 projects at 14 different sites received consideration in the initial screening analysis. These are listed in Table E-1, together with per- tinent data used in the evaluation. The projects are listed in Table E-1 with the highest benefit/cost ratios at the head of the tabulation. Further details on the projects which were screened out are presented in the section entitled "Hydro- electric Alternatives." For projects listed in Table E-1 the pertinent data is that used in the screening analysis. Further studies resulted in changes to the project physical data for Tyee and Cascade Creeks. This also resulted in changes to the benefit/cost ratios for those projects. For Cascade Creek Scheme #2, the original estimated cost was found to be too low, based upon observations during the field reconnaissance in June 1978. Scheme #2 for Cascade Creek was subsequently dropped from consideration, and the benefit/cost ratio shown in Table E-1 is no longer valid. Scope The hydropower analysis was limited to those project alternatives which appeared to show promise based upon the initial screening and the E-1 -·----o,:a rr~a~-~----··-----~ Pr_cj~~------- Tyee Lake Cascade Creek Sch<O,~ 2 Cc s•:<d;; Creek s~: he:~e I Tno··,s Lake 01 ive Lake Sunrise lake Sc.€c.try Lake (;'}-;: t (reek ~v[fl Lcke \' ~ ir.ia La I.e !.nit<' Crtek run I: La~e IIi lfes Creek ?.:~ r·uo Creei (r~ tL: rd':n (r'H·k fT1 I N 14.1 19.1 17. 3 19.0 3.8 1.2 18.0 14.0 6.7 40.6 2.5 8.0 1.4 94 10.0 Transmissicn i inP 42 2.0 14.8 4.2 14.8 4.2 20.1 0 22 2.0 6.6 2. l 19.3 ~.2 25 1.5 14.3 4.2 8.0 L5 1.6 to 0 Kunk Lake 14.1 1.1 20 2.5 21.0 l.S 6.5 2.0 TAKLI r l tiYfJ'.: 0\if R SCR! : :.(~ Mlf\L YS[S SOUffiU>l ALA SKI\ -f'[ ': ERS 8URG-WRAtlGEI.l ·-· -~i-:iit;l e·· -~~~~ -~il L·d ---··-- t nor~y Length ( f~ ,, ".L. ---. !ftl 161 1 ,380 za.:~o 1 J~ ,:;00 4,500 210 550 14 .~;)0 63,372 3,400 192 1 .300 3H, ~ JO Hl,oUD 11,600 158 274 6,:~0 2n,?80 4,200 65 370 3,."00 z:.\, "60 None 15 1,608 3,: JL) 1 '· '30 None 215 1,000 29, 1?,' ,}l)t) 17,000 153 905 1~ •. a f.':,.~70 5,700 31 1,260 ~~,: JO ~.1.210 7,000 414 163 9,150 ~a.GS(l None 27 1,007 3,00 15,144 None 74 310 3,110 1,600. 15 1 ,400 2 ·' :s 2,400 400 118 6,~.'3 None 20 200 5~0 ".400 None rutaY Aiu\,ia 1 Length Surge Height Benefits cost 0/C {ft)_ __ cr. amber _lf_li ____ .....J!!l2.~".!".h ...... •.••. .2J[!OUS.Oildi,_ ______ Ratio 2,000 Yes 60 Rock 8,823 1,802 1.13 1,200 No 50 4,091 3,522 1.16 2,215 Yes laketdp 12,115 7,540 1.61 600 Yes 3 Dams 1,705 1 ,!:l35 .93 4,5(,(} No 30 Rock 1,649 2,195 • 75 3,~c:o flo 40 Rock 931 1 '135 .82 5CO Yes 94 Concrete A.-cell 8,297 7,191 1.15 1,000 Yes 10· Rock 4,532 6,747 .67 2,6CO Yes 5? Rock 1,506 l,Y ~ .77 2,450 No no Rock 2,600 J~ 1}25 .66 6,300 No 60 Hock 1,932 4 ,G42 .42 1,150 No 110 Rock 1,950 No 3 DctmS 801 1 ,92,0 . 41 3,000 No 2 Dams 1,817 4,t)6.l .39 3,700 No 30 Rock 155 799 0.19 field reconnaissance. One alternative project is a two-phase scheme at Tyee Lake which includes an installed capacity of 14.4 MW for each phase. The second project is at Thomas Bay on Cascade Creek, and con- sists of two phases each having a total of 19.5 MW of installed capacity. The Tyee Lake Phase 2 includes a 150-foot bin wall dam. No dam is planned for the Thomas Bay site. Methodology The calculated set of 50 years of historical streamflow (1927-1976) for each project was used in a simulated re·servoir operation study. The computer program entitled "Empower 11 developed by the Alaska District was used for this purpose. The program provides estimates of both the installed capacity and total monthly generation for each reservoir operating design configuration. By performing successive runs with the program Empower, the maximum generation for the period of lowest streamflows was determined for both phases of both the Tyee and Thomas Bay projects. The program output using Empower was also checked using the HEC-e 11 Reservoir Regulation" program developed by the Hydrologic Engineering Center at Davis, California. Results were comparable in all significant respects. Both of the above computer programs include necessary assumptions which may materially affect the estimated total generation. Both programs indicated above have no seasonal volume forecast and consider the stream- flow only on a month-by-month basis. This also means that high flows of brief duration would not be taken into account for the monthly analysis. E-3 Power Production Variables The following variables include many of the necessary assumptions used in the hydropower analysis. Free Surface Evaporation: For both the Tyee and Thomas Bay projects no new reservoirs are proposed. Because the lake level would be raised at Tyee Lake in the second phase of development, the water surface area may be slightly greater than for natural conditions. The difference would~ however, be negligible because of the cool, cloudy weather which prevails in the project area. Accordingly in the power studies, no adjustment to the natural runoff was made for lake evaporation at either project. Effective Hydraulic Head: In both schemes under consideration, the powerhouse would be located near tidewater. The tailwater elevation was assumed to be 15 feet elevation for both projects, and no tailwater rating curve was used in the power studies. For Tyee Lake the conduit friction head losses averaged 30 feet. Because of the extremely long tunnel at the Thomas Bay site, the total conduit head loss is 45 feet. The values for effective head given in the following table are for average flow conditions at average lake elevation. Effective Head Project Net Effective Head (ft) Thomas Bay Scheme 1, Stage I 1,445 Stage I I 1 ,445 Tyee Creek Stage I 1 '322 Stage II 1 ,365 E-4 These were calculated by deducting the friction losses and tailwater elevation from the gross head. These values were used in the simula- tion studies. Sedimentation Sedimentation rates on Tyee Lake are assumed to be negligible and no adjustment in the storage capacity curve was made. For Swan Lake, however, a 50-year sedimentation of 1,500 acre-feet of the active storage was deemed necessary. The reducted storage volume was used in the operational studies but did not significantly affect the results. Plant Factor For the operational studies, a plant factor of 50 percent was assumed of the ultimate developmetn phase on both projects. The basis for selection of the plant factor for both projects is solely to maximize available firm capacity by utilizing all water that can be made avail- able eitehr from streamflow or reservoir storage. The selection of the 50 percent plant load factor is not necessarily optimum for the Petersburg- Wrangell service area from the standpoint of economics or system require- ments. Monthly Electrical System Load Curve Using the monthly system energy consumption for Petersburg and Wrangell combined, during 1970-1977, the following seasonal load curve was derived. E-5 Petersburg-Wrangell Monthly Electrical Load Month ~t Nov Dec Jan Feb ~r Apr May Jun Jul Aug Sep Total Percent Annual 8.4 8.8 9.6 8.5 7.8 8.8 7.5 7.6 7.5 8.4 8.7 8.4 100.0 The demand is at a minimum in June when streamflow is highest and at maximum in early winter when streamflow is very low, or moderate in quantity. The overall load is fairly even throughout the year. The above data, however, did not include the possible future addi- tion of load to the system from sawmills and canneries at Wrangell which at present generate much of their own power. Industrial consumbers might change the shape of the curve substantially. Also, not apparent in the above load curve is the fact that the loads at Petersburg and Wrangell tend to fluctuate heavily from year to year depending on the success of the commercial fish catch • . Flow Requirements In the power studies for both Tyee and Thomas Bay, no fish release requirements below the respective lakes were used. The rugged nature of the stream channels below the lakes precludes all but intertidal E-6 spawning. The possible need for maintianing the lake levels for recrea- tional purposes was not included in the power studies. This is an area for further refinement in future planning stages. Power Potential of Alternative Development The initial screening process resulted in the elimination of all but three of the original 14 projects. Then, following the field recon- naissance, one of the remaining three projects were eliminated. That project was a smaller scheme on Cascade Creek (Scheme 2) wherein Falls Lake rather than Swan Lake would be used as the operating intake reser- voir for the power tunnel to Thomas Bay. It was determined in the field that road access to Falls Lake would be prohibitively costly, therefore, rendering Cascade Creek, Scheme 2, unattractive for further study. The hydropower analysis for the remaining two alternatives were carried out with the following results. At Site Generating Capability Tyee and Thomas Bay Thomas Bay Scheme 1, Stage I Stage II Tyee Creek Stage I Stage II Installed Capacity (Megawatts} 19.4 38.8 14.4 28.8 Prime Energy (Megawatt Hours) 139,500 170,200 110' 200 126,500 E-7 Average Annual Energy (Megawatt Hours) 147,500 191,500 117,200 138,800 The prime energy is the dependable generation for the year with the most adverse water conditions. The difference between actual energy and prime energy is the secondary energy. The following are pertinent physical data for the Tyee and Cascade Creek alternatives. Storage Data Swan and Tyee Lakes Maximum Gross Active Inactive Water Surface Storage Storage Storage e 1 ev. ft. ac-ft ac-ft ac-ft Swan Lake Stage I 1 ,515 (Lake) 97,500 70,500* 25,500 Stage II 1 '515 97,500 70,500* 25,500 Tyee Lake Stage I 1,387 (Lake) 81 ,500 110,300 28,800 Stage II 1,420 97,900 126,700 28,800 * Adjusted for sedimentation E-8 EXISTING ELECTRICAL UTILITY SYSTEM At present, power in the Petersburg/Wrangell area is supplied by the city of Petersburg Municipal Power and Light Department and the city of Wrangell. Resources for Petersburg are the Blind Slough Hydro- electric Project with a nameplate capacity of 1.6 MW and diesel electric generation with total nameplate capacity of 6.9 MW. Resources for Wrangell are diesel electric. Total nameplate capacity is 7.75 MW with 2.25 MW due for retirement in 1985. HISTORICAL LOAD GROWTH Table E-2 shows historical annual system loads for the years 1968 to 1977. This information is derived from a report by Robert W. Retherford Associates, Preliminary Appraisal Report Tyee Lake Hydroelectric Potential, September 1978. FUTURE POWER NEEDS Three different load forecasts have been made for the Petersburg/ Wrangell market area. The medium load growth case is based on a 6 per- cent annual growth rate assumption made in the Virginia Lake Appraisal Report, August 1977, by R.W. Beck and Associates. In a letter from APA, they advised examination of one load case that would assume a move toward an all-electric economy. For this case we applied a 100 percent increase in 1990 energy demands over the figures shown in the Beck study. The low load case was evaluated using data from the Retherford report. E-9 TABLE E-2 HISTORICAL ENERGY AND PEAK DEMAND Petersburg Wrangell Total Year Enersf catacitx En erg) Catacitx Energ1 Catacitx (MWh kW) (MWh kW) (MWh kW) 1968 12' 191 2,400 6,663 1 ,470 18,854 3,870 1969 12,434 2,600 6,620 1 ,420 19,054 4,020 1970 13,673 2,650 7' 199 1 '700 20,872 4,350 1971 16,314 2,950 8,275 2,050 24,589 5,000 1972 16' 352 3,000 8,998 2,250 25,350 5,250 1973 16,314 3,200 9,724 2,250 26,038 5,450 1974 18,735 3,500 10,205 2 '150 28,940 5,650 1975 18,373 3,250 10,753 2,600 29 '126 5,850 1976 19,200 3,440 11 ,054 2,650 30,254 6,090 1977 19,344 3,750 12,405 3,000 31,749 6,750 E-10 COSTS Detailed construction cost estimates for Thomas Bay and Tyee Lake are presented in Section D, Project Descriptions and Cost Estimates. Construction of Phase I is estimated to start in 1986 with power-on- line in 1990. Phase II would have a 2-year construction period with second phase completion for the Thomas Bay project i• 2002 and in 1998 for Tyee. Total estimated first cost of Thomas Bay is $93 million and Tyee Lake is $97 million. INTEREST DURING CONSTRUCTION (IDC) Interest charged on money expended during the construction period is considered an additional cost of the construction phase. Simple interest is calculated at 6-7/8 percent for each year's expenditure and added to first cost to establish the investment cost. AVERAGE ANNUAL COST Expenditures and IDC made after the 1990 POL date of Phase I are discounted to 1990. The resultant total investment cost is then trans- formed into an average annual fixed cost by applying the appropriate capital recovery factor associated with the 6-7/8 percent interest rate and 100-year project life. OPERATIONS, MAINTENANCE, AND REPLACEMENT COSTS AN O,M&R cost of $450,000 is added to the average annual cost to obtain a total average annual cost. HYDROPOWER BENEFITS Power Annual power benefits were computed by applying the unit value of $62.5 per kilowatt year by capacity and 50.6 mills per kilowatt hour E-11 for energy to the usable output of the hydropower project. Benefits were computed for each year of the 100-year economic life of the project and were then discounted, using a 6-7/8 percent discount rate, to the 1990 POL date to determine the combined present worth. This present worth value is then transformed to an average annual benefit by applying the appropriate capital recovery factor. The medium load growth fore- cast for Thomas Bay results in an annual power benefit of $7,174,000. The corresponding figure for Tyee Lake is $6,036,000. Justification A summary of project costs and benefits for Tyee Lake and Thomas Bay appears in Table E-3. Project Tyee Lake Thomas Bay TABLE E-3 Average Annual Costs Interest & Amortization 6,960,000 6,637,000 OM&R 450,000 450,000 Average Annual Power Benefits Tyee Lake Thomas Bay $6,036,000 $7,174,000 Plan Justification Tyee Thomas Annual Costs 7,410,000 7,087,000 Annual Benefits 6,036,000 7,174,000 Net Benefits -1,374,000 87,000 Benefit Cost Ratio . 81 l. 01 Total 7,410,000 7,087,000 These figures indicate that the Thomas Bay project is marginally justified. E-12 Variations in the Load Forecast The high growth rate load forecast would result in more rapid utilization of power and thus, higher power benefits. In this case, net benefits for Tyee Lake would be 61,000 with a benefit cost ratio of 1.01. The same scenario for Thomas Bay results in net benefits of $2,838,000 with a benefit-cost ratio of 1.40. E-13 (/) 1- 1- <( ~ <( (.!) lJJ ~ z - >- 1- 0 <( a.. <( 0 - 50 40 30 20 10 TYEE MEDIUM PEAK LOAD CAPACITY FORECAST PHASE I 13.8 MW REQUIRED DIESEL 1.5 MW EXISTING DIESEL 12.38 MW PHASE n 12.1 MW ~ O~--~r----r----r----r----~~~~~~~~~~~--~~--~----r----r----T---~----,---~~---r---4 87 ~68 89 91 92 93 94 95 97 98 99 2000 2 3 6 (/) I- I- 140 120 tOO <( 80 3: <( (!) (!) z >-60 (!) a: laJ z laJ 40 20 rr, ' '-~ 0 PHASE I 111.9 GWH DIESEL EXISTING HYDRO 87 88 89 90 91 92 93 94 PHASE II 13.0 GWH '----DEMAND CURVE TYEE MEDIUM HYDRO ENERGY FORECAST 12.4 GWH 95 96 97 98 99 2000 2 3 4 5 6 '~ . ' 60 . .) 20 :::( 1. :::( .) 10 0 I e THOMAS BAY MEDIUM PEAK LOAD CAPACITY FORECAST I 9! PHASE I 18.8 MW I 91 EXISTING DIESEL 12.38 MW EXISTING HYDRO 1.6 MW PHASE U 17.3 MW ·--~--~--~.~--~.----r---~~----~~----J.~ ~ • 20• 2 .. 3 180 160 PHASE I 143.1 GWH 140 120 ,:n :~ DEMAND CURVE i~ i:.;: ;~ 100 t~ rc:!> "Z >-eo (_!) X: J.l z :'.J.I 60 THOMAS BAY MEDIUM HYDRO 40 ENERGY FORECAST DIESEL 20 "" I ....... '.J EXISTING HYDRO 12.38 GWH 0 "~ <>C: ""' ' . SECTION F ENVIRONMENTAL ASSESSMENT EXISTING ENVIRONMENTAL SETTING PHYSICAL SETTING General Description Southeast Alaska stretches nearly 600 miles along a narrow strip of mainland averaging 120 miles wide, east of longitude 141 degrees west from Dixon Entrance on the south along the Canada-Alaska border to Cape Fairweather on the north. Included in the southeast region is the Alexander Archipelago which lies directly offshore to the west. Sixty percent of the total land area is mainland and the rest consists of islands lying immediately offshore for a total surface area of approximately 42,000 square miles. Petersburg and Wrangell are located approximately one-third of the way up the Alexander Archipelago on Mitkof and Wrangell Islands respec- tively. The two islands are separated by 10 miles near the Stikine River Delta, with Wrangell lying approximately 30 miles southeast of Petersburg. See Project and Load Center, Figure F-1, for locations. Both the Thomas Bay and Tyee Lake project sites are located on the mainland in southeastern Alaska. Thomas Bay is located approximately 40 air miles northeast of Wrangell and Tyee Lake is 38 air miles south- east of Wrangell. Thick stands of coastal coniferous forest occupy both the Tyee and Thomas Bay basins from tidewater to approximately the 2,750-foot elevation. Interspersed within the basins are bogs and poorly drained meadows where tree growth is either absent or stunted. At higher altitudes, low, scattered shrubs and subalpine herbaceous cover prevail along with extensive areas of barren rock faces and rock slides. F-1 Geology and Topography The Tyee Lake, with a basin 14.2 sq. mi. drainage area at the pro- posed damsite varies in elevation from 1,387 feet at the lake to 5,000 feet at the highest point in the basin. The Thomas Bay basin with a 17.3 Sq. mi. drainage area at the proposed damsite varies in elevation from 1,514 feet at Swan Lake up to 6,300 feet at the highest point in the basin. The topographic features in the area influence drainage, climate, vegetation, and animal distribution as well as man 1 s occupancy of the land. The southeast has experienced fairly recent volcanic activity, indicated by post-glacial deposits of ash and pumice. The mountains on the mainland form a glacier-covered upland 5,000 to 10,000 feet high. Deep steep-walled U-shaped valleys dissect the upland, while numerous spectacular fjords afford passage far into the Coast Range. The massive mountains are bordered by cliffs that plunge several thousand feet to tidewater. Bedrock is exposed or near the surface throughout most of southeast Alaska, including the Petersburg and Wrangell area. Three northwest- trending belts of sedimentary and metamorphic rocks have been recognized, and igneous intrusives are widespread throughout. The dominant northwest- trending structure pattern is accentuated by numerous linements and faults of cretaceous-tertiary age. Unconsolidated deposits cover most all of the lowlands in this region, but they are thin or absent in much of the uplands. Deposits of sand, silt, and gravel occur along the streams, however, they are generally small. F-2 Glaciers are responsible for many distinctive land features such as sharp ridges between glacial troughs, extensive U-shaped valleys and truncated adjacent valleys, scenic linear fiords, scraped and scratched valley floors, and broad outwash plains. Much of the Petersburg area is mantled by a thin veneer of till, which has a district impact on drainage patterns and groundwater availability. The fine-grained com- ponents in glacial till affects porosity and permeability of sediments. Climate Petersburg-Wrangell area has a maritime climate characterized by mild winters, cool summers and year-round rainfall. The physical barriers posed by the Coast Range and lesser ranges cause high rainfall totals throughout southeastern Alaska. Petersburg•s annual average precipitation is 105 inches, varying between a high of over 17 inches in October and a low of between 4 and 5 inches in June. Snowfall is heavy and wet but seldom accumulates to a depth greater than 30 inches. Temperatures are strongly influenced by the proximity of the sea as well as by geographic latitude. As a result of the sea•s moderat- ing influence, Petersburg•s annual average temperature varies between the warmest (July) and the coldest (January) months at 26 degrees Fahrenheit. Climate conditions within the lower elevation of the area are not severe. However, in the higher elevations severe conditions with greater quantities of precipitation and higher winds prevail. Water and Air Quality Because of the near pristine nature of the project area, the quality of the water and air are high. Water and air quality have not been F-3 degraded, since there has been only limited human activity in the area. There has been little natural degradation of the water resources because the lakes act as basin catchments, reducing the maximum sedi- ment concentrations in the streams flowing from the lakes. In addition, most of the streams in the area are not subject to much glacial influ- ence. Principal sources of air pollution in the region are activities of the forest products industry. Esthetics Scenic values abound in this largely undeveloped region. Myrias islands, a deeply indented coastline, forests, mountains, glaciers, and the ocean combine to form superb vistas. The study area ranks high in all elements of esthetic quality including: vividness, visual intact- ness, unity, and visual uniqueness. Logging operations near the two project areas as well as along portions of the transmission route detract somewhat from the natural beauty of the area. BIOLOGICAL SETTING Vegetation Dense forest covers most of Mitkof and Wrangell Islands. However in areas of poor drainage tall tree growth degenerates into scrub forest, shrubs, and eventually, to muskeg. With the exception of the shore areas along the northern portion of Wrangell and t1itkof Islands most of the area is within the Tongass National Forest. Tall trees are generally hemlock-Sitka spruce in mixed stands with small mixtures of western red cedar and Alaska cedar. F-4 In the forest areas, shrubs occurring within the timber trees are predominantly huckleberry and blueberry, while mosses and ferns comprise the bulk of the ground cover. The muskeg areas are generally treeless and are covered mainly by sphagnum moss, sedges, rushes, and low shrubs, although some isolated open stands of lodgepole pine, hemlock or cedar do occur. Major vegetation types do not occur in clearly defined areas but intermingle greatly as a result of local variations in drainage and relief. There is no true alpine vegetation on either Mitkof or Wrangell Islands because elevations do not exceed 2,500 feet. At the upper levels of both islands, the dense forests give way to scrubby and shrub growth. Wildlife Terrestrial Species. The wildlife of any area is largely depen- dent on the vegetation available for its survival. Each type of vegetation supports a different type of wildlife, often on a seasonal basis. The region has a wealth of big game animals. Brown, grizzly, and black bears, moose and deer, typically inhabit the surrounding area. The area also has an abundance of small fur-bearing animals, including: otter, beaver, squirrel, mink, and ermine. Game birds include blue grouse and three species of ptarmigan as well as ducks and geese. Shorebirds, gulls, cormorants, herons, murrelets, murres, and cranes are abundant in these areas. Bald eagles reside and breed along most of the shoreline in the area. Trumpeter swans are known to breed at Crystal Lake on Mitkof Island and frequently migrate over the project site. F-5 At higher elevations on the mainland alpine tundra occurs in open terrain where barren rocks and rubble are interspersed with low plants, cassiopes, mountain-heath, dwarf willow, avens, alpine azalea, lichens and mosses. There is an abundance of marine related birds within the Petersburg Wrangell area. Two species of seater (surf and whitewinged), five species of gulls (bonapart, black-legged kittiwake, mew, herring and galacious-winged), the common murre and the pelagic commorant are the most abundant species found in the area. Marine Mammals. Harbor seals and harbor porpoise have been observed in the area as year around residents. Stellar sealions, Dall porpoise, humpback and killer whales are frequently observed in nearby Frederick Sound and Sumner Strait. Finfish and Shellfish. Five species of Pacific Salmon (chinook, pink, coho, chum, and sockeye}, two species of anadramous trout (steel- head and cutthroat) and one species of anadroamous char (Dolly Varden) are found in the Petersburg-Wrangell area. Spawning occurs from June to September with large numbers of migrating adults passing through the area. The young return to the sea between mid-March and early June. The area also contains halibut, sablefish, lingcod, greenling, several species of rockfish, several species of flatfish and noncom- mercial roundfish. Tyee Lake supports a population of Arctic grayling. Swan Lake at Thomas Bay supports a healthy population of stocked rainbow trout. F-6 Threatened or Endangered Species The only species listed by the U.S. Fish and Wildlife Service as threatened or endangered which may be present in the project area is the American peregrine falcon, (falco peregrines anatum). Several species of wildlife that are considered threatened or endangered in the lower 48 states have substantial populations within Alaska. Such species include the American bald eagle, wolf, and grizzly bear. There are no known threatened or endangered vegetative species in this social, economic, and cultural setting. Archeological Resources Knowledge of the prehistoric period for southeast Alaska is quite sketchy, although it is known that Tlingit Indians long had fish camps in the area. While archeological potentials have not been widely explored, potential sites are relatively abundant because of the long record of human occupancy in the region. ECONOMIC SETTING Fishing and Fish Processing. Both Petersburg and Wrangell have an economy based largely on fishing and the fish products industry. Salmon and halibut are the principal species caught and processed. However, crab and shrimp are also important to provide employment throughout most of the year. Sablefish, herring, sole, and flounder are also caught in commercial quantities. F-7 Mineral Exploration and Development. There are no known mineral deposits of commercial value in the immediate vicinity of Petersburg- Wrangell. However, both communities have played a supporting role as an outfitting point for mineral exploration along the Stikine River. Timber Processing. Logging and wood processing give added strength to the economies of Petersburg-Wrangell. There is one mill located in Petersburg which saws cedar for boats, fish boxes, home buildings and other local uses. The two mills in ~lrangell produce 40 percent of Alaska's lumber exports. Employment. Unlike many larger and less isolated communities, Petersburg has a relatively simple, clearcut economic base. Histori- cally, the basis of the city's existence has been fishing and fish processing, although this has recently been supplemented by logging. Economic activity in these two commodity producing industries has served to bring money circulating within the community. Since Wrangell's economy is somewhat less diversified and more dependent on the logging industry, the future of which is questionable, pending settlement of the land withdrawal issue, future employment projection is difficult. Transportation. Petersburg and Wrangell like all other Southeastern Alaska cities, are extremely isolated by physical barriers. The island location in the narrow mountainous Alaska Panhandle causes complete reliance on marine and air transportation. The Marine Highway Ferry System links Petersburg-Wrangell with other Southeastern Alaska cities as well as Seattle. This system is F-8 heavily used by out-of-state tourists, especially during the summer months. Both communities are served by scheduled commercial aircraft. Present jet flights provide convenient access to all parts of Alaska as well as to the contiguous United States. Commodities primarily are shipped containerized via the Alaska Ferry System or by privately owned barge companies. Tourism The tourist industry has become a major factor in the economy of southeastern Alaska. Each city along the inside passage route holds some special attraction and provides local guided tours and festivities designed to promote tourism. The Petersburg/Wrangell area has many local attractions such as the Stikine River and the migratory water foul nesting areas of Dry Straits. Most lands associated with the two hydropower projects are located within the Tongass National Forest. At the present time, a comprehensive land use plan is being prepared for the Tongass in accordance with the Federal Land Policy and Management Act of 1976. The future status of the project area lands is uncertain because of the Alaska Native Claims Settlement Act (ANCSA). In addition, Section 17(d)(2) of ANCSA (national interest lands for wilderness designation) may affect the proposed project although there are currently no proposals which would include the project area. The potential for the development of resources in the project area, notably timber and minerals is quite high. It is expected that F-9 any development in presently undisturbed areas will increase the potential for additional future development of the forest and mineral resources. This is because decision makers are ususally hesitant to make the initial decision which will irreversibly commit undisturbed lands. Once lands are disturbed further disturbance or development is not usually considered as major an issue as initial development. F-10 SECTION G CORRESPONDENCE FEDERAL ENERGY REGULATORY COMMISSION RI:GIONAL OFFICE !1!1!1 8ATT1£RY STREET, ROOM Atll SAN P'RANCIBCD. CA 94111 Colonel George·R. Robertson District Engineer Alaska Q1str1ct, Corps of Engineers P. 0. Box 7002 Anchorage, Alaska 99510 Dear Colonel Robertson: August 9, 1978 Please refer to your letter of June 1, 1978 (NPAEN-H-HY), in which you requested estimates of power values for Sitka and the Petersburg- Wrangell area. The power values are provided on the enclosed Tables 1, 2 and 3. We believe that all of the data you require for your sensitivity analyses studies are provided. A reasonable single power value for the combined Wrangell-Petersburg market area may be calculated by weighting the power values for the respective areas according to the 1977 peak demand and energy requirements shown on the tabulation below. Historical Power Reguirements Wrangell Municipal light & Petersburg Municipal Power & Power Oe~artment light Oe~artment Year Demand EnerW Demand Energy kW MW kW MWh 1972 2 250 8 998 3 000 16 352 1973 2 250 9 724 3 000 16 314 1974 2 000 10 305 3 500 18 735 1975 2 600 10 753 3 250 17 369 1976 2 650 11 054 3 670 18 103 1977 3 000 12 732 3 750 19 344 Growth in peak demands for the period 1972-1977 were at average annual rates of 5.9 percent and 4.6 percent respectively for the Wrangell and Petersburg systems. We suggest that a dependable capacity study of the proposed Takatz Creek project be made in view of the magnitude of present loads and the indicated load growths. _ .. - -2- If we can be of further assistance, please do not hesitate to call upon us. Attachments (3 tables) cc: North Pacific Div. Corps of Engineers Very truly yours, ~ -r-'=-:?. ~ <::::-:::--· >? ........ ~--'-' -f,-P ~. ol.-'( Euge~ 'Neblett Regiona.JI Engineer Table 1 Hydroelec~ric Power Plant Power Values at Market Wrangell, Alaska Plant Description Capacity Investment Cost Heat Rate Service life Fuel Cost Annual Plant Factor Capacity Cost Fixed Cfiarges (Costs as of 7/1/78) KW $/kW Btu/kWh Years (F02) ¢/106 Btu % Interest or Cost of Money Amortization (Depreciation) Interim Replacements Insurance Taxes Fixed Charges -Total Fixed Charges -Total Fuel Inventory Fixed O&M A~. & Gen. (39% Total O&M) Annual Capacity Cost at Bus Bar Energy Cost Fuel (311 ¢/106 Btu x 11,100 Btu/kWh) Variable O&M Total· Energy Cost at Bus Bar Diesel Engine-Driven Generating Plant 1 500 320 11 100 35 311 50 Financina · Municipal Fe eral - - -Percent -- 7.50 6.625 0.65 0.785 0.35 0.35 0.25 0.25 1.00 9.75 8.01 - - -$/kW-yr. - - -) 31.20 25.63 2.53 2.06 6.40 6 .'\0 24.94 24.94 65.07 ' 59.03 mills/kWh 34.52 13.14 47.66 34.52 13. 14 47.66 Hydroelectric Power Plant Power Values At Market , Wrangell, Alaska \}1 • (Costs as of 7/1 /78) Capacity Value Financing Energy Municilal Federal Value /kW-yr. mills/kWh A. Cost of Thermal Plant Output @ Generator Bus (Market) 1. Capacity 65.07 59.03 2. Energy 47.66 B. Hydro-thermal Capacity Value Adjustment 1. Capacity (5% of A 1) 3.25 2.95 c. Value of Hydro Plant Output @ Market 1. Capacity 68.32 61.98 2. Energy 47.66 . l I > ~I l \ ' ., l ·'f'\ I "-"" v ~· ~~ ~ ; ~~ •," ~ ' d 11 Hydroelectric Power Plant Power Values at Market Petersburg, Alaska ·Plant Description Capacity Investment Cost Heat Rate Service .Life Fuel Cost Annual Plant Factor Capacity Cost Fixed Charges (Costs as of 7/l/78} kW $/kW Btu/kWh Years ( Fo 2 ) ¢11 o6 Btu % Inter·est or Cost of ~toney Amortization (Depreciation) Interim Replacements Insurance Taxes Fixed Charges -Total Fixed Charges -Total Fuel Inventory Fixed O&M Adm. & Gen. (39t Total O&M) Annual Capacity Cost at Bus Bar Energy Cost Fuel (355 ¢/106 Btu x 11,100 Btu/kWh) Variable O&M Total Energy Cos~ at Bus Bar Diesel Engine-Driven, Generating Plant 1 500 320 11 100 35 355 35 Financing Municipal Federal - - -Percent - - - 7.50 6.625 0.65 0.785 0.35 0.35 0.25 0.25 1.00 9.75 8.01 31.20 2.02 4.48 17.46 55.16 39.41 13.14 52.55 · $/I<W-yr. mills/kWh 25.63 1.64 4.48 17.46 49.21 39.41 13.14 52.55 • ' A. B. c. Hydroelectric Power Plant Power Values at Market ,1 Petersburg, Alaska ~91 1 (Costs as of 7/1/78) Capacity Value Financing Municilal Federal /kW-yr. Cost of Thermal Plant Output at Generator Bus (Market) 1. Capacity 55.16 49.21 2. Energy Hydro-thermal Capacity Value Adjustment 1. Capacity (5% of A 1) 2.76 2.46 Value of Hydro Plant Output at Mark.et l. Capacity 57.92 51.67 2. Energy {cor 1 )• I Energy Va 1 ue, mi 11 s7k\ 52.55 52.:.. ; l lable 3 Hydroelectric Power Plant Power Values at Market Sitka, Alaska Plant Description Capacity Investment Cost Heat Rate Service Life Fuel Cost Annual Plant Factor · Capacity Cost Fixed charges (Costs as of 7/l/78) kW . $/kW Btu/kWh Years (F0 2 ) ¢/106 Btu % Interest of Cost of Money Amortization (Depreciation) Interim Replacements Insurance Taxes Fixed Charges -Total Fixed Charges -Totai Fuel Inventory Fixed O&M Adm. & Gen. (39% Total O&M) Annual Capacity Cost at Bus Bar Energy Cost Fuel (336 ¢/106 Btu x 10,000 Btu/kWh) Var.iable O&M Total Energy Cost at Bus Bar Diesel Engine-Driven Generating Plant 2 500 360 lO 000 35 47 30 Financin~ Municipal ~ederal Percent 7.00 6.625 0.72 0.785 0.35 0.35 0.25 0.25 0.35 8.67 8.01 $/kW-yr. 31.21 28.84 1. 31 1. 20 3.69 3.69 14.38 14.38 50.59 48.11 mills/kWh 33.60 33'. 60 12.62 12.62 46.22 46.22 ' .1, 1 I Hydroelectric Power Plant Power Values at Market Sitka, Alaska (Costs as of 7/1/78) Capacity Value Financing Municipal Federal $/kW-yr. A. Cost of Thermal Plant Output at Generator Bus 1. Capacity 50.59 48.11 2. Energy 8. Air-break Switch at Plant 1. Total Annual Cost 0.15 0.14 c. Cost of Thermal Plant Output at 12 kV Terminals 1. Capacity 50.74 48.25 2. Energy D. Hydro-thermal Capacity Value Adjustment 1. Capacity (5% of C ·1) 2.54 2. 41 E. Value of Hydro Plant Output at Market 1. Capacity 53.28 50.66 2. Energy lahle 3 {cont'd ,, \< Ener:gy Value mi 11 s/kWh 46.22 46.22 46.22 T!lO:·ll\S DAY POIVEH co:::.JISSIO:l TYEE LAKE HYDROELECTRIC PROJECT NOTICE OF INTENTION Public notice is hereby given t.'lat the Thomas Bay Power Com.'llission is actively engaged in preparing a Federal Energy Regulatory Commission (FERC) license application to construct the proposed project to be know1 . .:ls 'l'yee Lake Hydroelectric Project. Please direct correspondence to: Hr. Harry Sundberg, Secretary, Thomas Bay Power Commission, Box 613, Nrangell, Alaska 99929; copy of correspondence to: Robert i'l. Rether fo.r , Associates, P.O. Box 6410, Anchorage, Alaska 99502. The proposed project would be on the Tyee Creek, in latitude 56°ll'N and longitude 1Jl 0 3l't'i as shotvn on the U.S.G.S. quad sheet Bradfield Canal (A-5) Alaska (in the region of the City of Hrangell). 'l'he proposed project would affect lands of the United States, U.S. Forest Service, Tongass National Forest. The proposed development of the Tyee Lake Hydroelectric Project contemplates: A ten foot diameter unlined tunnel 4800 feet in length tapping Tyee Lake at elevation 1330 and the dotvn- stre<lm portal at elevation 1300; a gate shaft and gate at the tunnel entrance with gate controls placed above the second stage development; a surge tank near the lower tunnel portal excavated in bedrock; a steel penstock 7.050 feet in length from the tunnel portal to the powerhouse varying from 7' -6" dia.'Tieter at the top to 5' -0" diameter at the trifur- cation near the pmverhouse; a pmverhouse (probably underground) near the mouth of Tyee Creek at tidewater containing two 7, 500 K\v impulse turbine- generator sets; provisions for a third turbine-generator set of 15,000 J:.:I•T and the use of the tailwater for future aquaculture development.; a 115 KV tran~mission line approximately 42 miles in length ·,·lith the alignment along the north shore of Bradfield Canal to Blake Island, over water crossing to Blake Island and to Wrangell Island, northwesterly along Blake Channel to Capel point, across ~'irangell Island and northerly to a point near Ft. i<lrangell Seaplane Ramp; a substation to step down the voltage from 115 KV to 35 ~v for transmission to Petersburg and to the 1'/rangell distribution voltage; a 35 KV double circuit. submarine cable from Nrangell Island to t·ioronko fski Island approxi:nately 2. 5 miles in length, westerly across ~·roronko£ski Island to near \'ledge Pt., a double circuit subrn\lrine cable to Vank Island approximately 2.7 miles in length, north\,·esterly across Var.k Island to USC & CS station "t'<'l:ove", a double circuit subrnctrine cable from V<u:k Island to i·litkof Island E!pproxi- mately 3.1 mile!:> in length, then parallel the Nitkof highway to a substa- tion in the Sco'" Day <1rca of Petcr!jburg. The second stage development, circa 1995, will consist of a dam at the outlet of Tyee Lc1ke. for a normal n:axir:mm water surface elevation of 1440; install one 15,000 Kl.·J ir:l[Julse turbine-generator uni.t; install a step-up substation from 35 :r:.v to 69 KV a.t the South end of Hitkoff Island. The project is expectt;cl to prov.lde GC!1 180 :·ll·ih of primary and 34,141 t1'.~h of seconlluxy enerqy n the first stage development and 131,280 >Mh of primary and average c~crgy upon completion of the second stage to the Petersburg-Hrangell service area. Any agency, organization or person desiring to be heard is invited to comm·;:;nt on tl1e proposed project. Th;.; Thomas Bay Power Com..'nission antici- p<:!t<.::~.> fili.ny the Application for License in September 19'/':). Co1~.ments en the Project should be received prior to Jun. e l)\197.9 t.o· .. be incorporu.ted in the Application. /}J ~ i'i(") c~t;_(!l ~1~'k 0 ~ ~ ~ ~-c.r Harry SunBberg, Secretary~ Thomas Bay Pmver Commission RIVERS AND HARBORS IN ALASKA SITKA STUDY AREA Following is a January 1979 updated cost estimate of the Takatz Creek Project near Sitka. It is based on the design and quantities developed by the Alaska Power Adminsitration (APA) and presented in APA's January 1978 report. . Invitation No. Date I ./A of ' 24S£:::.PI97~1 I ' CONSTRUCTION COST ESTIMATE OrawingNok TA-11.1 79 RA'Y't PROJECT TAKATZ CREEK PROJECT OcoeE A OcoeE c Goot> ()F SITKA, ALASKA IC CODE B ncooE o IF$J(,ator j 1 Check~r LOCATION ( ;-IAP/ ..... 4.!:..:A.. Zl/ ~.1'7 1:.:. C..,.. TOTAL I QUANTITY MATERIAL LABOR FREIGHT Unit ~ Total Mat'l a Labor ~ Total No. Units Unit Price Cost Clnit Hrs. Rote Cost Olf Wt - CLEARING LANDS 2~a~c. , TOHERS AND FIXTURES I t).:;:>(j t!>OO POLES AND FIXTURES /, Dr::'O a-~ OVERHEAD CONDUCTORS AND / /, .::>oo ooo DEVICES / ROADS AND BRIDGES /So C>t:>D -" CLEARING LANDS .q/ a Oc> STRUCTURES AND IMPROVEMENTS 2, .Y 6 :;' aoc ; qf 47 L/-55" J; 00 S GP.! I" I~(!' ~<:::::'/ L..l r1 Ei'S (:z;:;, 1/j"O :cJ<" y) ··-1% -l?:A/71) PG.eJ ~riNC: ~~p~ . '--- .!/7:S:'O.:l~ ;:::::,.C" - -Ec.rDI 12' 8t ~.;I £ h:- .Orr/F-2 Co::;'/ f.ro=~~ '!"'I ;~i$. .. -. t=:ry) -.. , 9. 4191 00(: :::.:h 'jf"Jf3, _.;.)-./.r, /2":~ FANDD B'7 v St F:t:'l:' VIS~'('"> ,_j AA.J.V ~VM )'.(, h -·~- # .. -~--·-~ ~6 '-C"Jr 57-4'2/ 0 b~ - l - - NPA FORM ( ) FEB. 1964 23 Rev. CONSTRUCTION COST ESTIMATE 1--------- hwttahon No. Date I /5 f ')I .2 "f S .E.'P F/7 o Sht. --:-__:____: Drawino No. f.!.P.!.!R~OJ:!.!E::..::C~T-.~T~AKA~TL!:Z.,_ . ...!>.C:£R~Elii.E.!:!:.K...JPwR~O~J!.£Et.l.:Cc!.T _____________ .........j D CODE A D CODE C LOCATION SITKA, ALASKA IDcooE a D cooE o , __ o_u_A_NT...,I,T_Y_-+--,---,M,-A_T_E_R_IA_L __ ~ LABOR FREIGHT r-wt ./ T ofot No. Units Unit ~~i~e Cost T_o.!:!.J!.!r0~~-_J_;R!!!a!!..'t!..!e-+-~C~o.!..!st __ j.!!M!!:!o.!...lt'lc...:8~:e..J& l. . .loi.Ja ib~IO!.!..Ir_t"./"iJ'---"U~nn!.!.iitt-t-_W,, t TOTAL DAM STRUCTURE OUTLET WORKS --~~- I·--ST_R_U_C_TU_R_E_S_& __ I __ MPR __ OV~'E~ME:N~I~T~'S _____ 4-----4----4----4--------+----4----+----+--------~3~.~~/_4.~~=~=·~~---1- WATERWAYS WATER\~IEELS, TURBINES, & GENERATORS 1----------------+-----+---+--+-------+---· ~ ::J8d 0~ 'l .. 1 / !I 1 0·"""" __ _11 .... ACCESSORY ELECTRIC EQUIPMENT r. -'i./ f-M-I S-C-E-'L_L_A_N-EO-U._S_E_Q_U_IP_I:_fE_N_T ___ -+----1-----+·-··--,'5'B 1/-:oc-" ---1- ROADS AND BRIDGES ---+-----·-l-----+---1---------+----+-----b .:>o.B.~ r ~--=-=-::.:=--=-:..::...:._----+.-+----+----+---------+----+---+---+--~~""""+---.-l· STATION EQUIPMENT, ELECTRIC //.?, 00,_.-.:;, ~-- ······· -+-----+---t-·-·····---+-------+---t-----+----+-------1--<~L,t...: ,==~--·-T !--S-T-RU_C_T_UR_E_S_&_IMP_R_O_V_E_H_E-NT-S--+-----t-··-·------+---·····-+------+----1-----+---+----+--7--5,- 1 -o--o- 0 -, -t--·----,- STATION EC'UIPHENT ,-E--L-E-CT_R_I_C_+----+--+--+------t----+---+---+-----+-___::_....:::_t.._;:___........:"'-t--.. 1 { .. B57,n""""' 1--· ---------------. ..-----+---·---+-----·· --t-----~-----~---I ·······-··---~--------·--·-··--+-·-----f---.. ·--·-t----·--·1--·-·--------+----+----~!--··-----+---··-·---+----·---·---, .. 1 ---·-----·-----·-·--+-------!------+----····-·--· --------+-----+----+--···"·--·-!-----·--·-··-+-------f--I -----~----· ------··--·---·-·--------+-----+---·--· ~-·--+------+----+----.!-----+-----+--------------1 1------------·-------·-·----c-·· ·--+--------·-··1------lf----+---+----+-----f----------··--------.......... 1 ... --~----~----.~~--~-----~--~----~-------!~-_·-··_·--·----~r---_-+-_---------..J~----~-.__-----+--,==---=--~~- . · .. : FO · ··•· 23 ( Hev) FfA 1964 · ' . I lnvltat1on No. Data I I: Sht. L_ of l CONSTRUCTION COST ESTIMA'TE 2 2-51:?? 1'1 lb Takatz Creek Project OrawinQ No. PROJECT OcooE A OcooE c Alaska fC CODE ncooE I EStimator tt~ecker LOCATION Sitka, 8 D ~ / ·-, -' _, ,. I ·-~l-::1 : '" '• QUANTITY MATERIAL LABOR TOTAL FREIGHT Unit ~ Total ~ Tot DAM STRUCTURES No. Units Unit Price Cost t Hrs. Rate Cost Mat't a l obor nit w Care of creek during construe -~- tion & unwatering foundations LS loo.:?ooe Excavation, 21,500 CY / common iO -:Z/~~ Excavation, rock 11 000 CY ?o -.38".::!~ Mob & demob for grouting LS /5 00~ -·---- Drilling grout holes 12,600 LF 20 -?52. a~~ Metal pipe and fittings for - foundation groutin~ 3 200 LB 3~ /2/oe>a ··~ Hookups to foundation erout '- holes 230 EA ,-;5-I~CJ'5d Pressure grouting foundations 12_Ji00 SKS ..., ... -..;.t> .1_10: C)r:JQ .l!g_tal tubing and fit tines for eroutinl! contraC'.tion ioints 3 BOO LB 5-let oc.>a Hookups to contraction ioint ·- grouting systems 40 EA 195~ 5L/od / Pressure grouting contraction joints and temperature contra. I --- systems 250 SKS $5-B75o Cement 32,500 BBL 2o-6:54,o"o Reinforcement bars 61,000 LB ._,65 3~0:Jo ·-- ConcrPtP in dams 29 000 CY jr;;':!J:" ----~---· ',_; 5366,~ / NPA FORM ( ) FEB. 1964 23 Rev. lnYIIat•on No. CONSTRUCTION COST ESTIMATE PROJECT Takatz Creek Proiect OcooE A LOCATION Sitka, Alaska II CODE B QUANTITY MATERIAL Unit % DAN STRUCTURES (cont.) No. Units Unit Price Cost I Concrete in dam parapets and curbs 130 CY 475 He tal tubing and fittings for I temperature control systems 7,800 LF I !_J":./J -:'~ TPrnnPrRturF> rnnlrnl nf <'nn c_rete 0 000 CY .!.f 5o Thermocouple wiring 3,000 LF 6 - He tal seals -4,200 LF jLj-- Netal grout groove COVF>rS 200 LF g- ' Instrumentation of dams (collimation) LS Pipe handrails 2,000 LB -:£~ --r- S 1ht-nt-,:,l -- Contingencies (20%+) -.. Total ------------f----- .. ->--· ---------------~------------------.... ·--·--------. -----~-- -----~-- -----·--·-----·-~ ---- !-----· --f-·- i _l _ '--,~. -· _L ' ,-,-----_._ ----- Date I Sht Z-of DrawinC) No. OcooE c ncoDE [tsllmotor ~~h~~;e~ ( D .t: LABOR TOTAL FREt Total Hrs. Rate Cost Mot't 8 Labor % Unit GHl ra ~ ----r S~75o l '] _...,_ /0 0 ... "":·~ I i J./5", 000 }9, -1 /) 0 0 r 58 80 0 -, I I co DO ,---I I 35.ooo =t= I 47 ()()0 l -I-I Q 5 3C) "'~ I .) 1 D 1 q'J< I --I ' ~ I) '].'f 7 _, r-I I 0 ~l.\1.-, ~:~ --j I I _ _,__ --~~·----. ---------l--1 ·---~--r--------------------t· .. --------------r-I ----T I ---,f I ,-----1 ------'---- ' . I Invitation No. Date :::t COST ESTIMATE· jSht....;.:;:_ of_ CONSTRUCTION I Orawim~a No. PROJECT Takatz Creek Project OcooE A OcooE c I CODE DcooE ,E$Ilmotor tc~ecll!,--~~--,- LOCATION Sitka, Alaska 8 D 7 ~f:t? 1 :a '_.) QUANTITY MATERIAL LABOR TOTAL FREIGHT Unit ~ Total ~ Tot' OUTLET \~ORKS No. Units Unit Price Cost I Hrs. Rate Cost Mot'l 6 labor Jnit W• Excavation, common, for --- channel 2 ,20( CY ~-IS" U.OO Cement 32' BBL ::::o -I::; s;o o ",... Reinforcement bars SO. DOC LB jO"> f - .:.? '? \OD -~--- Concrete in trash rack struct. 7( CY --2-.s-000 :::'c.:Jt.::l _(:gn~rete in gatehouse super- structure 4C CY --oo,.!) ::.o ·) ·) l) "'~ Concrete in e:atehouse !=:uh- structure 14( CY -~~-L\'2. 00 0 -Concrete in blackouts 1C CY .(,~ 6 0 0 (') High pressure gates and hoist -- 4 by 4 feet, 4 each 100,00( LB ...... .::;-::> lc::;o_ IJt)Q ----~ Conduit liners, 4 bv 4 feet, 2 each 34,00( LB 3~ I \ () '5" ,')f) { Controls for high pressure gates 1,02 LB .B -8 I 1.~ :) ~Jkhead gate seat & guides 6 so LB 3-IC\ 5-":lO Bulkhead gate slot closure 6 ,00{ LB 4-~L.f 000 Access stairwav 20 50 LB :j-:_:) \ s--:n Electrical system, including ,___ - heaters LS 25CJ!}t-' I ·-- l.o56 ·o~ao NPA FORM ( ) FEB. 1964 2 3 Rev. lnv•tot1on No. CONSTRUCTION COST ESTIMATE PROJECT Takatz Creek Project DcooE A LOCATION Sitka, Alaska !r CODE 8 QUANTITY MATERIAL Unit ~ OUTLET \.JORKS (rrmr ) No. Units Unit Price Cost I s •• hr()t-.::11 Contingencies (20%+) Total ----- ---1--·--1-- -- --f-- 1------ ----c---·--------1--- f--- -· ----------------·----1-------------+-- ---------------·······---------------·------------1-· -~ -.__ -'-......__ I ----------~PA IM il FEB. 11f64 2~ l l'iev.) Date OrowinC) No. OcooE c ncoDE IEstlmotor D LABOR Total Hrs. Rate Cost I '":): ~ 01~!) I -::2., \ 2-1 z l-3l ZTZ... ' --- 1-- Mot'l TOTAL 8 Labor I L' Sht._f __ o ~~n:ec~ei ___ 2. --..,r;e FREI ~--WI Unit GHT To! w_ l ~---1 . -l 7·~1 (~;'.')·' --~~ -----.... , .... -. l _l ___ ., ,--I ,---------r·· I I I ---~-~~- 1 l F l -~---I :~r I --. ------1 I --I -I ·---------------T---I -+---1 ·----------, . -tT _______ l I -----L__ ---- ' lnvttotfon No. ;~ ; Dote . pnt.Lof ___ ' CONSTRUCTION COST ESTIMATE OrawinQ No. Creek Proiect PROJECT Takatz OcooE A D CODE c •1 CODE B rlcooE o 1 Estlmator ~c~~ck_er LOCATION Sitka Alaska z_ s E: ,, -: '' ' ) QUANTITY MAT ERIAL LABOR TOTAL FREIGHT Unit ~ Total ~ ·rotc STRUCTURES AND IMPROVEMENTS No. Units Unit Price Cost t Hrs. Rate Cost Mot't a Labar t Wt Excavation common (includes talus) 14 250 CY q-lz.B '2<;"0 3n -; gg Excavation, rock 6.600 CY ') Q () I Compacted backfill 3,400 CY /6-S'l no o ,., -) Concrete, first stage 2.800 CY :~1:3 &:f_n ·:100 j - 4,200 26 -Cement BBL Bw ODr: Reinforcement bars ! 10,000 LB CJ6§ ?_(c,(-" <::::)D Structural Steel 30,000 LB /.::::-~ ._.._ -·4-D -. "":> 0.')1 ···- Miscellaneous metalwork 15,000 LB .i~ --4 ;:;;;-' 00 f) I Metal decking, 2-inch insula- tion and rubber roof 6,540 SF ;q-Rs () 'D I Insulated metal wall panels 10,600 SF /o -i0bl)')') Niscellaneous building items LS LS 35c"Jt"'Jdo -' /5.o_Od(:) Heating and ventilation -LS LS , Embedded o:ininR' 8 oon T.R . Lf.-3;J. ODD +~ l Exposed piping 6,000 LB 2..l i)t}f) 4~ ·' Motor-driven water pumps 4,000 LB \ ~..., 000 I Fire pn •teet ion system for oi rooms 1,200 LB 6-l ?.oo Subtotal ~.::: l~o CJsol -- Contingencies (25%+) I ~:82 l ~g Total 3 'i 1 ~ G88 3. lf-I..Lf... ikhs -- --~-· --·- NPA FORM ( ) FEB. 1964 23 Rev. CONSTRUCTION COST ESTIMATE PROJECT Takatz Creek Proj._e.c..t_ LOCATION Sitka, Alaska QUANTITY MATERIAL Unit WATER\.JAYS No. Units Unit Price Cost Excavation_, common in o..E_en cut for in ta!<e structure and penstock anchors and piers 11, 50( CY /o -·-- _Excavation, all da~ses. .in open cut for intake structure atehouse 2 Eenstock anchors -and piers and surge tank 2 80( CY ::;a Excavation all classes for- _gate shaft and house, and surge tank 2,50( CY 1-..z-I I ' ]:xcayation, all classes, for :un~~l 10 2 40( CY /1}- Structural ilteeJ tunnel ilU[!- po ·ts 95) 00( LB 16o I -----~-"--- Drilling grout holes 2J70j LF ~--- Pipe and fitting for founda- tion grout holes l' 50( LB ~) ;:, l -1-----,_c __ r--~ _:.......,.;.. --- Hoolzups 9( EA __ r::' ,-- !--··"::>? Pre~~1Jre grouting 2 '70( CF ...., .;:; -·-.. ~~' -----------1---- Cement ___ ___2_!_80( r___})B!:__ .:_?-1--····---------·-· rJ.:l.S _Rei_!.lf9rc;ement ba_r_;:;_ I_iO, O_QJ 1~!? : -.... !------·---------- -· jf.·--·---.JPA .... ,ijM23(R' I FEB 1964 ev., -_j_ -_j_ -'-- tnvllahon No. OcooE A OcooE c lC CODE B _OcoeE D LABOR ~ Total Hrs. Rate t - I « -----t--- ..... __ f-- .. -·---------~ ----- Date . I Sht_1_ot Drawino No. ! Estimator t~.-reckif· 7-Z ~ TOTAL FREI Cost Mat'l 8 Labor ~ Unit GHf To .Y! \IS 0•!0 ------ \ -+ () 000 --l -T -1 1-j ~~ ") ()() T -~--· I '] -- lL,~ ]·;·; ., i""" :::')') I --t ,_ I ~:..+ ')n;) -I e::: .? -:::.o I -5~ ~ .;; ----' __ -~1 _, -: :::: )0 --- ; ,_:) "'),. ',-. .. ---·----~ ---I j '--' 9 I f) f)'i) ---r f' I --~--'----- "\ ID I i ' ) Invitation No. Date ) 7 CONSTRUCTION COST ESTIMATE ht. __ ot __ I 1 I Drawing No. Takatz r.reek Pro1ect PROJECT DcooE A OcooE c II CODE ncooE IEshmotor tChecker LOCATION Sitka, Alaska B D Z-?. -<~P -.~ C;. QUANTITY MATERIAL LABOR TOTAL FREIGHT WATERHAYS (cont.) Unit ~ Total ~ Total No. Units Unit Price Cost I Hrs. Rate Cost Mot'l 8 Labor Unit. Wt Concrete in inro'!kP f':trnrtnrP ·-···· ·.-......_ and gatehouse ~¥. ..::::-.-:")~I) ·-~·.:;j,;:l ·,.,':::;> . - Concrete in gate shaft and surge tank 1,100 CY -----.~: -::-; ..._,{) ·'" ., )"'" . ConcrPtP in nPnc::t-nrk Anrhors ·~- and oiers 1.750 CY Ll-ac:j-. ;· ')) ) '":'·") -- Concrete in tunnel lining 3,500 CY ~-c.;) ·. 4Q) )")') ) ; Concrete in blackouts 15 CY /" -br"YJ .;;j )(")) Trashracks 16,200 LB ;75 ·,..5:::-) Catehouse metalwork 3 200 LB ;)56 \ I 2.0:-J ._., J Roller mounted gate 6 X 8. foot, 1 each 24,000 LB .,2.5 ::::-r !") r;·"' --.. ' Frames and guides for roller- mounted 8,500 LB ,....._ gate -... ~ .~ ~):) ._j -' _Hoist for roller: rno.u.n..ted_gate .24 000 LB 3-l' ;J:) :? Control svstem 4 000 LB 9-:-=. -;._ ') ) :) __ Penstock and wve branch dia- BOO,OOO 2 -meter 66 inches LB l.!..:,. •) ;') /) :::v Bulkhead gate, 6 X 8 foot, 1 each 14,500 LB j'72 2-') ~lD r- Frames and guides for bulk- head gate 6 000 LB /~ I 0 ~ :JO NPA FORM ( ) FEB. 1964 23 Rev. IOYIIOtiOO No. CONSTRUCTION COST ESTIMATE PROJECT Takatz Creek Project OcooE A LOCATION Sitka, Alaska CcooE B QUANTITY MAT ERIAL Unit %. \.JATERHAYS (cont.) No. Units Unit Price Cost I Electrical svstem for remote operation LS LS Subtotal Contingencies (20%+) Total --· --- --· -- ·- f--· ------~---c-- ·-- ----·---·-~ ------------- # ·-~-· -----~------·-· ;,, -------·'---·-· OcooE c DcooE D LABOR Total Hrs. Rate ------- Date . I Sht_i_ of. OrawinQ No. Estimator [c;'~cker z -;f,'-/ "") ·.A TOTAL FREIG Cost Mat'l 8Lobor ~ Unit HT Tote W! T - L/6.ooa 01 3'2.. ') .g•....;.0 J \ ?Jr.,:.. I~"'~ \\ \ ss-Qr;,.'3 \\,\.85,::.\0..:l ' l .--~· r --I r------I 1 -r -r 1 ·---l -I -·---- f -------·· I --'---··· -r l 'i r t I j ' bate ~ lnvnatu:m No. . q f I CONSTRUCTION COST ESTIMATE 1ht._o __ 1 Drawing No. PROJECT Takatz Creek Proiect OcooE A OcooE c tt:.stlmotor :hi!!,.,kAr LOCATION Sitka, Alaska lr CODE B O~ODE 0 I zz <:,"EI' .... ::;. c QUANTITY MATERIAL LABOR TOTAL FREIGHT WATERt.JHEELS, TURBINES AND Unit ~ Total ~ ·rOtC' GENERATORS No. Units Unit Price Cost mt Hrs. Rate -~~-Q_st Motl a Labor t Wt Cement 1.200 BBL /') -~ 2-t+ ()()r) ' Reinforcement bars 90 000 LB ()t:>G -3 -~ -~-...... ---'); ') .. )Q Concrete, second stage 800 CY ::::.",::):;) --:z_ Lj 0 ')I")'} I Vertical impulse turbine, 4 ~·,..-- iets, 14 000 hp at 886 ft. ·--- head, 400 rpm, 164 c.fs, 2 ea. 60,000 LB .-,5;;::> -!-9 lt'J ~-'oo Governors for turbines, 2 ea. 24,000 LB LjG:::~ I f).C5 1 0<) I --- Embedded pipe 8,000 LB L/-3 2 {)f){) ---' Expo!:jed pipe 6,000 LB Lj-!:e> 2l ".YOr'J . Hot or driven water pumps 3,000 LB L).-l?-ooo Generators, synchronous, ver- tical, 3-phase, 10,000-kw, --- 0.9 pf, 6,900-volt, 400 rpm, 2 each LS LS -? 000 0~/) / / Carbon dioxide svstem for 1,200 /""'"' -(r; generators LB -::::::> 1)00 -----~--·- Subtotal : '-\ \ l soo ~- Contingencies (15%+ ") l z lo20 Total ~~'1~0 121: .~ -~-.(j '"') ·' ~ -:•{ --: ~ ./'"" ~ -J / ·-· .!::..:: .. ~:.:." NPA FORM ( ) FEB. 1964 23 Rev. lnvttotlon No. Date of CONSTRUCTION COST ESTIMATE _t~~ -~0 PROJECT Takatz Creek Proiect LOCAT!ON Sitka, Alaska --- QUANTITY ACCESSORY ELECTRIC..U. EQUIP. No. Units Unit Switchgear for generators 6.9-kv, with 1.200 amp, 250 mva breakers, surge protectiv equipment and potential trans formers, 2 each LS LS .G.ene.r.atQL_exci tation ruhi cl P~ • 2 each LS LS Rl11'l <:rrurtnre non -.::egregater! 3-phase, 15 kv, 1,200A 100 LF ... NP11rr.::~l o-rnnnrli no .,.,, 1 i r.mont- (10-kva, 6900/120/240-volt - distribution transformer and ---~~-- 7-kw, 3-ohm resistor) 2 sets LS LS . -·---~- Hain control and graphic ·--- boards, in-line, dual--type -·---- (8 panels) LS LS ----~ Unit gage boards (generator & --- hvdraulic panels) 2 each LS t--..1.L ·---- Station-service unit sub (two ··-~· 300 kva, 6600-480 volt trans- --------~ "" formers, two 6600-_volt discon f---.... i· .... --~ ne.c t· S!,r i t..ch--,.;omp~n.t.s..,..-.----.... __ ---- . ·~-·-· --·r--~ ~ ~--·""'-----~ - OcooE A DcooE c L CODE B OcooE 0 MATERIAL LABOR Unit ~~ Total Price Cost t Hrs. Rote - - --~~-~ .. ----·------~ -.. -------- 1----------·--·-----·--·- ------ Orawin'i) No. [Estlmotor Cost &a~~CJ 7 .5'~ ' 0·) L) ·' 5'o.o~.:) 7 u.;. / -/ () ::J '- 2v...J ,}·J - 2~Q?'Q TOTAL Mat'! 8 Lobor rheEkei _ ~-.: ::.::: FRE Wt ~ IGHT Tot! ----------l Ul)it l"" I -i ----=i -r f ~---I ... ··--·· T ·-. I ·-L -··---- --·-~ -------- 1 l I \ 1 I I l I I I l I .... ···-1---c• . ~·--------------1---·----.. -1--[ I l I ·--·--·· ... c .. ------· J-~ ·--.. ·-~-----··- '~ -'-----I ~--' _r I I l ~-l \ :. I E \ lnvetat•on No. Dote . ' ' _( Snt. ..:..:.__ of_ CONSTRUCTION COST ESTIMATE Takatz Creek Project OrawinCJ No. PROJECT OcooE A DcooE c IC CODE 1 t.sflmolor t~ecKer Sitka, Alaska llcooE -.. .... -LOCATION 8 D .__ ;;._ _ _)Ff-., I QUANTITY MATERIAL LABOR TOTAL FREIGHT Unit ~ Total ~ Tot ACCESSORY ELECT. EQUIP. (cont No. Units Unit Price Cost t Hrs. Rote Cost Mafl S Lobor Jnit w -· . -··-··--,..-- 460-volt switchgear section ·- with 2 main and 10 feeder .. ______ breakers LS LS .9;!,::? ·? D .. / --=-..... ' ----- Lighting transformer 75 kva, 480-120/208 volt, dry type, with ±10% voltage regulator, . ----·· .. - 1 each LS LS /C! (?c' 4 ~-·--···· Panelboards, 600-volt, a-c I ---· ·-· ·-- power distribution 8 each I.S LS -.;~. <'10 ,, Grounding svstem, copper 6 000 LB /5-_Z:;i/6~6 ·-,._...,....._ ___ , .. ·····- Battery_ chargers 1 two 25 amp - and panelboard LS LS I q """" I'J -'/ ·-- Station battery 125 volt ----~ ~ 200 ampere hour LS LS /S:e>c)6 Conduit, nonmetallic, 3-inch 100 LF I{-/66cJ L. . Cable No. 4 AWG, 7,500 volt '·- shielded rubber 20Q LF .~-12e>o "' ' ' ----' Conduit system, rigid metalli LS LS :J-s,~j ---·~- '' -- Station-service and control cable LS LS CO'> Test cabinet, 1 each LS LS .<o r.:>co f--·--.' . ---~- rfic]d test eq ,;,...monl-1 C!OI-T.S T S 6ooo ~ ,. -·- NPA FORM ( ) FEB. 1964 23 Rev. CONSTRUCTION COST ESTIMATE ----- PROJECT Takatz Creek Proiect LOCATION Sitka, Alaska --.-------------- QUANTITY MATERIAL (cont.) Unit ELECTRICAL EQUIP~fDT No. Units Uni! ___ Price Cost Supervisorv control equip. , ·--f--- for controlled & lnvttotton No. I ~ote 0 C;DE A 0 COD~ ;-r;"· NO ~ st motor lc CQDL!l __ O <:9J)J:_I) ~-~---~·· TOTAL LABOR -Total Cost Mot't 8 Labor Rate I I '7 Sht. __:_;;;;_ of Checker I FREIGHT IWt ./"1 Tot( Vi)nit I W1 5u:.: I Hrs. ·---:I~~=--~ ----l-··-I I I ---· '·~·-. ~ ~ ~-' I -relay type, ~--·.,--··· J. ~:G . I I controlling ends LS LS ~7q,ctJ:d .. ~- Power line carrier equip. for -·-~ ~ ··-· c;ontro]led and controlling --·-----"- .. ends LS LS 32096.. / 1--------'-· Subtotal --~-"'-'~- (1 ~":> 8 0 0 :-· ~-·-·- Contingencies (20% +-) 1 ss-li.o 0 Total II 1 1 o. 9ioo l ill ')::') . I I I I I I I I I I J -I ~1 I ---.-----I I -----·-· --------~ --__ ... ~ ~"---·-- --··- I I I I -----·--... ------ -·--·--------------~------··--·-~---------·-· --··· ---·-·--·· --~--·- ~~---· -·-------~ -· ----~ ------·-------~--------------·· ' ------·--·-·-----·-·-----------·-· -··~ --·-----·---··~· .. ----·- --------------f------····--··----f--· "----- I I ~ I I I -1 I f---··· --·~ ·---~----·--1-----------~-----· --,--·--·~·---· ---j I .. -- -. I t' --.,---.--_..._ -'--_c_ ----,_--·· --·1 __ I 1 I I lnv1lahon No. i I;-Date . CONSTRUCTION COST ESTIMATE-·i Sht. ___;;;;:_of_ OrawinQ No. PROJECT Takat7. Creek Proiect OcooE A OcooE c Sitka, Alaska I CODE ClcooE iEstlmotor ~CfH!Cke;-. LOCATION B D 72 '--:.~('--"' ~- QUANTITY MATERIAL LABOR TOTAL FREIGHT MISC. EQUIPMENT Unit ~ Total ~ To! No. Units Unit Price Cost I Hrs. Rate Cost ,ot'l S Labor t w Crane, so ton 71.00( LB 25_:: 177 Oo~ / "tolono rail hoist, 3 ton --~~-,. -- (machine shop) 1,00( LB ·3-3d 6c.' Outdoor monorail hoist, 3 ton 1.40( LB -..-.-r .tf2~ c_") 7 ,ooc J 75" ' -r-- Lathe, 20 by 96 inch LB 2.L ?<;o --- Upright drill press, 21 inch 3,00( LB 3~ H z_ c;-0 ---·-- Universal shaper, 24-inch 9,60( LB ~ 7..r:" . .... ~ (_, 00 I) ::;.75 I --- Power hacksaw, 6 X 6 inch 1,10( LB ..... -4 1"'2-0 Pedestal grinder, 12 X 2 inch 50( LB -:; 7.5 !9,1S ,; - Pedestal arbor press, 5 ton 75( LB ~3-::? 2'3 I ""2__ - Portable pi:pe and bolt thread· ing machine, 1/4 to 2 inch 60( LB 37§ z_-z...s-o -------. ~--- Air compressors and motors 5 00( -LB -o_, 21 t)()t:) -;7§ ·;---- Air receivers and P!Ping sys. 2' ooc LB ?1. '"'\ :)') ---- Fire extinguishing equipment 1,20( LB o-s..:: ----G 000 -- Oil purifier 4,00( LB ..c::--2.0 ')'""1 ·) ....... ·--- Subtotal 2:.\11 Be; n Contingencies (20%+) ;_,3 ~10 Total 38~ 8-z-c . :::' ~ .f.t_ ":.< " i--I -----~ -- --- NPA FORM ( } FEB-1964 23 Rev. CONSTRUCTION COST ESTIMATE r---------------------------~--------"--~--t---~~"----------------+.::;D'::":·,a::-:-:w:-':in=o•No. --- lnvtloltan No. Date \ Sht !'-/ nf ._P ___ R-'-O·J"'"E"-c-'--r _____ T_ak::..:..a;;.;,_t""'z;;.._.;:C:..::r:..;:;ec::e..:.:k_.;;;..P:::..ro:::.....L..CL. e:::..c:::..t:::..----------------1 D CODE A 0 CODE c I -0 rrsnmc_cif-or_-~--~ fCnecker Sitka, Alaska iC CODE B n CODE __L __ 2-z_. <)FfY __., ,: MAT E-R-1 A-L--Ll-!-==-=~~-'---'--LA"'-B><-'0"'-'R~ t()TA L -r-FRE IG H~ LOCATION QUANTITY Mot'l 81,.g~Qr ~~~ T~ ---r-1 Unit Hrs / Total ~R:::;OAD::::::.:S::._:A_::N_:::D::...._::B:.:.:R:.:::I_:::D::.::.GE_:::' S:::__ _____ .j.!N.!eo~. ::::U:.:.:ni_:_:t s4~U::_:_n:_!_i t----1f-!-P~ri:;:_:ce4 __ __:::C.:::.o':..:'--to:::;._/"1J___:::.h:.:.:.nn-'-'-111lt Hr s. Rote Cost Clearing road\·laV I I Excavation, all classes -I ----+-~--+---r~--t CHP, 60-inch, 12-gage ::r-----1 I '"'i"': ol :p ~:~p~::~::: , 12 gage ·-+-------+--+-:.:__:::_;:;:_f----------------t· ----__ -__ '= _ +~~-·--~-,~-:_+,-_ .• _-__ Reinforced concrete bridge, ____ _ 1 _2_o_x __ 2_2_0_f_o_o_t ________ --t_4_,_4_oo--+-_s_F___ //~-'-1.-3: /d. Reinforced concrete bridge, --"--+-----+---+-------------+-------+----l-----t-----t---····- _2 __ 0_X_l_O_O_f_o_o_t____ _ ____ .. __ 2_::.__, 000 __ __?E __ __/j___o -~ ~---~---+-----+------+---_____ 1 _-=....,--_-::_o=---·~--~-·-· ·-·-~.-r c;,1____ __ Guide posts 400 EA .:?5-1'-\.o ,-, I r------~-------------------+------t---~-'~4----------4-----+------·~ 1 Crushed rock surfacing 1 \0 ') )~') t---------------'"'-----+----"---~1-----t---'---=::::_-+-----t---· r-----1-----,- Y?_c_k_,_30_X_2_5_0 ___ f __ o_o _t ------+---+------------t-------+r--75o, ~).£.:::~ ----I I I I I I I I I I I I I :=s;,e=!.a=~-P•=l-=an:t'e=~f:l~o_a~~·============:=~~~~~~--~~::::~-~--------~-~---_~_-··-------P~~~~~--~ Subtotal -1 ;>~ -~::: ~n ge--i-e--s-_Q-01%-+·: )---t-----t--------+~---~-------+-t----_ -_ -----~-~+---===:=--~==:-_____ =·-· ----1 ... f-~-.-~ ..... ~:--<~'-':...,., 1=~.;,.e~...;;.r;+------~-····-~O .Y .,!, " I i --~---,.--1-======--f·---=~-:-.----=====::===--:=~-~-~~:_--.,....-_-........ ·=-'-,....· __ ' __ ..,._.._ __ /--.,------_·_ _[_ J ~~~-~~~~ ~-'\~ev.i , --c..- ' ' J ; ' i lnvllot1oo No. Data !. -- CONSTRUCTION COST ESTIMATE--' ,, Sht. /";---~~= Orawinljl No. PROJECT Takatz Creek Project OcooE A DcooE c Sitka, Alaska L CODE B ncoOE Estlmotor ~~n~cller LOCATION 0 -:' '"~ ~J~. --·"'-.. I STATION . TOTAL QUANTITY MATERIAL LABOR FREIGHT Unit ~ Total ~ Tor EQUIPMENT, ELECTRIC No. Units Unit Price Cost I Hrs. Rate Cost Mot't a L obor Unit w "Prrwo:>r transfonner 3-ohase 12,800-kva, 115 grd., Y/66.4- 6.6-kv, 2 each LS LS . -q g ~~r:~l:'~>_t:J / --·-- Switching bav 115-kv, with two horn-gap disconnect C~---- switches and one 2-pole auto- -- rnatic high-speed grounding switch LS LS 235..C>:Z2 - Transformer oil and fire pro-·-- tection piping systems 10,000 LB 5--::;a, ..odD Subtotal C:> 7 o. DI'>O Contingencies (15%+) Cj~ ()00 ., Total 11.2, ono .. ,_ .. I ---··- "'"""'~~~~ ~ ··--~- NPA FORM ( ) FEB. 1964 23 Rev. lnvttotton No. CONSTRUCTION COST ESTIMATE - PROJECT Takatz Creek ---Project DcooE A LOCATION Sitka, Alaska lC CODE 8 QUANTITY MATERIAL SUBSTATION-20,000 kv Unit ~ STRUCTURES A:.'ID INPROVRN'RNTS No_ Units Unit Price Cost I Grad tg' fencing, lighting, rf!Ud snrfacino LS LS Contingencies (25%+) Total ----·- -- !-·--- ----·----~- ~---------------- ------I----·-----~ -------------- ---·--·----------c·- ··-"----------~ --- ----···----- --·· ---------- "~--~--~-~------~--------------- ~----------""' r--''' ' ,,, __ ~-----·--.. ---------- ---~-------------~--r-'--- - OcoeE DcooE LABOR Total Hrs. Rate ----------- Date OrawinQ No. c 1 Estlmator 0 Cost Mot'l \ Sht. 10 of ---fcne~er 7 ~ ~ Fi:'-:' ...,.., """"' ' ' • .J TOTAL a l obor FREIG ~ Unit r-~- Hf To· ~ -I ~~bOO ·----- -------~- ~-----r ,_, __ I 15 (')1)0 l ----, IS f) I) f) ! I -_.,.. _ _...-. ---I --I ··---' I -----+ I -~-·-··· I -J I --1------------- 1 I ----I -------· T I I I ·--------c-----I ---r I ' '' I I ------------I -------····------------·---· ----------------------!·~----l ±-~= I '---· --"-~- ·~ r ·--------~ .. .:_'-----'---I --o,- . k [ ' I ! ' • i I lnvtlatton No. Date . COST ESTIMATE ' fSht. r7 ot __ CONSTRUCTION ,, 1 Drawing No. ,.~. ---- PROJECT Takatz Creek Proiect OcoDE A DcooE c Sitka, Alaska !L CODE llcoDE 1 Estlmotor tCheck~r / .. LOCATION B D 2 7 ~~ .., ~ :_.. QUANTITY MATERIAL LABOR . TOTAL FREIGHT Unit ~ Total ~ Toto STATION EQUIP~lliNT, ELECTRICAL No. Units Unit Price Cost I Hrs. Rote Cost Mot I 8 Labor Unit Wt Power transformer, 3-phase, 11,000 kva 110-12.5 grd. -- Y7.2-kv, 2 each LS LS 3j5~----/) I J-= Swit;~hin2: bav 115-kv with two horn-gap disconnect switches and one 2-pole auto- rna tic high. speed grounding switch LS LS 2q5ooo Switching bay, 12.5-kv with two horn-gap disconnect switches LS LS ,,.. ?,-, O:::J<) / Line bay, 12.5-kv, with 500 mva OCB LS LS /lo tJDQ Subtotal lU-s-D00 ' Contingencies (15%+) \ \ I lSC) Total s-, ':::> ._-, Is;;) ~~~ --~, (,C)( ) ("'I I --~-~--. --- ··--~-·- - NPA FORM ( ) FEB. 1964 23 Rev. CONSTRUCTION COST ESTIMATE PROJECT Takatz Creek Project LOCATION Sitka, Alaska 2 miles of steel .. 75-f towers, QUANTITY phase spacing, 170-ft to line Unit attachment, & 26 miles of woo !Wo. Units Unit Price pole H:.frame, no OGW CLEARING LANDS LS LS - TO\.JERS AND FIXTURES--2 MILES LS LS - POLES AND FIXTURES--26 MILES LS LS . -~- OVERHEAD CONDUCTORS AND DE- VICES--28 MILES LS LS --~---------,~-- ROADS AND BRIDGES LS LS -~--------~ 1-... - lnv•lat 1on No. Date Orawim,J No. OcooE A OcooE c rEshmotor IC CODE 8 OcooE 0 MATERIAL LABOR % Total Cost Hrs. Rote Cost Mot'l ' -1 aa~ .:jcv !oCJa ~GV / I/ Ol?"' CJ6 p [7 _j __ I. 0 ""'' ""' c b . _____ .,.__ ... ---- 75o ~f!II!J ··-/ f· 15 ..... , s-0 {)(', /' ·-· I l TOTAL a labor I Sht_:i_ ~ of !c;eclter ?. '::'>>=='. I_ FRE IGHT r-.. Wt / Unit ~ ---- Tore W! _._ 1----- I ~ -t ---~ ···---·--· ---·-· ··-f---- ---··· l l I ., I 1--------·--------·"-f--··----------!-------·· 1-----I i I ----·--------------------------*--·---·---·-1--- ---------·----. --1----------~~~ --t----····------· . ~- 1------~~--------.. ------------· .... ----•... f-----1-" -.. .. --·-·~--- '--"· ----· f---"---.~- ----·-·-'--··· t . ----. _c_____J .L_ JPA JM ---r ~ .. ~-. ·-·· ~.· j FEB. 19fS4 2~ \ Hev.) I 1 ! ' ' t i ' i . ' ' Invitation No. Date . IShl.~of __ CONSTRUCTION COST ESTIMATE I Orowino No. PROJECT Takatz Creek Proiect DcooE A OcooE c Sitka, Alaska lr CODE ncooE 1 Estlmator ~~hecker LOCATION 8 D _, -. .--Z..---r:::r' ..J ·- QUANTITY MATERIAL LABOR TOTAL FREIGHT Unit ~ Total ~ Tore CLEARING LANDS No. Units Unit Price Cost I Hrs. Rote Cost Mot'l 8 Labor t WI Campsite 3 AC 25~1'l'D / Contingencies (20%+) /..p 2.-~0 Total 2_1 ~50 3\ ~/"' .. J --------. ------··-- - 1------ NPA FORM ( ) FFB_ 1964 23 Rev. CONSTRUCTION PROJECT Takatz Creek Project LOCATION Sitka, Alaska STRUCTURES AND IMPROVEHENTS Site _grading, excavation Site grading, compacted em- bankment Water System Excavation CMP, 36-inch (perforated) Graded gravel backfill Chlorination house Chlorination equipment Supply line, 4-inch, 3-ft cover Storage tank, 20,000 gal. (steel and insulated) Hose stations, 2 each Distribution line, 4-inch (3-ft cover) ----SewerEZ_e Svstem Sewerage line, 6-inch Hanholes -·-· Septic tank, - Excavation Backfill ~ ~ . PA IM , n , FEB. 1964 c.~\ ev.l 4,000-gal COST ESTIMATE QUANTITY MATERIAL Unit No Units Unit Price Cost 28 000 CY 5- 24,000 CY 5- 200 CY Ia - 50 LF Ga- 200 CY lo - LS LS LS LS ---- 6,500 LF ~"- LS LS LS LS ------~~-r-----· .2..o -600 LF 1,600 LF ? --D 5 EA /.2~ 90 CY lo---f-····-···- 45 CY --? r-· lnv•tat1on No. Date Orawim~ No. OcooE A OcooE c Esllmotor ·C CODE B DcooE 0 LABOR ~~ Total Hrs. Rate Cost I 1'+0 ono l Z.o 000 ZooO :Soo o 2-o ''> o /5c;>ao ... -:::7 0 ,:}C) / \;jO.DoC:: 3o cJLJ ~ / 3 0.::)0 / )2 OtY) ------------- :::; -z.o,)u f---I ~.-)') r----~~ qoo Z-2C:: . i ~ Sht.~of I ~ ) \~,;necker · z.._ 2. .::.._ r;: p --: TOTAL FREI t.llat'r a Labor ~ Unit GHT Toi w_ -T 1 I 1 I I f l -~-----~ ===f' -I r--1 ··r--1 F -~ ---l --------T I ·---·r ----I -----··-+ .. I ·-------I ~._,FI ' lmntatton No. Dote . l 7. CONSTRUCTION COST ESTIMATE::. J Sht......::;:,l_ of_ Orowim~ No. PROJECT Takatz Creek Project OcooE A OcooE c L CODE B DcooE Estlmotor t~~cks~. LOCATION Sitka, Alaska 0 ~ 4.0 - QUANTITY MATERIAL LABOR TOTAL FREIGHT Wo. Units Unit ~ Toto I Mat'l S L obor ~w STRUCTURES & 1HPROVEMENTS (co Unit Price Cost t Hrs. Rate Cost ~ Concrete 20 CY 5oo 10 {):)0 Reinforcement bars 2,000 LB o6'5 1300 Paving, 2-inch bituminous, --r-- with 4-inch c.r. base 3,000 SY /5-45 1)()0 I Rlilrlinqc: 2-bedroom, 3 .. __ Residences, each LS LS 2-aooar Dormitory, 16-man, 2 each LS LS J5'CJOO<""Y': / Mess hall for 70 employees LS LS 2aooc:>~ Warehouse LS LS 2~.C'~I'l / Garage LS us /7o aoo 7 Administration building LS LS 2/'~. C>~, .• ··- Subtotal 2 L.\ 1..., C1 4-'2S ·--Contingencies (20%+) 4u.3 :135' -- Total 2.'11,~~\() 2 qr"\~ c OrO ) I ·- . - -----~ I '" NPA FORM ( ) FEB. 1964 23 Rev. E ~ d' ~ K U I U I . rf \) ~ + D ~ t ~ £ ...p ~ (" -o .. C" p ~ 0 1\ ~ •' .~ s u * Ill E II sr"~,r < ~ EXIST ING ROAD -/ ,I I ,; ,., ~fP .::IR "r I I I ' ' I I I ( ................. () ... ~ ...... ~ ... .., r "··~ 'to~ .... ·~,,. ... ~ .... A',,, IJ ~ ',V CJ CA 9LE G',_ 0 ~ WilANG~- ZAREMBO I. (J (): ~ ~ 1.1 '<'(]~ \'"., ·~}" <" "' IS' < -z_ , -.A·~~ u~ • t t'-~ .c. " t ...... ~ ... .................. \ ~ .., ..., (I ....... I I I I I . ..,.,. .. , ..... I ~· ·~1""~ • I .. _ I I SlU)Y LOCATION -, Pa f'''", Oc,an LOCATION MAP . ----... ~ ... -··· -· 5 0 5 10 15 20 U MAD'------------· :..1111 1tl.D \"'•• " ~ .;, ., --- ' ' " ' ' " SCALE IN MI L ES ~ ~ --~ 5J ' q, ~ ~ CREEK 6. R U T~ L AK E 7 SCE NERY L AKE B. SUNRISE L AK E 9. THOtootS L AKE 10 VI RGINI A L AKE 11 WILKES RA NGE TYEE LAKE RIVERS AN D HARB ORS IN ALASKA INTERIM FEASI BILITY RE PO RT ON HYDROELECTRIC POWER PETERSBURG /WRANGELL AREA,ALASKA STAGE II THOMAS BAY AND TYEE LAKE TRANSMISSION LINE A L ASKA OISf"ICT, COI'PS 0' f.NOIN f.[ltS ANCHO"AG[,ALASK A PLATE I ~ ·! ~ ·! .... ACCESS R:;AD ~ SEA ~ SCALE IN FEET PLAN 1000 0 1000 2000 3000 TO PETERSBURG '- LAKE ~ ' , . ,• # RIVERS AND HARBORS IN ALASKA INTERIM FEASIBILITY REPORT ON HYDROELECTRIC POWER 0 PETERSBURG/WRANGELL AREA,ALASKA STAGE ll THOMAS BAY SITE PLAN SELECTED PLAN ALASKA DISTRICT, CORPS Of' ENGINEERS ANCHORAGE , ALASKA PLATE 2 EXISTING a NORMAL POOL EL. 1514 ELI . CD I ,._ ,._ ·TRASH RACK (BY DIVERS) LAKE TAP ROCK TRAP AOIT 12" OIA . STREAM FLOW OUTLET PIPE -------~ CONCRETE UNING SLOPE 0.5% 20 TON MONORAIL DETAIL OF GATE STRUCTURE NOT TO SCALE 8' HORSESHOE POWER TUNNEL ACCESS HATCH ~ POWER ~ AD IT " INVERT EL. 1305 ' \_GATE STRUCTURE (SEE DETAIL) PROFILE SCALE IN FEET zce,. 9 290 4 00 600 .--1-----, : r----, I I I I I HYD . 1 1-~ I : 1UNIT I .,.. . ' -----•·J , HATCH ~ PLAN-GATE ROOM FLOOR NOT TO SCALE CONCRETE PLUG NOT TO SCALE PENSTOCK NOT TO SCALE ROCK TRAP . Cl) ' '!! ~---------ROCK BOLTS------, \ \ ~ ,· .\..._ ___ _ z ~ -,.., STEEL ORIFICE PLUG TYPICAL UNLINED TUNNEL SECTION NOT TO SCALE SURFACE 8'-o" MIN . SURGE TANK NOT TO SCALE AS REQUIRED DESIGN LINE--------... , . ., -+" "" TYPICAL LINED TUNNEL SECTION 6' DIAMETER STEEL PENSTOCK SURGE TANK COVER AIR FLOW NOT TO SCALE ~ , RIVERS AND HARBORS IN ALASKA INTERIM FEASIBILITY REPORT ON HYDROELECTRIC POWER .. 0 PETERSBURG/WRANGELL AREA, ALASKA STAGE II POWER TUNNEL PROFILE AND SECTIONS, GATE STRUCTURE PLAN AND DETAIL, SURGE TANK, PENSTOCK AND CONCRETE PLUG DETAILS THOMAS BAY SELECTED PLAN ALASKA DISTRICT , CORPs OF ENGINEERS ANCHORAGE, ALASKA PLATE 3 ----------------------------------------------------------------------------~----~--~----~---.___~~~· ~~~--------------0 --..---' ../"' rt££ t.AK£ EL 1420 WELDED STEEL FACE TO BIN WALL FOFi I.'PERVIOUS MEMBRANE ; I . -----==== SITE PLAN SCALE IN FEET ~ 0 ~ ~ I /"'STEEL BIN WALLS (RETA INING WALL) FILLED WITH ROCKFILL ' CONCRETE CUTOFF WALL STRIP EXISTING MATERIAL: SECTION 0 SCALE I N FEET ~ o ~ m ~ TOP OF IS1 SET OF BIN WALLS \ { EXISTING STREAM BED PROFILE ....-ROCK FILL -- ASSUMED BEDROC1( •'£ liiiCUI) STEEL ~STOCK, C'e TU TYEE LU'.£ RESERVOI II SITE ,·.zooo• . , • r E3..-:E:L -__~:'{ C I WILE ,.._._:;[ -:r=::=F ~ -.E3 ~ ( --~-....., '5000 ruT SECTION 0 SCAU .. f'EET w o ~ ~ •o -,c' ,......-I --< 7 4 TOP OF 4th SET OF BIN WALLS ~ --~ TOP OF 6th SET OF BIN WALLS RIVERS AND HARBORS IN ALASKA INTERIM FEASIBILITY REPORT ON HYDROELECTRIC POWER PETERSBURG/WRANGELL AREA,ALASKA STAGE li TYEE L AI<E DAM PLAN AND SECTIONS SELECTED PLAN ALASKA OISTitiCT, co.IPS OF ENG I NEEIIS ANCt«>~'AGE • ALASKA PLATE 4 :Y 14;;2 t lllN WALl. DAM CIIEST > LAKE TAP, ELV 1240' IIOCK TRAP SECTION 8 NTS POWER TUNNEL, e' H<lf~SESHO£ GATE CHAMBER 05'Y.. SLOPE - ., TAP AREA cb-l'"\:f4'--,_ __ ....1i,,G.'"o/"C-~--.-~ ''/ -, t L_ ---L_j SECTION 0 6~··~----------~~ LAKE TAP PLAN NTS DEAD END TRAP ~ ,~:., I• •; • i • .... ~ •I SURGE CHAMBER AIR FLOW I Sl..RGE CHAMBER \ ... ~ "~ PENSTQCI( ... ·. ,, .. 6'e STEEL PENSTOOK ''··. \ GROUND SURfACE :) ~ J " .. l RIVERS AND HARBORS IN ALASKA INTERIM FEASIBILITY REPORT ON HYDROELECTRIC POWER PETERSBURG/WRANGELL AREA,ALASKA STAGE n POWER TUNNEL PROFILE LAKE TAP PLAN AND SECTIONS TYEE LAKE SELECTED PLAN ALASKA OISTfiiCT, CORPS OF ENGINE EM ANCHORAGE , A.LASt<A PLATE 5 • GATE VAI.YE I I .... 1 STREAM F\..OW I ~·~~/~ • ·. .. . . . • '0> •• :I> 1:) I• II !II \GATE LEAF 6'X lc1 " :,.. $> .. ~ .. _.,._ . .. --~ t> ~ ~ ~· ~ -~ ·I:J' .. -· (T .. • .. • PLAN AT GATE CHAMBER FLOOR N .TS. • ~ 0 .. .· ... .. • ) ~ . . ~ ·. ·'. • . · . .. .. -. ~ .. • • ... ; • \0 ~ . . '· • ' ~ . --. ··. , ' '=· • 0 AQ~T --~'11. TYPICAL UNED TUNNEL SECTION N.l:S. ' ·' ~ . · • . I I I I I I I I I I ___ j ... ; . .. SECTION 8 N.TS. I DESIGN U ll[ I ~ I ---+----t--+-- TYPICAL ~UNED TUNNEL SECTION N. T.S. 0 RIV ERS AND HARBORS IN ALASKA INTERIM FEASIBILITY REPORT ON HYDROELECTRIC POWER PETERSBURG/WRANGELL AREA,ALASK ~I STAGE U GATE CHAMBER PLAN AND SECnONS AND T UI'I'£L SECTIONS TYEE LAKE SELECTED PLAN ALASl(A DISTRICT, CORPS 01' ENG INEERS ANCHORAGE , ALASKA PLATE 6 I I I