Loading...
HomeMy WebLinkAboutAlaska Dam Safety Program Phase I Inspection Report 1984SWITZER CREEK DAM NO. 1, AK00176 JUNEAU, ALASKA JUN 015 L- ALASKA DAM SAFETY PROGRAM PHASE I INSPECTION REPORT PREPARED FOR: STATE OF ALASKA DEPARTMENT OF NATURAL RESOURCES DIVISION OF LAND AND WATER MANAGEMENT BY CHAS. T. MAIN, INC. SEPTEMBER 15, 1984 PROPERTY OF: Alaska Power AuthoritY, 334 W, 5th Ave. · Anchorage, Alaska 99501' SWITZER CREEK DAM NO. 1, AK00176 JUNEAU, ALASKA RECEnveo JAN 1 5 1985 &AsKA POWER AUTHORITY. ALASKA DAM SAFETY PROGRAM PHASE I INSPECTION REPORT PREPARED FOR: STATE OF ALASKA DEPARTMENT OF NATURAL RESOURCES DIVISION OF k~ND AND WATER MANAGEMENT BY CHAS. T. MAIN, INC. SEPTEMBER 15, 1984 ~'\AI~ 1893 CHAS. T. MAIN. INC. 101 EAST 9TH AVE. SUITE 4A, ANCHORAGE, ALASKA 99501 (907} 272·5433 September 21, 1984 3945-1-1000 SUBJECT: Alaska Department of Natural Resources Dam Safety Inspection Program Switzer Creek Dam No. 1-AK 00176 State of Alaska Department of Natural Resources Division of Land and \Jater lianagement 555 Cordova Street: Pouch 7-005 Anchorage, Alaska 99510 Attention: Mr. Kyle J. Cherry, P.E. State Dam Safety Engineer Gentlemen: MAIN is pleased to submit herewith our final report on our inspection of Switzer Creek Dam No. 1, AK 00176. This inspection was conducted on 12 July 1984. APD/RJT/1em Very truly yours, CHAS. T. MAIN, INC. Registered Professional Engineers Alton p. Davis, .Jr. Project ~ianager Richard J. Tucker Project Engineer PHASE I REPORT ALASKA STATE DAJ1 SAFETY PROGRAM SWITZER CREEK DAM NO. 1 EXECUTIVE SUMMARY On 2 December 1977, President Carter initiated a National Dam Safety Program by directing the Corps of Engineers to administer a program of inspection of all dams classified as high hazard potential by reason of their location. The National Dam Safety Program was completed in 1982. It was intended that each state would thereafter accept responsibility for non-federal dams located within their jurisdiction. In July 1966, Governor William Egan signed Alaska Statute AS 46.15 "Water Use Act" under which the Alaska State Dam Safety Program has been initiated. Under AS 46.15, Switzer Creek Dam No. 1 was inspected on 12 July 1984 by Chas. T. Main, Inc. under contract to State of Alaska Department of Natural Resources, Division of Land and Water Management. Based on design drawings, it was determined that the project spillway was designed for the 100 year flood event. The dam could therefore be overtopped by approximately 2.7 feet in the event of a Probable Maximum Flood. Recommendations for remedial action of deficiencies are made such as clearing brush on the downstream embankment slope, restoring or relocating the roadway drain culvert on the left abutment and conducting studies to modify the dam to safely pass larger floods. TABLE OF CONTENTS EXECUTIVE SlJM:t-f.ARY TABLE OF CONTENTS GENERAL LOCATION MAP: Figure 1 PROJECT DATA 1. GENERAL 1 1.1 Authority 1 1.2 Purpose and Scope 1 1.3 Inspection Team 2 2. PROJECT DESCRIPTION 3 2.1 Location 3 2.2 .Size and Hazard Potential Classification 3 2.3 Purpose of Dam 4 2.4 Construction History 4 2.5 Geology and Soils 4 2.6 Basin Description 5 2.7 Description of Project 5 2.8 Operation and Maintenance 6 3. FIELD INSPECTION 7 3.1 General 7 3.2 Reservoir Area 7 3.3 Dam 7 3.4 Abutments 8 3.5 Outlet Works 8 3.6 Spillway 8 3.7 Downstream Channel 8 3.8 Instrumentation 8 4. HYDROLOGY 9 4.1 History of Flooding 9 4.2 Probable Maximum Flood 9 5. HYDRAULIC EVALUATION 10 5.1 Spillway Adequacy 10 5.2 Flood Routing 10 TABLE OF CONTENTS (Cont'd) 6. STRUCTURAL STABILITY 7. PRIOR REPORTS 12 8. CONCLUSIONS 13 9. RECOMMENDATIONS 14 APPENDIX A Inspection Photographs APPENDIX B Project Plates APPENDIX C Inspection Checklist w c:: ci :::l (!) z Li: :::i :::i <[ <t 0 0 0 • > Gl lll:: .J , w a.. w a.. a: :::l (.) rn a: w PROJECT DATA A. GENERAL Name .• Location • Year Built • Purpose Inventory of Dams I.D. Number Hazard Potential Classification Size Classification Owner B. DAH Type Crest Length . Crest Width . . . . Crest Elevation Height • • . • • C. SPILLWAY Type .• Location • Side Slopes Crest Elevation Bottom Width • Length . . . . Discharge Capacity @ Dam Crest • . Switzer Creek Dam No. 1 Juneau, Alaska 1972 Water Supply AK 00176 High Intermediate Southeast Utilities c/o Schneider Scott Mobile Home Park 6590 Glacier Highway, Juneau, Alaska 99801 Charles Schneider (907) 586-1635 Robert Scott (907) 586-2717 Concrete Faced Rock Fill 137 ft. 15 ft . 190 ft. 44 ft. Broad Crested Weir & Chute Centerline of Dam Vertical 187 ft. 12 ft. 110 ft. 190 cfs D. OUTLET WORKS E. Type • Location • Invert Elevation . Size . Length . Discharge Capacity @Dam Crest RESERVOIR Normal Maximum Water Surface Elevation • Water Surface Elevation @ Dam Crest Maximum Storage Volume @ Dam Crest Maximum Surface Area @ Dam Crest Storage Volume @ Spillway Crest. Surface Area @ Spillway Crest. F. HYDROLOGIC DATA Drainage Area Average Annual Rainfall Average Annual Discharge Flood of Record Project Design Flood . Probable Maximum Flood • . . . . . Low Level Outlet with Stem Gate Through Dam 168 ft. 32 in. Diameter 145 ft. 17 5 cfs 187 ft. 190 ft. 11 AF 0.65 10 AF 0.60 Acres Acres 0:41 sq. mi. 92 inches 2.4 cfs None Recorded 2300 cfs 2300 cfs 1. GENERAL ALASKA DAM SAFETY PROGRAM PHASE I INSPECTION REPORT OF SWITZER CREEK DAM NO. 1 AK 00176 1.1 Authority: Inspection authority is Alaska Statute AS 46.15 "Water Use Act" signed by Governor William Egan on 1 July 1966. Inspection procedures and criteria for a Phase I Inspection are set forth in the "Recommended Guidelines for Safety Inspection of Dams", Appendix D, Volume I, u.s. Army Corps of Engi- neers report to the U.S. Congress on National Program of Inspection of Dams, dated May 1975, and published under Title 33CFR Part 222. 1.2 Purpose and Scope: The purpose of the Alaska Dam Safety Program Phase I Inspections is to assemble information and records on existing non-federal dams located within the State of Alaska and to insure continued public confidence in the integrity and safety of these important structures. The scope of this report is to compile results of a visual inspection of Switzer Creek Dam No. 1 and an examination of currently available information relating to design, construction and performance history of the project. In addition, the potential risk to upstream and downstream residents is evaluated and preli- minary spillway adequacy and structural stability assessments are made. Finally, adequacy of existing records and documents relating to the project are discussed and recommendations for additional studies and/or remedial actions are made. -1- 1.3 Inspection Team: The inspection of Switzer Creek Dam No. 1 was conducted on 12 July 1984. The inspection team was composed of the following personnel: CHAS. T. MAIN, INC. Alton P. Davis, Jr. Richard J. Tucker DEPARTMENT OF NATURAL RESOURCES Kyle J. Cherry Kenneth B. Hunt Project Manager/Geotechnical Project Engineer/Hydraulics State Dam Safety Engineer Assistant Dam Safety Engineer Messrs. Virgil Hulse and John Woods of Schneider Scott Mobile Home Park and Ms. Sara Hunt of DNR Southeast District Office accompanied the inspection team. -2- 2. PROJECT DESCRIPTION 2.1 Location: Switzer Creek Dam No. 1 is located on an unnamed tributary near Switzer Creek at 58° 21.8' North Latitude, 134° 31.4' West Longitude near the Tongass National Forest. The nearest city is Juneau as shown on Figure 1. The nearest settlement is the Schneider Scott Mobile Home Park approximately one quarter mile southeast of the dam. The dam is owned by Southeast Utilities. The dam is being operated by Southeast Utilities as a water supply for the mobile home park. The National Dam Inventory for the State of Alaska identifies this dam as AK 00176. Switzer Creek Dam No. 1 is one of two dams which impound water for the mobile home park. Switzer Creek Dam No. 2 is located on another small creek just east of No. 1 2.2 Size and Hazard Potential Classification 2.2.1 Size Classification: The height of Switzer Creek Dam No. 1 is 44 feet and the reservoir has a maximum storage capacity of 11 acre-feet at the dam crest. The size classification is determined by the dam height or the maximum storage capacity, whichever gives the larger size category. An intermediate size dam is from 40 to 100 feet in height or from 1000 to 50,000 acre-feet of maximum storage capacity. A small size dam is from 24 to 40 feet in height and less than 1000 acre-feet of maximum storage. Switzer Creek Dam No. 1 is there- fore classified as Intermediate Size based on height of dam. 2.2.2 Hazard Potential Classification: Switzer Creek Dam No. 1 is classified as High-Hazard Potential for damage and loss of life in the event of failure. Specification of Hazard Potential for a dam does not infer anything with regard to safety of the dam; it simply states the hazard if the dam should fail for any reason. The downstream area is heavily forested and has a steep narrow channel exiting into the Schneider Scott Mobile Home Park. Numerous mobile homes and trailers line the channel through the Schneider Scott Mobile Home Park and would be at risk if the dam should fail. The breach discharge would then impact Glacier Highway. Due to the potential for loss of human life and the potential for damage, Switzer Creek Dam No. 1 is classifed as High Hazard Potential. -3- 2.3 Purpose of Dam: Switzer Creek Dam No. 1 was constructed in 1972 to provide water supply to the Schneider Scott Mobile Home Park. 2.4 Construction History: Switzer Creek Dam No. 1 was designed by R&M Consul- tants, Inc. in 1971. R&M maintains a complete set of drawings and copies of the construction specifications at their office in Juneau. The dam was keyed a minimum of 10 feet into the dense glacial till abutments and is founded on bed- rock in the creek channel. Construction of the dam was monitored by R&M. The dam was constructed in 1972. 2.5 Geology and Soils 2.5.1 Regional Geology: The project area lies within a belt of deformed and metamorphosed Paleozoic and Mesozoic sedimentary and volcanic rocks which flank the coast range of southeast Alaska and extend into British Columbia. Following a vague sequence of geological events including outpouring of lavas, metamor- phism, uplift and faulting, the area was modified by glaciation and erosion. The most recent glaciation is believed to have been in the late Pleistocene Time and the ice receded from the area on the order of 6000 years ago. The ice is estimated to have been perhaps 3500 feet thick and has considerably modified the character of the rock and overburden soils. 2.5.2 Site Geology: Switzer Creek Dam No. 1 is on an unnamed stream near Switzer Creek on the side of Thunder Mountain. The channel is characterized by very heavy vegetation ranging in size from bushes to very large trees. Examination of the bedrock visible at the site shows slight surface weathering and moderately spaced jointing. Test pits conducted during the design show relatively shallow bedrock but no details on rock quality. Typical of the local geology, the visible rock appears to be schist with numerous quartz seams. Bedding planes are rather widely spaced. The somewhat massive nature of the rock is substantiated by visible rock in the spillway discharge channel. The rock is fine grained and hard with no adversely orientated joints or obvious weak seams. Overburden till is fine grained with gravel and dense. -4- 2.6 Basin Description: The drainage basin is one of many watersheds which drain excess precipitation and snow melt from Thunder Mountain and Heintzleman Ridge near Juneau, Alaska. The headwater area begins on steep precipitous slopes whose peaks reach about 2,500 feet above the reservoir on Thunder Mountain. Lower elevations of the watershed are covered with dense stands of conifer trees underlain by a thick blanket of low growing vegetation and a surface mantle of spongy peat. As elevation increases, vegetation decreases. At about 2,000 feet, vegetation is near non-existent with the soil mantle removed to near bed- rock by past glaciation. Prevailing maritime storms drench the area with heavy precipitation during the summer and covers the higher elevation zones with deep snow in the winter. As the temperature moderates in the spring, snowmelt occurs leaving the area nearly snowfree by the end of July. Climatic records for Juneau show a mean annual temperature of 42.8°F with extremes of +84°F and -2l°F. Average annual precipitation is 92 inches of rainfall equivalent. Rainfall at over one inch per hour over a several hour period have been experienced. Under the general classification after Koppen, the climate in the Juneau area is classified Cfb or Humid Mesothermal. At higher elevations and on the easterly slopes of the Coastal range, the vegetation turns alpine reflecting the orographic effect of that range up to elevation 2000 which approximately delineates the tree line. Numerous glaciers and a large ice field are located just north and east of Juneau. 2.7 Description of Project: gravel fill dam, Photo No. 1. Switzer Creek Dam No. 1 is a concrete faced The dam is approximately 137 feet long including a 12 feet wide concrete lined chute spillway located at the center of the dam. The dam is approximately 44 feet high at its highest point. The crest width is 15 feet at elevation 190 and the face slab is 8 inches thick keyed into the foundation. An access bridge is provided to a 32 inch diameter outlet pipe upstream of the dam, Photo No.'s 2, 4 and 5. This slide gate is used to drain the reservoir for periodic maintenance of the water system intake, Appendix B, Plates II, III and IV. A six inch water main passes under the dam. The drawings in Appendix B are original design drawings provided by R&M Consultants, Inc. at the time of -5- the inspection. Minor as-built changes were made during construction to meet site conditions. Among these changes were relocation of the access road on the left abutment, Photo No. 1. Modifications of the access bridge design, Photo No. 2, and relocation of the pipe drain outfall to the right ot the spillway chute, Photo No. 4. A major change is that the spillway crest is only 3 feet below the top of the dam versus the four feet shown on the drawings. 2.8 Operation and Maintenance: Mr. Virgil Hulse, resident manager of the Schneider Scott Mobile Home Park, maintains and operates the reservoir and dam. -6- 3. FIELD INSPECTION 3.1 General: The field inspection of Switzer Creek Dam No. 1 was conducted on 12 July 1984 by Messrs. A. P. Davis, Jr. and R. J. Tucker of Chas. T. Main, Inc. accompanied by Messrs. K. J, Cherry and K. B. Hunt and Ms. s. Hunt of Alaska Department of Natural Resources. Messrs. v. Hulse and J. Woods of the Schneider Scott Mobile Home Park also accompanied the inspection team. The Inspection Checklist is included as Appendix "C". 3.2 Reservoir Area: At the time of the inspection, the reservoir was at elevation 187.1 or 1 inch over the spillway crest. There was a shoreline slide on the right upstream shore. This appears to be unchanged from photos taken in August 1979. A view typical of the upstream basin can be seen in Photo No. 2. The topographic map, Appendix B, Plate I, shows that peaks reaching 2,500 feet above the reservoir occur within 1.3 miles of the dam. 3.3 Dam 3.3.1 Crest: Switzer Creek Dam No. 1 is a concrete faced gravel fill structure typical of many current designs. Due to the use of native sand-gravel fill materials, the dam has flatter slopes than many similar designs. There was no evidence of settlement, dips or sags in the crest. There was no evidence of distress along the spillway crest walls at the dam spillway. 3.3.2 Upstream Face: The concrete face slab above waterline was in good condi- tion. The construction joints around the spillway appeared tight and there was no evidence of cracking or deterioration of the face slab. 3.3.3 Downstream Face: The downstream face was heavily covered with brush and small trees which partially obscured the slope from inspection, Photo No. 3. There was no seepage at the abutment contacts and there was no evidence of sags or slides on the downstream face. Bedrock was observed in the downstream channel toe area only at the spillway chute (Photo No. 5). -7- 3.4 Abutments: Both abutments appear to be dense glacial till. There was no evidence of erosion or seepage on the downstream abutment contacts. A small slide area was observed on the right upstream shoreline near the abutment, how- ever, this appeared unchanged from photos taken in 1979. 3.5 Outlet Works: The access bridge to the outlet stem gate operator is shown on Photo Nos. 1, 2 and 4. The bridge deck is in need of repair. 3.6 Spillway: Approximately one inch of water was flowing over the spillway at the time of the inspection (Photo No.'s 3 and 4). The concrete retaining walls and chute slab appeared in good condition with no misalignments or off- sets. Spillway discharge impacts on bedrock in the downstream channel (Photo No. 5) which is hard schist. 3.7 Downstream Channel: The downstream channel was inspected to evaluate potential hazard to life and property in the hypothetical event of dam failure. Photo No.'s 7 and 8 show the areas that would be impacted. Photo No. 7 is looking up the creek channel from a point near the center of the mobile home park shown in Photo No. 8. 3.8 Instrumentation: There are no records of instrumentation or monitoring programs at the dam. 4. HYDROLOGY 4.1 History of Flooding: No specific details of past flooding were available. No general information was found regarding local floods on the creek or in the area which may have overtopped the dam or caused local damage. 4.2 Probable Maximum Flood: HMR No. 54 "Probable Maximum Precipitation and Snowmelt Criteria for Southeast Alaska" was used for the PMP/PMF analysis of Switzer Creek Dam No. 1. The Depth-Area-Duration values as ratios at the 24 hour -10 square mile PMP value were used to determine a regression curve of total PMP vs. Duration for the 0.41 square mile drainage basin. The incremental PMP values for 15 minute intervals were calculated and arrayed. A 0.1 inch/hour loss rate was applied up to the time of maximum incremental rainfall to obtain rainfall excess values. These rainfall excess values were then applied to the derived unit hydrograph to obtain the PMF. This gave a PMF peak of 2000 cfs (when superimposed on a 500 cfs peak snowmelt estimate) and a Creager "C" equal to 100. Because of the small size of the basin and the lack of data with which to confirm the unit hydrograph, the Creager "C" was increased to 115 for conser- vatism to yield the adopted PMF of 2300 cfs. The PMP was estimated at 23 inches in 24 hours with a peak of 5.25 inches per hour. -9- 5. HYDRAULIC EVALUATION 5.1 Spillway Adequacy: The project spillway is an uncontrolled crest spill- way. The spillway crest is a broad crested weir discharging to a concrete chute on the downstream face of the dam, Photo No. 3. The spillway crest length is 12 feet with a 12 foot width and 3 foot height to crest of dam. The spillway is capable of passing 190 cfs at zero freeboard. Based on estimates of Probable Maximum Flood (PMF) of 2300 cfs, the spillway can safely pass 8.6 percent of the PMF. In the event of a PMF, the dam would be overtopped by approximately 2.7 feet. 5.2 Flood Routing: Due to the relatively small size of the reservoir, it is expected that Switzer Creek Dam No. 1 would have little attenuation affect on major floods. Due to the downstream hazard potential, Switzer Creek Dam No. 1 was evaluated for full PMF. -10- 6. STRUCTURAL STABILITY A review of the construction drawings prepared by R&M Consultants, Inc. indi- cates the dam is conservatively designed in terms of current worldwide practice for concrete faced rockfill dams. The 2.0H:lV side slopes are conservative for the sandy gravel material used. The concrete face slab appears properly tied into bedrock and abutments to form a watertight membrane. Based on the state of the art for concrete faced rockfill dams, Switzer Creek Dam No. 1 is adequately stable for all reasonable loading conditions. The project is located in Seismic Zone 4 of ER 1110-2-1806 dated 16 May 1983, which recommends a 0.20 g earthquake coefficient. For dry sandy gravel at these slopes, this presents no stability or settlement problems. The dam would be overtopped during a PMF event by approximately 2.7 feet. The sandy gravel shell material would likely erode under such overtopping and sta- bility of the dam cannot be assured for extreme flood conditions. Reinforcement of the downstream slope especially at the abutments, provision of additional spillway capacity and/or emergency warning plans should be studied to insure safety of downstream residents in the event of a major flood condition. -11- 7. PRIOR REPORTS Copies of three design drawings were obtained from R&M Consultants, Inc. These drawings are included as Plates II, III and IV in Appendix "B". R&M Consultants, Inc. retains the original drawings and specifications at their Junean office. A set of four photographs from August 1979 were on file with DNR's Dam Safety Engineer. -12- 8. CONCLUSIONS From this inspection of Switzer Creek Dam No. 1, MAIN presents the following conclusions: 1. A High Hazard Potential classification is appropriate for this dam due to the potential for loss of human life in the Schneider Scott Mobile Home Park downstream of the dam. The reservoir size classification is Intermediate based on height of dam. 2. The dam and its appurtenances appear in generally good condition and no emergency remedial work is indicated. 3. Analysis of spillway adequacy indicates the dam can safely pass less the 9 percent of the Probable Maximum Flood. Overtopping of the dam during major floods could cause loss of the dam. 4. Additional studies should be conducted to evaluate how the dam would react under overtopping by a PMF event. 5. The dam appears properly designed and constructed and should be stable for all reasonable loading conditions with the possible exception of overtopping during a major flood. 6. Brush and trees on the downstream slope should be removed and con- trolled to permit regular inspection by owner staff. -13- 9. RECOMMENDATIONS 1. Brush and trees on the dwonstream embankment slope should be removed and controlled to permit inspection by owner staff. 2. Additional studies should be conducted to evaluate how the dam would react to overtopping by a PMF event. 3. The sluice gate should be exercised annually. 4. A procedure should be developed to warn downstream residents in the event of a developing emergency. -14- APPENDIX A INSPECTION PHOTOGRAPHS: 12 JULY 1984 ~o. 2 No. Switzer Creek No. l Showing l'pstrenm Face of nam and Sp il I wav Switzer Creek No. 1 Reservoir Looking l'pstream . . ~(). 3 Sp illwav Chute No. 4 Bridge to Low Level Outlet Stemgate No. 5 Jnw Level Outlet Pip~ and Toe nf Spillwav !'/(). 6 Broken l~oadwav llra in P ipl' Outfall al l'ikt• :\hutmt•!!l Contact ~(l. 7 Pn\"n...:t r••.uu !! i \'l'r Chann,•l l'hr,>u>!_h ~!,,hi !,• llnmc· l'.t r k Photograph Switzer Creek Dam No. 1 on Left Switzer Creek Dam No. 2 on Right Date: 2 June 1982 ' Flight: 513 APPENDIX B PROJECT PLATES t N ~ SCALE' I"= 1000' 11 SWITZER CREEK DAM NO. I GENERAL S1TE MAP ALASKA DEPT. OF NATURAL RESOURCES ~ 101v. OF LAND AND WATER MANAGEMENT ~AI~ 1803 "" SEPT. 15, 1984 .... , ... ,,,,. 394!5 NYL.¥?QLOQICAL DATA Afor1~ rDhltJ/1 ~Hy • /I ,-i;v;,.. ~ Arour /'IW ,_.-.-tnn . .N """nvM ~) A-~ ~I n:»nlb/1 = EO rnch- Hbhlr~~ "'.:'!50~ S/o.-17? r~F cO<rl'"l'ic~i =" 0.56 ~91'7 l"'"rn!-baord 01"-cn!'f$}'•/5 l'f!rt ("/a:?~.slt:;y,n) ~56~~7 • /~~cc;;A .Sp//,.,.,y co.,aocil"'y 0 • CH\ W {JI..Y30)\(/2) & /9..3 c~ Avt"~ onnuta/ ...&/,Y ~ '.c-t {61?~ _x-raoA-~) • 1 :5S ,.-If:?# 901 ..---oby WATER US€A6€ R~tR€NENTS /Warb"'l' ~ vnd!:. ~ ., 109 JVoArr-~·~~.....,..1'"6~700 ~ d£NERAL NOTe!: I ~sf }llfllu w•rr •xf,.ntfrd I1J' ~ ;._)6 .,.~ ::;;~~:.~~~: :J"t::";~";' l_,.,,,tl lt.,W I HtHr IKilflllfll ., .moot'll -.. Jll• /'J, .,.. 'V'f""'"i/Mf,. ~'.r J All uMr~lr ,sJ,./1 Ju JOOO ~~ cMVrfr 110----~ 20()-- /10--- / / t------~----------- I 1 I I \ \ .e.....,..,n::..,. Cat:ter•~ Slt~b- ' -".--- \ C'-"DDY HID/I--~ fr~ "' \ \ \ \ w ......),__ \ -\-- \ : \ r IZ' \ I ,, PLAN ___ -100 ~---~~""''"'' --~~/-- -----~::_"'-~-"":~ / / '----- -------- Sp,/fway / /~:Rop-•p -/'- / ~ -----7 ----__ C.~o!!Ect~4 / --; ,. ~----- ,'\ \ \ ' -1~0 ,·170 \( ___ f \. \. ,-~,1 ' \ ' ' \ ~ ~\ . " . ~-~~1 -------- -_,,0 -,r3---r ~~~ ----tro '®I RaM -· · -fNGN"ERN3 I GEOLOOICAL a:HSULDINTS ~VItUV ALASKA ,....._SI SQftEIOER SCOTT MOBILE HOME PARK WATER RESE~ PROPOSED """ .. au.;w.. Crill( JIIJIII!IO,o"n PLATE II N-t~s--16 190 Woff'r l•..-.1 J.!UO- 110 170 1,0 --· !50- !10 liD 170- t<O Crn'l £1.11'<7ftfln /1110 -4r-------1 ~· i' I ~: IPSTRE:AM ELEVATION J ll'W,. c,.,, _.,, TYPICAL SECTION --b• ~ c~.n. -c",..,. ""''' !o' 1~..-f ~ Or'" da~r~,'!_•d bf riM E179117••r / ,.,:;.··,.- -~ I~n,-.VIIOUS &cl<ftl/ !I;( --. __ J __ j:•.•oo;:;y_ c~ cc Cvl'gl/" ) oncr•n. S/.-... """" il' ._. u,.,t/1.-ru~Sod~/ -........~--R•m~d a...::.-. ..... J"i,e• I PL~_AL§E;(:TIOAJ !J.BUTMEAIT KEY- ·~ ~'-~ ~ ·-~~/E_mt>.m•-•' j.J~........__, -~-~­ ~-~ v' : ', / ' ·~ ---••. ~~•li?!p.upJ ' ..-,.,:".,~ .. ----.:--,:-;---"::::---··-:,_ : -•" I ----------£::0.."'-----,---.c,,=------.:~ -------------------;,.~~ ------------H;5· F-/ter M<Jtt:nal---' ~- SECTIOIJ EMBL1NKMEAif-DETt11L _ Flh•r M•t~rul .ro • -Hil? . .d~ Wo,.......Ao.-7-e 2.0'£ "'""'"'"'"""" ~ __ __f___,~ --'/C~:x: /7<·7~ ~ ~~ . ~-\..1_?_ / . . ~ ',~ ' <t l\i ,\; ~ ~ ~ -t. -1 ~ :: ...... MAP SCALE·!",. I MILE TOPOGRAPHY MAP OF DAM AND ADJACANT LANDS SCALE. 1111 • 50' ______ ...., __ Q '. / '\o, // _,':_~~ _"' ./"'(/ / '><I ;" ~--I "'-----~ t) ~- / :,cc_c:_ c;::_-_ ~ L \ ---yc::'':-_~o-:-c.. '-"-;6o.c~<. - -----~-.:11" / I P\...A.t-.l v\ew DAM SITE HA.UI_ 12-CA\:) ...,,..., .... ,t··~· LOG OF TEST PROBES VERTICAL SCALE· 1•,. 4' T~~~ ~ O-~ ""'""'-'"MAT ..1'-4' (,Ut~NJC lllf/ YRME D, dlltlfV,.L # IUOROCX I' rP"4 Q 0•# 0~6AMC .WAr ~ • "WROCK? TP"T F:l 1)-I.T' Oltfih'tiViC MAr ~ I..S'4~P.-K"If r T?"IO W #1·11 . .:Wt;.ANJC ·MAt" W/ TIIACE t:V' fVI,.fveL #.f' N'DAIPCK ~ '!j»rf.\\l"f',,...or'i ~'-'r-..4"i \...,...-· _.J:Jr"~· tl-/-<~.... .• " TP*Z ~ q 4' 0~0;4/J/C ,.,,..,. 1!''-,1' (;lf,JIII.f't... M•$~ ;1 1 Jl£r>Ag:l'l? TP*J ~ p • Q~6~>C M<' ~· ~~J)Ifo/:1'( ~ /, TP"'.! 1'-,1' ,u.tT ;w'r.JVN~ ~ li:lf..WEF-~ P·l' Olttf.AI'II(t M./T ~·~J' .$M-1Y i:~t~ .S-~ I $' J!UtJI'IC<K? T~~~~ ill 0-U OR&.NK M_.T [_J 0 ,r,. /JffP.•UN'If" ? ['j I <J, ., :l :;, jl L ·., > ~ ~ ·,~ ::>. • 'l,J-·.,0' "t • to.."'\ !!>A' q• 'l,.0\.!)1' \..~ ~"L"')e; TP"~~J ~ 0~ 0-<' MAT fiii/YIIAC'E il' GltAVE'- J-§. At~ .JO.MT W/ ?E411l1'.1, M~l'l" f JJ.t'O~Ki' lP"O n 0-L'' l>l'ti;ANIC MAr ~ 1!' 1/I'P//OCK I' T?119 ~ o ;; o.""'""c "'"' if -4 f' ::WGAN!C' »{ ~ rRACE o.r GA.'Iv;L M -'<i'JI ' <111' 8,$JJIIOCII! ~NK SYJII/JaS 0 SAND rg C:it.14V£ OJ ~p,tOJ.:x ~ ~v ' :-l :. cB· f '?~'\,.0 ~9-Q,. .. ~..,·f"·ke iMU ()II IV !/""105"""1'>1 ·-·~ •.. , _.., ____ _ ·· .... B s 0 L ·- ATIVE MAP OF 4 --j" ... -----I ' ' I I I I ····· H -- ' ' I I I I ' I ' ·-EARTHQUAKES tt ACCUMUL W&GI'IITUO[ • o•ro'"" ''" ( .. C[_J( •••• 1 ~ ~. ... IH•~ AH[II TO ::,:...._.!.:!.!:.:.__l:ZY.'-::"!:·:....: ~::l~~:-:-:..0< u•DIOL••ID •uw !.:."• f ,,.. ·- /,,,. \ .... PLATE v .... ' APPENDIX C INSPECTION CHECKLIST . . • I APPENDIX E VISUAL INSPECTION CHECKLIST !1.A .. 'i:E OF DA..'i:: .SwtfC.(...Y-Crt<-k.. No. i OWNER: 5 <> J J. h (. "' s .J.. u t J/JJ,e.:. STATE: AlA.) k ""- COUNTY: C ti-t P.. ... .,.( f3c· YC'-' 1"' l! 1-J"""" '"' t.l I 2.)1/8 'f DATE INSPECTED: ,J' tJ / y WEATHER: A~ I~ INVENTORY NO. : If)( 00 I ·=I-&. HAZARD CATEGORY: l·htj S, TYPE OF DAM: e~n c..H.h F,~J e•·rft. /d( TEMPERATURE: s-s-0 , POOL ELEVATION: -166' I TAILWATER ELEVATION: N~·.,~ Directions: Mark au "X" iu the YES or NO colum1. If an item does not apply, write "NA" in the REMARKS colum1. ITEM YES NO REMARKS 1. CREST. a. ~lY visual settlements? b. Nisaligument? c. Cracking? 2. UPSTREAM SLOPE. a. Adequate grass cover? b. ~1y erosion? c. Are trees grow11ing on slope? d. Lom;itudinal cracks? e. Transverse cracks? f. Adequate riprap protection? g. ~1y stone deterioration? h. Visual depressious or bulges? i. Visual settlements? 3. DOWNSTREAM SLOPE. a. Adequate grass cover? b. ~1y erosion? c. Are trees growing on slope? d. Longitudinal cracks? e. Transverse cracks? f. Visual depressions or bulges? g. Visual settlements? h. Is the toe drain dry? 'V!im;, i. Are the relief wells flowing? N/11- j. Are boils present at the toe? ~illiffiJ l--~k~.~I~s~s~e~e~p~a~g-e~~p:r~e~se~t~lt~?~~~~~----~----4~~i~*;----------------------------- 4. ABUTHENT CONTACTS. a. Any erosion? b. Visual differential movement? c. Any cracks noted? d. Is seepage present? 5. INTAKE STRUCTURE. a. Do concrete surfaces show: ( 1) Spalliug? (2) Cracking? (3) Erosion? ( 4) Scaling? (5) Exposed reinforcement? (6) Other? ' I ' I ITE?1 YES NO REMARKS ----------------------------~---~,-----------------------~ b. Do the joints show: (1 Displacement or offset? (2 Loss of joint material? (3 Leaka~<e? c. Metal appurtenances? ( 1 (;o_rrosion present? (2 Breakage present? (3 Anchor system secure? a. Is the conduit concrete? IAJ//1 A b. Do concrete surfaces show: 1 Spalling? 2 Cracking? 3 Erosion? . 4 Scaling? (5) Exposed reinforcement? (6) Other? c. Do the joints show: (1) Displ..,,...,.m"'!nt or offset? (2J Loss of joint material? 3 J Leakage? V d. Ls the conduit metal? X. < 1 J Corrosion present? !mmm 2 Protective coatings adequate? Wmmm 3 Is the co11duit misaligned? tmmm 7. STII .. LING BASIN. a. Do concrete surfaces show: ( 1} Spalling? 2) Cracking? (3) Erosion? ( 5) Other? 6) ,..,. ....... .,~d reinforcement? b. Do the joints show: (l Displacement or offset? (2 Loss of joint material? (3 Leakage? c. Do the energy dissipaters show: 1 Signs of deterioration? Z Are they covered _with debris? 3 Other? d. ls the Channel: l Eroding or backcutting? 2 Sloughing? 3 Obstructed? e. Is released water: 1) Undercutting the outlet? (2 Eroding the embankment? 8. SPILLWAY. a. Does spillway concrete show: l Spalling? 2 Cracking? _;; Erosion? \ \ ~~--:_-:_-_-c;4::-::-):-:s~c:a~l~i-l~:-gT.._·-:_.-M_-:_-_-_-_-_-_-_-:_-_-_ .. _-_-_ .. _-_-_ _..-;I-Y_E_s-R-!i*~i+! -----RE-MAR--KS------- < s) Other 1 gm~m: (6) Exposed reinforcement? b. Do the joints show: (1) Displacement or offset? (2) Loss of joint material? (3) Leakage? c. Do the energy dissipators show: (1) Signs of deterioration? (2) Are they covered with debris? (3) Other? d. Is the spillway earth cut? (l) Are slopes eroding? NA (2) Are slopes slous;hiu."(? (3) Other? e. Is the channel: (1) Eroding or backcutting? (2) Obstructed? f. Has released water: ( 1) Eroded the embatlkment? (2) Undercut the outlet? (3) Other? g. Is weir in good condition? h. Is control at the weir? 9. GATES • .. a. Are the flood ~ates: (1) Broken or bent? iN/A m~mm (2) Corroded or rusted? mmm (3) Periodically maintained? m ~~m I (5) Date lst operated. Y b. Is there a low !eve 1 gate? )( c. Is the low-level gate operational? !H~~m~ 10. RESERVOIR CONTROL. a. Recent upstream development? b. Slides in reservoir area? c. Change in reservoir operation? d. Large impoundment upstream? 11. INSTRUMENTATION. a. List type(s) of instrumentation. b. In good condition? i~i' NIA c. Read periodically? IH I d. Is data available? iH Other Comments: 1o -b J111"l<'Y" .sr .• !t. . . APPENDIX E P9 B POD HJt B [32) STATISTICS I I_ u .. u.J. MISCDATA MISC. DATA tC untinucd) MISC. DATA (Cur.tinued) REMARKS ENG FORM 1 DEC 77 (49D 4474A • • PART II -INVENTORY OF DAMS IN THE UNITED STATES (PURSUANT TO PUBLIC LAW 92-367) PJB SPILLWAY [46 n See reverse side for instnJction.s, G34 D VOLUME OF DAM (CY) !JSD (36~ POWER CAPACITY (47) 1311 psg (391 OWHER EHGIMEERING BY [SO) GstD (531 11540 INSPECTION BY i40D FORM APPROVEO OMB NO. 49-M421 .. 110 IDEHTITY HUMBER REOUIREM~~~~.:g;:~~i SYMBOL I 1-,-I . I -,-I . I H4tU [42 D (43 D U44D [450 I48D COHSTRUCTION BY (S2U nss I AUTHORITY FOR iNSPECTION • .. . .. I ~I ~ ... IDENTITY w PART I -INVENTORY OF DAMS IN THE UNITED STATES FORM APPROVED .... ... NUMIIER OMB NO. 49-R0421 t- (PURSUANT TO PUBLIC LAW 92--J67) "' I J2 31•151~>17 REQUIREMENTS CONTROL SYMBOL ~lx oiCJI 1 l rjL 1 See reverse side lor instructions. OAEN-CWE·-17 1...-- IH DJH 040 usn D6D 01~ msn lf9D HIOD n 11 n n 12n -1 • • • 1 I r J f I i I I I I i I I I I I I I 1 I I I 1 1 1 1 J 1 1 1 1 I j IDENTIFICATI~ I I I I i I I I I~,-, 'I I I I I'"','"' I nnn 0 t4 D POPULAR NAME ID~(~(~~~~~~!!OHI 1 • 1 1 • r 1 1 1 1 1 t 1 r t 1 t. r r 1 1 .I 1 1 1 t 1 1 r 1 1 1 1 1 I 1 1 1 t r 1 1 1 1 1 t 1 1 L_l_l ~• 1 .I _r .I 1. r _r__r. r.. L.L_t 1 1 L l __ l _I t··J n•sn U6H Ht7 n n 1s H 19 D Q20D RIVER OR STREAM POPULATION LOCATION 2.1c:.!(A H2 STATISTICS ft28 D REMARKS B 9 J_/ ENG 1 ~~~17 4474