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Home My WebLink AboutSilver Lake Appendix 8 1992.. APPENDIX 8 Alternatives No. 8 and No. 9 Silver Lake Hydroelectric Project APPE."l>IX 8 LIST OF TABLES Table l -En~rgy ~lode! -Alternative A Table 2 -En~rgy Model -Alternative B Table 3 -Cost Estimate -Alternative A Table ~ · Cost Estimate -Alternative B Table 5 -O&M Cost Estimates Table 6 -Results of Economic Caparison of Projects Table 7 -Comparison of Alternatives LIST OF FlGl..iRES Figure 1 -Estimated Average Monthly Flows Figure 2 -Silver Lake Storage Curve LIST OF DRAWINGS Drawing 1 -Silver Lake -Alternative A -Site Plan Drawing 2 -Silver Lake -Alternative B -Site Plan Appendix 8 Introduction Silver Lake is located approximately 15 miles southwest of Valdez, A.K. The lake is approximately 3 miles long. has a maximum width of about 0. 7 miles, and has a surface area of about 978 acres at water surface elevation 306. The outlet of Silver Lake fonns the Duck River which flows into Galena Bay. Silver Lake was identified by the USGS in 1915 as having significant hydroelectric generating potential. The project was most recently studied in 1982 as pan of the Cordova Power Supply feasibility studies. HDR was contracted by the Alaska Energy Authority in the summer of 1992 to incorporate the alternative of a Silver Lake Hydroelectric Project into their Allison Lake Reconnaissance study as a means of providing power to the City of Valdez, AK. This appendix contains an up-to-date reconnaissance level estimate of the costs and energy production for two alternative Silver Lake project arrangements as discussed below. The costs and energy production estimates were then insened into the Allison Lake economic evaluation model and the results compared to the other Allison Lake alternatives. General Project Fearures A variety of possible configurations for a hydroelectric project at Silver Lake have been proposed in the past, each with different project features, dam height and energy output. To select the configuration as the subject of this reconnaissance repon, HDR reviewed the extensive literature developed by USGS, the Army Corps of Engineers, ud the Alaska Power Authority in the 1982-83 time period. HDR also interviewed Mr. Thorn Fisher of Whitewater Engineering of Bellingham, WA, who is the project proponent of a potential project on Silver Lake. Since the completion of the draft Allison Lake Reconnaissance Study, the future energy demand situation in Valdez has been clarified somewhat by the actual start of constnJction of the Petro Star refinery (making the "high" load energy growth scenario much more likely). Annual energy requirements of the refmery should average about 25 million kWh/year. lbat, with the Valdez current diesel requirement of about IS million kWh/year, indicates that a Silver Lake project of at least 40 million kWh/year would be desirable to be able to offset all diesel generation, at least for some time into the future. A Silver Lake project with 45 million kWh/year capacity or more would be desirable to allow diesel generation to be avoided at CVEA for a longer period into the future. Based upon these developments, HDR selected two basic Silver Lake Hydroelectric Project configurations to be used for this reconnaissance evaluation. Alternative A is the largest of the Page 1 Appendix 8 alternatives studied by Stone & Webster Engineering in their 1982-83 work (Reference 8). It would incorporate a 125-foot-high RCC (roller-compacted concrete) dam, 6,000-feet of 108-inch pipeline and a 15 MW powerhouse located at El. 65 on the Duck River. The powerhouse would be equipped with three 5 MW Francis turbines. Transmission to Solomon Gulch would be via approximately 22 miles of overhead transmission line. Annual generation would be about 44.8 million kWh/year as discussed below. Alternative B is the general project configuration being proposed by Whitewater Engineering in 1992. It would consist of a l()()..foot·high RCC dam, 10,000-feet of 108-inch pipeline along the access road and a 14 MW powerhouse located at el. 10 on Reverse Creek. The powerhouse would be equipped with two 7 MW Francis turbines. Transmission would be via 2.2 miles of overhead ttansmission line to Galena bay and then by a submarine cable to Valdez. Annual generation would be about 48.8 million kWh/year. For each alternative. selected turbine size was based on the anticipated peak demand load from Valdez so the project could act as a backup to Solomon Gulch. Site plans of the two alternatives can be found on Drawings 1 and 2 at the end of this appendix. An alternative briefly considered was the concept of a tuMel and lake tap into Silver Lake with no dam. This alternative has potential of producing about 29 million kWh/year. Compared to the Allison Lake TuMel with Hydro option, this project would be more expensive both to build and operate. It would require roughly the same tuMelling volume (shoner length but large diameter), a much larger powerhouse (roughly 15 MW vs. 3.5 MW) and a much longer transmission system. Since this alternative would be very costly and would not meet Valdez's demand as described above, it was ruled out for funher study. Presently, the only access to the Silver Lake area is by air or water. Each alternative plans to make use of a new pennanent dock siruated on Galena Bay connected to the project site by about 2 miles of pennanent access road. The project would be operated remotely from Valdez. A caretaker would be required to perform routine maintenance and observation tasks and would live at or near the site. Options for project configurations might include a concrete gravity or arch or embankment dam instead of the RCC dam proposed, or a ttlMel to replace the pipeline as a means of conveyance. It is felt that generally these options would be more of a technical challenge and would be more costly than the configurations studied here. The selected configurations, in our opinion. represent projects that are large enough to displace the diesel requirements for CVEA while remaining technically straight-forward. Although .~veral optional configurations for each alternative exist, optimization of the design is beyond the scope of this study. Hydrolo&y Hydrologic information for the Silver Lake basin is very limited. Stream gage data for Duck Page 2 ... -.. --- ... • .. • - • • ... • .. .. - .. - .. Appendix 8 River is only available for a seven·month period in 1913 and a five-month period in 1982. Nonnally, at least a lO·year period of record is desired to synthesize flow records with any confidence for a given stream. Due to the lack of data, we have chosen to make use of monthly average stream flow data based on a correlation to Power Creek as referenced in Table A-vn of Reference 5. Based on this correlation, the average monthly flows are shown in Figure 1 below. Based on our review of the methodology used to generate this data, we believe it to be of acceptable accuracy for this level of study. SiLVEH LAKE 600 ,---------------------------------------~ 500 400 l "' I .... <.) \0.1 li 'i :;cor u !/) 0 :<CO Figure 1 Enera:y Production It is assumed that due to the large storage capacity of Silver Lake, the Silver Lake Project would be operated as a fully regulated project. This method of operation would allow the project to Page 3 Appendix 8 produce power on demand. The reservoir storage and the sizing of the units would also allow the project to serve as a backup to the Solomon Gulch Project, supplying all of CVEA · s capacity requirements in the event Solomon ·JUlch had to shutdown temporarily. A reservoir storage curve for Silver Lake is shown in Figure 2. To simulate energy production for Silver Lake, a spreadsheet model was developed which assumes this totally regulated flow. In the model, the reservoir is assumed to stan full in October. The monthly average energy requirement that would be placed on the project is determined by assuming a total yearly energy demand for Valdez from the load forecasts and subtracting what could be generated from Solomon Gulch. Valdez's demand is assumed to be distributed 70% for winter and 30% for summer as in the Allison Lake Reconnaissance Study. To calculate energy production for a given month, an average head is determined by making use of the reservoir storage curve and comparing inflow to outflow. For each of the Silver Lake alternatives we have assumed that a 5 cfs minimum instream flow release would be required. Head loss in the system has been assumed to be a constant 10-ft. Efficiencies and losses have been assumed as follows: Efficiencies Turbine 92% Generator 98% Transformer 99% Losses Station Service Downtime Transmission 1% 4% .3%/mile The combination of these efficiencies and losses results in an average net efficiency of 80% . To determine the ma.x.imum energy production capacity for each alternative, the yearly energy demand is increased in the model until it reaches a point at which the Silver Lake alternative is just able to meet the demand and still be able to refill to the original starting pool elevation. The simulations can be seen in Tables 1 & 2. The model indicated that an average of approximately 44,150 MWh (43,57.5 MWh winter/1, 175 MWh summer) annually could be produced from Alternative A and 48,750 MWh annually (46,375 MWh winter/2,37.5 MWh summer) could be produced from Alternative B. Alternative B, with a lower dam, makes more energy than Alternative A because the powerhouse is set closer to sea level, increasing the average net head. Project Costs Project costs were determined by estimating quantities for major construction features and applying unit costs to these quantities. To estimate the costs for Alternative A, quantities established by Stone & Webster (Ref. 10) were used with the same 1992 unit costs applied as Page 4 ... .. .. -.. ... • -.. .. .. • -• .. .. • .. - -.. - .. Table 1 =:-=-:::-=--:-:::-==-==-==-===-:--=(: .hvd .•8 ~ Sllve r Sllv~ r "k: ALASKA ENERGY AUTHORITY ALLISON LAKE RECONNAISSANCE STUDY ~------.-----~-·-- Alteroative A -Stooe & Webster Eodneeri.ag Yearly Demand 99~50 M'Wars Intake Elev.: 306 Storage Sol. G. Summer 28600 M 'W "hrs Pool Starting Elev.: 415 161:!33 Sol. G. \\'inter .25900 M'W"hrs Powerhouse Elev.: 65 ft L"n-met Summer 1175 MWhrs Assumed Head Loss: 10 ft Cn-met Winter ·H.57.5 ~fWhrs Assumed Eft. 0.8 Min. ln.stream Flow: 5 cfs i Pool I Pool Monthly ' : 1 Avg i Start . Monthly Ending Average Energy Month Inflow Acre-ft 1 Demand! EJev Flow Storage , Elev Generation Oct :129 19922 5447 425 315 163175. 425. 5447 ~ov 172 9937 5447 425 317 153995 423 5447 I Dec Jan Feb :\far Apr Mav June July Aug ~Qt 64 3628 5447 420 324 138084' 415 5447 53 2951. 5447 410. :B4 120874: 405. 5447 .51 2555 5447 399. 346 102539 I 393 5447 33 1722 5447 387 361 82515. 381 .5447 35 1785 5447 374 379 61471 366 I .5447. 19~ 11~83' ~447 3~! 396 49301 ~~4. ~447 441 294 73981 1 25 44 34 21 359 i 294 545 33204 294 368 20 106005: 379: 294 506 30806 294 389 18 135703 399 I 294 486 28622 294 408 17 163276' 417 294 Ending Pool Elevation 425 SUMMARY OF GENERATION Storage Used: 171721 Replaced: I 727W 10]8 OK . Winter Prodllction 43575 100% Summer Prod!Jction __ I::..:lc..:.;75"-100~ 44750 MWhrs Yearly Demand Sol. G. Summer Sol. G. Winter Un-met Summer L'n-met Winter ·Month Inflow Oct 329 Nov 172 Dec 64 Jan 53 Feb 51 Mar 33 Apr 35 Ma\' 195 June 441 July 545 Aug 506 Se:Qt 486 Table.::! ALASKA ENERGY AUTHORITY ALLISON LAKE RECONNAISSANCE STUDY Altemative B -Whitewater Engineering 103250 MWhrs Intake Elev.: 306 28600 MWhrs Pool Starting Elev.: 400 25900 MWhrs Powerhouse Elev .: 10ft 2375 MWhrs Assumed Head Loss: 10 ft 46375 MWhrs Assumed Eff. 0.8 Storage 121..\90 Min. lnstream Flow: 5 cfs ' i I Pool i I Pool Monthly i j Avg j Start 1 Monthly. Ending Average Energy ! Acre-ft Demand Elev I Flow I Stora Elev Generation ' 19922 5797 400; 309 122807' 400 I 5797 9937 5797 400 i 3lli 114016 ; 398 I 5797 J 3628 I 5797: 395 317 98510 i 390 5797 2951 5797: 384: 327· 81740! 379 5797 2555. 5797. 373! 338 63891 I 367 5797 1722 5797 360: 353! 44349 1 353 5797 1785: 5797 345 i 370 23796 I 337 5797 ; 11683 5797 328 I 388 1,107 3~3 5797 25944. 594 317, 39 35696. 328 594 :;no4. 594 :n8: 36 66705: 350 594 30806 594 362: 34 95454 372 594 28622. 594 382 32 122124 : 391 594 Ending Pool Elevation 400 SUMMARY OF GENERATION Storage Used: 172130 Replaced: ]72759 629 OK Winter Production 46375 1009( Summer Production _ ____,!2~3:..:..:75::..._ 100% 48750 MWhrs .. ... .. ... • ... • .. - • .. • .. • • .. • • .. • • --- • ... .. .. - "'5: -+4: - 420 ! 4:!G ._ r-I .., 36G -,, ~ 360 ' -~ ! > ;; :!4: -;; ~ 320 -.... v L z: 300 0 ' -:180 l :( > L w :215C ~ "" L 24C ;<;,Q I I :2CO I ' 190 Figure 2 / I ' I Q i I 100 50 Appendix 8 I 200 150 CTnousands) SiO~GE Ctcre-ft) I I 250 350 were used for all alternatives in the Allison Lalce Reconnaissance study. For Alternative B, new quantities were estimated and the same unit costs applied. As a basis for the estimate, it is assumed that access to the site would be via boat to a newly construe led dock on Galena Bay. and then by a pennanent access road to the powerhouse and dam. The pipeline has been assumed to be placed in the finished road bed. The dam was assumed to be constructed of roller-compacted concrete. RCC was selected due to its speed of installation and low cost as compared to conventional, formed, structural concrete. The RCC gravity structure was assumed to be lined with structural concrete to provide additional freeze-thaw and erosion protection. PageS Appendix 8 The powerhouse is assumed to have a structural/mass concrete foundation, CMU walls, and a metal, trussed roof. Additional line items have been included in the estimate for HVAC, plumbing. electrical, miscellaneous metals, and inlet valves. Mobilization was considered to be a significant factor affecting the cost of construction. The remote access and climatic conditions are going to hamper construction and limit the number of contractors vying for the construction contract. The shon construction season may require multiple mobilizations. It has been assumed that once the major equipment has been mobilized and a base camp established, construction will proceed at conventional rates. Due to the lack of accommodations in the area, an additional cost will be incurred in either housing or transponing the work force. To account for these factors, a 15% mobilization cost has been added to the dam and powerhouse cost estimates. The estimated 1992 construction cost of the two alternative configurations are: Alternative A (Stone & Webster) Alternative B (Whitewater) $54,350,000 $60,560,000 For a detailed breakdown of the above costs, refer to the attached detail sheets, Table 3 & Table 4. It is assumed that both options would stan in 1998. In establishing these costs, it should be noted that unit quantities and prices were estimated so that adjustments could be made easily in the future. These opinions of probable construction costs are based on only this reconnaissance level study of the site. However, unit prices used in these estimates are the same as in all other estimates in the Allison Lake Reconnaissance Study. Therefore, we believe the relative ranking of projects that will result from the economic analysis that follows will be valid. Environmental Considerations This section provides a brief description and discussion of some of the environmental issues that may arise as a result of development of a project at Silver Lake. This review is not intended to be a complete environmental impact assessment as this is beyond the scope of this level of repon. Rather it is intended to highlight some of the environmental differences between the two studied alternatives and identify environmental impacts of both alternatives that might require funher studies in the future. Reference S represents the most extensive environmental research done to date at and around the project site. Topography Silver Lake is situated in a glacially fonncd bowl surrounded by steep mountains on three sides. The eastern-most section of the lake is bordered by a low lying delta. The natural nonnal pool Page 6 - .. .. - .. • .. • • • .. • ... - • .. - - - FERC -\.:..: :-; ~' ... ' ·-.. ... ~:;! .. .1 ' ·- .3 A .5 .6 332 .l .l ~ .3 ... .5 .6 a. !'1. ~ , .... .! ~ ·-_'I ... l~~ .l .~ 334 .1 ~ .3 33.5 .l \.L'I.SK.-\ E.'-"E.RGY -\L-rHC•RfTY ::=!L \ E L~ PROJECT \.L lt:.R. "'·-\ TIVE A -ST 0 ~ '"E 0. V.. 1: BSTER DEPJLED COST ESTL\t~ TE tl99: Dollan) Descr.nuon Quant ltv L-\.'\U :>.SD L-\.SD RIGHTS Land R:ghts -Generation Plant I CSFS Spec1al Cse Perrnu 1 Surveymg , L FERCt.'SFS Land L"se Fees :; T ota.l -o\cc Nc .. >Xl -La.nd and Land R12hl.$ STR UCT'l 'RES A;"''D IMPROVE:ME!'.'TS POWERHOUSE E:scavat1on 4j00, Concrete t mcludmg remiorcmg) 1.100 Building SupentNcnae 1 HVAC. Plumbmg &. Electrical L Miscellaneous Metals l Inlet \' alves :; Subtotal. Mobilization 11 I Total -Ace No. 331 -Srucrures and Jmprovemenl.$•' RESER VOlRS. DAMS. AND WATERWAYS DAM. INTAKE. SPIU..WAY Dock :1 II :\ccess Road :1 28CXXJI E::lcavauon SOO>i Rock Drilling (Grout holes & dratn5) 4.(00 Grout Curtain 1400 I Concrete Structural 1.500: RCC .soo:XJ! DivcrsJOn & Care oiWatcr 1' -I PE.'ISTOCK :i Steel Penstock Material (108" installed) I 600)1 I SuPJ)Qns (Concrete) 400). Surge Tank ! 14(J)X) I ., Trll'urcauon SUbtotal iJ 1 Mobilization •i Total-Ace No. :t~2-Reservoir. Dams.&. Waterwavs1t TL 'RBINES AND GENERA TORS II Supply li 31 Install :I 31 I I Total -A« No. 333 -Turbines and Generators 1i :! ACCESSORY EILCTRICA.L EQUIPMENT !l I Swi\Chge2r 1\ Control Panel 1, ! Miscellanoous Elecuicai ' ll I ' Total -Ace No. 334 -Ac:c. Electrical EQul!nnent 1 I :I MISCEI.l.A."''EOUS MECHANICAL EQUIPMENT . Crace(20Ton) i) 1 ! I Total -Ace No. 33.5 -Misc. Mechanical EauiDment ·I 198: 198: :99: :)~: Cmt Cnlt Pnce :\moun! iS) Cn11 Pnce .V!lountiSl S837-~ S837.100 Sl.OOJ.COJ Sl.OOJ.OOJ L.5 so so S:;Q.OOJ S.10.00J LS so so S!OO.OOJ; SlOO.COO YR so so Sl5.00J $45 . .))) S837_100 s 1.1':'~ .00> CY i Sl6 S72J:X:Xl $75 S:l3ij00 CY Sl.995 $2.194.500 Sl.OOJ SUOO.CXX> LS ! s:.;66.188 1.'7,66.188 $600,00) I S600.1XD LS so so 5100.000 Sl<Xl.OOJ LS so so sso.ooo s.so.ooo EA so so sso.ooo. Sl50.1XXl $2.632.688 s::.13~ .SOO so S73U50 S2.63Z.OIJ8 $2.5''1~0 LS i Sl$0.(0.) i Sl50.CXXJ $400,00). S400.000 u= $601 S1.680.CXXJ S75 S:!..!OO.cro CY ' $40.00 f $200..00) S75 • S375JXD ' u= S2S I SlOO.OOJ .. SS<l S200,1XX) CY I 5501 $7'0,(00 SlOO; S140.00J CY 1 Si80! S1.170.<XXl S1.CXXl' s 1.500.00) CY i 5601 S3.(XX).<XXJ 5100! s.5 .IXX),IXX} IS I l<XXl<XXl \ Sl.CXX:).(:XD ssoo.coo S.500.<ro ! i 1 LF ' 52..400 I S14,400,<XXJ $1.000 S6.000.00l CY S7801 S..'l.17n00J $.500 S2.00J.CXXJ I.B : S4i S5t'iO.<XXl $..'1 $420,!Xll LS SOl so SllO.CXX) suo.coo $2S~.~ Sl8. 745,COO Sl.874..SOO 'OArnf !IIl S20.619.500 I EA i 5990JD): Sl.970.<XXJ S l.O!O.IXlO I s:uso.ooo EA I SOl so s.11s.cm: S945.000 'S2.970.<XX> I s-&.09S.<m LS I S300.CXXI $300,<XXl SZSO.OOJI SZSO.IXXI LS so so S90.COO. S90.(XX) I LS ! SOl so $100.CXXli $100.(0) I I I tm.OOJ I S440.CXD ; I l LS i SO! so S50.00J I S50.COO so I s.so.cm FERC Acr ~C' .~.s: .1 ~ --~ .. ~~~ .1 ~ ·- :lS6 . .. Table 3 -\L-\:iK.-\ E.'"'ERGY ALTIJoRm· SILVER LAKE PROJECT . -\LTER....,AID"E A-STONE & \\"EBSfER DETAILED COST ESmiATE 11992 Dollarsl Descri'ptton Quanttt\' Unn 511\ UCTL 'RES .Au.'"D IMPRO\'E.\.-fE.'"TS (fRA."lSMISSIOI" FAClUTY) Substallon Foundauoos Oil Spill ContaJNnent Grounding Grtd Tota.!-Ace No. :<52-Structures&. Improvements SCBST A TION EQUIPME.."''T &. STRUCTURES Main Transfoauer ,. .'\ccessory Swnch~ar Equipment Total -Acx: No. ~S~ -Substation Ecruroment &. Structures FIXTI..'RES. CONDUCTORS&. DEVICES NewPoleLne Total-Ace No. 356-Fixtures. Conductors& Devices;. SUMMARY LAND AND lAND RIGHTS STRUCIURESAND IMPROVEMENTS RESERVOIRS. DAMS. AND WATERWAYS Th'RBINES AND GENERA TORS ACCESSORY ELECTRICAL EQUIPMENT MISCEllANEOUS MECHANICAL EQUIPMENT STRUCTURES AND IMPROVEMENTS SUBSTATION EQUIPMENT&. STRUcruRES FIXTURES. CONDUCTORS&. DEVICES Total Direct ConStruction COStS Design Engineering@ ~ FERC and Other ucensing ConstructtCII Mgmt. @ 8% Subtotal: Contingency ( 20% on equipment) Conttngency ( :'.0% on remainder·! Interest D.tring ConSt. (2 J1fS@ 4.5%) 1992 E.sumated Project Cost 199S Estimated PrOJect Cost ( @S% per Year) Plant Mu. OUtput (MW) ProJected Annual EnerSY-MWh.']T Cost Per Installed kW -1992 -1995 Annual Debt Servu:e ( 100% debt. 9%. 30 y:r) 30 Year Levelized Power Cost per kWh O&.M Allowzce Estimated Annual Cost -1995 1 LS l LS [ LS 1 LS 1 LS 22 • MILE' 1982 Unit Prtce so so so SSOO.OOJ so . S42.S.CXXl 1982 Amount{$) so so so so SSOO.OOJ so SSOO.CXXl S9.350.CXXl S9_150Jl'Xl $8:'17.100 52.632.688 S26.0SO.CXXl $2.970.\XX) SJOO.CXXl so so SSOO.CXXJ S9.1SO.CXXJ S-42.639.988 199.2 Unit Price S10.CXXJ i SlO.CXXl SlO.OOJ. $200.(XX) SHXl.CXXl SJOOJXX> JYSI:: Amount tS) SlO.OClO S!O.OOJ · $[0.0Cl0 SJO.CXXJ S200.(XX) SlOO.(XX) SJOO.(XX) S6.600.CXXl S6.600.COO Sl.l iS.OOJ S2.S7l.:SO 520.619.500 S4.095.(XX) S440.(XX) S50.CXXl SJO,(XX) S300.CXXl -.. .. - • • .. .. • .. .. ... .. ... .. • .. S6.600.(XX) S~5.880.i50 s:~.219.268 - S400.CXXJ $2.870.460 .. S4l..130.4 78 ... SZ..29":' .CXXl S7-118.7::.5 • S2..i:;9.8~9 S54.<~.0J2 - $62.900.749 .. 15 (XX) ...a"'5(1 .. $~.6!:! S4.l9~ • 56.11:.5:9 .. so.:~ 50.00':'0 • so 1 4:;B ... n::RC .),.:: s .' .. .. . ·- ~ -.. 44. " 1 . 1 . .. .. < ... .:' .6 J~2 .1 .l .. ... .3 A .5 .G a. h. ~ , ·- 1 . ' ' .3 A .5 ~~,:. .1 . .. .. 334 .1 , .J ~35 .1 ,_.:_ \:::-K."'-:=:_,·E;;: _:j J "'-L ;.-!.::: R5TY ~IL\'ER L~ PRCJECT :..L TER. -.;.-\Tl\ E 8 --~ Hr:l: WATER E.---:Gr-;EERc-;G DET~LED COST EST:~l-\rE 1:99: Dollars 1 Descnpt!cn QuantHv L~...;o -~"D L~SC RIGHTS L..lnd RighiS -Generauon Plant 1 L'SFS SpeClai Use Permit i Sur.-eyLng 1 FERC t:SFS Llnd Use Fees . _, Total -Ace No. ;;:;o-Llnd and Land Ri2h1S STRUCTURES AND IMPROVEME'ITS PO\\'ERHOl:SE Etcavatlon 1.000 . Concrete (mcludt.ng remfon;mg) 500 Building Superstruct:ure 1 : HV A C. Plumbing&.: Electncal '! 1 . Miscellaneous Meta.ls 1 ' Inlet Valves 2 Subtotal Mobuizauon Total-AccNo.3Jl-St:ucturcsandlm'Drovementa.! ' RESERVOIRS. DAMS. AND WATERWAYS DAM. INTAKE. SPillWAY I Dock I 1 ; I Access Road ,I 25000. E.tcavat1on I 5000; i Rock Drilling (Grout holes & drams) 4.000! Grout CUnam i 14001 .I Concrete StNcrural 5000 i RCC :I 14300/ DiversJon &. Care of Water ;I 1 : " PENSTOCK Steel PensUldt Material (108") 100001 Install a lion 100001 Suppons (Concrete) i 52001 Surge Tank 'I 1i Bifurcation I 11 Subtotal, Mobilization il Total-Ace No. 332 -Reservoir. Dams.&. Waccrwan il i TilRBINES AND GENERA TORS Supply ti 2i Install 2: !I I Total-Ace: No. 333-Turbines and Generators I! I ' ! ACCESSORY ELECI'RICAL EQUIPMENT I Switchgear tl Control Panel 1 : Miscellaneou.s Eec:tncal lj Total-Ace: No. 334-Ace:. Elec:tric:al &uie>mentj ' ! I MISCEllANEOUS MECHANICAL EQUIPMENT ! Crane ll ' Total-Ace No. 335-Mise. Mechanical &ui'Dmentl ·--,.;. L'n11 L'm: Pr:ce .·\.:ncunr 1 S 1 LS s 1.000.000 ' Sl.000.00) LS SJO.OOO SJO.OOO LS s1oo.ooo· SlOO.OOO YR Sl.5.000 S*5.000 s 1.1 ':'~ ,ry)f) CY S7.5; S".5.000 CY Sl.OOO S500.COO LS $250.000! $250.000 LS $100.000 SlOO.OOO LS sso.oooi S50.000 EA S50.000 SlOO.OOO Sl.075.(X)J Sl61 "!50 Sl.2.~.250 LS $400.000' S400.DOg LF S75 51.875.000 CY S7S' s:;1s.ooa LF SS01 SlOO.OOO CY $100! Sl40.000 CY : Sl.OOOi 5.5.000.000 i CY stool Sl,430.000 LS ' ssoo.ooo: $500.000 i I I lF ' S4001 $4,000.000 lF S600 1 $6.000.000 cY S500l 52.600.000 LS S300.000 $~00.000 LS saooool $80..00) ' i 522.900.000 S3.435.00J Sl0.335,000 i EA ' Sl-'OO.COO I $3.000.000 I EA I $4.50.000! $900.000 ' ! ' ! $3,900.000 i I i s~.ml LS S250.<XXI LS $9().00)! $90.00) LS Sl00.£XX) SlOO.(X)) i I S440COO ' LS S.50.CXX> I sso.ooo S50.000 FERC Ace Sc ::.~: .l . '* ' - 1C\~ . 1 . .. :J5c .1 . ·- \.; .. A . .SK.-\ E:"ERGY .-\l.,'THORm· SIL\'ER L~ PROJECf .-\LTER.'-'.-\ TI\'E B-V.liTTE WATER E.'IIG~EERr-:G DETAILED COST ESTL\1/\.TE (1992 DoUars1 Descnot!On STRUCTURES AND IMPRO\'EMEJ\'TS (TRA.."'SMISSION FACIUTI' > Substation Fou.ndatlons Oil Spill Contamment Grounding Grid Total -Ace No. :15:: -Strucl\lres &.ImerovementS SUBSTATION EQUIPMEJI.'T &. STRUCTURES MaiD Transformer Acce550ry Switchgear Equipment Total -Ace No. 35:<-Substation E.Quioment &. Structures FIXTURES. CONDUCTORS&. DEVICES NewPolel,jne Submanne Cable to Valdez .. Total -Ace No. :<56-Fixtures. Conducmn &. Devices•: SUMMARY LAND AND LAND RIGHTS STR UcnJRES AND IMPROVEME.llfl'S RESERVOIRS. DAMS. AND WATERWAYS TURBINES AND GENERATORS ACCESSORY ELECTRICAL EQUIPMENT MISCEllANEOUS MECHANICAL EQUIPMENT STRUcnJRES AND IMPROVEMENTS SUBSTATION EQUIPMENT & STRUCTURES FIXTURES. CONDUCfORS & DEVICES Total Direct Construcuon CostS Design Engineering @ 9% FERC and Other Licensing Construction Mgmt. @ 8% Subtotal: Contingency (20% on equipment) Contingency (30% on remainder) Interest During Const. (l yrs@ 4.5%) 1992 Estamated Project Cost 1995 Estimated Project Cost (@S% per Year) Plant Max. Output (MW) ProJected Annual Energy-MWht]'r Cost Per Installed leW-1992 -1995 Annual Debt Service (100% debt. 9%. :W yr) 30 Year Levelized Power Cost per kWh O&M Allowance Estimated Annual Cost -1995 Quar: t:n1t 1 LS 1 LS 1 LS 1 ' LS 1 LS 2.2. MILE 1 LS L'nit Pnce SlO.OOJ: S10.000 $10.000 5200.CXXl i SlOO.CXXl: 5JOO.CXXl; S6.000.CXXJ Amount lSI S10.0CXJ S10.000 SIO.OCXJ s~o.ooo S200.000 SlOO.OOO S300.000 5660.000 S6.000.000 $5.660.00) SLI75.000 51.2.16.250 526_135.000 53.900.000 5440.000 550.000 SJO.OOO $300.000 S6.660.000 S40.ll6.2~0 S:\.6 I I-l6:< 5400.000 S3.210.100 $47.147.713 52.270.000 $8.632.875 Sl~'H 1.016 560.561.604 570.107.626 14.000 48750 S4326 55.008 56.824.021 S0.1400 $0.0070 S0.1470 - - .... .. • • .. • ... - • .. • •· • .. • • .. -.. ... -.... .. .. Table 5 SILVER LAKE COST ESTI~tA TE 0707J-Ol0-l.S9 08H92 f: .byd\585.silver·silvro&m. wk 1 OPERATIONS & MAI~'TE:--;A."'CE ALT A Stone & Webster ~I~TE~~~t~~------~~--~-------------=En~eermg Hydro Mamtenance ( .S9C of equip. costs) $120,000 Pipeline Maintenance $20,000 Road Maintenance $40,000 Operator Subsistance $50,000 Boat'Ai.r Travel Costs To Site $17,000 Snow Equipment Costs SlS,OOO Insurance $80,000 Labor SlOO,OOO FERC & Other Permit Fees $18,000 Major Replacements Reserve Fund $50,000 Fuels/OiJstConsumables $15,000 d · · at' Cos SO Total Notes: l. This assumes two operators Jivmg m housmg provided at the site. 2. Project will have to maiiitam a seaworthy boat to insure access to site under most conditioDS, a snowcat to msure access to dam and powerhouse aU winter, as weU as a truck, plow andsmaU backhoe. 3. Travel costs to site cover costs for maintenance crews to get to and from site for any major repairs, annual shutdowns, inspectioDS, etc. 4. Assumes salary of SSO,OOO!yr for each of two operators. ALT B Whitewater Engineering $120.000 $20,000 $40,000 $50.000 $17,000 SlS.OOO $80,000 $100,000 $18,000 SSO,OOO ~.This assumes no annual charge for use of native lands or related annual fees. Appendix 8 elevation of Silver Lake is El. 306. The outlet to Silver Lake fonns the Duck River which flows westerly for about 1.5 miles where it discharges into The Lagoon at the head of Galena Bay. The upper ponion of Duck River flows through steep rock canyons and has 5 waterfalls of at least 10 feet, the highest waterfall being about 60-feet-high located about 3000 feet upstream of the lagoon. This waterfall has been considered by many to be the first impassible fish barrier on the Duck River. Wildlife Habitat Silver Lake and the surrounding area is the home of a sizeable goat population and is one of the most popular goat hunting areas in Prince William Sound. Black bear habitat in the region is also rated good to excellent, with bears feeding on the salmon that spawn in the area. Deer are few in the area and waterfowl use is not extensive (Ref. 8). There will be a loss of habitat associated with both of the alternatives proposed for Silver Lake due to the raising of the lake elevation. For Alternative A, the pool elevation would be raised 125 feet to El. 425 increasing the surface area of the lake by about 700 acres. Alterative B would raise the lake 100 feet to El. 400, increasing the sutface area of the lake by about 600 acres. The effect of raising the pool elevations on loss of wildlife habitat for both alternatives will have to be srudied funher before any conclusions can be drawn. What is known is that access and exposure to the region will be increased with any development in the area. Both alternatives as srudied in this appendix will use a pipeline to convey the water from the intake to the powerhouse. At this time it is envisioned that the pipeline will be buried for the majority of the route and that it shouldn't pose a barrier to the free travel of wildlife. Air Quality An advantage of either of the hydroelectric project alternatives investigated here is the improvement of air quality in Valdez due to the reduction of required diesel generation. The amount and duration of the air quality improvement is variable and dependent on a number of factors. A detailed review of this is beyond the scope of this section. Fisheries The Duck River and surrounding lagoon area is reported to be one of the most productive regions in Prince William Sound for pink salmon. Pink salmon escapement has been estimated to average around 51,000 per year (Ref. 8). Chum salmon and Dolly Vardon are also abundant in the area. Salmon spawning beds have been identified in the Duck River, The Lagoon. Reverse Creek and a number of other small tributaries in the area. Development of a Page 7 - • ... • • .. .. • • .. • .. • .. ---.. .... • .... '" Appendi.x 8 hydroelectric project at Silver Lake will introduce some issues that will require funher study. Perhaps most importantly is the issue of minimum instream flow. How, when, and where this flow is release-d could have an effect on salmon production in the region. The distinguishing factor between the two alternatives presented here is the location of the tailrace, or the point where flows are returned to the stream. The Alternative A powerhouse is located on the Duck River at El. 65 above what is considered to be the impassible fish barrier. Water would be returned to the Duck River prior to reaching the salmon beds. Minimum instream flow for this alternative would most likely be based on supponing the aquatic life in the bypassed reach of the Duck River above the impassible salmon barrier. This requirement is anticipated to be small and attainable. Alternative Bon the other hand plans to make use of a powerhouse located on Reverse Creek. This configuration will pennanently lower the flows on the Duck River even in the spawning areas and increase the natural flows on Reverse Creek. What effect this altered flow regime will have on the overall fish population for the area will require detailed funher study. Each alternative will be using an intake located at or about El. 300. At certain times water would be drawn from deep within the reservoir. This water would tend to be colder and have a lower dissolved oxygen content than the corresponding surface water. How this would affect the fisheries is unknown, however much could be done with regulation and design detail modifications to offset or mitigate these concerns. Other There are additional environmental issues associated with project development at Silver Lake. including erosion and sedimentation control, aesthetics, noise, recreation, and others. It is reasonable to expect some level of study will be necessary to address each of these issues if fun her project development proceeds. Detailed review of these issues is outside the scope of this study. Ecogomic Eyaluatigg Using the estimated construction costs, the two alternatives were plugged into the economic analysis model developed for the Allison Lake Reconnaissance study. Annual O&M costs were estimated for both alternatives to be about $575,000 per year (sec Table 5). Variable O&M savings for both alternatives were taken at the high level ($.03165/kWh) since at least in early years, all diesel generation by CVEA could be offset. Runs were made for all combinations of load growth and fuel price escalation as iD the Allison Lake Reconnaissance Study. Run output is attached at the end of this section. The results are \hown below in Tables 6 & 7. The project with the highest benefit:cost ratio is still the Allison l.a.ke w/ Hydro option, as found in the Page 8 I Appendix 8 Allison Lake Reconnaissance Study. Table 6 Results of Economic Comparison of Projects I. ALTERNATIVE (3) Allison Lake Tunnel w/ Hydro (1) Silver Lake Alternative A (1) (Stone & Webster Engineering) Allison Lake Pipeline w/ Hydro (1) Silver Lake Alternative B (1) (Whitewater Engineering) Raise Solomon Gulch Spillway 32 ft. ( 1) Raise Solomon Gulch Spillway 5 ft. (2) Lower Solomon Gulch Intake (2) End Use Conservation (2) Allison Lake Stand Alone Hydro (1) l:ses variable O&M savings of $0.03165/kWh. Uses variable O&.M saviD1s of $0.01/kWh. Net Benefits Benefit: Cost Ratio $20,320,658 1.70 $29,291,969 1.58 $9,805,844 1.55 $29,440,364 1.53 $6,509,336 1.33 $1,009,602 1.66 $530,132 1.43 $300,069 1.73 ($12.191.263) 0.73 Average Annual Diesel Displaced {M\Vh) 27396 44053 15434 . 47439 14817 1674 1025 747 19666 3. All cases using "Hip" load JTO'Wth forecut (w/ Petro Star) ud AEA fuel price escalatioo forecast. Page 9 ... ... ... - .. ... • .. .. .. ... • • - • i; .. • -.. -.. .... .. - •· .. Appendix 8 Conclusions The Allison Lake Tunnel w/ Hydro option has the highest benefit:cost (BC) ratio of all options investigated. with a net benefit of about $20.3 million. Both Silver Lake options investigated had slightly less but still attractive BC ratios of 1.58 and 1.53. Net benefits of both options were higher than Allison Lake Tunnel w/ Hydro at about $29.3 million. Clearly, both Allison and Silver Lake projects have attractive features. Allison Lake Tunnel w/ Hydro has a lower 1992 capital cost of about $34 million compared to Silver Lake at about $54 million. Operating uncertainties are less wilh Allison Lake, and its proximity to Valdez makes construction logistics easier to handle. The Allison Lake project, however, does not satisfy all of CVEA's diesel generation demand for the high (w/ Petro SW) load growth case. Silver Lake does, at least in early years of operation. Silver Lake, being a larger project than Allison Lake, also generates a higher net benefit. The analysis of the Silver Lake Project points out one area of possible risk with the project. Referring to Table 7, it can be seen that under the high load growth forecast (with Petro Star) the Silver Lake Project has the highest net benefits. Under the medium or low load growth forecasts, however, the net benefits drop considerably, and are negative for all cases in the low load growth projection. This is because under low load growth, not all the energy from the project could be used right away. reducing the fuel and O&M savings. Although the Petro Star load and the economic activity from the Alyeska Pipeline appear stable at the present, it is possible the pipeline could shutdown sometime early in the next century. If this occurred, and the Petro Star load was lost, Silver Lake project economics could be adversely affected. We believe that constructing either of these two projects, Silver Lake or Allison Lake, does not rule out construction of the other. As can be seen from the high load growth case economic model runs, if either Silver Lake option is constructed and is on line by 1998, CVEA will still need to resume some diesel generation by 2004, only 6 years after the project comes on-line. Should load growth exceed the "High" case scenario, diesel generation would be needed again even sooner. An integrated approach to providing power for CVEA and the Valdez area is necessary. From the technical standpoint, projects at Allison Lake and Silver Lake are feasible. Under high load growth projections, both projects are beneficial. Under medium or low load growth scenarios. the Silver Lake project is less beneficial. We recommend both projects be studied in greater detail. Selection of which project to proceed with fU'St will depend on actual load growth. availability of capital to both CVEA and the State of Alaska, and other institutional issues. Page 10 Appendix 8 References l. 2. 3. 4. 5. 6. 7. 8. 9. 10. Alaska Power Authority, Application for Preliminary Pennit for the Silver Lake Hydroelectric Project, P-6861-000, November 18, 1982. Alcat Engineering, Cordova-Valdez DC Transmission Tie Line Feasibility Repon. May 1' 1982. DOWL Engineers, Cordova Power Supply Feasibility Analysis: Silver Lake Alternative - "Study Plan" Environmental, May 1982. DOWL Engineers, Geology and Geotechnics of the Proposed Silver Lake Hydropower Project, Draft, Spring 1983. DOWL Engineers, Draft Environmental Field "Study Plan" (1983-84), Silver Lake Alternative, Cordova Power Supply Feasibility Analysis: Phase U, June 10, 1983. International Engineering Company, Inc., Final Report: RecoMaissance Study of Energy Requirements and Alternatives for Cordova, June 1981. Stone & Webster Engineering Cotperation, Cordova Power Supply, Interim Feasibility Assessment, Execunve Summary, June 1982. Stone & Webster Engineering Cotperation, Cordova Power Supply, Interim Feasibility Assessment, Volume 1, June 1982. Stone & Webster Engineering Cotperation, Cordova Power Supply, Interim Feasibility Assessment, Volume 2, June 1982. Stone & Webster Engineering Cotperation, Cordova Power Supply, Interim Feasibility Assessment, Addendum 1, Revised Cost Estimates, November 1982. Page 11 ... -.. - .. • .. .. .. .. • .. • • • .. .. ---.. - ... - Allison Lake Reconnaissance Study Prepared for State of Alaska Walter J. Hickel, Governor Alaska Energy Authority Charlie Bussell, Executive Director 701 East Tudor Road PO Box , 90869 Anchorage, AK 995, 9 (907) 561-7877 September 1992 PrePared Under Contract No. 2800413 by: HOR EnginHring, Inc. Building B 4446 Business Park Blvd. Anchor•o•. Al•lka 99503· 7 1 1 8