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HomeMy WebLinkAboutAPA6~ ~ I I i DRAF.... SUSITNA REPORT SUMMARY PRO.JECT MARCH I '1982 HYDROELECTRIC I I .~, .-'i .~.PC7=,-ALASKA POWER ~UTHORITY -I [ [}{I&[R3 ~&0 §[ID&®©@ SUSI TNA JQI NT VENTU RE 711 H STREET Alaska Department of Fish and Game 333 Raspberry Road Anchorage,Alaska 99502 Attention:Mr.Donald McKay Habitat Biologist ANCHORAGE,ALASKA 99501 March 24,1986 1.17.4.2 TE L.(907)272 5585 Subject:Susitna Hydroelectric Project Document Transmittal Dear Mr.McKay: Alaska Department of Fish and Game has provided the enclosed errata sheets for the report entitled "Report No.10;Preliminary Evaluations of Potential Fish Mitigation Sites in the Middle Susitna River"(Document No.2908).The pages (one set)have been T-punched to accommodate report update. Very truly yours, Paul T.Lambert Administrative Manager kif Enc:as noted cc wlo Ene: S.Ellingwood,Power Authority 226771/3 ALASKA POWER ",\UTHORITY 8 jK 14;;)S .Sa ft~3 no.4J Phone:(907)277-7641 (907}276-{)OOl ,"1arcll 15.1982 334 WEST Slh AVENUE -ANCHORAGE,ALASKA 99501 , ·1 I -I I 1 I I An Open Letter to the Publ ic At Large and To All Jntere~t~d Agencies and Organizations: ~I I 1 t \ Ll It is with great pleasure that I am providing for your review and corrment the draft surrrnary report on the Feasibil ity Study of the Susitna Hydroelectric ProJect.This sumary draw~upon material presented in the detailed fea~ibility report and supporting documents.to which reference should be made for a mOre comprehensive discussion of the \ltrr;ous top;Cs. This report represents the culmination of more than two yeers 0 war••undertaken by Acres American rncorporated in accordance with the Plan of Study pnsented in February,1980.~nd subsequent imprQvements and re',;sions whirh were IHgely prompted by your suggestion~and cancer"s,I n add iti on to the extens i ve te-chni ca 1 and e-conomi c evaluation of the proposed development of the Susitne River Basin,the program has;ne 1uded a comprehen I j ve eva 1ua t i on of -the environmental issues associated witb the project.Public preferences identified in the course of se.eral meetings held during the study period ha.e been fa ctored,into the proposed p 1an,and we look fa ""a rd to cont i nu i fig th i s diologue in the weeks and months to come.Publ ic meetings are pla"oed for late March -.lnd mid-Apr;I in Anchorage.'airbanks,and Talkeetna. Sub~eQuent to the~e meetin9~.the Board of Directors of the Alaska Power Authori ty wi 11 be formul at ing "recontTlendation as to whether Or not a license appliCation shouid be filed and developmental activities cant inued. Sincerely, C'".-~.-~/ C-:'----:r~j-~ Eric P.Yould El<eClit he 0;ree tor I] ARL1S Alaska Resources Ubrary &Information Services Anchorage Alaska u 1 I I I j I 1 !'I J ,\ I ! I 1 I I I TABLE OF QONTENTS 1 .INTROOUCTION, 2 NEEDS 3 OPTIONS 4 PEVELOPMENT SELECTIONI 5 PROPOSED DEVELOPMENT 6 PRO.JECT OPERATION 7 CONSTRUCTION I B CC?STB \ 9 ENVIRONMENTAL ISSUES 10 ECONOMICS 11 FINANCING AND MARKETING 12 IMPLEMENTATION 13 REFERENCES AND ACKNOWLEDGEMENTS FRONTISP1ECE -WATANA DAMSlTE Page 1 :3 '7 11 17 27 31 35 39 47 51 53 55 '"!'? ===--j-'"I 10'" Ej6°N-~-;;"(jJ@.4L _!i:C11,,10 .-6~II'N ;.:,.v\., 1 l PLATE4IJ LOCATION PLAN ,I .! I I INTRODUCTION' The Susitna River,with a drainage area of more than 19.000 square miles,is the sixth largest in Alaska.(See Plate 1.)Rising in the glaci~r-topped m~untains of the Alas1ka Range abou~90 miles south of Fairbanks,the river meanders across a broad allUVial fan for about SOfmiles in a southerly direction before it turns westward and begins a 7S-mile plunge between essentially continuous canyon walls. Turning once again to the south,it flows for another 125 miles before discharging into the upper reaches of Cook Inlet west of Anchorage.An important and productive fishery resource,the Susitna 'also contributes to the sUpp0rt of significant wildlife populations In the virtually untouched and relatively inaccessible lands across which i'flows. Contained entirely within the southcentral Railbelt region,the Susitna basin is strategically situated between the two largest Alaskan population centers of Anchorage and Fairbanks. The extensive hydroelectriG potential of the Susitna River first came to public attention in 194tl when the Bureau of Reclamation issued a report of its initial investigations there.Since that time.various development schemes have been advanced by public agencies and private organizations.A common thread in the many earlier reports is a virtually unanimous agreement that some project should proceed. Acres American Incorporated was commissioned by the Alaska Power Authority,in December 197~,to conduct adetailed feasibility study In order to determine technical feasibility,economic viability, and environmental impacts of an optimal development in the basin.. A rigorous progr&m of field investigations,alternative plan evaluations,design studies.environmental studies,and economic analyses led to the production of a final draft feasibility report issued for public comment in March 1982.This document provides a summary of the detailed report. ~ Throughout the stUdy period,an agressive public participation program was conducted by the Alaska Power Authority.Comments from interested organizations and individuals have greatly influenced the work.In addition,coordination with federal and state resource agencies has resulted In the selection of design criteria, project features,and operation plans which appear to offer balanced solutions to sometimes conflicting objectives. A separate and independent study of alternatives to the Susitna project has been prepared by Battelle Pacific Northwest Laboratories under the terms of an agreement with the Office of the Governor.State of Alaska.Both the Battelle Report and the detailed feasibility study are available for public review at libraries throughout the Railbelt. THE EXTENSIVE HVDROELECTRIC POTEN,TIAL Or:.THE SUSI1NA RIVEIR FIRST CAME TO PUBLJC ATTENTION IN 1948 ... [PAGE 1 N GAS 76 % ,COAL 12% GENERATING PLANTS II EXISTING THERMAL ...EXISTING HYDRO "PROPOSED HYDRO TRANSMISSION LINES ---EXISTING - --PROPOSED NET GENERATION BY TYPES OF FUEL OIL 2% ~AFOGNAK -V ISLAND r-',,~~,~~,~):dJ ~t\:;'!v~'/(r"'"~'~"'~~.~.,~~fl/<YLlv~~o ."~.)plV.,~O~P ~"",V .(J~.,R"~PART ,fllV~ :lv'..~ANAJ<t\.'~(~!..Y -9 'A C .vER~!v-9)~Y-~-l\',~1l/4 RIVC'..p OUNB1\f!,~/!TH ~~\r-rvf 'V,·r.........i POLE "'i,I~.~",./•••--(~'7'-:r=~{ ,-"~..I ~O1'YJ i'ct,•'<,~",.~J \rf;~...~I '"-4-1--;:.~!1 \l\~.vY(})..\\,~N~~ r;::l;-i ~.i'i :",~}•~,t.-<,:~-';'0 "r~~(~\~CA>lTWELL.-'9 l.t>I~.l·'\\'-~'..{/SUS,,",)h r (' MCGRATH /..~.,~I.----..~ '(~GOLD CREEK "'iii ..\'CURIfr \)(l _\,N"fll'yI:JI CO'PER CENTER !"-r;'l~~..o..o~ t l ,~:(j'TAZUN~~;P CHITltj4 -9/1--.;IJ.LAKE '!~"~-'9 "\II ($"~0 ~VALOCZ \ '-----~-"04-....III ..a.'. '"~V£f/","--.,--= t o 65 I~ I !I MILES PLATE 2 GENERATING AND TRANSMISSI ILITIES I } j NEEDS Current Generation Syst,em About 90 percent of the current total net generation of electricity in the Railbelt depends upon the use ¢f fossil fuels.Anchorage and other communities in the south now enjoy relatively low-cost enl:lrgy because of their proximity to Cook Inlet gas fields and to existing small hydroelectric plants,In the north.the Fairbanks- Tanana Valley area gepends primarily upon coal (which is mined near Healy)and a small amount of oil.Plate 2 provides a breakdown of generfltion by fuel types. At the present time,the northern and southern load centers are not interconnected.T~us,generating systems have evolved independently over the years in these two areas.The total installed capacity in the Railbelt,exclusive of military generation,is nearly 1000 MW. Five electric utility companies serve the Anchorage-Cook !nlet area. The two largest,Achorage Municipal Light and Power and Chugach Electric Association,operat'e the bulk of the generating resources. Alaska Power Administra\ion,a federal agency,operates the 30-MWrEklutnahydroelectricplant,marketing wholesale power to several of the utility companies.Aside from the Eklutna plant,most generating resources in the south are concentrated around urban areas or near Beluga,west of Anchorage,where natural gas is piped from various wells.Transmission interconnections between utility systems generally exist in the Anchorage-Cook Inlet area. The Fairbanks-Tanana Valley area is served by two utility companies:Golden Valley Electric Association and Fairbanks Municipal Utilities Svstem.A coal-fired plant operated near the mine mouth at Healy sllpplies energy to communities to the north through a 138-kV transmission line. Military bases in the Railbelt independently operate generating units,as does the University of Alaska at Fairbanks.The Glennallen- Valdez area,east of Anchorage,is served by the Copper Valley Electric Association. 2 Scheduled Additions An intertie permitting transfer of up to 70 MW of power between Anchorage and Fairbanks is currently planned by the Alaska Power Authority.It will provide an opportunity for economic interchange of energy and will permit sharing reserve capacity.Provisions have been made for integrating the intertie into a future larger transmission system in the event that the Susitna project or other regional-scale facility is constructed. THE TOTAL INSTALLED CAPACITY IN THE RAIL- BELT,EXCLUSIVE OF MILITARY GENERATION,IS NEARLY 1000 MW. Five new generating units are currently planned in the Rail belt.Two hydroelectric plants will provide about 97 MW with perhaps another 45 MW of spinning reserve.The larger of these is the Bradley Lake Project east of Homer,now being considered at alternative capacities of either 90 MW or 135 MW.Grant Lake would add a further 7 MW.One gas-fired combined-eycle unit and two gas turbines will add another 160 MW.When scheduled retirements and new additions are accounted for,the total system capacity in the early 1990s is expected to be about 1200 MW Historical Trends Between 1940 and 1978,electricity sales in the Railbelt grew at an average annual rate of 15.2 percent -roughly twice that of the nation as a whole,Plate 3 illustrates the historical growth in electric energy demand between 1965 and 1980.Although the rate of demand increase in the Railbelt has consistently exceeded the national average:the gap has narrowed in recent years as the Alaskan economy has matured.Past high growth rates can be attributed both to rapid population increases and to installation of electric service in households which had not previously been served. PAGE :3 , J 20102005200019951990!985 YEARS 198019751970 P.?' 1965 12 II 10 I 91 !_""am.}FORECAST RANGE 8 8 1 I , 0-I MOST LIKELY VALUEx I 3:7 ~I ~;:_J::::J::'!;'l HISTORICAL DATA ~ 0z ~6 W0 >-<:) f5 5 Z W -l<t~4crt- U W -l W 3 I /:.....,.. I~ 2 PLATE 3 RAILBELT ENERGY DEMANDS 1 1 J ! Currently,about 47 percent of utility sales are to residential customers,1 percent for miscellaneous use (e.g.street lighting), and the remaining 52 percent t9 the commercial-industrial- government sector.This split has been relatively constant during th~past decade. Forecasts of future D'emand A great deal of uncertainty is necessarily associated with the preparation of demand and load forecasts.Population growth, industrial activity,government expenditures,energy prices, conservation measures and a variety of other factors will affect - and are frequently laffected by -future demand.To ensure objectivity,a range of load forecasts was Independently derived. Initial work accomplished by the Institute for Social and Economic Research,University of Alaska,was subsequently updated by Battelle Pacific Northwest Laboratories (Battelle).Plate 3 illustrates the December 1981 Battelle forecasts used in the final evaluation of Susitna project viability.Between 1981 and 2010,the mid-range forecast suggests that el~ctrical and energy demand will grow at an annual rate of about 3.5 percent,with the high and low range limits at about 4.6 percent and 2.8 percent,respectively,The mid-range value was selected as the base case for planning future generation needs in the Railbelt.Sensitivity tests were conducted for the high and low cases (see Section 10), All forecasts include sUbstantial electricity conservation due to the cost of power.In the low case,l~dustrial developments such as mining Beluga coal,U.S.Borax mining,a petrochemical plant.and a Valdez refinery are assumed not to occur.These developments do appear in the high ¢ase,but no additional major capital projects for which planning has not yet commenced are assumed.In each case, demand was sensitive to energy costs.Thus,more energy demand is assumed to occur tor the least cost alternative than for higher cost alternatives. Military bases and self-supplied industries are assumed to continue to generate electricity for their own needs and they are not included in the demand forecast. Electric space heating which now warms about 21 percent of the households in Anchorage and 9 percent in Fairbanks is assumed to change in relation to price differences between electricity and alternative heating fuels.Growth in population and tourism varies from case to case.Battelle indicated that the chances of realizing lesser and greater demand than the mid-range forecast are equal. Requirements for Additional Capacity Under the mid-range forecast,currently scheduled additions are sufficient until 1993 to meet rising demand as well as to replace aging units which must be retired.Between 1993 and 2010,about 1400 megawatts of capacity must be added to the system to meet additional demand as well as to replace aging units. ...THE MID~RANGEFORECAST SUGGESTS THAT ELECTRICAL ENERGY DEMAND WILL GROW AT AN ANNUAL RATE OF ABOUT 3.5 PERCENT. If reqUired system expansion occurs by continued use of the thermal generating plants,a shift toward increased use of coal will be necessary not only because the Cook Inlet gas reserves may be insufficient to sustain long-term reliance upon natufal gas in the face of increased demand but also because sharp increases in gas prices will occur in the next decade as old supply contracts expire. The installation of thermal (coal-Or gas-fired)plants to meet the demand would offer the consumer no protection against rising costs,si nee fuel prices wi II conti nue to be exposed to inflation and to extraordinary escalation occasioned by world market conditions. Thus,it is appropriate to consider what other options may exist,as well as to ponder important implications and risks which might be associated with them. PAG,E 5 j 1 ~ [ i I i J 1 } 2010 2.5% 20% $636 1.8% 0% 3% $2.70 4.84 30 70 MW GAS-FIRED COMBUSTION TURBINE $300 2000 2.6% 1.2% $2,242 18% 0% 3% $16.83 0.60 30 '''i''*!:~~!:ii;i;ri¥fjglmMMI;!I~il EXISTING AND COMMITTED HYDROELECTRIC 1990 VALUES OF SELECTED PARAMETERS 200 MW COAL -FIRED PLANT (BELUGA) $1.43 ::::::;:~»>>>'ii>>)1~~tttt~~~~II1~I~~~it~~~i~~~I~~~~i@f~I~i~~~~~~~if~i~~Ht~~tiItI~iIrr@fif~itlti~itHi~~t~iI~iI~~~1~fItt TOTAL j DISPATCHED ENERGY FUEL PRICE (I~82 $/MMBTU)--------- ANNUAL FUEL PRICE ESCALATION' 1982 -2000 ---------- 2000-2010 ---------- CAPITAL COSTS (1982 $/KW)--------- ANNUAL CAPITAL COST ESCALATION ------ INFLATION RATE DISCOUNT RATE------------- ANNUAL OPERATING AND MAINTENANCE COSTS-- FIXED (1982 $/KW)------- VARIABLE (1982 MILLS/KWH)--- ASSUMED USEFUL LIFE (YEARS)------- o I !I ', 1980 61 I I ~ 2 8 I i I 2 'J: ~ 8 ~,~4 I. I >- ~ 0:: W Z W PLATE 4 BASE CASE INSTALL~SEGU 1 ~ ! OPTIONS In Battelle's preparation of load and demand forecasts, consideration was given to the extent to which reasonable and extreme conservation measures might be taken to minimize growth in electricity consumption.Indee~,conservation assumptions contributed in part to the earlier noted major decrease in growth rate frdm historical trends to alternative future expectations.It follows that the post-1993 demand must be met by physically installing additional generating units.An additional consideration,regardless of load growth,is the'possible value of substituting new generation modes for eXisting fossil fuel-fired facilities subject to significant cost increases. While it was not the pprpose of the Susitna feasibility stUdy to define the preferred alternative to Susitna development,it is nonetheless true that a reasonable "without Susitna"plan had to be developed as the basis for determining the nature,phasing,and economic viability of the apparent optimum Susitna project. A computerized generation planning model,Optimized Generation Planning (OGP),is commonly used in the utility Industry to assist in making decisions abou~future system expansion.This tool was employed to develop an apparent least-cost non-Susitna thermal generation plan.Given a list of possible additions -each with associated capacity,capital costs,fuel requirements and costs, operating and maintenance costs,reliability and availability data- the model selects appropriate additions on an annual basis throughout the planning period.Plate 4 illustrates the Installation sequence developed for the "all thermal"non-Susitna plan,together with a tabulation of selected additions and key cost parameters.It is this plan which provides a base case for comparing alternative Susitna developmerts and for evaluating net benefits. Although different methodologies and planning models were employed,the base case thermal plan shown on Plate 4 is similar to that produced by Battelle as Plan lA in the independent alternatives study. :3 Certain non-Susitna hydroelectric options are available in the Railbelt.Of these,the most attractive from an economic standpoint would appear to be the Chakachamna project,located about 80 miles west of Anchorage.Chakachamna does not appear in the base c~se plan primarily because It may have a substantial fishery impact and because studies to date have been insufficient to determine expected capital costs with precision.Even so,as will be seen in Section 10,sensitivity analyses were conducted to determine the extent to which Chakachamna development would change net project benefits ...THE BASE CASE THERMAL PLAN IS SIMILAR TO THAT PRODUCED BY BATTELLE . PAGE 7 201020052000 ~.,:,;,;,.,;,:,-..,.,., 1994 YEARS 1994 BETWEEN 1994 AND 2010, THE COST OF ELECTRICITY WILL NEARLY TRIPLE IF THE THERMAL ALTERNATIVE IS SELECTED 2010 J PLATE 5 ANNUAL COSTS -BASE CASE ? Future Electric Energ,y Costs If the base case plan is implemented,certain relatively dramatic changes in Rallbelt energy costs will pccur during the study period, as shown on Plate 5.In part,the expected electricity price rise can be..ascribed to the insidious effects of inflation,assumed to average about 7 percent per annum through 2010.In part,the compounding effects of continuing fuel cost escalation over and above inflation will be translated into higher electricity bills.But other influences come into playas well,and they represent important considerations. Not shown on Plate 5,but nonetheless significant to the consumer, particularly in Anchotage,is the fact that between 1982 and 1993, many of the long-term contracts now held by utility companies for very favorably priced Cook Inlet gas will expire.Not only will major increases in electric energy costs result from the requirement by local utility companies to purchase gas at market prices,but also known Cook Inlet gas reserves may have been depleted in the early 1990's to the point that reliance upon natural gas as the principal fuel for electric energy genehtion would no longer be possible.The availability during the study period of North Slope gas near Fairbanks remains uncertain.Even if the gas pipeline Is built, however,the gas price is projected to be higher than that for the Cook Inlet resource.For these reasons,use of North Slope gas for electric energy generation is not considered a viable alternative. The base case plan calls for the addition of two 20Q-MW coal-fired steam plants at Beluga in 1993-94.~oal mining is assumed to occur at Beluga and an export market for Beluga coal is assumed to exist. To recover the investment in these plants and to account for anticipated major intreases in gas costs,as well as inflation and fuel price escalation above the underlying inflation rate,the wholesale price per kWh for electricity will have risen by 1994 to 145 mills (14.5¢)per kWh and will continue to rise thereafter.It is this price trend against which any proposed hydroelectric development on the Susitna River must compete. If the mid~range forecast is realized,another 200-MW coal-fired plant will be required,probably near Nenana,in 1996 -accounting for the sharp increase between 1995 and 1996 shown on Plate 5.By 2007,a 20Q-MW coal-fired plant must be added.probably at Beluga. In the meantime,a number of gas turbines must be installed to maintain system peaking capability,to satisfy reserve requirements, and to replace similar units which will have reached the end of their useful operating life.Existing and planned hydroelectric plants are included in the base case plan and no hydroelectric units are assumed to retire during the study period.If the Bradley Lake Project is not constructed,costs for the non-Susitna plan will be greater than those shown on Plate 5. An important assumption in the development of the base case plan has been that coal mining operations in the Beluga fields will have been conducted on a commercial scale within the next decade. Even with the assumed transition from gas to coal as the principal fuel for Railbelt electricity generation,coal demand within Alaska will have to be supplemented by substantial coal export requirements before opening the Beluga fields becomes an economically wise decision.Thus,there is some risk associated with reliance upon the Beluga coal scenario.The energy prices reflected on Plate 5 would rise dramatically if Healy fields were to represent the only reasonable coal source or if the only market for Beluga coal were to be for electric energy generation in Alaska. i AN IMPORTANT ASSUMPTION ...HAS BEEN THAT OPERATIONS IN THE BELUGA FIELDS WILL START WITHIN THE NEXT DECADE. It may be anticipated that,if primary dependence is placea upon fossil fuels for energy generation,electricity costs will rise after 201 0 at a rate similar to that reflected in the last five years shown on Plate 5.As will be seen in Section 11 of this report.development of the upper Susitna basin could result in suppression of long-term growth in energy prices and a true saving to consumers.Even so,important potential risks and environmental impacts must be pondered. PAGE 9 DAMSITES (""v .f') J ( l.",. \ \ ~'-. •__._.~.K!!:E'!!!!-.) --\--"'---..\--- \ ..-) ../'-/ ../'''/....--. ~\ ~") 1~i ~TYON~4.-:-'JI -rOlr J A L4xn-\ \~~~\\~SUS/~..fV,.-...A ')I \I.I.ME·".;,;~( "'-.~'.~,;..;~\ J---'\<,k,.~ ~,. r} ...'t!o\J~/!<.~tJ () \ \ \ ----........O~---"""~<I '\.te-'f~4>,-..; DEVIL CREEK .~<"~ ~¥'C'/v-!"~ ~ I .fi,vt;/L·ALt<"~---- ;.~~ .$:-1:6 ~o, ~~ WATANAR~FOGer- ,CREEK CANVON .....,._..SUsrTNA ill ~. \'p-·/\'_·'/·I...../V :,(NO DEFINITE 'J... •LOCAnON)~('\... \,j ...."r;-"(I") \~/i \.--" )) '\(.."JCp 1'"~'!t"i"'Y\~fl . t.(f_.r-._..-.l l.-' / .(,~/ (j ~ ~ o 10 ZO I j I ""LES N tL lr ::;.-., PLATE S UPPER SUSITNA BASIN ~ I UNDIFFERENTIATED SURFICIAL DEPOSITS METAMORPHIC AND METAVOLCANIC DRAINAGE BASIN IVVVY>! IV\!V Y V v.,,·/V V ~GRANODIOR ITE AND ~DIORITE D oomt.:1 ARGI LUTE AND····;:W::::~::GRAYWACKE@ ~V">V':~"v;~ Cc;,vvvvvvvyvvvvi 'VVVVV'vV\lVVV\ ~~-4~~~~~~~~~~~~JII v v v v v v v v v v V v y'V v v v v V ~~~~~~~~~~~~~~~r~~ 'VVVVV~~"""i:/,~vv>J,J~v'p"''''(.>1- DENALI FAULT ~ CASTLE MOUNTAIN FAULT 20 MILES ! ---------~~~w >-"\)\..CH .O~O~~~~\)\..i y/tO~~~UY~ 'l.y ~/ / /"1. /'1. ~ 'l //~)~/~~~y '<.Y-'v..J4Y.>/,,( ~r$~0"~;'/.,( d~<~!W ~--~.,(41:.{[~*$'·~~~7 ~?~~~UV~~A~rP$"-I;/'A -<.~~:t~t::~,..·~A ~<;~~~,IC~~.- ...~<;.:~,~cy'A,-<,.-<'_A""~i'Y I /-rvvv"v"?,YC/1"',"""'-.(vvvvv"vvv -\.r ..v vVV"v v v ~"'~\''''vvvv~""«;","".JU<..,.A~«; ,(-<,.~'v ,( / A / .,( / ~ /' A' ./ ~ ./ .,< ,/ /' I L ~ I ~ OEVELOPMeNT SELECTION Basin Characteristics The Susitna River exhibits two distinct seasons of flow.Between May and October,snow and glaci!il melt,together with heavy rainfall,contribute about 90 percent df the annual total flow.Modest wi?ter flows occur in the ma;nstem,and many smaller tributaries freeze solid in the coldest months.Less than 20 percent of the total Susitna discharge into Cook Inlet is contributed by the Susitna river above Devil Canyon.As the river turns in a southerly direction after leaving the steep narrow canyons of its westerly leg,major tributaries,including the Chulitna,Talkeetna and Ventna Rivers, contribute to the bulk of the total discharge which ultimately reaches the mouth.I Occasional high flows in the Susitna contribute to the formation of productive habitat both for fisheries and for wildlife as land is alternately inundated and exposed and as sedimentation and debris is picked up and redeposited.However,Portage Creek.just west of Devil Canyon (see Plate 6),is the furthest point to which salmon migrate.Raging torrents in the canyons beyond Portage Creek present a natural barrier t\>further upstream movement.Floods with return periods of 50 to 10,000 years range from 48,000 cfs to 200,000 cfs at Devil Canyon.The probable maximum flood (expected never to occur)is 366,000 cfs at Devil Canyon. The upper Susitna basin has a complex geology,as will be seen on the overlay for Plate 6.A history of at least three periods of major tectonic deformation contributes to this complexity.Volcanic flows and limestones,formed 250 to 300 million years ago,are overlain by sandstones and shale.A tectonic event dated approximately 150 million years ago resulted in the intrusion of large diorite and granite plutons.Marine de~sition of silts and clays followed.Faulting and folding of the Talkeetna Mountains area in the late-Cretaceous period (65 to 100 million years ago)resulted in the formation of argillites and phyllites near Devil Canyon.The diorite pluton that forms the bedrock of the Watana site was intruded into sediments and volcanics about 65 million years ago.Andesite and basalt flows nearby were intruded after this plutonic intrusion. 4- A third regional uplift about 20 to 40 million years ago raised portions of the basin as much as 3000 feet.Since then.erosion, glaciation,and active downcutting of streams and rivers have combined to form the current topography. The upper basin lies in a highly seismic region.Historical earthquakes within 200 miles of the upper Susitna River have generally originated from deep within the earth (the Benioff Zone) and from the crustal seismic zone.Major faults include the Denali fault system and the Castle Mountain fault.The Denali fault lies 30to 40 miles north of potential dam sites and it is capable of causing earthquake magnitudes of 8.0 on the Richter scale.The Castle Mountain fault is 60 to 70 miles to the south and could cause earthquakes of magnitUde 7.5.The most dominant earthquake source,however,is the Benioff Zone,which itself contains two distinct segments separated by a transition zone of low seismic activity,The shallower portion could produce earthquakes of 8-5 magnitude within about 57 miles of Devil Canyon and 40 miles of Watana,The deeper segment could generate 7.5 magnitUde about 19 miles closer to Devil Canyon.The absence of faults with recent displacement in the vicinity of the sites sets an upper limit on the magnitude of an event that could have occurred in the crustal zone without detection.However,a remotely possible "terrain" earthquake occurring with a magnitude of 6.25 less than 6 miles from the sites must also 'be considered. It tollows that jf hydroelectric development does proceed in the basin,proposed projects must be sufficiently robust to withstand occasional high floods and major earthquakes.At the same time, impacts on important downstream fishery resources and on wildlife populations in general must be minimized. THE UPPER BASIN LIES IN A HIGHLY SEISMIC REGION. PAGE "J11 IEFINE OBJECTIVES PLATE 7 INPUT FROM,AVAILABLE SOURCES-PREVIOUS AND CURRENT STUDIES FEEDBACK FEEDBACK DEVELOPMENT S'ELECTION PROCESS 1 1 J Plan Formulation A generalized plan formulation and selection process was developed to guide the various planrvng studies.Plate 7 illustrates the procedure.Of the numerous planhing decisions made,perhaps the most important were the selection of the preferred Susitna basi n development plan and appropriate routes for access and transmission lines.In broad terms,a large number of possible choices was subjected to successively tighter criteria screens until a preferred plan was defined. , The steep narrow canyons in the upper basin offer an unusually large number of possible dam sites.They offer opportunities as well for considering a ranbe of alternative developments at any single site.Plate 6 locates the many sites which were reviewed in the development selection process. After detailed screening to account for important technical, economic,and environmental criteria,three general plans emerged as being appropriate for more detailed evaluation:(1)the Watana and Devil Canyon sites,~2)High Devil Canyon and Vee sites,and (3)a combination of a dam at Watana,a relatively low regulation dam midway between Watana and Devil Canyon,and a tunnel from the low dam to a downstream portal near Devil Canyon. A technically sound preliminary design was produced for each plan, and preliminary cost and energy production estimates were prepared.The OGP model was run to evaluate economic viability as well as to determine optimum date~upon which the various stages of alternative Susitna developments should be operable. Quantitative and qualitative environmental and social data were compiled and cOrl)parisons were made.Sensitivity tests were conducted to determine the extent to which differences between expectations and the potential extreme values of certain key parameters affected each plan. The Watana-Devil Canyon plan was found to be clearly superior to development of the High Devil Canyon and Vee sites on economic, energy contribution,and environmental grounds;and it was found marginally better in terms of social criteria.Both plans are technically feasible. The Watana development is common to both remaining plans. When compared to the tunnel alternative,the Devil Canyon dam was found to be significantly .better in terms of economic and energy contribution criteria,and marginally favored for social criteria.The tunnel scheme was moderately favored environmentally,While both plans appear to be technically feasible,however,a greater degree of technical uncertainty was associated with the tunnel plan.A clear economic advantage of the Devil Canyon dam was judged to outweigh the reduced environmental impact associated with the tunnel scheme. Thus,the selected arrangement involves construction of dams at the Watana and Devil Canyon sites.It lends Itself well to staged development since the second dam can be deferred or accelerated as a function of actual future growth in Railbelt energy demand. ...THE SELECTED ARRANGEMENt JNVOLVES CONSiRUC110N OF DAIMS AT THE WATANA AND DEVIL CANYON SI'TES. PAG'E 13 o 10 ZO I I J 1 1 I t t 1 ACCESS· PREFERRED ROUTE ALTERNATE ROUTE TRANSMISSION LINE_.-ROUTE ,..--.\ <:') --~l i~~~"./) ~'l. (yO!'I£' LAJ(E' I ~ '~'''' I .~'"'~~I9IV<,,~ ~ D~~(CANYQN /t ",,-9:........:.'1''v...-''\._../\_...r...:..~__/~~{'".- \t'} -J 'J--"~ f.1l "__(\ R'Y •....../r-"(J,f~ft ~\~,"'''~""./i (~."\\,--'./J'\"t~)I ~ \(p"vf ll 1 \'~~..........."",y -!:..A!.5..!;...Oi.!!!!-."/((f I /~- t ((-.....r-._._..-./l ...-" (}/Vo~7 U N t :--' M'lES PLATE B ACCESS ROUTES ) j Access Route Selection The generalized plan formulation and selection process illustrated on Plate 7 was also applied to the selE/ction of important access and transmission line routes.Plate 8 dispfays various candidate choices copsidered in the upper basin. Three main access corridors emerged after initial screening.Each was assessed by conducting environmental and engineering studies,reviewing a~rial photography,and preparing geologic maps.Important objectives included allowing construction to proceed on schedule,minimizing construction and logistics costs, facilitating operation and maintenance.minimizing adverse biological impacts,l accommodating preferences of local communities and Native landowners,and accounting for the concerns of interested resource agencies. A total of eleven different plans was produced from the three main corridors. No single plan was found to be consistently best in meeting all objectives.Even so,tra~offs were made between environmental impacts and socio-cultural impacts,and a preferred access plan was selected.Plate 8 traces this route.Important features include: provisions for limited access between Gold Creek and the Watana site by way of a pioneer road to commence in mid-1983;deferment of road access from the Parks Highway until after award of a federal license for the project;rendering the pioneer road impassable in the event that the project does not proceed:use of special construction techniques to minimize environmehtal damages;controlling public access;and special mitigation recommendations.such as a full service constructio?camp,to minimize undesired changes in local communities. Transmission Line Routes Transmission line route selection followed a similar pattern to that for access routes.I nitial corridor selection resulted in narrowi ng the options from 22 possible choices to three which reasonably met established objectives.The selected transmission line route generally parallels the Alaskan Railroad between Willow and Fairbanks.Between Willow and Anchorage,the route extends in a southerly direction to a point west of Anchorage.where undersea cables will cross Knik Arm.Between Willow and Healy,the route would utilize the transmission corridor previously selected by the Power Authority for the Railbelt I ntertie. Plate 8 displays that portion of the transmission line route which lies within the upper basin. NO SINGJ..E ACCESS PLAN WAS FOUND TO BE CONSISTENTLY BEST IN MEETING ALL OBJEC- TIVES. PAGE 15 1 I 1 ) I I I I I ] J 1 o 2000 40C() I 1 I FEET ,/\ '" WATANA SITE FACILITIES r ~CONSTRUCTION ~.';;~~1/· I ~~--Y .--J.:.(l ..r;' !):( (---;..:-::JJ{ !\RlJNWAY ""!£:;--~NSTRUCT'ON~'~'1 {t~'r \,.,\)VILLAGE .-~.•\.,-~2200,~"I~'" .----/~rJ ~ ..f'..-/-.(.-2000~_._'f .-J,vcc>--------;-fI..•__,1/"~_'~/~~,J~'-'(/,~#'-..l.(,\c:::: ,~"'-=-.~..r-,-_J ).".,...__'Ilf1J /_-._'"'-_:::-.:-......."-""r _......._~~,.._,,_..'.'~..),.I '__.J'"".............--::-.='-....._--,JJ ,.__................. I ./'-',£"rr............../''/_.......-......,......~_....!//-v,,-..y _-~_~'"J _/ r__,,:-_~;/__.,,-'"/~---,"'\--~_;Jrtf~__~;:::-......_~.-#--)~-=:-~===.....".,,'.,)I';v---,....--,",-_,I ~......._--.,;-_..~....",)-...-.....-/'-,.-.~.~;/~/..-/_-,_,,-__./~..../,_,.\l .~-._.......-:::\:,:"-.~L1~--:__.Jr--"--....<~-J..-.--....J 1,./ l·""'./....,.1./~.;:.-..•//".~~.~-' ~_~;:_~f-~~/--••~'V --..J 'r---'L~ N MILES ~ o I '1<00 _ rI400~________ o "IlIII RESERVOIR PLAN N C':\(p""""0 ),,,,,d!"'~'~t!--"' ~~~I~ N tL ,li PLATES PR'EFERRE DEVELOPMENT LAN ~R'OPOSED DEVELOPMENT The proposed plan for full basin development is shown on Plate 9.In the event that the State decides to develop this plan.two major reservoirs will be formed.The larger reservoir extends 48 miles upstream of the Watana site and has dn average width of about one mile and a maximum width of 5 miles.The Watana reservoir has a sUrf~ce area of 38.000 acres and a maximum depth of about 680 feet at normal operating level. The Devil Canyon resetvoir is about 26 miles long and one-half mile wide at its widest point.A surface area of 7,800 acres and a maximum'depth of about 550 feet represent conditions at normal operating level. Temporary constructidn camps near each of the dam sites will be removed after construction is complete,but a permanent townsite will remain in the project area to accommodate the needs of the operating and maintenance staff.Appropriate recreational, educational.medical.commercial,sanitation.water supply,and religious facilities will be included in the townsite.Access and egress will follow the saVle route as was originally provided for construction purposes.A permanent 6.oo0-foot airstrip will be constructed. Staged development is planned to provide maximum flexiblity in meeting actual growth in energy demand as it develops.An initial installation of 68a-MW of capacity at Watana will be available to the system in 1993 and 340 MW will be added in 1994.If the mid-range forecast is realized,Devil Canyon will be completed by 2002 with an installed capacity of 600 MW.Ev&n so.the commencement of construction and the completion date for this second stage can be deferred or advance<;l as necessary to meet future needs. I 5 THE WATAttA RESERVOIRWILL:BE48MILESLONG AND THE DEVIL CANrYON R'=:SERVOIR 26 MILES LONG. PAGE 17 FREEBOARD DIKE ~ N t o 400 800 1200 I I 1 I rEEt )C 2\OO~ EMERGENCY SPILLWAY MAIN ,/____ACCE~:~HOUSE] __.l-\<:fJ ~,,,p--.p>~ / y~ .z~oo_------...."" ......-..- 1 PLATE 10 WATANA GENERAL ARRANGEMENT Watana Details The general arrangement for development of the Watana site is illustrated on Plate 10 and a sk~tch appears on Plate 27. Comparisons of embankment and arch dam altematives at Watana showed significant cost advantages in favor of the former. The main dam will be an earthflll structure with a maximum height of 885 feet,a crest length of 4,100 feet,and a total volume of about 62,000.000 cubic yards.During construction,the river will be diverted t,hrough two concrete-lined diversion tunnels,each 38 feet in diameter,in the right (north)bank of the river.Upstream and downstream cofferdaflls will protect the dam construction area from floods with return frequencies of 50 years or less. The power intake includes an approach channel in rock on the right bank.A multi-Jevel,reinforced concrete,gated intake structure~ capable of operating over a full 140-foot drawdown range will facilitate maintenance of downstream water quality (especially temperature control -an'important consideration for Susitna fishery resources).StX ci;>ncrete-Iined penstocks,each 17 feet in diameter,lead to steel-lined sections terminating in an underground powerhouse complex where six Francis turbines,each producing 250,000 hp at rated head,can be accommodated.The initial stage includes four such units together with 180-MVA generators to be installed by 1993,followed in 1994 by the final two units.The turbines discharge into a surge chamber and thence to the river via two concrete-lined 30-foot diameter tailrace tunnels,one of which connects with one of the original dfversion tunnels.A transformer gallery is provided upstream of the powerhouse cavern.Oil filled cables extend from Te transformer g~lIery to a surface switchyard. Outlet facilities incorporated into the arrangement will discharge floods with return frequencies of 50 years or less through six fixed- cone valves to minimize undesirable downstream.nitrogen supersaturation -another important consideration for fishery resources. Two spillways will also be provided.Flows with return frequencies between 50 years and 10,000 years will be handled by a main chute spillway on the right bank.An emergency spillway,also on the right bank,will permit discharge of the probable maximum flood without overtopping the dam, . ~lN) ""~I.-l(fvA.~ot f OUTLET :FACILITIES WITH:FIXED-CONE VALVES WILL .MINIMIZE UNOESIRABLE DOWNSTIREAM NITROGEN SUPERSATU.RATION. PAiGE "18 2~OO 2.200 2000 :;;...... ~ 1800 Z 2.. <II>... 1600 -'... 1<'00 1,00 2200 2000 ........... ~,eoo z 0;:::; w 1600 ~ 1400 SuRGE CHA""'ER SHAn ~-TYPIC.AL ROCK ,BOLT PATTERN POWER~OUSE I I I I ~ACCESS I I I I I I I I I I I IO£LlEf~ r--0RIlIM .L"OA~ DRAINAGE GALLEf\Y ~eox DRAINS (TTl!) OuTLET IFAClUTt£S TUNNEL ~:ERl.lTION GALLERY «TyP )~ DRAINA~ HOLES TO BO'ORAiN GROUT CuRTAIN 1200 I \CONCR.ETE LINED J I 1400'I 2400 I r POWER IIHA~£ MAXlf'L. "T £1._2__0' t;;2000 \.:Jj N.e."",'~k'~'" ...\/17'I 0.PENSTOCK... !:(CONCRETE LINED I g'BOO 1 ,~I TRANSFOR"ER ,GALLERy <II>... ~1600 I CONSTRucnON AOIT 1400 2200 MAX.W~t..-------=n.2/85_0'----:;~~~---i POWER INSTALLATIONS PROFILE ~ ~1800 ;::..>... ~1600 l-2000w...... SPILLWAY PROFILE 2400 ,rl- OA"CREST 2400 ...MAX.W:r.£L 21850"... \ ---...-->- z 2000 ... - ... z I ,2000 ... 2 ----I,~..gREAM z ~1600 OowNSTRE~M 0 ...COI'FEROAlI RIP RAP COFFERDAI4 ;::: ;j ~H ,&~1600 :;... -'w 1200 '! MAIN DAM SECTION I 1200 PLATE .,.,WATANA DETAILS ,I Details of certain components at the Watana site are shown on Plate 11. The main dam at Watana will be amorg the highest in the world.Its 885-foot height will exceed that'of the highest completed elT\bankment dams in North America at Mica Creek in British Columbia (794 feet)and at Oroville in California (771 feet).Two dams under construction in the USSR will exceed 1,000 feet,but only one dam higher1than 800 feet has been completed there. At least seven large (over 500-feet high)embankment dams have been built in seismically active areas.The proposed core width upstream and downstream slopes,and other parameters of the Watana design are cohsistent with and generally more conservative than corresponding average values for precedent structures.Even so,special features are incorporated In the Watana section to provid,e additional safeguards against the effects of seismio loading. The dam foundation will be excavated to solid rock throughout its cross-section and allowances have been made for extensive consolidation and curtain grouting.Grouting will be accomplished from underground galle~es,after which the same tunnels will be used to facilitate drilling drainage pressure relief holes. The core of the main dam is a trapezoidal section,separated from granular fill sections by coarse and fine filter zones.Rip rap protection is provided upstream and a coarse filter zone will be placed at the downstream toe. Field investigations conducted to 'Oate have provided supporting data for selection of the proposed general Watana arrangement. Even so,extensive data collection is expected to continue into the construction phase (0 ensure the safety and reliability of the various structures,One area of particular concern is a buried (relict) channel which runs from a point upstream of the proposed dam site to Tsusena Creek,a distance of about 1.5 miles.This channel represents a potential source of leakage from the Watana reservoir and remedial measures may be required to guarantee the integrity of the reservoir rim through the channel area.Allowances have been made in the project estimate to account for this feature.If no major problems are identified in continuing field investigations ofthe relict channel,construction costs will probably be less than those indicated in Section 8 of this report. THE MAIN DAM AT WATANA WILL BE AMONG THE HIGHE.ST IN THE WORLD. PAGE 2'\ - ) I i ( 8 \""- \. :j.,8 8 u. N o ... 2w ~w (!J 2 ~ [[ II« ..J« .J->w D lU ~ w ~ ..J D. Devil Canypn Details Plate 12 illustrates the general arrangement for development of the Devil Canyon site and a sketch is prlsented on Plate 28. The narrow "V"shaped canyon allows a number of alternative dam types to be considered.Detailed analysis indicated that a thin arch concrete dam is preferred over either a rock-fill embankment dam or a concrete gravity arcjh dam. The main dam will be a double-curved arch structure with a maximum height of about 645 feet and a crest elevation of 1463feet. The crest will be a uniform 2(}-foot width and the maximum base width will be 90 feet1 The center section will be founded on a concrete pad,carried to bedrock beneath the river sediments,and the exteme upper portion of the dam will terminate in concrete thrust blocks located on the abutments.A two-center configuration will be adopted for the arches to counteract the slight asymmetry of the valley and to give more uniform stress distribution across the dam.A rock-fill saddle dam on the left (south)bank of the river will be constructed to a m~imum height of about 245 feet above foundation level Flow during construction will be diverted through a single.30-foQL 'ameter concrete-lined pressure tunnel in the left bank.C~ms and the diversion tunnel provide adequate protection during construction against floods with return periods of 25 years or less.The selection of a lesser return period than that used at Watana takes into account a shorter constrLJction period,the availability of regulation at the then completed upstream Watana dam,and the fact that not only is the main concrete dam at Devil Canyon less susceptible to damClge than an earthfill dam if it is overtopped during construction:but also that outlet facilities at the base of the dam will have been constructed well before the entire dam is completed. The power intake on the right bank will include an approach channel in rock leading to a reinforced concrete gate structure which will accommodate a maximum drawdown of 55 feet.Four concrete-lined penstocks,each 20 feet in diameter,will lead to an underground powerhouse,where four 225.000 hp (at rated head) Francis turbines will be housed.A single 38-foot diameter tailrace tunnel will lead from a surge chamber downstream of the powerhouse cavern. The transformer gallery,oil-filled cable arrangement,and surface switchyard are similar in concept to those at Watana. Seven individual outlets,each with a fixed-cone valve,will be located in the lower part of the main dam.and will be designed to discharge all floods with return frequencies less than 50 years.Once again,this approach,though more costly than conventional surface spillways.minimizes nitrogen supersaturation problems downstream. Floods with return periods between 50 and 10,000 years will be handled by a chute spillway on the right bank,similar in design to that for Watana.An emergency spillway on the left bank witl permit discharge of the probable maximum flood without overtopping the dam. "'~~~!lA.}7.f}'~-. THE MAIN DAM AT DEVIL CANYON W.ILL BE A POUBLE-CURVED CONCRETE ARCH STRUC- TURE. PAGE 23 TRANSFORMER GALLERY SURGE CHAMBER 950 ~Q'O I- .J~~I w w... Z .~(-~~850 ~ ;::«>w ..J W 800 -U 750 ORAn TUBE ;'0:::71, .~\\~~:.:. CABLE SH~n\GROUTING bllERY r CONCRETE LINEDIPENSTOCK /- \/\/TRMISITiON "\~lENGTH,\,/"\ 1"<"[STEEL LINED,'-PENSTOCK"...."............---~-----------~--- --------------------------'--.--1',.I BO~- 950 -- ~OO I- '"'"... ~ Z 8~0Q I- ~ '";j 800 POWER INSTALLATIONS SECTION 1600 I MAX,...L ELI~550' '.00 f-~~- I-Ee "375.0''"""... ~ 2:1200Q I-«>w ..J W 100O 800 ..AERATION G~L!,..ERY /rIAXTwL EL 9150 :60e t;;1400 W... ~ 2.i 200 I- ~ W ..JW '000 800 r LOW LEvEL OUTLET / .--EL,~'OO T....L,£4.89~,O ·~jr ,'~L El 820.0' 1 MAIN SPILLWAY PROFILE ARCH DAM SECTION PLATE 13 DEVIL CANYON DETAILS Details of certain components at Devil Canyon are shown on Plate 13. Eight major arch dams greater th"n 650-feet high have been constructed in the world,the highest being 858 feet at Veneto.Italy. A new arch dam is under construction at Inguiri in the USSR.Upon completion in 1985,it will be 892 feet high. The Devil Canyon tl1in arch dam will be designed to withstand dynamic loadings from intense seismic shaking.High earthquake loadings at the 548-foot high Vidraru Arges dam in Rumania and at the 372-foot high Pacoima dam in California have been experienced with no loss of structural integrity. The arch dam will be founded on sound bedrock located 20 to 40 feet below the normal bedrock surface.To minimize stress concentrations and to increase symmetry,rock surfaces will be trimmed.Consolidation grouting will be provided over the whole of the foundation area and a double grout curtain up to 300 feet deep will run the length of the dam.As at Watana,galleries will be provided both to facilitat9(grouting and for the purpose of collecting any seepage to be drained through holes drilled downstream of the grout curtain. The saddle dam is similar in design to that for Watana,except that the saddle dam shells will be rock-filled. EIGHT MAJOR ARCH DAMS GR'EATER THAN 650 FISET HIGH HAVE BEEN CONSTRUCTED. PAGIE 25 10 ,iii ! J 201020001990 2 o ',I ' 1980 8 I I I ~I 1 ~61 I COAL FIRED --l ~I I<.!>,THERMAL, 8 I UI~rHI\.;nl...U I _~"""""""~QEMI~ANW~IQ_"l ___\.~ t.,I ~"-'\."\."-'\."'-'-'-"-'-""'-1'-....'""'-"-"'-'-'J'-..>- <.!> ~41 ~~~~I \ $152 50 100 1020 MW WATANA 600 MW DEVIL CANYON (SECOND STAGE 1 o $3,186 18% 0% 3% $100 VALUES OF SELECTED PARAMETERS 1020 MW AT WATANA (FUEL PRICE (1982 $/MMBTU)--(FIRST OSTAGE) CAPITAL COSTS (1982 $1 KW)$3,643 ANNUAL CAPITAL COST ESCALATION 1.8 % INFLATION RATE 0% DISCOUNT RATE 3% ANNUAL OPERATING AND MAINTENANCE COSTS (1982 $IN MILLIONS)--------- USEFUL LIFE FOR ECONOMIC ANALYSIS (YEARS)-- EXPECTED USEFUL LIFE OF PROJECT (YEARS )--- PLATE 14 S'US'ITNA INSTALLATION SEGUENCE PRO.JECT OPERATION The OGP model described in Section 3 was used to determine the optimum project staging sequence under each of the demand forecasts.As may be seen from Plate 14,in the case of the mid-range forecast,the Susitna project represefJts a major portion of the net energy generation when its various stages come on line,though this share would gradually decrease after 2010 if demand continued to rise. Operating Constraints The extent of the concentration of Railbelt,generation once Susitna has been built requires that special attention be paid to system reliability.To this erd,four major categories of operational reliability criteria wenol applied in generation planning and project scoping:(1)total system loss of load probability must be less than one day in ten years,(2)a single contingency situation (e.g.,loss of a single generating unit or a single transmission line)must be met without overloading remaining system components:a double contingency situation should be handled within emergency ratings of surviving system com~onents for the probable duration of the outage,(3)provisions must be made for maintaining system stability and voltage regulation through a broad range of likely incidents,and (4)in the event of catastrophic loss (e,g.all transmission lines on a single right of way),rapid restoration of supply must be possible,A risk analysis of the proposed, transmission system confirmed that these criteria will be satisfied. In addition to meeting technical criteria,project operation must also accommodate vagaries of nature (e:g.,a year of unusually low flow conditions),a variety of important environmental constraints (e.g., downstream water quality and quantity),the performance oharacteristics of g~nerating units (e.g.,rough operation at less than 50 percent of maximum output for any singleturbine-generator represents an equipment constraint),and geotechnical concerns (e.g.,reservoir slope stability problems can be exacerbated by extreme drawdown and filling limits). A mathematical model of the reservoir was used to evaluate the s optimum method of operating the Susitna reservoirs and power plants to meet these criteria:from this it is estimated that average annual energy output of 3540 GWh at Watana alone and 6790 GWh for the total project can be achieved.Firm energy,corresponding to a low flow sequence expected to occur only once in 70 years,is about 5400 GWh per year. AVERAGE ANNUAL ENERGY WILL BE 3450 GWh FOR WA'fANA ALONE AND 6790 GWh FOR THE TOTAL ,PROJECT. PAGE 27 _TALKEETNA RIVER GOLD CREEK DEVIL CANYON SITE PARKS HIGHWAY BRIDGE'- CHUUTNA ________ RIVER TRIBUTARIES 1%- S PRE -PROJECT PRE -PROJECT J A POST-PROJECT N D J F M AM J MONTH OF THE YEAR GOLD CREEK PARKS HIGHWAY BRIDGE U'l b 60 ooo ~40 80 01 '_3 i ; I I ,I I I ! ! 30 ~u 820 Q ~ -TRIBUTARIES "\1YENTNA________ 0 N 0 J F M A M J J A S I RIVER MONTH OF THE YEAR 140~ il ~~----~---I SUSITNA SUSITNA STATION STATION 120 ~ UIOO 0 I -,,-I I I"'\J~~g 80 z-60 ~g 40 lL. f~3i ,'1 I L 0001(INLEi ;I I !I I I 0 N 0 J F M A M J J A S MONTH OF THE YEAR PLATE,~5 I SUSI·TNA RIVER FLO\NS 1 1 Reservoir Considerations A particularly critical period for effective project implementation occurs during impoundment of the ratana reservoir.Based upon meeting minimum post-project flow requirements in critical months for river maintenance and fisheries needs,about 2-1/2 years of ....average stream flow is required to fill the reservoir.Filling will commence aHer dam construction proceeds to a*point where impoundment concorrent with continued construction can be accommodated even if a flood with a 100-year return frequency is realized during the filling operation.Once Watana reservoir is operational,later impoundment in the smaller Devil Canyon reservoir can be acc~mpljshed with relative ease. Downstream Flows Plate 15 provides a hydrograph which relates average flows under natural conditions with those which would normally be provided after the project is completed.Below the confluences with major tributaries of the Susitna River,differences between pre-and post- project flow conditions will be less pronounced,as the entire upper basin contributes less tban 20 percent of the total discharge into Cook Inlet. Reservoir Induced Seismicity After the reservoirs are filled and particularly during the early years of project operation.some potential exists for reservoir induced seismicity (RIS).Earthquakes which would occur at some point in time under natural states of stress may be triggered by the increased weight of water in a new reservoir or by lubrication and hydraulic action upon highly stressed rock.Based upon mathematical models and data collected during the feasibility study,it is estimated that there is a 90-percertt probability of an RIS event if both reservoirs are considered as a single hydrologic regime.The maximum magnitude of such an earthquake is estimated to be 6.0 on the Richter scale. which is within the range of extreme seismic events which the dams are designed to withstand.This maximum magnitude is no greater than that which could be produced under natural conditions if the project is never constructed. tle-JlS~ 'f~ ~~o.-VJfurJ? ~vf"r IT WILL TAKE 2-1/2 YEARS TO FILL THE WATANA ,RESERVOIR. PAGE 29 ---- >'- (DEVIL CANYON){ \1982 1983 ~4 1985 1986 1981 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 \"'--~IEW PIONEJR ROAD MAIN ACCESS ROAD CAMPS ~ND qTH~R SITE FAC!LlTIES 1.--I DIJERSION SPILLWAYS <J I I ,~I CONSTRUCTION OF MAIN DAM-1--.,...-- POWER ~ACIUTIES I\~,i ~I DETAILED DESIGN : I I : "+IMPOUNDMENT I C""-~-""'- colT'NUOUS ENVIRONMENTAL STUDY AND MONITORING 1 OPERATION 0'0«7-:<-f-/'~:'lllSW.~,j'V.@;l'i~.m<,~r"~T~m:,~v~,;;;;.,'?'>m~1~:::':':::'i,*,j:"r'8i8'::~:''';:''~I~@.'':=:~~~~ (r'WATANA). ' 1991 Jll92 1993 '1994 1995 1996 1991 1998 1999 2000 2001 2002 2003 2004 2005 2006 1'--.//CAM)S AND O~HER SITJ FACILlTI~S DIJERSION SPILLWAYS--1-......, f CONSTRUCTION OF MAIN DAM -..L I 1--,...- I i POWER FACILITIES : f--J I DETAILED DESIGN ~-~ ~IMPOUNDMENT I I .~CONTINUOUS ENVIRONMENTAL STUDY AND MONITORING OPERATION H:Gi>~-ilWo_=~~~:::'<::~'~¢"«"-:T'~'t";""'I;""'=:=W;"'"""""');T~~~I;:l~W""'T""*"~~"m!<-"""~"=i:ii';~li::f ::::W"n~..:-........:.,',"/"".':':':'.':'..,:'I '-=--'.....~.,''''''',''.'.·:,:·:·:···.."r .....,,':·",··T" PLATE.,S I PRC.JECT SCHEDULE 1 J ~ ~ ! I I I r I 1 CONSTRUCTION Because generation planning studies indicated that capacity must be added to the Railbelt system in the early 1990s,construction planning for the proposed Susitna project has been based upon meeting a 1993 power-on-line da'.Plate 16 provides a broad schedule of activities which must take place if the Susitna project is, to assist in meeting perceived needs implicit in the mid-range fore- casts. The Licensing Period ShoUld the State of Alaska decide to proceed with the project,a license application will be SUbmitted to the Federal Energy Regulatory Commiss)on (FERC)on September 30,1982.Given the large size of the project and the inevitable changes its construction - would cause,it may be anticipated that concerned agencies, organizations,and individuals will avail themselves of the opportunity to be heard.Thus,a period 0t,27 months has been set aside to accommodate license processiIlQ.Commencing in mid- 1983 and concurrent with this processing period,construction of a 'iTmlte<l access pioneer r-pad is planned.Necessary permits for this activity will be submitted by .?eptember 1982. Detailed design and the preparation of initial construction bid packages will also proceed during the license processing period. Important field investigations,particularly in the environmental and geotechnical areas,will continue. Post-License Activities Upon award of the FERC license.bids will be solicited for required early construction 'lctivities and for equipment with long lead times. The pioneer road will facilitate the transportation of equipment and camp modules to the Watana site so that camp and diversion facilities can be developed while construction of the main access road proceeds. By mid-1985.work will commence on the first diversion tunnel at Watana.All diversion facilities,inclUding cofferdams,will be operable in the spring of 1987.Thereafter.major construction activities for various project features will generally proceed in parallel.Reservoir impoundment will begin after breakup in 1991 and as soon as the main dam elevation is high enough to saT"ely- permit it. The construction schedule for Devil Canyon is less critical,since under the mid-range forecast,power is not needed there until nearly a decade later than at Watana. ~~~~~,0 \.i)~0J\~'f~ 'iJ '\)vl'\'\0-~'v\' SHOULD THE STATE OF ALASKA DECIDE TO PROCEED WITH THE PROJECT,A LICENSE APPLICATION WILL BE SUBMITTED TO THE FEDERAL ENERGY REGULATORY COMMISSION ON SEPTEMBER 30,1982. PAGE 31 PLATE'!7 WORK FORCE [ Risks Although the project scheduling has taken into account historical data for normal efficiency and productivity in northern regions and allowances have been made for a range of possible adverse condi- tions,it is nonetheless true that important uncertainties remain,A schedule risk analysis was conduyted to account for unusual extremes in nature,labor and matehal,and other variables.This indicates that while there is a 65-percent chance that the Watana project will be completed on or before the scheduled date,there is about a 10-percent chance that the power-an-line date will be delayed by two years 'or longer when important regulatory risks are accounted for (especially the possibility of delays in FERC licensing).Risks are further discussed in Section 8. Manpower Employment opportunities will be significant during construction of the Susitna project.A gradual increase In the work force will lead to an average requirement of about 1,450 persons between 1985 and 2000,and a peak of about 3,500 in 1990.Plate 17 plots manpower needs during the construction period of both projects. 'I I EMPLOYMENT OPPORTUNITIES WILL BE SIGNIFI- CANT DURING CONSTRUCTION OFTHE SUSITNA PROJECT. PAG~33 WATANA ~ I ~ t $230 5/ 78 1,532 100 391 378 2,760 482 ROADS LAND AND LAND RIGHTS POWERPLANT DAMS AND SPILLWAYS MECHANICAL AND ELECTRICAL EQUIPMENT TRANSMISSION CONSTRUCTION INDIRECT COSTS SUBTOTAL CONTINGENCIES $ DEVIL CANYON 39 0 22 76 635 68 0 91 188 1,1 19 196 I I I ALL COSTS IN MILLIONS (JANUARY 1982 DOLLARS) 50 40 30 20 10 PERCENT OF TOTAL o 405 $3,647 ENGINEERING AND ADMINISTRATION TOTALS ESTIMATED TOTAL COST OF PROJECT =$5,127 I~J-.\t~.~~~ 165 $1,480 o I 10 20 30 40 PERCENT OF TOTAL 50 LATE 18 I ESTIMATE OF COST COSTS Capital Cost Estimate Assumptions were generally conservative and the total project cost estimate is on the order of 50 percent higher than the January 1982 dollar value of the most recent estimate by the U.S.Army Corps of Engineers for a similar development of the upper Susitna basin. Cost and Schedule Risks Extreme floods or major earthquakes can lead to serious cost con- sequences if they occur during construction.although the project is designed to safely withstand such events after it is completed. Geotechnical investigations to date have included an unusually extensive drilling program for feasibility determination,but excava- tion during construction may yet reveal unfavorable and unanticipated conditions for which expensive remedial measures must be applied. A risk analysis was conducted to determine the confidence level of the estimate as well as to define the probability of exposure to serious overruns.Up to 10 possible magnitudes for each of 21 different risks were considered,and probabilities were associated with each.Estimates were made of the conditional probabilities of B various damage levels if any single risk magnitude were to be realized;and minimum,modal,and maximum values were assigned to the cost and schedule implications of appropriate responses.In addition to considering unusual and unexpected possibilities,the risk analysis also took into account historical variance between initial estimates and actual costs on various completed water resources projects, PREPARATION OF THE PROJECT ESTIMATE TOOK INTO ACCOUNT DETAILED ALASKA- SPECIFIC DATA ... PAGE 35 WATANA COST RISK0.18 =;r-----=====:--I:1 II o 16f-----f 0.14 riUi;;i1wi NO OVERRUN l:lllitllF~2~~~~~:ei:~LTEPROJECT PROBABILITY THAT CAPITAL COST!WILL BE WITHIN !NDICATED RANGE 0121 I o NET PROJECT BENEFITS MAY BECOME NEGATIVE 0041 I 0.02 OL..-__......."""'::':"-""'"-"::'::'""'::'::-"-"""""~7'-''"'''::"'::-'"=''''f'':'~~''''''''~~9~~~''""'"'~~:.L-_-~ WATANA SCHEDULE RISK (EXCLUDING REGULATORY) 022 oro~t \ 018 0.16 o 14 PROBABILITY THAT WATANA WILL BE 012 COMPLETED WfTHIN INDICATED TIME 0.10 INTERVAL 0.08 0,06 r' 004 0,021- 0 «15)(151 -(10)(101-(5)(5)-0'0-5 5-10'10-15 MONTHS FROM SCH$ULED COMPLETlcJN ~:I~~ >15 !:f:jw:::frl o POSS IBLE IMPROVEMENT IN ECONOMiC VIABILITY SOME REDUCTIONS IN NET BENEFITS POTENTIALLY SERIOUS FINANCING AND MARKETING IMPLICATIONS PLATE1S RISK 'C~TA Probability distributions for selected intervals of possible cost and schedule variations are presented on Plate 19,As may be seen from the cost risk histogram,the probability that the project will be completed at a total cost between 9q!percent and 100 percent of the estimate Is about 0.15.A probability of 0.73 (73 percent confidence le~el)that the actual cost (in January 1982 dollars)will not exceed the project estimate can be determined by adding Individual probabilities for each interval. There is a 7-percent chance that the proposed Susitna development wlll experience overruns so great that the base case thermal alterna- tive would be favorable. The second histogra\n on Plate 19 indicates that there is about a ~ percent chance that delays other than those caused by regulatory matters will be long enough to cause serious financing and marketing implications. In short,the estimated cost and schedule are likely to be achieved, although a not Insignificant exposure remains.-Ope~ation and Maintenance As is characteristic of most new hydroelectric developments.the capital cost of the Susitna project per unit of installed capacity Is much greater than that for conventional thermal plants.To the extent that net benefits are demonstrated for Susitna.they are largely derived from avoiding escalating fuel costs which form a large portion of the annual operating costs in the thermal case. When the Susitna project is fully operational,a central maintenance staff and an operating staff,together with appropriate support personnel,will be (ocated at the permanent townsite.Power plants at both dams will be controlled from the Susitna Area Control Center at Watana.In January 1982 dollars,the annual operating and maIntenance costs wlJI be $10 million for the first stage Watana project and $15.2 million for the complete development.For operation of the project within the Railbelt system.a Central Dis- patch Control Center is planned near Willow. POWER PLANTS AT BOTH DAMS WILL BE CON- TROLLED FROM THE SUSITNA AREA CONTROL CENTER AT WATANA. PAGE 37 1,168,000 I 2,300-SOCKEYE 700,000 CHUM 231,000 COHO 148,000[Ji0 3,900 PINK (000 YEAR) AVERAGE ANNUAL COOK INLET HARVEST SUSITNA CONTRIBUTION POTENTIA L POST -PROJECT LOSS BEFORE MITIGATION SALMON ISTRIBUTICN IN THE SUSITNA MITIGATION MEASURES HAVE BEEN INCORPO- RATED INTO PROJECT DESIGN ... 'g.S· ~~ Because of the natural barrier to migration near Devil Canyon,the ~i principal direct impacts of reservoir impoundment will be felt only,. by resident fish popUlations.Some loss of spawning areas will be ". com ensated by an increase in overwintering habitat and the ~ reservoirs I e a I a essary or the existing \$'\:) population of resident fisheries. he ultimate objective of all the various mitigation measures is to chieve no net loss.Potential losses need not occur if proposed artificial measures to maintain the fishery resource are taken. \Y~?:~~~ .£ooY y--~~~ ,~ )lvY"'V Environmental issues are addressed Initially in this section in the context of the proposed Susitna development.Potential impacts associated with the non-Susitna plan are summarized In the final portion.( Fisheries ENVIRONME"NTAL ISS'UES The Susitna River is a major contributor to Cook Inlet fisheries. More than half of the combined Cook Inlet total of chum,sockeye. coho and pink salmon return to the Susitna to spawn.Resident fish species abound as well in the basin.The mainstem provides a migratory corridor and most of the spawning habitat is located within tributaries.sid~channels and sloughs.Plate 20 illustrates estimated migratory distributions for important anadromous fish. If the Susitna project is constructed,the principal fishery impacts will be measured upstream of the confluence of the Talkeetna River and the Susitna mainstem.In the absence of any mitigation efforts, the greatly altered post-project flow regime and warmer water temperatures in winter could result in a reduction of 63,000 to 126,000 chum from the cL(rrent long-term average annual Cook Inlet harvest of 700,000.There would also be a decrease of 2,300sockeye from an annual harvest of 1,168,000.and other losses as shown on Plate 20.In any single year,relatively large differences from these estimated long-term averages can occur.In 1981,for example, chum losses would have been 68,000 and sockeye 14,000. Mitigation measures incorporated into project design include the effective removal of nitrogen supersaturation as a contributor to fish....____ mortality and....Qrovisions for some water temperature cont!2!,l1S earlier described in Section 5.Other mitigation plans under con- sideration Include rrXldification of operating procedures to increase downstream flows during critical times,streambed modification to compensate for lost spawning habitat (though the effectiveness of such a measure is by no means certain -homing problems could ensue),and construction of a hatchery to replace losses. ~v..;>~~. PAGE 39 L .-..p-._ I <$> I -I., "4 I \ .~I .-.......Jf.,(....."\.J?~".1'-oJ .....", 1-'- r ~r>-C/)f-Zf-I.LJ C/)0 C/)0 zw co z ~0 0) w 0 :::) I I ~0 ClW t.) 0 ~I cr .-J<t ~ D []....~ "....;)\\ (t\ '1"-~(> ~~'Ii..~ oj oco 0) 0:: W lD ~ W>oz -.. :Jm-II rn 1 t Wildlife Resources The principal species of big game in the proposed project area are moose,caribou,wolf.wolverine.be~r and dall sheep., Plate 21 provides relative distributions of moose observed during th~field investigation program.In addition to direct loss of inundated moose habitat and displacement of home ranges within the reservoir area,some reduction in downstream browse may occur as altered flow regimes affect vegetative succession.Habitat management is the principal mitigation measure being explored to maintain the moose population.Controlled burning to stimulate browse growth and reclamation of areas of disturbance are typical examples of habitat Inanagement being considered. Although not recently used,an important historical migration route for caribou will be intersected by reservoir impoundment.Mud flats and shore line ice conditions could impede caribou migration despite their excellent swimming capability.Monitoring spring migration to locate calving areas and protection of calving grounds from human intrusion puring the calving period are proposed. Clearing and removal of trees from the reservoirs is also proposed, 10 prevent mortalities which may be caused by floating debris. Black bear prefer the forest habitat which lies within the impound- ment zone.Nine known dens in the Watana reservoir and one in Devil Canyon will be flooded.Reductions in black bear population are likely if the project proceeds.Lesser losses will be suffered by brown bear as a result of reductions in seasonal foraging areas, though no known dens will be flooded.Restrictions will be imposed to reduce human-caused disturbances,and maintenance of a healthy moose popUlation will aid in prOViding a food source for bears. The Watana dall sheep herd uses a mineral lick along Jay Creek. Partial inundation of this lick will occur,and in the event that use by the herd is discontinued.an artificial lick with similar chemical composition will be established. Furbearers will suffer some habitat loss and increased trapping and hunting pressure can be expected.Measures have been included in project planning to limit human access and to create common corridors for transmission and ground transportation.Hunting and trapping regulations will be enforced. Active and inactive nest sites for golden eagle,bald eagle,and raven lie within the proposed reservoir area.Even so,creation oftwo large impoundments may result in an increased eagle population in the upper basin.Measures will be taken to preserve clumps of tall spruce trees to encourage nesting and the possibility of and need for constructing artificial nests will be explored. No endangered species (the bald eagle is not endangered In Alaska) have been identified in the project area, Historic and Archeological ResQurces Archeological sites representing human occupation during the last 10,000 years and historic cabins built in the 1920s were located during the field investigation program.Mitigation will be accomplished through avoidance,preservation,and where appropriate,excavation and removal of artifacts to museums. NO ENDANGERED SPECIES ...HAVE BEEN IDENTIFIED IN THE PROJECT AREA. PAGE 4'1 '-"-.,.r"-"\ /'.L., \ \ ~'-.':t) C"V' -...~-...-..-- \ \. ) USE INTENSITY ~I RECREATION MEDIUM \.2 MINING MEDIUM ')3 RECREATION MEDIUM ---../4 MINING/RESID HIGH~~~5 MINING HIGH~. .~.:-L."1 6 REC./RESID.HIGH \n,~\7 RECREATiON HIGH ~",..LA<T ._8 RECREATION LOW (:."P:,'SIJ5,r.\d.)9 RECREATION MEDIUM"....L!4/(L • (10 RECREATION MEDIUM II RECREATION LOW J 1 ..- \. \ \\L (~jr-._.~.. '), """'". \\ .(\". 'l (\-'-'\.../,\.-'II •••./"J'IP<.Xth: • -J ~i\.'f.t%];:p;:'~8 '" 1.)•....c.',~~~~~J-._____ (,~. "1', (J~ '\... ~ \ ~ -~ -',%:-,,:,'0 01 '.",,,-<-"'., o 10 20 I !I MILES N --'IL l, PLATE 22 LAINO USE 1 r 1 \ Socioeconomics The population of Alaska has increased steadily since the 1940s, with accelerated growth occuring in 1he 1970s.About 50 percent of the total is located in the greater Anchorage area,and the Railbelt as a 'whole contains 70 percent.Historical spurts have been occasioned by major project activities,generally followed by short- term decline or a leveling off.The Trans-Alaska Pipeline System provides the most recent example of this phenomenon.Increases in population during the past decade have been particularly pronoun- ced in the Matanuska-Susitna Borough,within which the proposed dam sites are contained.The borough is more dependent on seasonal employment than large urban centers and has consistently had high unemployment rates. As was indicated in section 8 of this report,significant employment opportunities will be generated over a period of 15 years if Susitna proceeds. Demands for services (e.g.water supply,education)will increase in general by less than.5 'percent above baseline conditions. particularly if much of the required work force is drawn,as planned, from within the state. The greatest relative impacts are likely to be felt in Talkeetna and Trapper Creek,where housing shortages may occur and where proportionally greater numbers of visitors and would-be residents, particularly during the construction period,can be expected. To mitigate adverse impacts on local communities,the proposed site facilities include construction camps and a permanent town site fully equipped witt}all amenities,thereby reducing the need for travel to and servi~e from these areas.As the project proceeds, coordination will be maintained with local communities in order to maintain a proper balance between preservation of desired life style and local economic needs which project management may be able to satisfy. land Ownership and Use Most land In the project area and directly south has been selected by Native corporations under provisions of the Alaska Native Claims Settlement Act.The U.S.Bureau of Land Management generally manages lands to the north. Existing land use in the upper basin is typical for that of interior undeveloped Alaska (see Plate 22).Broad expanses of wilderness areas are present,access is severely restricted,and only a few man- made developments or structures are currently found.Early in the feasibility study period,a camp near the Watana dam site was erected on Native land to support field investigation activities.In the event that the Susitna project does not proceed,this camp facility may revert to Native ownership.If so,some further developments on Native land would probably occur. If the project does proceed.only low-level recreational development is currently proposed.Camp grounds,picnic areas,boat launches. and hiking trails are planned,as are scenic overlooks. While the creation of major dams and reservoirs will necessarily change the aesthetics,efforts were made in project planning to minimize visual impacts.Powerhouses will be underground,flow will be maintained In the short stretch between Devil Canyon dam and the tailrace portal downstream,borrow areas will be within the impoundment area where possible and will otherwise be restored or converted to ponds,and other similar measures will be taken. MOST LAND IN THE PROJECT AREA AND DIRECTLY SOUTH HAS BEEN SELECTED BY NATIVE CORPORATIONS ... PAGE 43 POTENTIAL IMPACTS ALTERNATIVE GENERATING UNIT ANCHORAGE-COOK INLET AIR QUALITY IWATER QUAL!TERRESTIAL ECOLOGY AOUATICI MARINE ECOLOGY NOISE, VISUAL B.OOOR HEALTH AND SAFETY JOBS IN ALASKA BOOMI BUST EFFECTS LAND-USE ISUSCEPJlBIUTY EFFECTS TOINFLATK>N ,GAS TURBINE COAL-FIRED FAIRBANKS -TANANA VALLEY GAS TURBINE COAL-FIRED HYDROELECTRIC CHAKACHAMNA MINOR IMPACTS MODERATE IMPACTS SIGNIFICANT IMPACTS PLATE 23 BASE CASE IMPACTS ~ J ) 1 J J l Water Quality In its natural state,the Susitna River is turbid atter breakup.The estimated annual transport of suspended materials at the Gold Creek gaging station is 7.7 million t~ns.Winter flows are relatively free of sediment. Sediment capture efficiencies for proposed reservoirs are estimated at 70 to 100 percent.In 100 years,the esti mated sediment deposition will represent about 5 percent of the gross reservoir volume at Watana and about 14.2 percent at Devil Canyon.No reduction in energy production as a result of sedimentation is anticipated during the project life.As a result of sedimentation entrapment,flows downstream of Devil Canyon will be considerably less turbid in late spring,summer,and early fall.Winter flows will be more turbid than under natural conditions,Other water quality changes will occur, but no signjficantly adverse impacts are anticipated. Non-Susltna Expansion It was earlier noted that significant generating capacity must be added to the Railbelt sy,stem during the study period if the mid- range forecast is realized.If,instead of proceeding with Susitna,the base case representative thermal plan is followed,different types of environmental impacts can be expected.Plate 23 summarizes impacts as presented in the Battelle report for system additions common to both Battelle's Plan 1A and the representative thermal plan.Chakachamna appears on the summary because the economic effect of its inclusion was tested in the sensitivity analysis., Coal-fired steam generating plants,the principal component of the representative non-Susitna plan,will be developed in open,well- ventilated sites as pear as possible to available coal fields.Visual impacts will be significant since plumes from cooling towers and smokestacks will be seen for miles,particularly in winter months. Local air quality degradation will be inevitable.Relatively large land areas will be required to accommodate major plant components, stockpiles,and mining operations.Lesser,but nonetheless important impacts in other categories as shown on Plate 23 will occur. Gas turbines would be environmentally superior to coal-fired plants, but new units of this type will serve primarily to satisfy peaking needs and to maintain system reliability criteria.Neither gas supply estimates nor cost expectations support long-term reliance on gas as the principal fuel for generation of electricity, Construction of a hydroelectric plant at Chakachamna would introduce impacts generally of the types described in preceding paragraphs for the Susitna project.Studies to date by others on Chakachamna have not advanced sufficiently to make definitive estimates of potential fish losses,but initial indications are that they will be greater on a relative basis that those associated with the Susitna project I'"100 YEARS,THE ESnMATED S·EDIMENT DEPOSITION WILL REPRES'ENT ABOUT 5 PERCENT OF THE G:ROSS RESERVOIR VOLUME AI WATANA AND ABOUT 14.2 PER,CENT AT DEVil CANYON. PAGE 45 -1000 BASE CASE -500 a 500 1000 1500 NET ECONOMIC BENEFIT (1982 DOllARS IN MILLIONS) 2000 ELEMENT TESTED BASE CASE VALUE HIGH LOAD FORECAST 7,800 GWH IN 2010(11,400 GWH IN 2010 ) LOW LOAD FORECAST 7,800 GWH IN 2010(6300 GWH IN 2010) 5 %REAL DISCOUNT RATE 3% 4 %REAL DISCOUNT RATE 3% 2 %REAL DISCOUNT RATE 3% HIGH CAPITAL COST FOR ALTERNATIVE BATTELU:. (20 %ABOVE ESTIMATE)ESTI MATE LOW CAPITAL COST FOR ALTERNATIVE aATTI:tlE (10 %BELOW ESTIMATE)ESTIMATE LOW SUSITNA CAPITAL COSTS PROJECT (83 %OF ESTIMATE)ESTIMATE HIGH SUSITNA CAPITAL COSTS PROJECT (117 %OF ESTIMATE)ESTIMATE ZERO CAPITAL COST ESCALATION 1.8 %IANNUM HIGH CAPITAL COST ESCALATION 1.8%IANNUM(3.6 %I ANNU M ) HI GH BASE COAL PRICE ($2.08 IMM BTU)$1.43 IMM BTU ZERO FUEL PRICE ESCALATION 2.6%TO 2000 1.2%TO 2010 HIGH FUEL PRICE ESCALATION 2.6%TO 2000 ( 5 %TO 2000 2.2 %TO 2010 1.2 %TO 2010 CHAKACHAMNA ALTERNATIVE ALL THERMAL PLAN ] ] 1 I J ] J PLATE 24 SENSITIVITV ANALVSIS J 1 1 1 1 1 J 1 J l J l ECONOMICS In spite of the fact that some legislative support has been 'demonstrated for subsidies and grants for hydroelectric development,all economic analyses to identity plans and to determine net benefits were condUcted on a common,non- subsidized basis.ThUS,competing plans were tested on equal•terms. Net economic benefits were calculated by comparing the system- wide production costs of electricity with and without the Susitna project.The OGP model was employed for this purpose,and forthe set of economic parameters considered most likely in the base case, the Susitna project was shown to have an advantage over the representative thermal plan of $1176 million (expressed as present worth in 1982 dollars of the difference in total costs of the two plans over an assumed 50-year operating period).A great deal of uncertainty was associated with the various parameters whose values contributed to this result,however.II was noted in Section 8. for example,that a range of possible Susitna capital costs must be contemplated,and earlier in Section 2 that demand can vary across a broad spectrum.Other~parameters are far from firm, Sensitivity Analysis A sensitivity analysis was conducted to determine the extent to which a reasonably conceivable change in any single parameter would affect the outcome of the analysis.Results are presented on Plate 24. The most sensitive parameter is clearly the assumed future escalation of fuel prices,particularly coal,over and above the underlying inflation rate.Simply stated,it would be an unwise economic decisionf to develop Susitna if long-term fuel price stabil ity could be assured.High fuel price escalation in the future,on the other hand,would make Susitna Increasingly attractive. Varying the real (inflation adjusted)discount rate also demonstrates strong effects.The apparent "break even"discount rate is about 4.1 percent. ~c The Chakachamna project had not been included,in the base case for reasons earlier noted in Section 3.If environmental issues can be resolved there and if the initial cost estimate Is adhered to,a combination of the Chakachamna hydroelectric project and thermal generation additions would present a lower cost alternative than the all-thermal plan,but Susitna would continue to be favored. Tests were also made to evaluate the economic effects of delays.A one year delay for the Watana project alone would reduce net benefits by $43 million.Delaying both Watana and Devil Canyon one year causes a reduction of $103 million.A two year delay for both yields a decrease of $168 million. Not shown on Plate 24,but also worthy of consideration is the extent to which a decision not to proceed with the currently planned Bradley Lake Project would change net benefits.Such a scenario would make the non-Susitna plan more costly and would raise the net benefits of the Susitna plan from $1176 million to $1453 million. ...ALL ECONOMIC ANALYSES TO IDENTIFY OPTIMAL PLANS AND TO DETERMINE NET BENEFITS WERE CONDUCTED ON A COMMON, NON-SUBSIDIZED BASIS. pAGE 47 ------- oa It) 10 aa 10 <t aa '"r<l a ~"';;";..,.f."';;'';;'''~;;;;;;;;;''''''+_"",.~~;.4.",,~ N 00 10 Cf)...Z -I-0 )~-J W -J -0 Z ::i;...0 ILl 10 CDZ -~~UJ 0 ZN 2OJ (Jl W0 0 In10 W 0 ~0 It)- oo 10 N- o f---+---+---+----+----1---+--+--+--+---j~..... o Allll81j80Cld 31\I.l'i1ln~n::J N oo 10<t In N W <t .Ja. J ~ ] } I 1 l 1 "Multi-Variate"Analysis Given the uncertainties involved in'each of the parameters subjected to sensitivity tests,there is/no reason to believe that only on~will ultimately vary from the assumed center-point values.To test the effect of multiple variations,a "decision tree"was con- structed and the probability of occurrence was assigned to each of three possible values for the four most sensitive parameters.OGP runs were made to determine long-term present worth costs of each possible combination of load forecast,Susitna capital cost, alternative capital cost,and fuel cost escalation.Discount rates were not included infthis analysis because their determination is largely a matter of policy. Based on this analysis,the cumulative probability that a particular net benefit will not be exceeded is plotted on Plate 25.As may be seen from that depiction,there is about a 23 percent chance that a decision to proceed with Susitna will result in negative or zero net benefits,and the maximum negative exposure is about $2.5 billion. Correspondingly,the cl1ance that Susitna will produce positive benefits over a 50-year operating period is about n percent,with cost advantages as high as $5.5 billion. Conservative Treatment Certain features of the economic analysis probably introduced a measure of conservatism into the calculation of net benefits.The first and most significant such feature is the fact that constant production costs were assumed after 2010 in all cases tested.This assumption has the effect of excluding both real escalation in fuel prices after 2010 an4 the replacement costs of thermal plants which have a shorter operating life than hydroelectric facilities. A second consideration has to do with load forecasts.For purposes of the economic analysis,no further growth was assumed after 2010.Thus,no benefit to Susitna accrues for available energy output of about 340 GWh which is not forecast to be required by the system by 2010.In addition,no cost penalties were assigned to thermal plants to account for possible future environmental legislation;finally,indications by the OGP model that a new thermal plant would be needed in 2011 if only a minor increase in load occurred thereafter were Ignored. It was earlier noted in Section 3 that important uncertainties exist with respect to economic development of the Beluga coal fields and the long term availability of Cook Inlet gas.Nonetheless,the economic analysis was conducted as if no such constraints were present. CERTAIN FEAliURES OF THE ECONOMIC ANALYSIS PROBABLY IN1RODUCED A MEASURE OF CONSERVATISM INliO tHE CALCULATION OF NET BENEFITS. PAGE 49 , 400 I "1 i J 1 1 1 1 .1 J J'514131209201011 COST SAVINGS GROWING OVER WHOLE OF SUSITNA LIFE 07 08 MINIMUM STATE APPROPRIATION a= $2.3 BILLION WITH 7%INFLATION AND 10%INTEREST 06 .~....•.......... YEARS 04 05 ,,,-BASE CASE THERMAL PLAN 02 03 SCENARIO 9 2000 01876(5 \ ~SUSITNA WHOLESALE ENERGY PRICE 140 Ed 100 120 220 280 320 380 200 300 360 340 (/)w U 0:::a.. oz<r (f) l- (/) 8 >--(!) ffizw I 3: ~...... (f) --l --l ~ PLATE2B ANNUAL COS COMPARISION l } 1 } J ] •t~ u J FINANe'llNG ANO MARKETING Having demonstrated.by the economic analysis described in the previous seeton,that there is a high probability that development of the hydroelectric potential of the Susitna basin would provide significant cost advantages when cor;npared to alternative means of ImeetingprojectedRailbeltpowerdemands,further analyses were made of the financial aspects of the development program.These furthe(analyses were aimed at determining whether the project could be financed in an inflationary economy and what impact various scenarios for state participation in funding woulq have on the ultimate cost to the consumer.The results of one such analysis are plotted in Plate 26. The sharply rising red line on Plate 26 traces the unit energy costs associated with the representative all-thermal plan.The same cu rve had been presented earlier on Plate 5.The dashed curve lying above thermal plan costs in the early years of project operation Is associated with a Susitna case with no state participation.It exhibits a characteristic which is common to many major capital-intensive projects.Simply stated,the Susitna Hydroelectric Project would be more costly to the consumer in its early years of operation,if no state participation is involved,than the thermal plan.After about a dozen years,rising thermal plan costs intersect those for Susitna. Thereafter,the Susitna plan looks increasingly more attractive and, over a 50-year economic life,it can be shown that Susitna would generate important cost savings -even without state funding participation.The project is expected to remain operational long after the 50-year life upon which economic and financial analyses were based.Once project debts ate amortized,Susitna costs will drop dramatically. The third curve,sh9wn as the solid blue line on Plate 26,illustrates the case for which state participation is just enough to make the entry costs for Susitna comparable to those for the thermal plan, increasingly great savings being realized thereafter.Other financing variations were explored in the detailed feasibility report.It is anticipated that conventional financing will be used to provide required funding over and above whatever state participation is ~~ involved.State participation at the level indicated by the solid blue curve would provide an 11 percent return on investment. Financing Risks Financial risks to the state and to consumers were analyzed.taking into account such factors as the risks of bond requirement overrun, inadequate debt service cover and others.The analysis suggests that there is a probability of 0.73 (73 percent confidence level)that savings to the Alaska consumer will be equal to or greater than those calculated. Marketing Considerations The Railbelt market area was earlier described In Section 2.In the absence of any plans to merge existing utilities into a central power authority,it was assumed that various utilities will enter into contracts for Susitna energy if it il3 seen as the lowest cost alternative available for meeting demand.Under the minimum state appropriation scenario,purchase of Susitna energy woulq be found preferable to installing and operating new thermal plants either to meet demand or to replace retiring units. The relatively large capacity associated with each successive stage of the Susitna project will inevitably lead to periods during which more capacity is available to the system than prudent reserve criteria would otherwise require.As a result,it may be anticipated that those thermal units which are most costly to operate will be shut down temporarily until demand rises once again to the point that additional capacity is needed.During wet years,hydroelectric energy production in excess of estimated firm energy output will be available at virtually no incremental cost,and it will be used to displace higher cost energy from some thermal plants which may be operated only during years of low flow.In short,under the minimum state appropriation scenario.total system generation costs (and. therefore,costs to the consumer)will be less after various Susitna stages come on line even though a temporary surfeit of capacity may exist. PAGE 51 I f J ~ t IMPLEIMENTATtON The essential conclusions of the detailed feasibility study are that the project is technically feasible and economically vi,able.The safety of the population in the vicinity of the project will not be impaired and the unavoidable impa</ts which this large project will cause on the environment will not be unduly severe and can be ad'equately mitigated.Financing of the project is also feasible with state assistance at acceptable risk to consumers in the Railbelt region. In the event that the state decides to proceed with the project,a license application will be prepared and it will be filed with the Federal Energy Regulatory Commission by September 30,1982. The high level of acti~ity associated with environmental studies will continue unabated throughout the licensing period.which is assumed to extend until December 1984,and into the construction period should this proceed.Technical field investigations wlll continue as well.Future environmental and engineering findings will influence detailed design. Prior to sUbmission of lhe license application,the Alaska Power Authority will accept competitive proposals for detailed engineering services from qualified firms and will select one or more organizations to continue the work after September 1982 when the contractual obligations of Acres American Incorporated will have been fulfilled. Aside from the construction of a limited access pioneer road commencing in mid-1983,activities within the proposed project area will not cause irreversible change before award of a license and prior to a fu rther decision by the state to construct the fi rst stage Watana dam and ¥sociated facilities. No major commitment of funds is necessary to support preparation of a license application since its content will largely be based upon studies completed to date.Continuation beyond that point will require an investment in excess of $50 million,including land costs, before the end of 1983 to support continuing investigations and the ~ commencement of detailed design and pioneer road construction. Immediate action is necessary to ensure that reqUired lands are available for this early construction activity.Options open to the Power Authority include purchase.lease,and land transfer options. THE ESSENTIAL CONCLUSIONS ARE THAT THE PHOJECT IS li"'ECHNIICALLY FEASIBL.E AND ECONOMICALLY VIABLE.UN,AVOIDABLE IMPACTS WILL NOli PE UNDULY SEVERE AND CAN BE ADEQUATELY MmGATED. PA,GE 53 REFERENCES AND ACKNOWLEDGEMeNTS 1,3 References Information presented in this summary report is drawn from two principal sources. both of which have been distributed to libraries throughout the Rallbelt: (1)Draft Susitna Hydroelectric Project F.easlbllity Report,Acres American Incorporated.March 1982'I 'Volume 1 -Engineering and Economic Aspects Volume 2 -Environmental Aspects Section 1:General Description of the Locale Section 2:Water Use and Quality Section 3:Report on Fish,Wildlife.and Botanical Resources Section 4:Report on Historic and Archeological Resources Section 5 Report on Socioeconomic Impacts SectIon 6:Geology and Solis Section 7:Report on Recreational Resources Section 8:Report on Aesthetic Resources SectioA'9:Report on Land Use Section 10:Alternatives to the Susitna Project Section ,,'list of Literature 1 t t Section 1: Section 2: Section 3: Section 4: section 5: Section 6: Section 7; Section 8: Section 9; Section 10; section 11: Section 12: Section 13: Section 14: Section 15' Section 16: Section 17; Section 18: Introduction Summary Scope of Work Previous Studies Railbell Load Forecasts Railbelt System and Future Power Generation Options Susitna Basin Susitna Basin Development Selection Selection of Watana General Arrangement Selection of Devil Canyon General Arrangement Selection of Main Access Plans Watana Development Devil Canyon Development TransmissIon Facilities roJect Operation timates of Cost Development Schedule Economic and Financial Evaluation Acknowledgements Malor subcontractors to Acres American Incorporated who made significant contributions during the course of the study Include: R&M Consultants,Incorporated Cook Inlet Region,Incorporated/Holmes and Narver,Incorporated Woodward-Clyde Consultants Frank Moolin &Associates,Incorporated Terrestrial Environmental Specialists,Incorporated,together with subcon- tractors and members of the facUlty of the University of Alaska. NUmerous other participants In Alaska provided responsive logistical support and related activitIes. State agencies working under the terms ot reimbursable services agreements with the Alaska Power Authority conducted studies and Investigations,without which this report would not have been possible: Institute for Social and EConomic Research,University of Alaska Alaska Department of Fish and Game Cooperation and assistance from resource agency representatives who served on the Steering Committee Is gratefully acknowledged,as IS the extraordJnary effort of the Public Participation staff of the Alaska Power Authority. Rigorous professional review of all major aspects of the proposed Susi'fna development was accomplished by the External Review Panel which reported to the Alaska Power Authority,and by a second Review Panel and numerous consultants who assisted the Acres'team throughout the course of the work.The diligence and skill of these eminent experts has been important to the successful identification and resolution of problems and to the development of optimal plans. Space limitations preclUde the mention by name of the many others whose interest. support,and healthy criticism have been invaluable,but their ~11less efforts are sinoerely appreciated. Finally,the expert management and guidance prOVided by the Executive DIrector and the staff 01 the Alaska Power Authority and the unusual professionalism they have displayed throughout the study period are particularly worthy of note. .1 Volume 3 -Plates Volumes 4 through 8 -Appendices (2)Comment Draft Railbelt Electnc Power Alternatives Study:Evaluation of Railbelt Electric Energy Plans,Battelle Pacific Northwest laboratories.February 1982 PAGE 55 Your comments on the feasibility report are invited.To be considered in preparation of thle final report and in the Power Authority's pending decision on the filing of a license application, comments will have to be received by April 21,1982.They should be addressed to:Eric P,Yould,Executive Director,Alaska Power Authority,334 W.6th Avenue,Anchorage,Alaska 99501. 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