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Unalaska Geothermal Project Financial Analysis 1988
Alaska Power Authority UNALASKA GEOTHERMAL PROJECT FINANCIAL ANALYSIS April 25,1988 Introduction In 1987,the Alaska Power Authority initiated an economic feasibility study of developing a geothermal power system to meet the power require- ments of Unalaska/Dutch Harbor.This study was performed by Dames & Moore in association with SAI Engineers,Inc.,and Mesquite Group,Inc. The results of the study showed that while such a project is technically feasible,the economic feasibility was dependent on the parameters assumed for load growth and fuel price escalation.(See Appendix 1.) Because the 7-megawatt project appeared to be the most economic,the Power Authority contracted with Power Engineers,Inc.,to perform an independent cost estimate of that configuration.Power Engineer's analysis showed a cost estimate somewhat similar to that of Dames & Moore.However,an alternative design concept was proposed by Power Engineers with a construction cost of $35.3 million,significantly below that of other estimates.Power Engineers also estimated that annual operation and maintenance costs for a geothermal plant would be sigqnifi- cantly higher than the Dames &Moore estimate. Further analysis was felt to be warranted including input of financing costs for the proposed project.This report addresses the annual costs of the project as compared to the alternative diesel generation.Such an analysis assesses the early-year impacts to the rate payer and theStateofAlaskaifthePowerCostEqualization(PCE)program continues. Assumptions Basic to the analysis is the use of the Dames &Moore economic analysis results,although it has been adjusted for Power Engineers'lower construction cost estimates and higher operation and maintenance costs and includes estimated financing costs.The economic analysis incorpo- rates assumptions on project outage rates,hourly load patterns,re- source replacement schedules,and other resource/load characteristics. These have not been changed for this financial analysis. Construction costs of the project have been assumed to be financed through the issuance of tax-exempt revenue bonds and amortized on a levelized basis over 30 years.The bonds would fund not only con- struction costs,but also interest during construction,financing costs,and any reserve funds required.(See Table 1 and Appendix 2.) One such reserve fund is the Debt Service Reserve Fund,equal to one year's principal and interest payment on the bonds.While the size of this fund is significant,the additional debt service due to it is relatively small.This is because the fund is used only in the event of a shortfall in principal and interest payments.Thus,the fund can bereinvestedatinterestratesuptotheinterestrateincurredonthe 2428/0D34/1 1 bonds,and the reinvestment earnings can be used to offset other annual costs. It should be noted that financing methods used to reduce interest during construction have not been used in the analysis.Such methods should be evaluated in the event of a bond issue,taking into consideration market conditions,expected cash flows,and legal constraints. Results The results of the analysis show that for most cases,the 5-megawatt and 7-megawatt projects incur costs significantly greater than the dieselalternativeduringthefirstelevenyearsofoperation(See Table 2.) Only with the high load growth/high diesel escalation case does the costs of the project become less expensive within the first eleven years(1991 -2001). Costs could be lowered through two alternatives --direct equity contri- bution or rate stabilization.If equity contributions were sized such that project costs broke even in the first year,an amount equal to over one-half of the construction costs would be required.This could be reduced somewhat if rate stabilization were used in lieu of equity contributions. An assumption used by Dames &Moore in its economic analysis was anoutagerateof25percent(3 months)per year.Such a rate requires substantial diesel generation under the geothermal alternative.The Power Engineers'proposal,however,estimated an outage rate of only one month per year.A sensitivity analysis was conducted to approximate the lower outage rate estimate.The analysis indicated that rate stabi- lization amounts could be reduced by $2 to $3 million and cross-over periods could be shortened by approximately two years. 2428/0D34/2 2 Table 1 Unalaska Geothermal Project Bond Issue Summary(000) 5-Megawatt Construction Costs: 1988 dollars (1)$31,000 Inflation (2)4,501 Subtotal $35,501 Interest During Construction (3)7,756 Debt Service Reserve Fund (4)4,076 Financing Costs (5)1,314 Subtotal -$48,646 Interest Earnings (6)(4,826) Rounding (21)Bond Size $43,80 7 -Megawatt $35,307 5,124 (1)As provided by Power Engineers,Inc.Estimate for 5-megawatt project is preliminary. (2)Based on an assumed inflation rate of 5 percent over the construc- tion period. (3)Based on an assumed interest rate of 8.5 percent per year. (4)Equal to one year's debt service. (5)Estimated to be 3.0 percent of the bond issue. (6)Based on assumed reinvestment rates ranging from 7.5 percent to 8.5 percent. 2428/D034/3 3 Table 2 Unalaska Geothermal Project Financial Analysis Summary ($000) Annual Savings Cumulative Savings Project Load Diesel (Losses)(2)(Losses)(3) Size Forecast Escalation(1)19971 2001 2001 2001 P.V.(4) 7 MW Base Medium (3,130)(1,357)(25,534)(18,778) 7 MW High Medium (2,756)(864)(20,807)(15,600) 5 MW Base Medium (2,884)(1,513)(24,721)(17,983) 5 MW High Medium (2,625)(1,270)(21,600)(15,860) 7 MW Base High (3,058)(202)(20,646)(15,987) 7 MW High High (2,669)457 (15,160)(12,368) (1)Medium -2 percent real escalation (above inflation)through 1996;0 percent thereafter.High -3.5 percent real escalation through study period. (2)Savings (losses)from operating geothermal system as compared to the all-diesel alternative. (3)Summation of total savings (losses)from 1991 through 2001,the first 11 years of operation. (4)Discounted to 1991 using an 8.25 percent discount rate. 2428/0034/4 4 cents/kWhFigure 1 Project Size Sensitivity 20 -- 18 -OT Nee==ee eet 16 - = 14-7 12 - 10 - 8 - 6 - 4 i all pate --Diesel Alternative -Base Case Load Growth 7 a_megawatt prolect2-7 -Medium Diese!Escalation -megawatt Frojec 4 0 T T T T T I T T T T T 1988 1990 1995 2000 2001 cents/kWhFigure 2 Load Growth Sensitivity 20 =ee ee are 7 NO yA18-Senn ss nl - 16 7 eee eee TT eet 14-4 12 - 10 - 4 8 - 4--Diesel Alternative Major Assumptions:----7-MW Project (Base Load Growth) 2-7 -5%general inflation ---7--MW Project (High Load Growth)_-Medium Diesel Escalation U0 T I T T I T T I I T 1 I 1988 1990 1995 2000 2001 Appendix 1 Economic Findings TABLE 4-6 ECONOMIC COMPARISON OF ALTERNATIVE GENERATION SCENARIOS FOR UNALASKABASECASELOADVS.HIGH CASE LOAD DIESEL DIESEL ALL-+5 MW +7 MW SCENARIO DIESEL GEOTHERMAL GEOTHERMAL 1986 Present Worth of Scenario 1988-2016 (Million 1986$) BASE CASE LOAD GROWTH DIESEL PRICE: MEDIUM 73.0 73.4 74.2 LOW 60.1 68.3 70.6 HIGH 85.9 78.5 77.8 HIGH CASE LOAD GROWTH DIESEL PRICE: MEDIUM 93.5 89.2 |87.4 LOW 77.3 81.8 82.5 HIGH 109.6 96.6 92.3 MLF6/CT9 DIESEL +9.5MW GEOTHERMAL 87.5 97.1 Appendix 2 Bond Sizing Analysis CONSTRUCTION COST WORKING CAPITAL EXPENSES: DISCOUNT F.A,FEE F.A,EXPENSES B.C.FEE B.C.EXPENSES APA EXPENSES ANNUAL CASH FLOW (CY) 1987 $ 1988 ) 1989 7,088 1998 24,008 31,008 NOML $ e 7,718 27,783 35,5¢1 GENERAL INFLATION 5.0%S us INTEREST RATES:BONDS 8.5% REINVESTMENT RATES: CONSTRUCTION FUN 7.5% CAP INT FUND 7.5% DSR FUND 8.5% OTHER FUNDS 8.5% CAPITALIZATION PER.25 MONTHS AMORTIZATION PERIOD 38 YEARS ANNUITY FACTOR 8 PROJEKT CONSTRUCTION FUND CAP INT FUND DSR FUND OTHER FUNDS TOTAL PCT FUNDS INT FUNDS INT FUNDS INT FUNDS INT FUNDS INT C.F.1ST OF MO C.F.©EARN {ST OF MQ)0OC.F.EARN 1ST OF MO EARN 1ST OF MQ EARN {ST OF MO EARN { 0.0 8.8 0.8 0.8 0.8 9.8 14.6 25.8 20.8 15.8 10.8 7.@ 38,654 r')192 7,76 316 48 4,076 29 8 tC]42,486 e639 190 5.@ 38,923 385 (tsa 7,446 a7 4,076 29 8 6 42,445 267 5.0 30,00 38 ©6191 7,446 47 4,076 29 e @ 42,326 267 7.0 30,686 S@ 19 7,446 47 4,076 29 e ®42,207 266 7.0 «38,411 =S818 7,446 47 4,076 29 e e 41,932 264 8.0 638,134 G17s«86 7,446 47 4,076 29 e e 41,656 262 12.@ 29,779 S%18 7,446 1,862 47 4,076 29 e e 41,308 ©25914.0 ©29,111 1,888 179 5,565 35 4,076 29 e ®38,71 242 15.0 28,273 1,158 173 5,585 ks]4,076 29 e e 37,933 237 10.@ 27,382 772 169 5,585 35 4,076 29 e e 37,013 232 8.@ 26,813 617 166 5,585 35 4,076 29 7)8 3,473 229 5.0 26,425 386 164 5,585 35 4,076 29 e )36,085 228 4.0 ©26,267 389s]5,585 1,862 35 4,076 29 e )35,907 227 108 5.@ 26,185 1,389 159 3,723 BB 4,076 29 ®@ 33,984 sit 5.@ 25,007 1,389 -152 3,723 23 4,076 29 e @ 32,806 284 7.8 23,822 «1,905 143 3,723 23 4,076 29 e 8 31,621 195 7.@ 22,073 1,905 132 3,723 23 4,076 29 e @ 29,871 184 8.0 20,312 2,223 «128 3,723 23 4,076 29 e e 28,118 =172 12.8 18,261 3,334 184 3,723 1,862 23 4,076 29 e @ 26,068 «156 14.@ 15,083.3,898 82 1,862 12 4,076 29 e ®21,628 §©=123 15.8 11,316 4,167 58 1,862 12 4,076 29 e @ 17,253 98 10.@ 7,247 2,778 37 1,862 12 4,076 29 @ )13,184 71 8.@ 4,586 2,223 al 1,862 12 4,076 29 @ 7)10,483 62 5.@ 2,385 «1,389 it 1,862 12 4,076 29 8 )8,322 5 4.0 ©1,047)1,111 3 1,862 1,862 12 4,076 29 e @ 6,984 ry) 108 35,501 3,357 7,75 7A7 Te2 @ 4,826 BOND SUMMARY ($000) CONSTRUCTION COST DISC.&FIN. CAP.INT.FUND DEBT SVC.RESERVE WORKING CAP.,OTHER SUBTOTAL INT.EARNINGS ROUNDING SURPLUS TOTAL ANNUAL DEBT SERVICE INT.EARNINGS 18-Apr ASSUMPTIONS CONSTRUCTION COST WORKING CAPITAL EXPENSES: DISCOUNT F.A,FEE F.A.EXPENSES B.C.FEE B.C.EXPENSES APA EXPENSES ANNUAL CASH FLOW (CY) 1987 $NOWL $ 1988 @ )1989 6,008 «8,B28 1990 27,307 31,Bt 35,387 40,431 GENERAL INFLATION '_INTEREST RATES: BONDS REINVESTMENT RATES: CONSTRUCTION FUN CAP INT FUND DSR FUND OTHER FUNDS CAPITALIZATION PER. AMORTIZATION PERIOD ANNUITY FACTOR 5.8% 8,5% 7.5% 7.5% 8.5% 8.5% 25 MONTHS38YEARS @ Vo Atul =Peaoys/EcT CONSTRUCTION FUND CAP INT FUND DSR FUND OTHER FUNDS TOTAL PCT FUNDS INT FUNDS INT FUNDS =-sINT FUNDS INT FUNDS =INT C.F.{STOFMO C.F.EARN ISTOF MO C.F.EARN JSTOR MO EARN JISTOF MO EARN 1ST OF MO EARN 1988JON 8.0FEB0.0MAR8.0pPRe.8 my 0.8JUN9.8JU14.8AUG25.8SEP20.8OCT15.8NOV18.8DEC7.8 34,993 @ 219 8,854 354 5 4,653 3 e e 48,508 3871989108JPN5.@ 635,300 AL 8,588 53 4,653 33 e e 48,453 (385FEB5.@ 35,165 441 218 8,580 53 4,653 3 e e 48,317 384 mR 7.0 «635,028 =G17.-its«8,500 53 4,653 33 @ @ 48,181 383PPR7.0 34,716 617 285 8,568 53 4,653 3B e @ 47,066 3 my 8.0 34,3989 896786 -t-=«i 8,See 53 4,653 33 e e 47,558 299JUN12.0 33,991 1,058 209 8,580 2,125 53 4,653 3B 8 e 47,143 295JUL14.0 33,228 1,235 2A 6,375 rr 4,653 3 e ®M255 277AUG15.@ 32,289 «1,323 18 6,375 se 4,653 3 e )43,297 =278sep10.0 31,217 a2 192 6,375 rv 4,653 3 e e 42,244 265ocT8.8 86 .30,688 786 t-i«BD 6,375 rv 4,653 33 e e 41,627 262NOV5.@ 38,156 AA 187 6,375 rr 4,653 3 e e 41,186 288DEC4.0 629,975 353s'186 6,375 2,125 40 4,653 3B ®)1,003 2591998108JAN5.0 29,881 1,581 182 4,258 rs)4,653 3 8 e 38,784 atFEB5.0 28,542 1,581 173 4,258 27 4,653 3 e e 37,445 233MAR7.0 27,198 2,213 163 4,258 27 4,653 3 e r)36,097 223PPR7.8 25,206 2,213,151 4,258 27 4,653 3 @ @ ,1e7 temay8.8 23,282 «92,5299 9137 4,258 27 4,653 3 e ®32,106 197JUN12.0 20,669 3,793 «119 4,250 2,125 27 4,653 2B e @ 29,772 178JU14.8 17,254 4,426 94 2,125 13 4,653 3 ®®24,032 2148AUG15.0 12,969 4,742 66 2,125 13 4,653 3 e @ 19,74 =12Sep10.@ 8,339 3,161 42 2,125 13 4,653 33 e @ 15,117 88OCT8.8 5,267 2,529 25 2,125 13 4,653 33 e e 12,044 11Nov5.@ 2,689 1,58!13 2,125 13 4,653 33 e ®9,587 59DEC4.@ ==1,287 1,264 r 2,125 2,125 13 4,653 3 e e 8,065 5@ 108TOTAL 40,431 3,835 8854 B52 824 @ 5,511 BOND SUMMARY ($800) CONSTRUCTION COST DISC.&FIN, CAP,INT.FUND DEBT SVC.RESERVE WORKING CAP.,OTHER SUBTOTAL INT.EARNINGS ROUNDING SURPLUS TOTAL ANNUAL DEBT SERVICE INT.EARNINGS Appendix 3 Financial Runs UNALASKA GEOTHERMAL PROJECT INPUT ASSUMPTIONS Table 3 -1 GEOTHERMAL PARAMETERS GENERAL PARAMETERS (Dollars in thousands) Inf lat ion 5.ox Construction Cost $35,387 Te ote Interest Rate Bond Size $50,000GeothersalA254O8n$058 Base load Diesel 7.0%Insurance te]Load Scenario 1 now #10 Mes.Fuer Eseacarreds (i=Base,2=High,3-Low)Easeaunt t»] City Busbar Cost ($/kih)$0.13 Royalty Schedule Project Size 2 DIESEL PARAMETERS (1=50i,2=70,3=Seida) Sve.Life 16 Fuel Price 00.67 /gal Fuel Escalation 1 (15400,2aHigh) Fuel EFF.14 badh/gal ECONOMIC OUTPUTS From Dames and Moore Study 1988 1989 1998 1991 1982 1993 1994 198 1996 1997 1998 1999 2000 200! Low 20%2.08 2.0%2.0%2.08 2.0 2.0%2.08 2.0 6 e 6 e 6 High Re:LB 3%3%aa eS Y Ra Lm 3%3%au 3%Le Ra9ENERGYREQUIREMENTS Low desand 18,200 «28,308 21,088)21,108 21,208)21,288 21,821,388 21,40821,40821588 21,588 2,608 21,788BaseCaseDemand22,80 «25,808 31,831,808 2,108 2,462,008 8,R38,708 =39,088 =39,388 44,688 4h,088Highdesand22,700 «31,308 37,008 42,008 43,208 43,708 4,208 49,608 50,108 58,708 51,288)51,788 =57,088)57,708 REPLACEMENT CAPACITY All Diesel Case Low Load Growth 1,718 tv's}&S 8 6 6 6 9 6 e e 6 e J Base Load Growth 2,565 oS 6S Ss 6 6 ss Ss e 6 e 6 oS S&S High Load Growth 5,138 1,710 ss t=}6 6 i [ 's})6 [ '.}6 Ls)8 7 Mi Geothernal Case Low Load Growth 1,718 [oss]ws}8 6 6 9 ]6 )6 e é 8 Base Load Growth 2,565 Less]6S 6 8 e 6 6 6 6 ]6 )e High Load Growth 5,138 1,710 Ss 6 e 6 e 6 e 6 e 6 6 6 GEOTHERMAL GENERATION 5M Project Base Load Growth 6 (@ 26,818 24,983)(25,008 «25,118 95,8938,95 27,881 =27,169 927,233 ABI =28,917 High Load Growth 6 6 @ 28,739 «26,852 20,969 27,668 3319 416 |=-8St9 622,231,635 31,2797MlProject Base Load Growth 0 6 @ 28,99 23,143 «29,318 29,4881,RB 32,2885 4576)4,787 High Load Growth 6 6 @ W566 8 H,623 Beil 33,560 37,044 937,258)37,424 37,6247,79839,492-39,74LowLoadGrowth66@17,35 =19,428 19,173)19,1597,98417,868 17,843)17,8867,791 16,759 16,762 Energy Aequirenents (Muh) GEOTHERMAL CASE Geothersal Project Added Capacity (Ku) Replaced Capacity (Kw) Installed Capacity (Kw) Generation (Muh) Diese!Support Added Capacity (dé) Replaced Capacity (kW) Installed Capacity (ki) Generation (Muh) DIESEL ONLY CAGE New Capacity (Ki) Replaced Capacity (Ki) Installed Capacity (Kw) Diese!Generation (Mal) Real Fuel Escalation 1988 «1989 22,300 25,008 'e ]e e e a 6 2,565 65 e 6 4,100 4,955 22,3 25,00 2,565 a57]e 4,100 4,955 22,30 25,800 200 (es LoadsandResources 1999 =19911992 31,388 31,008},188 6 7,000 e r e °@ 7,000 =(7,000 @ 8,998 29,143 55 e e e e e5,610 5,010 =5,818 31,30 2,862,057 8s 05 6 e e ®5,810 6,665 6,665 31,380 31,000 32,108 rr ry) 1993 1994 2.08 196 0 197s«1988 38,308 38,700 39,008 e )e e e e 7,000 =-«7,008-7,080 2,066 2,208,341 ]e e e ®®5010 ©5,818 5,818 6.2%©6492 =659 6 e e e e e 435 83 66,35 3,3e 38,700 35,008 rn.ee 199 eee 39,300 44,000 44,000 e e e e e e7,000 =7,000 -s7,008 245 45%4,787 e e e e 8 e501065,ate '5,818 6,855 10,024 18,893 ®a5 655 e e e 8375 9,288,085 33,0 4,600 44,808 ry ee ee UNALASKA GEOTHERMAL PROJECT Busbar Cost Comparison -(Dollars in Thousands) 1988 1989 1998 1991 1992 1993 19%1995 1996 1997 1998 1999 2008 2081 Energy Reqats (sh)22,300 «25,808 31,388 31,808 2,108 2,408)32,708 38,088 =38,308 =38,708 =39,008 =39,4A COR 44,888 GEOTHERMAL CASE Geothermal Project: Debt Service (1)*6 SO GA,SAT $4,547 84,547 84,5474,SAT 84,47 84,547 64,547 84,547 84,547 84,547 Interest Earnings (2)e 6 6 (330)we)(30)(338)(338)(30)(330)(338)(30)(330)(330) Net Debt Service 6 6 )4,217 4,217 4,217 4,217 4,217 4,217 4,217 4,217 4,217 4,217 4,217 Operating Costs Fixed O84 6 6 6 304 1,033 1,085 1,139 1,196 1,256 1,319 1,385 1,454 1,526 1,603 Replacements 6 6 6 a e 6 é e 6 e e L)6 e Adainistration LY 6 e 6 6 6 6 6 e e 6 )6 6 Insurance 6 ]e e e 0 )6 e ®é )6 6 Royalties e 6 8 1s 19%a7 218 248 293 K |325 wv 333 ww Other 6 6 6 17 18 19 20 ai 2 3 24 26 4]28 Subtotal 2 *$0 95,404 05,464 05,528 95,594 05682 85,787)5,067 =6,039 GI 86,282 Diesel Support: Debt Service %in 165 165 165 165 165 165 165 165 69 5 6 6 Fuel 1,067 1,221 1,715 165 16 oa?231 467 313 %61 Sd 633 1,ee2 1,059 Fixed 0 6 4 208 rs)K 34 ue 37 35 4 44 Ex)a6 479 23 528 Variable 02%sv 433 se bs rt ]63 69 17 147 161 174 108 [|Ks} Subtotal 1,600 2,178 2,741 ™%74 m3 al i,t62 1,239 1,321 1,32 1,34 1,793 1,892 Total Project and Support Costs: Dollars 1,000 2,178 2,741 6,110 6,212 6,321 6,435 6,845 7,026 7,188 7,253 7,393 71,97 6,144cents/kih 8.1 6.4 8.8 19.2 19.4 19.5 19.7 1.6 18.3 18.6 18.6 14.8 17.8 18.2 ALL DIESEL CASE Debt Service %138 165 ete oe rd 25 2308 r+|28 19%168 183 206 Operating Costs: Adain &Insurance 6 6 6 6 ft)6 6 6 6 a e 6 e 0 Fuel Cost 1,067 1,321 ins 1,864 2,014 2,75 2,349 2,928 3,149 3,3,336 3,74 4,458 4,702 Fined 08 4 208 24 Ks]324 we k=?)Ein)34 a4 cx a]456 Lye)33 528 Variable 0 8 4 433 He 389 624 662 7a %bs}bY}1,016 1,073 1,282 1,R2 Total Project Costs: Dollars 1,800 2,178 2,741 2,988 3,180 3,3%3,678 4,408 4,739 5,626 5,202 5,456 6,425 6,767 Cents/kih at a4 8.8 9.4 9.9 18.5 i.2 1.7 12.4 13.6 13.3 13.9 14.4 15.1 GEOTHERMAL PROJECT SAVINGS (LOSSES) Wominal Dollars: Annwal (3,130)(3,032)(2,925)(2,765)=(2,385)=(2,268)«=(2,162)(2,052)1,938)(1,See)(1,357) Cuulative (3,130).(6,162)(9,067)(11,852)(14,236)(16,504)(18,666)(20,717)(22,655)(24,177)(25,534) Present Worth: finnual (3,130)(2,801)(2,496)(2,180)(1,737)(8,526)(5,344)(1,178)(1,628)(746)(614) Cumulative (3,130)(5,931)(8,427)(10,687)(12,343)(13,869)(15,213)(16,390)17,418)(18,164)(18,778) fy..-at Debt Service Added Diese!Capacity (Geothersal Case) 1999 2008 2001198691998199119921993199419951996199719981988 er ewereccneces)eeaeeeaenvanvece | soncesccescs | esneeccocece | Renee SSCSS | Rane ecece | Reneeoee l eaneocce | Rageore | aaaee | Rea? l RB || UMPonmOren Um«&ee 1”165 165 165 165 165 16S 165 165 69%Total (All Diesel Case) Annual Debt Service Added Diese?Capacity 1999 200s 20011989199819911982199319941951996199719981988 JorcrRerseercen 1g [ccmneezgesce 1g |canneezseces [2% | #amheezgee [2 | #anneezes [2 jxsaneeze | [Raeanees [2 | xsanee |x [esane iE: |xaa5 [x |xs {2 |wa |8 |" |* UNALASKA GEOTHERMAL PROJECT INPUT AGSUMPTIONS GEOTHERMAL PARAMETERS GENERAL PARAMETERS (Dollars in thousands) Inflation 5.0%Construction Cost Interest Rate Bond Size Geotheraal 6.25%og Diesel 7.08 Insurance Load Scenario 2 a (1=Base,2=High,3-Low)Easenent City Busbar Cost ($/kddh) floyalty Schedule Project Size DIESEL PARAMETERS (190,2870,3-Wila) Sve.Life 10 Fuel Price $0.67 /gal Fuel Escalation 1 (f=Lom,2=High) Fuel Eff.14 both/gal ECONOMIC OUTPUTS Fros Dames and Moore Study 1968 1989 1998 1991 1992 Low 2.0%2.0%2.0%2.0%2High3.5%33 3.5t 3.52 35% ENERGY REQUIREMENTS Low demand 16,200 «28,308 21,008)21,108 21,208 Base Case Denand 22,30 8=625,80831,831,888 =32,108 High demand 22,700 «=31,38 37,088 42,808 43,288 REPLACEMENT CAPACITY All Diesel Case Low Load Growth 1,710 as t's]6 e Base Load Growth 2,565 8S [ss][ss]6 High Load Growth 5,138 1,710 aS aS e 7 4 Geotheraal Case Low Load Growth 1,710 [. 's}aS e e Base Load Growth 2,65 ss oS J 6 High Load Growth 5,138 1,718 6 8 GEOTHERMAL GENERATION 5 Ml Project Base Load Growth )6 @ 24,810 24,983 High Load Growth e 8 @ 2,739 28,82 7 Md Project Base Load Growth 6 6 @ 28,998 =29,143 High Load Growth e 6 ©4,646 3,823 Low Load Growth 6 6 @ 17,55 =19,128 2.6% 3% 20 3.5% 25,118 27,668 25,48033,560 19,159 T-Atel MIGH LOAD MED.FYEU ESC 4hLaTiond 1996 1997 1998 1999 oeee oeet 20%)6 ]8 6 3 3%au Rah 3.5%3% 21,400 «21,408 21,508 21,5882,68821,70836,30 3,708 5,008)39,308 44,008 44,88850,100 58,700)Si,288 51,708)57,288)57,708 6 6 e e 6 e e 6 6 6 [=x]8 6 6 [ss]()eS 6 6 6 6 0 6 6 6 6 e e 6 e e e e 8 6 6 26,985 «27,081 =27,169 27,233)28,B11 =28,9170416==-638,519 =G21 72 831,635)=31,279 R66 32,208)82 6M 4576 4,787 37,238 =37,424 37,624 =37,798 =39,492 «39,74 17,066 §=17,843 «17,806 =-17,791 16,759 16,762 Energy Requirewents (Muh) GEOTHERMAL CASE Geothersual Project Added Capacity (KW) Replaced Capacity (KW) Installed Capacity (KW) Generation (Mh) Diesel Support Added Capacity (hd) Replaced Capacity (id) Installed Capacity (idd) Generation (Muh) DIESEL OMY CAGE New Capacity (KW) Replaced Capacity (Ki) Installed Capacity (KW) Diesel Generation (10H) Real Fuel Escalation 22,708 2.0% 31,300 31,300 2.0% Loads and Resources 1998 «199k n982 37,000 42,808 43,200 e 7,00 e e e eeo7,00 =(7,00 ©34,646 34,823 055 e e e 6 e6,665 6,665 6,665 3,018 3T7 5 855 8 e e e9,238 18,085 10,085 37,000 42,000 «(43,280 20 20 2s 1993 1994 43,700 |44,200 e e 8 e7,000 =(7,000 35,011 33,560 6 e e 66,665 6,665 6,689 10,640 e e ®® 10,065 16,085 43,700 44,200 20 8 86(2at 49,600 56,100 1997 51,200 13,5%13,918 57,200 17,788 Oo 17,9% 12,658 57,700 Om UNALASKA GEOTHERMAL PROJECT Busbar Cost Comparison (Dollars in Thousands) 1988 1989 1998 1991 1992 1993 1994 1995 1996 1997 1998 1999 one 2081 Energy Reqats (ih)22,700 §=31,308 37,008 42,888 43,208)43,708 44,208)49,608)50,108 =50,708)51,208 =51,788 =57,208 =57,708 GEOTHERMAL CASE Geotheraal Project: Debt Service (1)*Co $0 $4507 64,587 ASAT 4,SA7 4,507 64,547 84,547 84,587 84,547 84,587 84,547 Interest Earnings (2)6 e e (3308)(338)(330)(338)(338)(330)(338)(338)(ae cee](330) Net Debt Service 0 6 e 4,217 4,217 4,217 4,217 4,217 4,217 4,217 4,217 4,217 4,217 4,217 Operating Costs Fined 08 8 6 6 6 964 1,633 1,085 1,139 1,196 1,256 1,319 1,365 1,454 1,526 1,683 Replacesents Ly e e e e e )6 6 a e )e 6- Adainistration 6 6 e e 6 6 tL)6 é 6 e tL)6 tL) Insurance e 6 e e 6 e e e 6 e 6 6 6 e Royalties 0 6 e rt)261 276 278 373 333 5 438 62 37 535 Other 6 e 6 17 18 19 2 21 2 3 24 rs)rai 28 Subtotal e to]$0 «85,465 95,538 05,597)S654 85,807)=85,888 «=95,9746 OA GIS,277 06,383 Diesel Support: Debt Service 192 a9 255 25 2s 25 25 25 25 25 103 5 8 6 Fuel 1,006 1,603 2,@27 476 335 583 164 5 1,058 1,146 1,231 1,324 1,770 1,889 Fined O &rs.)2%mw 324 we kj Kip)Ky]4s ay 4%499 303 326 Variable 0 8 #%3 526 633 bY |163 in 228 263 mm Re Rw)al bs)K3 Subtotal 1,%2 2,682 3,283 1,248 1,326 1,413 1,662 1,936 2,671 2,265 2,143 2,219 2,782 2,968 Total Project and Support Costs: Dollars 1,922 2,682 3,283 6,714 6,853 7,010 7,316 7,743 7,99 6,179 6,287 8,377 9,659 9,343cents/kih 6.5 6.6 6.9 13.7 13.$16.6 16.6 13.6 1.9 16.4 16.0 16.2 15.6 16.2 ALL DIESEL CASE Debt Service 192 a8 26 32 Re x2 we 7 Rit]am 27 178 192 15 Operating Costs: Adain &Incurance e e 8 6 (]))6 6 6 J e 6 6 Fuel Cost 1,086 1,683 2,027 2,509 2,710 2,933 3,174 3,812 4,120 4,37 4,42 4,21 3,747 6,055 Fixed O8 #208 2M Ks)4 ue 37 375 Ry]a4 ay 456 479 303 528 Variable 0 2 4 %3 526 653 793 ae ase 8 1,117 1,186 1,258 1,33 1,415 1,644 1,741 Total Project Costs:;Dollars 1,%2 2,682 3,283 3,558 4,222 4,515 4,829 5,699 6,095 6,447 6,669 6,985 6,655 8,479 Cent s/kih 8.5 6.6 8.9 9.2 9.8 10.3 10.9 1.5 12.2 12.7 11.@ 123 14.1 14.7 GEOTHERMAL PROJECT SAVINGS (LOSSES) Nominal Dollars:, Annual (2,756)(2,631)«=(2,495)(2,487)(2,044)1,865)(1,732)1,538)=(1,393)(1,084)(864) Cumulative (2,756)(5,387)(7,882)(10,368)(12,412)(14,277)(16,009)(17,547)(18,940)(19,944)(28,867) Present Worth: Arma)(2,756)=(2,438)(2,129)(1,968)(1,488)(1,254)(1,076)(883)(739)(492)(391) Cumulative (2,756)(5,186)(7,315)(9,276)(10,764)(12,019)(13,095)(13,978)(84,787)(15,209)115,688) aonnmewnwa=wantnewn=-tf..Debt Service Added Diesel Capacity (Geothersal Case) Arewal Debt Service Added Diesel Capacity (All Diesel Case}g|192 259 g|a||g|3|377 efeeesSAEan i997 -_wokecetnc|4|ZwecccccctiSe!BechkecettSel#g3wKeohecettice!SBekKeekecoeeXeooeieSekKeeheveocece{2 .UNALASKA GEOTHERMAL PROJECT INPUT ASSUMPTIONS GEOTHERMAL PARAMETERS GENERAL PARAMETERS (Dollars in thousands) Inf lation 5.0%Construction Cost Interest Rate Bond Size Geothermal 6.25%On Diesel 7.08 Insurance Load Scenario i ROW (1=Base,2=High,J-Low)Easenent City Busbar Cost (6/kih) Royalty Schedule Project Size DIESEL PARAMETERS {1h 2570,3=Sela) Sve.Life 1e Fuel Price $8.67 /gal Fuel Escalation 1 (1=Lom,2=High) Fuel Eff.14 hudi/gal ECONOMIC OUTPUTS Frou Danes and Moore Study 1988 1989 1998 1991 1992 Low 2.0%2.08 2.0%2.0%2.08 High Lu La 3.9%am Lm ENERGY REQUIREMENTS Low demand 18,200 «=20,308 21,0889 21,108 =21,288 Base Case Demand 22,30 25,8081,831, High demand 22,700 «31,38 37,008 42,808 43,288 REPLACEMENT CAPACITY All Diesel Case Low Load Growth 1,718 [ss]8 e Base Load Growth 2,565 eS 65 e High Load Growth 5,138 1,710 Lvs}SS 6 7 MH Geothersal Case Low Load Growth 1,710 tw}6S 6 e Base Load Growth 2,565 [ss}ss)6 e High Load Growth 5,138 1,710 [.w's}L)6 GEOTHERMAL GENERATION 5 Mi Project Base Load Growth )6 @ 24,818 24,983 High Load Growth 6 J @ 2,739 28,82 7 Mt Project Base Load Growth 6 6 @ 28,998 29,143 High Load Growth 6 6 @ W646 3,823 Low Load Growth L)6 @ 17,535 =19,126 Table 3 -3 $31,000$43,000 $050 ) #10 15 $0.13 I 1931981995 260 20)(hesre.eS ee| 21,200 21,388 21,300 3,000 32,700 38088 43,700 44,200 49,600 ®e e e 855 85 )e 55 e 8 e e e e e e e 25,008 ©25,118 26,893 28,969 27,668 38,319 29,310 29,488 31,928 35,011 33,568 37,044 19,173 19,159 17,984 S$-Atw BASE Load MED.Fuvew EscAcazro | 2.08 8 e r)e ce.eS ee eS 21,400 21,408 21,588 21,5881,ae ae 38,708 35,008 35,308 44,608 50,100 50,780 (51,208 51,780 57,200 e e )®e e e ®e 65 e e 855 0 #55 e e 6 e e ®e e e e e e ®e e 26,905 27,081 «27,169 27,233 28,Ot30,416 30,519 38,6218,78231,635 32,066 32,208 32,361 245 34,57637,238 37,424 «37,624 37,798 39,49217,068 (17,043 17,806 17,791 16,759 Energy Requirements (Hh) GEOTHERMAL CASE Geothermal Project Added Capacity (KW) Replaced Capacity (KW) Installed Capacity (Kw) Generation (Mh) Diese}Support Added Capacity (kid) Replaced Capacity (kW) Installed Capacity (ki) Generation (ih) DIESEL ONLY CASE Wew Capacity (Kw) Replaced Capacity (KW) Installed Capacity (Kw) Diese]Generation (MH) Real Fuel Escalation 22,00 2.0%2.08 Loads and Resources 31,300 (31,000 (32,100 ©Sone e e e 8 6 Seo 5,008 2.0%28 2.0% 5,000 1995 38,08 1997 44,600 6.6 i UNALASKA GEOTHERMAL PROJECT Busbar Cost Comparison {Dollars in Thousands) 1988 1989 1998 199]i992 1993 1994 1995 1996 1997 1998 1999 oeee 2001 Energy Reqats (Midh)22,300 =25,808 =31,308 31,888 =32,108)32,488 =32,788)38,088 =38,308)38,708 =39,008 =39,308 4h,44,B08 GEOTHERMAL CASE Geotherual Project: Debt Service (1)*$8 $@ ==$3,983 $3,983)$3,983)=$3,983)83,983 =83,983 =$3,983 =63,983 =83,983 =63,983 =83,983 Interest Earnings (2)6 tL)e (289)(289)(289)(289)(289)(289)(289)(289)(289)(289)(289) Net Debt Service 6 L)6 3,64 3,694 3,69 3,64 3,694 3,694 3,69 3,69 3,6%3,69 3,694 Operating Costs Fixed 08 A 6 e 6 bt)1,033 1,085 1,139 1,196 1,256 1,319 1,385 1,454 1,526 1,683 Replaceaents 6 t)6 e 6 e 6 tL)e e e )e ) Aduinistration e é e 6 6 6 e 8 6 6 6 )6 e Insurance 6 6 6 e e 6 e e 6 6 6 6 6 6 Royalties )6 e 168 148 1%164 164 1%26 216 227 206 m1 Other 6 e e 7 1a 19 r |ra 22 23 24 r.27 28 Subtotal be %$8 «$4,835 =$4,893 84,554 85,017 85,096 85,166 =85,241 =65,319)$5,401 =85,533 ==$5,625 Diesel Support: Debt Service %ie |165 165 165 165 165 165 165 165 69 5 6 e Fuel 1,067 i,321 1,715 ae 1 496 M5 mo 8 1,003 1,073 1,149 1,578 1,667 Fined O8 8 208 2 K )Kv.)we 37 35 Ryo)414 ay 4%479 303 328 Variable 0 2 Mt 37 433 we fe 10 151 163 2%67 206 me we oO 479 Subtotal 1,000 2,178 2,741 1,@28 1,097 1,178 1,247 1,663 1,777 1,691 1,986 1,993 2,535 2,674 Total Project and Support Costs: Dol lars 1,008 2,178 2,741 3,664 3,998 6,123 6,265 6,758 6,943 7,132 1,225 1,394 6,068 6,308cents/kih 6.1 6.4 8.8 18.4 18.7 18.9 19.2 17.8 18.1 16.4 18.5 16.8 18.1 18.35 ALL DIESEL CASE Debt Service %138 165 eee ote eee 245 rs |2 200 1%160 183 206 Operating Costs: Adain &Insurance e 6 6 e 6 e e 6 a 6 6 6 6 tL) Fuel Cost 1,067 1,321 1,715 1,864 2,014 2,175 2,349 2,920 3,149 3,341 3,336 3,741 4,458 4,72 Fined O8 M one 4 Ks)324 we 37 5 394 4l4 43 4%479 3 528 Variable 0 &&1B 2 389 624 662 Tei 656 05 961 1,016 1,075 1,282 1,382 Total Project Costs: Dollars 1,600 2,178 2,741 2,908 3,186 3,3%3,676 4,468 4,759 5,826 5,282 5,456 6,425 6,787Cents/kwh 8.1 8.4 6.8 9.4 9.9 16.5 fl.2 1.7 12.4 13.8 13.3 11.9 14.4 51 SEOTHERWA.PROJECT SAVINGS (LOSSES) Nominal Dollars: Annual (2,884)(2,009)(2,727)(2,595)=(2,298)(2,184)(2,805)=(2,023)1,938)=(1,643)(1,513)Cumulative (2,884)(5,694)(8,421)(11,016)(13,314)(15,499)(17,604)(19,626)(21,564)(23,208)=(24,721) Present Worth: Annwal (2,884)(2,595)(2,327)(2,046)=(1,674)=(1,478)(1,308)(1,161)(1,828)(885)(685) Cumulative (2,884)(5,480)=(7,807)«=(9,852)(11,526)(12,996)(14,304)(15,466)(16,493)(17,298)(17,983) finnuas vebt Service Added Diesel Capacity (Beothersa)Case) 1999 208s oeet19891998199119921993199419951996199719961988 ||jesneeeceeeeeRe QeeeceRaReeeRaBe?oRaBeRBRAR -NVOw-enoO hy Bese un«+ee ete 138 165 165 165 165 165 165 165 165 69%Total finnual Debt Service Added Diesel Capacity (All Diesel Case) 199 eee eee19691998199119921993199419351996199719981986 poraneczgeces| tsaneezzece | RaBRO Bees | ##BReoe see43 4 | saaRe* 43 | kaBRO* | kaaRo*|,kane|Ra|RamtRS|R ---uNneewrnworenrea VM=a== 21%24516513 GENERAL PARAMETERS Inflation 5.0%Construction Cost Interest Rate Bond Size Geotheraal 6.25%Osn Diese)1.0%Insurance Load Scenario 2 now (1=Base,2=High,3-Low)Easesent City Busbar Cost ($/kih) Royalty Schadule Project Size DIESEL PARAMETERS (129M,2270,3=9Mia) Sve.Life 16 Fuel Price $0.67 /gal Fuel Escalation t (Low,2=High) Fuel Eff.14 kady/gal ECONOMIC OUTPUTS From Dames and Moore Study 1988 1969 1998 1991 1932 Low 2.0%2.0%208 2.0%2.0% High 358 3%3%3a 35 ENERGY REQUIREMENTS Low desand 18,200 «26,308 21,008)21,108 =21,208 Base Case Desand 22,30 =25,008 =31,388 31,808 32,108 High demand 22,700 «31,037,008 42,80843,208 REPLACEMENT CAPACITY All Diesel Case Low Load Growth 1,718 [ 's}SS 6 e Base Load Growth 2,565 [ss][5's]85 a High Load Growth 5,138 1,718 [ws}oS L) 7 41 Geothermal Case Low Load Growth 1,718 655 ts}e 6 Base Load Growth 2,55 ts}[sis]6 e High Load Growth 5,13 1,me 85 6 e GEOTHERMAL GENERATION 5 MH Project Base Load Growth 6 6 @ 24,8160 24,993 High Load Growth i]e @ 28,739 «28,2 7 WM Project Base Load Growth 6 0 @ 28,999 «29,143 High Load Growth L))@ 3,646 34,823 Low Load Growth 6 6 6 17,35 =19,128 UNALASKA GEOTHERMAL PROJECT INPUT ASSUMPTIONS GEOTHERMAL PARAMETERS (Dollars in thousands) Table 3 -4 $31,008$43,000 $658 r”) $10 $5 $0.13 1 199319981995 20068 Ot er | 21,200 21,388 21,ee 32,400 32,708 38,00843,700 44,208 49,600 e e e e 855 85 e r)65 e ®e e 6 e )e e 25,008 25,118 26,893 28,969 27,668 38,319 29,318 23,408 31,928 35,011 33,568 37,004 19,173 19,159 17,904 Ss -snd MIGH Losd MIED.FUEL ESCHLATIOAS Cn a a a | 2.0 e e e e e eS eS es ee | 21,400 21,408 21,508 21,588 21,608 21,78838,300 38,708 39,008 «39,308 44,600 44,800 50,100 50,788 (51,288 «51,708 57,200 «57,708 e e e e r e e e )e 5 855 e 8 65 e 855 ) 8 e e e e e e 6 e e a e r e ®8 a e 26,965 27,081 27,169 27,233 «28,811 28,917 3,416 38,519 38,621 8,782 31,635 31,279 32,066 32,208 «32,341 32,445 34,576 34,70737,238 37,424 «37,624 «37,798 39,492 39,70417,860 17,043 17,006 17,791 16,759 16,762 Energy Requirewents (Muh) GEOTHERMAL CASE Geothersal Project Added Capacity (KW) Replaced Capacity (KW) Installed Capacity (KW) Generation (Mh) Diesel Support Added Capacity (kt) Replaced Capacity (idé) Installed Capacity (hdd) Generation (Muh) DIESEL ONLY CASE New Capacity (Ki) Replaced Capacity (Ki) Installed Capacity (KW) Diesel Generation (4H) Real Fuel Escalation 22,708 31,30 31,208 Loads and Resources 198 =19911982 37,000 =42,800 43,200 0 S608 e e e 6@See|5,008 @ 79 |Aas a5 e 6 e e ®6,665 6,665 6,6S 37,008 14,061 14,348 85 a5 e e e e 9,238 18,005 «18,085 77,000 (42,000 43,208 20062 28,69 14,731 16,532 49,600 2,319 19,281 3,416 i937 2,519 28,181 51,208 31,279 26,421 UNALASKA GEOTHERMAL PROJECT Busbar Cost Comparison (Dollars in Thousands) 49,500 «50,100 50,708 $3,983 =$3,983 1998 1999 oes 51,200 51,708 57,208 $3,983 03,983 63,983 (289)(289)(289) 335 1,44 1,52666e 6 6 e 6 6 6 276 29 314 24 r 27 RE+)2s 25 25624b|989 1,187a4wek- 7/Rin) 268 279 Ri mh $5,200 «=95,298 1968 Energy Requts (Muh)22,7108 GEOTHERMAL CASE Geothersal Project; Debt Service (1)cS] Interest Earnings (2)( Net Debt Service e Operating Costs Fixed 0 6 6 Replacesents 6 Administration 6 Insurance 6 Royalties e Other 6 Subtotal te] Diesel Supports Debt Service 192 Fuel 1,006 Fixed O84 288 Variable 0 6 4 %3 Subtotal 1,922 Total Project and Support Costs: Dol lars 1,922 cent s/ith 6.5 ALL DIESEL CASE Debt Service 192 Operating Costs: Adain &Insurance 6 Fuel Cost 1,066 Fixed 0 8 4 266 Variable 0 4 8 %3 32 we aw ae 8 6 6 2,09 2,710 2,933 3,17434ueK /5m3ane692wa 16.3 16.5 16.4 ar 178 ise 42 4921 5,717 4%4793 503 1,34 1,415 1,644 Total Project Costs:Dollars 1,922Cents/kih 8.5 GEOTHERMAL PROJECT SAVINGS (LOSSES) Noainal Dollars: fina Cusul ative Present Worth: Annual Cumulative 3,58 4,222 4,515 4,829 9.2 9.8 10.3 10.9 (2,625)(2,531)(2,429)(2,416)(2,625)(5,156)(7,585)(18,682) (2,625)(2,338)(2,873)(1,905)(2,625)(4,963)(7,036)=(8,941) 6,669 6,985 6,6512.6 13.5 ia (1,670)1,567)41,299)(17,465)(19,032)(20,330) (353)(831)(636) (13,618)(14,649)(15,285) anrweww=Cantnuwerwrth.2s Debt Service Added Diesel Capacity (Geothersal Case) Pmual Debt Service Added Diesel Capacity (All Diesel Case) $988 1989 i990 1931 1992 132 S92 67 67 5 3S 6 6 6 2S es 1991 1992 ise 192 67 67 5 5 7 7 6 Re Re 2|eeths&|eeeKS¥|7 (3eeeeeoeaekle£KeekecetiiGellg|eKeckeccititices|FSeKeeokeoadNeee|7]|akeKecheccccce|# UNALASKA GEOTHERMAL PROJECT INPUT ASSUMPTIONS GEOTHERMAL PARAMETERS GENERAL PARAMETERS (Dollars in thousands) Inflation 5.0%Construction Cost Interest Rate Bond Size Geothersal 6.25%oan Diesel 7.08 Insurance Load Scenario 1 au (1=Base,2=High,3-tow)Easenent City Busbar Cost ($/iddh) Royalty Schedule Project Size DIESEL PARAMETERS (1530,257M,3-Rhia) Sve.Life 10 Fuel Price 00.67 /gal Fuel Escalation 2 (f=Lom,2=High) Fuel Eff.14 keh/gal ECONOMIC OUTPUTS From Bases and Moore Study 1986 1989 1998 1991 1992 Low 2.08 28 2.2.0%20High3auaReLs ENERGY REQUIREMENTS Low demand 18,200 §=28,308 21,0889 21,108 =21,288 Base Case Desand 22,30 8=-25,80831,831,808 =32,108 High desand 22,700 «31,30 937,008 42,8 43,28 REPLACEMENT CAPACITY All Diesel Case Low Load Browth 1,718 t. 's}aS 6 6 Base Load Growth 2,65 [. '}t's}[ss]6 High Load Growth 5,138 1,718 [ws]Ss 6 7 WM Geothersal Case Low Load Growth 1,710 SS [ss]e 6 Base Load Growth 2,55 [ss]t+}]] High Load Growth 5,138 1,718 ts}®L) GEOTHERMAL GENERATION 5 Mi Project Base Load Growth 6 6 @ 24,818 24,983 High Load Growth 6 6 ©2,739 28,e2 7 i Project Base Load Growth 6 e @ 20,999 29,143 High Load Growth 6 e ©W646 3,823 Low Load Growth 6 ]©17,65 =19,128 Table 3 -5 $35,307$50,000 $058 °e si0 rs) $0.13 2 199319881985 re?es re er.ee 21,200 21,30 21,30 2,40 3,70 8 43,700 44,000 «(49,608 8 e e 6 [.w's]ss a e 55 e e e e e e e e e 25,008 25,118 26,893 28,969 27,668 38,319 25,310 29,400 31,928 3,6 33,568 37,044 19,173 19,159 17,904 T-rtw BASE Load AGH Pues ESCALATIOA nn nn ne.| 2.08 e e e eeseeeeee| 21,400 «21,408 21,588 21,588 21,600cea>oe ae eh0,100 «SA708 |S1,200 «51,708 57,208 8 8 e e e 6 8 e e 5 e e a5 e oS e e e e 6 e 6 )e e 6 e e e e 25,965 27,081 «27,169 27,2338,B113416-8519 3,621 88231,635 32,066 32,208 32,51 8S 4S 37,2 «37,424 «37,624 37,798 39,492 17,868 17,843 17,886 «17,791 16,759 200) 6 3% 21,708 44,00057,708 28,917 31,279 3,707 39,74 16,762 Energy Requirements (Mh) GEOTHERMAL CASE Geothermal Project Added Capacity (Kw) Replaced Capacity (Ki) Installed Capacity (KW) Generation (Wh) Diesel Support Added Capacity (ki) Replaced Capacity (kW) Installed Capacity (ki) Generation (Mdh) DIESEL ONLY CASE New Capacity (Kw) Replaced Capacity (KW) Installed Capacity (KW) Diesel Generation (Mai) feal Fuel Escalation 35 xo} Loads and Resources 198 =19911982 31,300 ©31,008 32,100 eo 7,00 ® e e e67,00 =©«67,008 ©20,998 29,143 Cs)e e ®6 e 'See 865,818 S010 3,e 2,818,957 85 855 e e e e 5,810 6,665 6,665 31,308 31,808 32,108 Lm ORS OLS 33 19941955 32,700 38,000 e e e e7,000 «=-7,008 29,408 31,928 e r) e e 5,810 5,818 3220 «6,672 05 85 e e 7,320 «375 32,700 (38,008 oe 1996 1997 i999 44,600 xa UNALASKA GEOTHERMAL PROJECT Busbar Cost Comparison (Dollars in Thousands) 1988 1989 1998 «1991 1992 1993 1994 1995 19%«=«1997,(s998i-id999stié Energy Reqats (Muh)22,300 25,080 31,300 31,808 32,100 32,408 32,700 38,008 38,388 38,700 39,008)39,3844 cee 44,808 GEOTHERMAL CASE Geothersal Project:. Debt Service (1)*to]$B GA,SAT 84,764,547 84,547 84,547 4,57 84,547)84,547 84,587 84,547 $4,547 Interest Earnings (2)6 6 e (3380)(330)(338)(338)(330)(330)(330)(330)(330)(338)(330) Wet Debt Service 6 6 6 4,217 4,217 4,217 4,217 4,217 4,217 4,217 4,217 4,217 4,217 4,217 Operating Costs Fixed O88 6 tL)e 984 1,033 1,065 1,139 1,196 1,2%1,319 1,385 1,454 1,526 1,663Replacenents666666aeeee6e6 Administration )e e e 6 6 e 6 é é 6 6 6 e Insurance e 6 )6 tL]e e é e e tJ e L)6 Royalties 6 6 )15 19%7 218 248 233 x]35 vw 383OthereJ6iv1819rs22233)r 27 28 Subtotal **60 65,404 65,464 «$5,528 95,594 85,682 «95,787 85,867 «$5,951 06,839 06,154 96,252 Diese]Support: Debt Service %138 165 165 165 165 165 165 165 165 69 5 6 6 Fuel 1,067 1,30 1,763 172 196 222 Bi 514 373 7 Tal 66 1,27 1,395 Fixed O88 rs.)+8)Re]324 we K=)/373 4 44 an 4%4799 33 32a Variable 0 6 4 37 433 2 3 %6&3 69 137 147 161 174 168 Ks] Subtotal 1,600 2,197 2,789 3 606 861 1,210 1,299 1,408 1,419 1,307 2,068 2,227 Total Project and Support Costs: Dollars 1,000 2,197 2,789 6,117 6,223 6,335 6,455 6,852 7,087 7,275 7,770 7,346 6,221 6,480 cents/kWh 6.1 6.5 4.93 19.2 19.4 19.6 19.7 16.1 16.5 16.8 18.9 19.2 16.4 180.9 Ail DIESEL CASE Debt Service %138 165 ote ane ote 245 2 oe 290 1%160 183 206 Operating Costs: Adein &Insurance 6 6 e )8 6 e 6 6 8 6 6 6 6 Fuel Cost 1,067 1,340 1,763 1,944 2,129 2,32 2,553 3,219 3,528 3,659 4,220 4,614 5,661 6,192FixedO08H2082%Ks)324 ue a 375 34 a4 ay 456 a7 528 Variable 0 6 4 7 4B 352 389 624 662 ve Ls)5 %1 1,016 1,075 1,282 1,32 Total Project Costs: Dollars 1,600 2,197 2,789 3,69 32%3,353 3,875 4,759 5,138 5,45 5,887 6,329 7,648 8,277Cents/kth 6.1 4.5 6.3 9.6 10.3 11.6 11.8 {2.3 13.4 14.3 15.1 16.1 17.1 16.5 GEOTHERMAL PROJECT SAVINGS (LOSSES) Nominal Dollars: Annual (3,058)=(2,927)(2,783)(2,581)(2,034),957),731)1,484)1,217)(373)(202) Cumulative (3,058)(5,985)(8,766)(11,348)(13,482)(15,439)(17,870)(18,654)(19,878)(20,444)(28,646)Present Worth: Annual (3,058)(2,704)(2,375)(2,034)(1,554)(1,387)1,076)(852)(645)(281)(32) Cumulative (3,058)(5,762)(8,137)(18,271)(11,725)(13,041)(14,017)14,969)15,614)(15,895)(15,987) 1999 200e ry19911992199319941951996i9971998 4 Debt Service 1998 Added Diese!Capacity (Geothersal Case) 19891988 69165165165 RKREQeZeCe | 165165 adie | RABe | 16S RAB ! 165 RA 138% x= Verner Ore Total eee ee |B& i998 1991 1992 1993 194 1995 1996 1997 1998 (All Diesel Case) 19869 Arnal Debt Service Added Diesel Capacity RSEBROPTSe®REBRESSSVERABROSSSRSBReeRaRBRORABEROBRSR= UMP MWe aeneaneunm+ee ee 165130 UNALASKA GEOTHERMAL PROJECT INPUT RSSUMPT IONS GEOTHERMAL PARAMETERS GENERAL PARAMETERS (Doh lars in thousands) Inflation 5.0%Construction Cost Interest Rate Bond Size Geothermal &.25%On Diesel 70 Insurance Load Scenario 2 Au (i=Base,2=High,J-Low)Casement City Busbar Cost ($/kbh) Royalty Schedule Project Size DIESEL PARAMETERS (13M,227i,3=Fila) Sve.Life 16 Fuel Price $0.67 /gal Fuel Escalation 2 (i=Lom,2=High) Fuel Eff.14 kuh/gal ECONOMIC OUTPUTS From Dases and Moore Study 1988 1989 1998 1991 1982 Low 2.0%2%2.0%2.0%2.68 High ca RS.J RS |au a] ENERGY REQUIREMENTS Low desand 18,200 =28,021,008)21,108 21,208 Base Case Demand 22,30 8625,800 31,388 31,808 =32,108 High dewand 22,708 8 8=31,30 937,008 42,888 43,208 REPLACEMENT CAPACITY All Diesel Case Low Load Growth 1,710 855 Ls's}6 6 Base Load Growth 2,565 iss}65 6 High Load Growth 5,130 1,716 [ss]ss 6 7 1 Geothersal Case Low Load Growth 1,718 e e Base Load Growth 2,565 6S 6S e 6 High Load Growth 5,138 1,710 t's]é 6 GEOTHERAAL GENERATION 5 1 Project Base Load Growth 6 6 @ 24,816 24,983 High Load Growth 6 6 @ 2739 =28,82 7 Project Base Load Growth 6 6 6 26,999 29,143 High Load Growth 6 8 @ W646 %,823 Low Load Growth 6 6 6 17,85 =19,128 Table 3 -6 $35,3076Su,008 sae * sie Ss $0.13 2 1993 19%1995 rs eeee 21,208 «21,388 21,0832,408 «32,7083,088 43,700 44,200 «(49,560 6 6 6 e [ss]oS ®en --) 0 6 e )6 8 6 e 6 25,006 §=25,118 26,89328,969 27,668 =38,319 29,310 «29,480 =31,928 35,011 33,568 37,044 19,173 19,159 17,904 T=Atel HIGH Load MNWGH Pues EScarcazvow 19719981999: e e r)6 eoSeS”ne rr 21,400 21,580 21,508 21,600 21,70034,700 39,008 39,388 44,080 44,808 50,700 51,208 «51,708 57,200 57,788 e e e e e e e e 855e65e055 e e e ®e e e e e e e e e e e e 27,081 27,169 27,233 28,811 28,917 30,519 30,621,782 31,635 31,279 32,208 32,341 32,445 34,5764,787 37,424 37,624 37,798 33,452 39,704 17,043 17,006 «17,751 16,759 16,762 Energy Requirements (sh) GEOTHERMAL CASE Geotheraal Project Added Capacity (Ku) Replaced Capacity (KW) Installed Capacity (KW) Generation (Mh) Diese)Support Added Capacity (kW) Replaced Capacity (kW) Installed Capacity (kw) Generation (Mth) DIESEL ONLY CASE New Capacity (KW) Replaced Capacity (Ki) Installed Capacity (Ku) Diesel Generation (MH) Real Fuel Escalation 3.58 3.5% Loads and Resources 37,000 42,800 43,200 43,700 6 7,000 6 6 6 6 6 6 6 7,008 7,000 7,000 37,000 8,154 6,377 6,689 Ls]6 e e 6 6 e 3.58 358 3 a3 7,000 16,648 49,680 12,56 Sa,100 12,878 1997 13,276 13,576 51,708 12,918 17,708 Ra} 17,996 3.38 UNALASKA GEOTHERMAL PROJECT Busbar Cost Coaparison (Dollars in Thousands) 1968 1989 1998 1991 1992 1993 1994 1996 1997 1998 1999 2008 2081 Energy Reqats (4h)22,700 =31,308 =37,088 42,808)43,208)43,708 44,208 49,608 =58,100 50,708)31,288)=51,78857,20857,708 GEOTHERMAL CASE Geothersal Project: Debt Service (1)”se 9 OASA7 84,547 84,547 84,547 04,547)04,547 64,547 04,547 84,587 64,547 84,547 Interest Earnings (2)6 6 6 (338)Re (338)(3)(338)(30)(330)(338)(30)Qm)(330) Wet Debt Service 6 e 6 4,217 4,217 4,217 4,217 4,217 4,217 4,217 4,217 4,217 4,217 4,217 Operating Costs Fixed O68 6 e e ba)1,633 1,085 1,139 1,19 1,256 1,319 1,385 1,454 1,526 1,603 Replacenents e )e 6 e e e e a 6 a )6 6 Administration 6 e 6 )8 e e LJ 6 6 6 6 e e Insurance L)6 e e e e e 6 a )e e 6 6 Royalties 6 6 6 ae 21 276 278 373 333 413 438 62 7 535 Other i]]e 17 18 19 r ]2 2 23 r+)%27 28 Subtotal *2 60 «95,4665 |=05,598)85,597 85,654 OF 5,874 86,0640,158 6,277)=86,383 Diese)Support: Dedt Service 192 a8 235 oS 25 25 25 256 2S 2s 103 R ]e 6 Fuel 1,086 1,625 2,085 498 6 623 631 1,064 1,183 1,324 1,469 1,633 2,26 2,487 Fined O88 280 2 mw ks)we K 7/Roe)Re]44 wy 4%4799 23 528 Variable 0 &M 43 326 653 mt 18 iv?283 ™Re]K ))381 bs]3 Subtotal 1,92 2,76 3,341 =1,268 1,1,45 1,729 2,035 2,198 2,383 2,381 2,28 3,267 3,358 Total Project and Support Costs: Dollars 1,922 2,765 LMI 6,734 6,883 7,@2 7,383 7,042 6,084 6,57 6,446 8,686 9,545 9,51cents/kih 4.3 8.6 9.0 13.7 13.9 16.1 16.7 1368 16.1 16.3 16.5 16.8 16.7 17.2 ALL DIESEL CAGE Debt Service 192 29 2%we ze we Revd mm mam 77 27 178 192 135 Operating Costs: Adain &Insurance 6 8 e 6 é 6 é e 6 6 )8 e 6 Fuel Cost 1,086 1,625 2,085 2,616 2,865 3,145 3,451 4,282 4,605 5,056 5,540 6,078 7,286 1,975 Fixed O8 @ 208 2m my 324 we 37 375 ™44 4u 456 4799 3 528 Variable 08M x%3 326 653 m3 oe ee ba)1,117 1,184 1,258 1,334 1,415 1,644 1,741 Total Project Costs: Dollars 1,92 2,765 3,341 4,065 4,378 4,726 5,106 6,089 6,560 7,126 1,567 6,133 9,624 16,398 Cent s/kWh 6.5 8.6 9.8 3.5 10.1 10.8 11.6 12.3 131 41 14.8 15.7 16.8 18.0 GEOTHERMAL PROJECT SAVINGS (LOSSES) Nominal Dollars: Annwa)(2,669)(2,506)(2,325)(2,277)(1,752)(1,504)1,231)(878)(353)t]457 Cumulative (2,669)(5,175)(7,501)(9,777)(11,530)(13,034)(14,264)(15,143)(15,696)(15,616)(15,168) Present Worth: Annual (2,669)(2,315)(1,984)(1,795)(1,276)(1,012)(765)(se)(294)39 a7 Cumulative (2,669)=(4,984)(6,969)(8,764)(10,040)(11,052)(11,816)(t2,321)(12,614)(12,575)(12,368) Canruneww-WanOOeeWh=1968 is se Aon..Debt Service Added Diesel Capacity (Geothersal Case) 1969 1998 1991 1992 1993 1934 1995 1996 1997 1998 192 192 192 192 1s 192 is2 192 ise ] 67 67 67 67 67 67 6?67 67 67 3S 3 3 k=)K ]Rs]3s 3S 3S 6 6 6 6 6 6 6 8 6 e 6 6 6 6 6 e e 6 6 6 6 6 8 8 6 8 6 8 6 e 6 6 6 6 6 i] Annual Debt Service Added Diesel Capacity (All Diesel Case) 1989 1338 1991 i932 1983 1994 1935 1996 1997 1998 192 192 92 ise 192 192 ise 192 192 ] 67 67 67 67 67 67 67 67 67 67 Ks)S 3 3s 3S R ]5S 3S 3S 7 v7 v7 7 vw av 7 v7 6 6 8 6 6 6 6 8 8 6 6 6 6 e 6 6 6 6 tL)"S Ls]Ls] 8 6 ] 6 6 sx 259 26 Be Re Be Be 377 m7 m7 TAS]geKeckecetties|¥o|eccccccecticn!FwecccccnccccelfPeKeckccctecce|# CHARACTERISTICS AND DEVELOPMENT OF ALASKA'S GEOTHERMAL RESOURCES Dr.John W.Reeder,Geologist Alaska Division of Geological and Geophysical Surveys P.QO.Box 772116 Eagle River,Alaska 99577 David Denig-Chakroff,Project Manager Alaska Power Authority 334 West 5th Avenue Anchorage,Alaska 99501 INTRODUCTION Alaska has an abundant supply of geothermal resources including over 100 surface manifestations such as hot springs,fumaroles,mud pots,and wells.The use of these resources for health and recre- ational purposes is well documented in historic records.In more recent times,direct uses have been expanded to include space heat- ing in lodges,cabins,and greenhouses.Elsewhere in the world, geothermal resources have been used successfully for many commer- cial applications including electric power generation.The first geothermal power plant was established in Italy in 1906.Over the past several decades,geothermal heat has emerged as a commercial competitor with other forms of energy for both electrical gen- eration and a variety of direct-use applications. An important consideration in geothermal development is that power facilities or direct-use applications must be located near the resource.Due to its potential for heat losses,geothermal energy cannot be transported great distances.Although Alaska has an abundance of geothermal resources,there are only a few areas where the resources occur close to a potential energy market.Conse- quently,any plans for geothermal development in Alaska must be based on both the nature of the resource itself and on the economic feasibility for its development. This paper presents an overview of the nature and occurrence of geothermal resources in Alaska and a discussion of their develop- ment and potential for development.It also presents a summary of the Unalaska Geothermal Project and discusses its potential for development as the first geothermal power project in the State. THE RESOURCE AND ITS DEVELOPMENT With respect to the nature of the resource,the characteristics of the heat source and of the reservoir are important.Two generic types of geothermal resources have been recognized based on the 8321/350 Page 1 origin of heat that drives their convective circulation systems. These generic systems,in turn,correspond to high temperature(i.e.,392°F or greater)versus moderate or low temperature resources.In addition,the reservoir can be large,moderate,or small in size and usually is within four miles depth.Geothermal fluids can also be classified on the basis of their geochemical and/or geophysical character.For example,geothermal systems can be dry-steam dominated,wet-steam dominated,or more commonly water dominated.The water dominated systems are usually characteristic of the moderate or low temperature resources,and the steam dom- inated systems are for all practical purposes restricted to the high temperature resources.The recognition of these contrasting types of geothermal resources provides a fundamental basis for the serious planning and evaluation of specific geothermal development projects.If the nature of the resource or even its existence is unknown,then serious geothermal development plans are impossible to undertake! The most common utilization of geothermal energy is the "location intensive"small scale use of hot water for various "direct heat” applications.A number of Alaska's thermal spring sites have been used for recreation use,while a few have been used to heat dwell- ings,bath houses,and greenhouses (e.g.,Bell Island,Chena, Circle,Goddard,Manley,Melozi,Pilgrim,and Tenakee Springs). The "location intensive"character of such resources is principally caused by the economic difficulty in transporting such resources. Considering the remoteness of most geothermal sites in Alaska,the development of such resources will probably need to wait until Alaska's energy demand greatly expands.Summer Bay warm springs near Unalaska might be a near-future exception. Ground water at depth can be quite warm due to the heat flow from the Earth's interior,whether hot igneous rock exists or not at shallow depths in the region.Such ground-water bodies might exist in large sedimentary basins that occur throughout a large part of Alaska.Smaller ground-water reservoirs might also exist in frac-ture zones within metamorphic and igneous (plutonic)rocks that also occur throughout the State.If fractures extend to the sur- face for both situations,then the ground water can circulate to the surface or at least to shallow warm-water reservoirs by means of a density-driven convective system.The widespread hot spring occurrences throughout Alaska's Interior,Seward Peninsula,and Southeast Alaska appear to be principally related to such con-vection in fractures related to igneous (plutonic),somemetamorphic,and very limited sedimentary rocks (Waring,1917;and D.G.G.S.,1983). Typically,the regions of deeper hot-water reservoirs where moder- ate temperatures can occur will be overlain by shallower,cooler aquifers that contain water slightly under boiling temperature. Such shallow aquifers would be more likely found if shallow 8321/350 Page 2 sedimentary rock exists in the region in contrast to normally denser metamorphic and plutonic rocks.At Pilgrim Hot Springs near Nome,a shallow aquifer with temperatures near the boiling temperature occurs in sedimentary rock,which is easily located and produced with volumes and temperatures suitable for space heating or other similar direct applications.This shallow reservoir, which is at depths of less than 100 feet,can produce over 300 GPM artesian flow at 194°F with existing wells that were drilled with State funds.Based on the temperature gradient of these wells,it has been interpreted that the deeper reservoir exists at a depth of about 5000 feet and at a temperature of 302°F (Economides and oth-ers,1982). Such shallow geothermal resources (i.e.,normally at depths of lessthan500feet)are often accessible by typical water-well drillingrigsasopposedtothedeeperreservoirs(i.e.,normally at depthsof4,000 to 6,000 feet)with higher temperatures.The moderate temperatures at the deeper reservoirs are attractive,but the ulti- mate cost associated with drilling up to 6,000 foot wells in remote locations for a resource best suited for just direct utilization such as space heating is discouraging.These moderate temperature resources are amenable to electrical generating production through binary power generation,in which a secondary working fluid is vaporized by the hot water and then the organic steam turns the turbines.This approach unfortunately is expensive. Large-scale geothermal electrical power development projects require temperatures normally in excess of 392°F for efficient operation.Such high temperature geothermal systems are almost exclusively associated with igneous heat sources.The classic major geothermal systems around the world,such as those at Wairakei,New Zealand;at the Geysers of California,U.S.A.3;and at Larderello,Italy are all associated with young (i.e.,less than 1millionyearsold)igneous systems of a particular type,that is those consisting of a rhyolitic magma at shallow depths that were produced from the melting of shallow crust.By contrast,most other volcanic and/or plutonic igneous occurrences that do not consist of rhyolitic melts do not have associated high temperature hydrothermal systems.Rhyolitic rocks are lacking for a majority of Alaska's 55 plus active volcanoes,which are located in the Aleutian arc.Thus,Alaska's active volcanoes are most likely associated with low to moderate temperature geothermal systems than with high temperature systems if such geothermal systems even exist.Nevertheless,Alaska's andesitic volcanoes may be underlain by "trapped"magma that has risen from great depths.Such magma bodies might serve as a significant heat source for large moderate- temperature and with luck maybe even high-temperature geothermal systems. 8321/350 Page 3 THE UNALASKA GEOTHERMAL PROJECT The Makushin Volcano region of Unalaska Island is typical of these andesitic volcanic systems.Prominent fumarole fields wereobservedinthisregionin1980(Reeder,1982).In 1981 the Alaska Legislature appropriated $5 million to be administered by the Alaska Power Authority for geothermal drilling and exploration at Makushin Volcano.The Power Authority selected Republic Geothermal,Inc.of Santa Fe Springs,California to be the consultant to plan and coordinate the exploration and drilling program.The program consisted of three phases.Phase I activities included data review and synthesis;technical planning; land status determination;permitting requirements;acquisition of baseline environmental data;geological,geochemical,and geophysical investigations and mapping;and the drilling of three temperature gradient holes.Phase II activities included continued and more extensive testing of the geothermal resource,the drilling of a fourth temperature gradient hole,and an_electrical resistivity survey to delineate the extent of the reservoir. Under Phase I,the first three temperature gradient holes were drilled in 1982 to depths of 1500 feet and encountered temperaturesofupto383°F (195°C).Two of the holes indicated a close prox- imity to geothermal resources below,while the third appeared to be on the fringe of the geothermal system.The Phase I final report was completed in 1983 concluding the strong possibility of a water-dominated geothermal system in excess of 480°F (250°C)on the eastern flank of Makushin Volcano at a depth of less than 4,000 feet. Phase II was initiated in the Spring of 1983.The exploratory well was started in early June.After numerous delays caused by diffi- cult drilling conditions,on August 25,1983,the well encountered a fracture zone from 1,946 to 1,949 feet containing a substantial geothermal resource.Although the exploratory well tapped the res- ervoir by means of a large fracture within plutonic rocks,which are common throughout the region in both plutonic and volcanicrocks(Reeder,1985),the actual reservoir is probably located immediately beneath the Makushin volcanic pile within fairly perme- able brecciated rocks.Initial well testing confirmed a wa- ter-dominated geothermal system with a steam cap and bottomholetemperatureandpressureof379°F (195°C)and 478 psi respective- ly.The onset of inclement weather prevented further resource testing during the 1983 field season. Phase III of the project was conducted in 1984 and consisted of further well testing and reservoir analysis as well as drilling a fourth temperature gradient hole and conducting an electrical resistivity survey.The temperature gradient hole,drilled in an area that would be more accessible to development than the explora- tion wellsite,showed no indications of the presence of a similar 8321/350 Page 4 geothermal resource.The electrical resistivity survey revealed that the site of the current exploration well is the most accessible site where significant geothermal resources are likely to be encountered at a reasonable depth.Flow tests and reservoir analyses conducted in 1984 indicate that a single commercial-size well located near the current exploration wellsite could produce between 1.0 and 1.5 million lbs/hr of fluids.A calculation of the estimated reserves reveals volumes of at least three-quarters of acubicmile(Economides and others,1985).These figures indicate that the resource is capable of meeting the current and projected power needs of the island for hundreds of years. However,the existence of a prolific geothermal resource by itself does not justify development of a geothermal power project.That decision must be made based on an analysis of economic feasibility. This means forecasting population,commercial,and industrial growths,power demands,and fuel prices and determining the costs and benefits of a potential project.In the case of Unalaska this may not be an easy task.Unalaska has long been dependent upon the ups and downs of the fishing and crabbing industries.Its power requirements,likewise,follow this cyclical trend.Power demand may range from a peak of 13 MW at the height of a good fishing sea- son to an average of 2 to 3 MW during the off-season.In recent years,Unalaska has attempted to diversify its economy with the development of marine support facilities,a bottomfish industry and,most recently,tourist trade.In addition,the U.S.Coast Guard is considering the island as the site for a large search and rescue facility and the petroleum industry could use Unalaska as a staging area for offshore oi]development.Whether these ventures will succeed and result in an increase and/or stabilization of electrical loads remains to be seen. A geothermal power plant at Unalaska would have to be located at the site of the resource which is 15 miles west of the communities of Unalaska and Dutch Harbor in a remote,roadless,rugged terrain. It is anticipated that construction of a 10 MW power facility including a road and transmission line would cost at least $40 million.A detailed feasibility analysis is needed to determine whether the cost and dependability of power from such a facility will compete with the existing diesel power generating systems. CONCLUSION A significant and impressive quantity of geothermal resources occur in Alaska,capable of large and small scale development and both direct use and power generation.However,geothermal energy devel- opment is often limited by the remoteness of its occurrence and the availability of a potential energy market.Consequently,any pros- pects for geothermal energy development should be carefully analyzed in terms of the nature and capability of the resource as well as the economic feasibility for development.Recent advances 8321/350 Page 5 in technology and worldwide successes in geothermal resource devel- opment assure geothermal energy a role as a viable competitor among the variety of energy options and alternatives.With Alaska's abundance of geothermal potential,this alternative deserves serious consideration. REFERENCES Division of Geological and Geophysical Surveys of the Alaska Department of Natural Resources,compiler,1983,"Geothermal re- sources of Alaska":National Oceanic and Atmospheric Administration,U.S.Government Printing Office,1 plate. Economides,M.J.,Ehlig-Economides,C.A.,Kunze,J.F.,and Lofgren,B.,1982,A fieldwide reservoir engineering analysis of the Pilgrim Springs,Alaska,geothermal reservoir:Proceedings of the Etghth Workshop of Geothermal Reservoir Engineering,Stanford Geothermal Program SGP-TR-60 Report,Stanford University,pp 25-30. Economides,M.J.,Morris,C.W.,and Campbell,D.A.,1985,Eval- uation of the Makushin geothermal reservoir,Unalaska Island:Pro- ceedings of the Tenth Workshop of Geothermal Reservoir Engineering, Stanford Geothermal Program SGP-TR-62,Stanford University,in press. Reeder,J.W.,1982,Hydrothermal resources of Makushin Volcano re- gion of Unalaska Island,Alaska:Transactions Third Circum-PacificEnergyandMineralResourceConference,American Association of Petroleum Geologist Circum-Pacific Series,pp.441-450. Reeder,J.W.,1985,Fault and volcanic dike orientations for the Makushin Volcano region of the Aleutian arc:Proceedings of the International Symposium on Recent Crustal Movements of the Pacific Region,held February 9-14,1984,at Victoria University, Wellington,New Zealand,Royal Society of New Zealand Bulletin,in press. Waring,G.A.,1917,Mineral springs of Alaska:U.S.Geological Survey Water-Supply Paper 418,114p. 8321/350 Page 6 -DRAFT 8707-0 RECEIVED EVAULATION OF THE MAKUSHIN GEOTHERMAL RESERVOIR,| UNALASKA ISLAND DEC 10 1984 ALAMichaelJ.Economides(1),Charles W.Morris(2),SKA POWER AUTHORITY and Don A.Campbe11(3) ABSTRACT Analysis of an extended flow test of well ST-1 on the flanks of Makushin Volcano indicates an extensive,water-dominated,naturally fractured reservoir.The reservoir appears to be capable of delivering extremely large flows when tapped by full-size production wells.A productivity index in excess of 30,000 Ib/hr/psi implies a phenomenal permeability-thickness product,in the range of 500,000 to 1,000,000 md-ft. The flowing bottomhole (1,949-foot)temperature of the fluid is 379°F,(190°ewhichislowerthanthemeasuredstatictemperatureatthatdepth(395°F). This phenomenon,coupled with an observed static temperature gradient reversal from the maximum 399°F observed at 1,500 feet,indicates that the reservoir proper is located some distance from the well.Presumably tt 1s at a temperature slightly lower than 379°F and communicates with the wellbore via a high conductivity fracture system. A material balance calculation yields an estimate of reserves that are Capable of sustaining all of the present power needs of the island (13+MW peak)with a geothermal power plant for several hundred years.Theoretically, a single large diameter well at the site of ST-1 could satisfy this requirement. 1.University of Alaska,Fairbanks,AK Now with Dowell-Schlumberger,London 2.Republic Geothermal,Inc.,Santa Fe Springs,CA Now with Schlumberger Offshore Services,New Orleans,LA 3.Republic Geothermal,Inc.,Santa Fe Springs,CA Se 77.03 STATE OF ALASHA ) --oe DEPARTMENT OF NATURAL RESOURCES /; f O)POUCH 7-028 DIVISION OF GEOLOGICAL &GEOPHYSICAL SURVEYS -PHONE.07)2762689 W794 UNIVERSITY AVENUE,BASEMENTFAIRBANKS,ALASKA 99701December6,1984 PHONE:(907)474-7147 David Denig -Chakroff Project Manager Alaska Power Authority 334 W.5th Avenue,2nd floor Anchorage,Alaska 99501 Dear David: Please find enclosed an interim inter-agency report on our study of Makushin geothermal fluids and mineral alteration.The report contains a series of preliminary geochemical data tables and lithologic logs and brief discussions of their significance. We feel we have accomplished much and we are beginning to develop some exciting hypotheses regarding the histories of the Makushin geothermal and volcanic systems.The final results of this work should have a direct bearing on understanding the hydrothermal system and estimating its overall geothermal energy potential. We have experienced cut-backs in funding and manpower and therefore our laboratory and data analyses work has taken longer than originally anticipated.Because of these delays we must request an extension of the deadline for submittal of our final report to APA,from December 30,1984 to March 15,1985.I hope that this delay does not present an inconvenience to you. Should you have any questions regarding the enclosed report or our work on the Makushin project please do not hesitate to call me. Sincerely, in (2Dr.Roman J.Motyka Manager,DGGS Geothermal Project Enclosure 1983 and 1984 DGGS Geothermal Fluids Sampling and Well-logging at the Makushin Geothermal Area An interagency interim progress report submitted to the Alaska Power Authority under RSA #RSO8-8227,Unalaska Geothermal Drilling. December,1984 Prepared by Roman J.Motykal and Lawrence D.Queen! Participating Scientists:C.J.Nyel,C.J.Janik2,D.S.Sheppard3, R.J.Poreda4,M.A.Moorman!,and S.A.Liss!. lalaska Division of Geological and Geophysical Surveys,Fairbanks, Alaska. 2U.S.Geological Survey,Menlo Park,California. 3Department of Science and Industrial Research,Wellington,New Zealand. 4scripps Institute of Oceanography,University of California,La Jolla, California. INTRODUCTION This report presents preliminary results of DGGS geothermal fluid and mineral alteration investigations conducted on the Makushin geothermal area during the 1983 and 1984 field seasons.The report focuses primarily on the sampling and analyses of thermal fluids from test-well ST-1 and on the logging of core from the test-well and the thermal gradient holes.Also included are updated tables of geochemical data on fumaroles,thermal springs,and cold waters.The report is intended for rapid interagency transfer of data and information.Interpretive discussions are therefore kept brief and are considered preliminary.The format is informal with rough drafted figures and tables and a minimum of references. Under the provisions of the FY-85 RSA extension agreement with the Alaska Power Authority,DGGS primary responsibilities were to be: 1)The sampling and analysis of fluids encountered during the deepening of ST-1; 2)Shipment of rock core from thermal gradient hole A-1 and from ST-1 from Unalaska to Fairbanks. The first task could not be carried out because of APA's decision not to deepen ST-1.The second task was accomplished for core retained from A-1l. Approximately 1,860 ft of rock core was shipped and is being temporarily stored at the DGGS Fairbanks Warehouse. In the RSA agreement,DGGS also stated its intent to perform several additional tasks if time and funding were available: 1)Sampling and analyses of thermal fluids from ST-1 during the terminal stages of the 40-day flow test of ST-l:this task was accomplished during the week of August 1-8,1984.Description of 2) 3) 4) 5) the sampling procedures and preliminary results of analyses are presented in this report. Trace element analyses of volcanic rocks associated with Makushin area magmatic systems:funds for this task have not become available and it is probable that trace element information will not be included in our final report to APA.It is our intent to standardize and calibrate our in-house X-ray flouresence unit for trace elem@ént research.Results from this effort,however,are unlikely to be available until late next spring. Compilation and interpretation of available volcanic rock geochemical data:analyses of whole rock geochemical data is currently underway and should be available for our final report. X-ray and petrographic identification of hydrothermal alteration mineralogy in rock cores obtained from drilling:this task has been accomplished for thermal gradient holes Bl,El,and I1 and for test-well ST-1.Lack of funding has limited investigation of core from A-1 to hand specimen analyses with only minimal thin-section and X-ray work. Production of a geologic plate showing lithologic logs and alteration mineralogy of core from ST-1 and thermal gradient holes. This has been accomplished for Dl,El,Il,and ST-1 and has been published as a Report of Investigation which is included as Appendix A of this report.Hand specimen log and discussion of alteration mineralogy in A-l are presented in this report. GEOTHERMAL FLUIDS FROM ST-1 Introduction DGGS undertook the sampling of geothermal fluids from test-well ST-1 as part of an overall geothermal exploration drilling program at Unalaska Island funded by the State of Alaska.The program is administered by the Alaska Power Authority with Republic Geothermal,Inc.of California the prime contractor.Fluid sampling by DGGS was accomplished through the helpful cooperation of both these organizations. Test-well ST-1 is located near the head of Makushin Valley (fig.1).The wellhead sits upon the upper edge of an apron of pyroclastic debris that fills the bottom of upper Makushin Valley (Nye and others,1984).Except for the top 10 meters which are composed of pyroclastics,ST-l penetrates a gabbro-noritic pluton to a depth of 1,946 ft (Queen,1984).The production zone for the well is an approximately 3 foot wide open fracture at the bottom of the hole.Bottom hole temperatures during the 1983 and 1984 flow tests were measured to be 193°C by RGI scientists.A static hole temperature check made July 2,1984 by RGI gave a bottom hole temperature of 202°C with a maximum temperature of 204°C occurring at the 1,600 foot depth.Water table in the system as estimated from down-hole pressure measurements appears to lie between 750 and 800 feet below the surface. Samples of fluids produced from the test-well were collected both in 1983 "and 1984.The majority of the samples are of fluids from the major production zone at 1,946 foot depth.These samples were obtained between 8/27/83 and 9/3/83 and between 8/1/84 and 8/7/84.The test-well was closed from 9/3/83 until 7/4/84,then run nearly continuously until shut-down on 8/8/84. Objectives of the geothermal fluids investigations include: 1)Characterization of reservoir water and gas chemistry. 2)Determination of potential scaling and environmental pollution problems. 3)Provision of pre-development geochemical data base. 4))Study of fluid-mineral equilibria. 5)Information on deeper reservoir characteristics and origin of chemical constituents in reservoir waters. 6) Geothermometry. 7)Mixing relationships. 8)Comparison of isotopic and chemical composition of reservoir fluids to neighboring fumaroles and springs. 9)Research data base for understanding Aleutian-arc type hydrothermal systems. With regard to the latter,the Makushin hydrothermal system is the first in the Aleutian-arc to be successfully drilled and produce thermal fluids at temperatures above atmospheric boiling. Sampling Procedures Samples of gases and waters from test-well ST-1 were collected using a Webre type mini-cyclone separator.Design and use of the separator are described in Nehring and Truesdell,1983.The separator was attached off the side of exhaust manifold at a point about 15 feet from the wellhead and 'several feet before the throttling orifice.Separator pressure was monitored with a high pressure gauge located before the separator's water exhaust valve.Fluid collection pressures and temperatures together with sampling dates and steam fractions are given in table l. The separator was first adjusted for collection of the water fraction. Fluids emerging from the water exhaust port of the separator were routed through a condensing coil immersed in an ice bath,then collected and filtered through 0.45 micron filters.The sample suite normally consisted of 1 liter filtered untreated,1 liter filtered acidified (HCl),1 liter filtered and treated with formaldehyde for 189-so,determinations,100 m1 of water at a dilution of 1:10 and 1:5 for silica determinations,1 liter of untreated water for tritium determinations,and 30 ml of water for stable isotope determinations.In addition,raw untreated samples were collected for in-field determination of HCO3,pH,H20,and NH3.In two cases (samples 77 and 02),waters were filtered through 0.1 micron filter and treated in the field for Al analysis following methods described by Presser and Barnes,1974, As an additional check on chemistry,water samples were collected from the end of the exhaust manifold.This was done by placing a bucket beneath the pipe-end and allowing the flashed water to flow into the bucket. Steam and gas samples were then collected after first adjusting the separator for pure steam phase fiow.The steam and gases were routed through the condensing coil then collected in sodium hydroxide charged evacuated. flasks.Additional samples were collected in uncharged evacuated flasks for 3He/4He analyses.A 500 ml sample of the steam condensate was collected for Cl analyses as a check against water phase contamination.30 ml samples of the condensate were also collected for stable isotope analyses. Methods of Analyses Water:HCO3,pH,H2S,and NH3 were determined in the field following methods described in Presser and Barnes (1974).The remaining constituents were analyzed at the DGGS Geothermal Fluids Laboratory in Fairbanks.Major and minor cation concentrations were determined using a Perkin-Elmer atomic absorption spectrometer following standard procedures. Sulfide and bromide were determined on a Dionex ion chromatograph.Fluoride was determined using the specific ion electrode methods.Chlorides were analyzed by Mohr titration and boron,by carminic acid method.Aluminun, arsenic,and iron were determined by atomic absorption spectroscopy.Silica concentrations were determined by the molybedinate blue method. Stable isotopes (189/169 and D/H)were analyzed at Southern Methodist University,Dallas,Texas and at U.S.Geological Survey,Menlo Park, California.Tritium concentrations were determined at the University of Miami,Miami,Florida. Gases:Residual gases,i.e.,gases not absorbed in the sodium hydroxide solution (He,Hg,Ar,09,No,and CHy)were analyzed on a dual-column gas chromatograph with both argon and helium carrier gases at the U.S. Geological Survey,Menlo Park,California.Moles of residual gas were calculated from measured gas pressure and head space volume.Carbon dioxide and hydrogen sulfide concentrations in the sodium hydroxide solutions were determined by titration and by ion chromatography respectively. Concentrations of these gases were also checked by gravimetric methods using SrCl9 and BaCl9 to precipitate SrC03 and BaSO4.The SrCO3 precipitate was then reacted with phosphoric acid to determine CO?yield. The evolved gas was saved and analyzed for 13¢/l2c¢,Steam content of the gases was determined by weight difference before and after sampling. Ammonia was analyzed by specific ion electrode method. Adjustments were made for head space gases dissolved in the solution using Henry's Law.Moles of each constituent collected were than determined and mole %of each constituent was calculated.A correction was then made for air contamination by using the ratio of oxygen in the sample to oxygen in air.The gas concentrations in mole %were then recalculated on an air-free basis. Helium isotope ratios (3He/4He)were determined at the Scripps Institute of Oceanography,La Jolla,California.Carbon isotope ratios in carbon dioxide (13¢/12¢)were analyzed at U.S.Geological Survey,Menlo Park,California. Results The results of the geochemicaland isotopic analyses of the geothermal fluids from ST-1 are presented in tables 2 through 17.New analyses and updates of previous analyses of waters and gases from fumarole fields,hot springs and cold waters in the Makushin geothermal area are given in tables 18 through 30. Waters:Reservoir water chemistry calculated from separator conditions are given in tables 4 and 5.The reservoir chemistry calculated from exhaust water analyses gives concentrations of constituents 10 to 15 percent higher than separator values if the exhaust water fraction is calculated on the assumption of atmospheric pressure--boiling point conditions.D.Michaels (pers.comm.,RGI,1984)however believes flashing at the exhaust end occurs to pressures well-below atmospheric.Supporting evidence comes from a temperature measurement made by P.Parmentier (RGI)of the center of fluid flow from the exhaust.The temperaturey measured was 60°C indicating that low-pressure effects that are not yet well understood is causing increased flashing of the exhaust fluid.Using the 60°C temperature as the end point results in an exhaust-end water fraction of 0.75.Applying this water fraction to exhaust chemistry gives results in close harmony with those obtained from the separator chemistry. Additional support for basing reservoir chemistry on the analysis of the separator water fraction comes from RGI's reported analyses of 1983 ST-1 water samples.Two of their samples were obtained under high-pressure conditions using a technique entirely different than DGGS used.These high pressure water samples yielded results nearly identical to DGGS results when back-calculated to reservoir conditions (RGI,1983,pg.XII). The reservoir waters can be characterized as moderately saline low-bicarbonate waters.Comparison of 1983 to 1984 chemistry show the waters to be nearly identical;the 1984 waters are slightly less saline and slightly richer in HCO3.The reservoir waters are high in arsenic which may pose a potential water pollution problem. Using the average back-calculated isotopic composition (table 8)the reservoir waters appear to be shifted approximately 1.5 to 2.0 mils with respect to meteoric waters. The results of applying geothermometers based on water chemistry and isotopic composition to the Makushin reservoir waters are given in tables 9, 10,and 11.Silica concentration appears to be slightly out of equilibrium with quartz at the measured flowing bottom hole temperature (BHT)of 193°C but is near equilibrium with quartz at the measured maximum static BHT of 204°C. 9 Since the host rock is a gabbro-norite the basaltic Na/K geothermometer of Arnorsson (1983)is probably the most applicable of the Na/K geothermometer.The results of this geothermometer are in close agreement with the Na-K-Ca geothermometer of Fournier and Truesdell (1973).These cation geothermometers suggest that either the system is out of equilibrium or that the waters were warmer and have cooled before entering the borehole. Cooling could come about either by conduction or mixing of cooler waters or combination of both processes. The 189/160,S04-H20 geothermometer of McKenzie and Truesdell (1977)predict even higher reservoir temperatures.Using the reservoir isotopic value for 189/160,gives reservoir temperatures of 245-250°C. Gases:Air corrected analyses of gases in mole per cent are given in table 12.Gas content in total discharge and partial pressure of C09 in the reservoir are given in tables 13 and 14 respectively.Of the 1984 gas samples,MVTW-2G-B is the least air contaminated and its analyses is considered the most reliable and representative of the geothermal system. Inspection of the gas tables shows a slight decline in the overall concentration of gases in the total mass discharge between 1983 and 1984. Hydrogen content appears to have dropped significantly,nearly an order of magnitude since the well was first opened in 1983.Methane concentration appears to have also dropped and was present in only trace amounts in the 1984 samples. Overall gas concentrations in the reservoir fluid is extremely low,0.02 %of total discharge.Hydrogen sulfide,although 2 to2.5 %of the total gases on a steam-free basis,is in such low concentration in the overall discharge it should not pose any significant health hazard or pollution problems, 10 Application of three different gas geothermometers to the ST-1 gas analyses is given in table 15.In the majority of cases the three thermometers agree quite closely with temperature estimates varying between 190°C and 250°C.The majority of estimates,however,fall between 210 and 225°C which is in fairly close agreement with the cation geothermometers. Note that for cases in which CH,concentration is not known,a valve of 0.001 was used in the D'Amore-Panichi geothermometer. Carbon isotope analyses given in table 16,show a drop of 1.7 mil in 13¢composition of CO between 1983 and 1984.The 13¢values of -13 to -15 suggest a possible organic-sedimentary origin for COg in the geothermal system. With the exception of a brief comment on gas geothermometry,the tables of data on chemistry and isotopic composition of fumarolic gases,thermal Spring waters,and cold waters (tables 18 through 20)are presented here without comment.Discussion of much of this data can be found in Motyka and others,1983. -The gas geothermometer of D'Amore and Panichi applied to analyses of fumarole gases is given in table 26.Temperatures Tl were calculated using a partial pressure of CO9 equal to one bar as per instructions in D'Amore and Panichi,1980.Temperatures T2 were calculated using a partial pressure of 0.5 bar,approximately that found at ST-1.From comparison of the two temperatures it is apparent that the geothermometer is quite sensitive it COz partial pressure.However,even the T2 temperatures average about 20°C lower than the Tl temperatures,in many cases the temperatures are still substantially higher than temperatures found at ST-l.This is particularly true for fumaroles in field #3,suggesting either that the D'Amore-Panichi geothermometer is not accurate when applied to fumaroktes or that the system is much hotter at the head of Glacier Valley. ll DESCRIPTION OF CORE FROM A-1 Rock Units A preliminary log of core from drill hole A-l is given in Appendix B. The rocks from the core can be divided into three basic units.The unaltered volcanics,the Unalaska Formation,and the gabbro-hornfels complex:the unaltered volcanics are present at the surface and extend to a depth of 122 ft.This unit includes surface ash and cinders,andesite flows and a basal lahar.These rocks are Quaternary in age and are essentially unaltered except for surface weathering. The Unalaska Formation includes the Unalaska clastics and the Unalaska volcanics.Both are metamorphosed to lower greenschist facies and are similar in composition and permeability.The Unalaska Formation extends from 122 ft to about 1,620 ft.There are two minor gabbro dikes in this interval.One from 458-478 ft and the other from 942 to 1,020 ft.The former lacks a hornfels envelope and the latter has only a minor hornfels aureole. The gabbro-hornfels complex extends from 1,620 ft to the bottom of the hole at 1,864 ft.From 1,620-1684 the complex consists of gabbro dikes cutting hornfelsed Unalaska Formation.Below this the well appears to intersect the pluton proper. Alteration The alteration pattern observed in Al is,in general,consistent with the present temperature profile.In addition,the changes in the alteration 12 appear to mark changes in the fluid composition of the different portions of the reservoir.Only in the lower portions of the core are alteration assemblages indicative of higher temperatures present, The upper 122 ft of the core consists of unaltered Quaternary volcanics. Below these,down to about 400 ft,the alteration is argillic.This clay-bearing alteration is indicative of low to moderate temperature,acidic waters.These conditions are typical of surface weathering and steam dominated portions of the geothermal system. From 400 ft down to approximately 900 ft the alteration consists of bladed calcite,amorphous silica,pyrite and some clay.Much of this alteration is localized around the breccia zones which mark this section. The noted assemblage was shown to be related to boiling of low salinity, near-neutral waters in the Yellowstone area.The temperature profile is isothermal,at about 100°C,through this section indicating it is likely a zone of steam. Below 900 ft the boiling related assemblage is replaced by "dogs-tooth" calcite,quartz,anhydrite,and zeolites.Pyrite,while still present,is less abundant.These changes result from an increase in temperature and a cessation of boiling (due to increased pressure).The fluids depositing these minerals are likely slightly saline and near neutral.The presence of zeolites (mordenite to about 1,200 ft and laumontite from 1,500 1,780 ft) indicates that the CO9 partial pressure is low. While zeolites are somewhat indicative of temperature they are not abundant in this core.However,the presence of laumontite at 1,780 ft indicates that since its deposition the temperature at this depth has not exceeded 200°C. 13 While most of the alteration can be assumed to reflect current condition, there are some veins present which seem to be relicts of an earlier,hotter stage of geothermal activity.These veins have an assemblage of epidote+ anhydrite+magnetite +calcite.The theoretical stability limits of this assemblage exceeds the current bottom hole temperature of this well. The veins are locally cut by younger veins indicating they are not in equilibrium with the present system.The veins bearing the assemblage occur from 1,100 ft to the bottom of the hole.Similar veins occur in El and ST-1. FLUID INCLUSION STUDIES Fluid inclusions in hydrothermal quartz from cores El and ST-1 have been examined on a heating-cooling stage to determine fluid compositions and homogenization temperatures.The fluid compositions agree well with the current reservoir conditions as indicated by waters sampled from ST-1.All the inclusions measured indicate a freezing point depression of between -0.1 and -0.7°C.The mean depression is -0.35°C.This gives a composition of approximately 6,200 ppm NaCl equivalent,thus it seems that the fluid composition has not varied greatly with time. The homogenization temperatures indicate the temperature at which the mineral enclosing the fluid inclusion formed and thus give the past temperature of the system.The mean temperatures measured are consistently 80-100°C higher than the current temperature at the depth from which the sample was recovered.Some samples exhibit a systematic decrease in temperature indicating that the higher temperatures represent an earlier stage of the present system .The lack of abundant fluid inclusion at the aeweeee 14 present thermal gradient indicates that the system is either not depositing minerals or has not been at the current state for a geologically significant amount of time. DISCUSSION OF OTHER PRELIMINARY RESULTS Evidence gathered from geologic mapping and detailed study of volcanic stratigraphy indicate massive fluxes of magma passed through the crust and were erupted onto the surface in the period between the end of the Wisconsin .Glaciation (10,000 yrs ago)and about 6,000 yrs,the time of a neoglacial advance.Heat transferred from this magma to the shallow crust during its ascent and heat from residual magma emplaced in the shallow crust during this episode may be the source of heat driving the present day hydrothermal system at Makushin. Evidence for a recent and rapid change in water table and cooling of the upper part of the Makushin geothermal system continues to mount: 1)Alteration mineral assemblages and trace-element geochemistry found in the rock cores indicate a hot-water system existed nearly to the present day surface in the very recent past. 2)Evidence of fossil chloride thermal springs on neoglacial moraines in the upper part of Glacier Valley also indicates a hot-water system reached the surface in recent times. 3)Present-day water table depth,as determined from drill-holes,lies at a depth of 750-800 feet below the surface in upper Makushin Valley.Thus,a vapor-dominated zone presently extends,from this depth to the surface.pemeeee 15 4)Fluid inclusion studies on vein-deposited quartz and anhydrite geothermometry indicate temperatures in this upper zone were 50 to 100°C hotter than present-day temperatures. 5)The fluid inclusion studies also indicate the waters from which the quartz veins were precipitated had a salinity nearly the same as the present-day hydrothermal system . Our working hypothesis to explain these phenomena is that the elevated temperatures recorded by the fluid inclusions were the result of an increase in hydrostatic pressure caused by ice-loading during a neoglacial advance. Fluid inclusion temperatures indicate hydrostatic head would have to have been 300 meters higher than the present-day surface at ST-1.This head could easily have been supplied by a valley glacier.Subsequent deglaciation would decrease the pressure rapidly causing boiling in the upper zone of the hydrothermal system.A net loss of water from the boiling and perhaps from decrease of recharging glacier meltwater would cause the water table to drop. | The drop in temperature in the upper part of the system then,may reflect an episode of intense boiling and water loss rather than overall cooling of the system.If so,then the deeper part of the hydrothermal system might still be expected to be at temperatures similar or greater than the fluid inclusion temperatures found in the upper part of the system.The sulfate-water isotope geothermometry does predict a maximum reservoir temperature of 250°C which is similar but lower than fluid inclusion temperatures, The question of whether or not the Makushin geothermal system is in retrograde (i.e.,cooling)is important for estimating the geothhermal energy potential of the area and its future development. REFERENCES CITED Arnorsson,Stefan,1983,Chemical equilibria in Islandic geothermal systems -implications for chemical geothermometry investigations: Geothermics,v.12,no.2/3,p.119-128. Arnorsson,Stefan,Gunnlaugsson,Einar,and Svavarsson,Hordur,1983, The chemistryof geothermal waters in Iceland.III.Chemical Seothermometry in geothermal investigations:Geochimica et Cosmochimica Acta,v.47,no.3,P.567-578. Chiba,Hitoshi,Kusakabe,Minoru,Hirano,Shin-ichi,Matsuo,Sadao,and Somiya,Shigeyuki,1981,Oxygen isotope fractionation betweenanhydriteandwaterfrom100-500 deg.C:Earth and Planetary Science Letters,v.53.,Pp.55-62., D'Amore,F.,and Panichi,C.,1980,,Evaluation of deep temperatures of hydrothermal systems by a new gas geothermometer:Geochimica et Cosmochimica Acta,v.44,p.549-556. D'Amore,F.,-and Truesdell,A.H.,»Gas geothermometry for drillhole fluids from vapor dominated and hot water geothermal fields: Fouillac,C.,and Michard,G.,1981,Sodium/lithium ratio in water applied to geothermometry of geothermal reservoirs:Geothermics, v.10,no..1,p.55-70. Fournier,R.O<.,and Truesdell,A.H.,1973,An empirical Na-K-Ca geothermometer for natural waters:Geochimica et Cosmochimica Acta,v.37,p:1255-1275. Fournier,R.0O.,and Potter,R.W.,1978,A magensium correction for the Na-K-Ca chemical geothermometer: U.S.Geological Survey Open-file Report 78-468,24 p.; Fournier,R.0.,1984,Application of water chemistry to geothermal exploration and reservoir engineering,in Ryback,L.,and Muffler, L.P.J.,eds.,Geothermal systems:Principles and case histories:. New York,Wiley and Sons,p.109-744, Fournier,R.O.,and Potter,R.W.II.,1982,A revised and expanded Silica (quartz)geothermometer:Geothermal Resources Council Bulletin,v.11,no.10,p.3-12. Fournier,R.0.,1983,A method of calculating quartz solubilities in aqueous sodium chloride solutions:Geochimica et Cosmochimica Acta,v.47,no.3,p.579-586. Lloyd,R.M.,1968,Oxygen isotope behavior in the sulfate-water system: Journal of Geophysical Research,v.73,no.18,p.6009-6710. 16) Mc Kenzie,W.F.,and Truesdell,A.H.,1977,Geothermal reservoir. temperatures estimated from the oxygen compositions of dissolved sulfate in water from hot springs and shallow drillholes:Geothermics,v.5,p.51-671. Motyka,R.J.,Moorman,M.A.,and Poreda,Robert,1983,Progress report-thermal fluid investigations of the Makushin geothermal area: Alaska Division of Geological and Geophysical Surveys Report ofInvestigations83715,48 yp,Nye,C.J.,Queen,boDO and Motyka,R.J.,1984,Geologic map of theMakushingeothernialarea,Unalaska Island,Alaska:Alaska Division of Geological and Geophysical Surveys Report of Investigations 84-3,2 sheets,1:24,000. Nehring,N.L.,Truesdell,A.H.,and Janik,C.J.,1982,Procedure for collecting and analyzing gas samples from geothermal and volcanic systems:U.S.Geological Survey Open-file Report (in preparation). Presser,T.S.,and Barnes,Ivan,1974,Special techniques for determining chemical properties of geothermal waters,U.S. Geological Survey Water-Resources Investigation Report 22-74,11 Pp. Queen,L.D.,1984,Lithologic log and hydrothermal alteration of core from the Makushin Geothermal area,Unalaska,Alaska:AlaskaDivisionofGeologicalandGeophysicalSurveysReportof Investigations 84-23,1 sheet. Republic Geothermal Iac.,1984,The Unalaska Geothermal Exploration Project,Phase II Final Report,prepared for the Alaska PowerAuthority. Truesdell,A.H.,1976,Geochemical techniques in exploration:United Nations Symposium on the Development and Use of Geothermal 'Resources,2nd,San Francisco,1975,Proceedings,v.1, p.liii-lxxix. 167°00"4 166°30° t .nf S37 45+ wl 167°OO .166°30° Figure 1.Well locations,Makushin geothermal area. Table 1,Fraction of Steam Separated from Flashed Well Fluids! Sample #9 Collection Collection Steam DGGS USGS Date Time Pressure,Bars Temperature,°C Fraction 71 1 8-27-83 (+1.5 hr)2.00 120 0.144 74 2A 9-1-83 17:30 3.17 135.5 0.116 75 3B 9-2-83 10:10 3.03 134 0.119 76 4B 9-2-83 16:20 4.48 147.5 0.093 77 5A 9-3-83 19:50 4.55 147.5 0.092 84-1 -8-4-84 15:00 2.65 129.5 0.127 84-2 -8-7-84 13:00 2.79 131 0.124 1.Fluids collected using Webre type mini-cyclone separator. 2.Parenthetical value for 71 is the time elapsed after initial discharge from fracture zone at 1946'depth. Well was then shut-off until 9-1-83.Well was re-opened at 14:40,9-1-83 and was run continuously until about 22:00,9-3-83.Well was re-opened again on 7-4-84 and run nearly continuously until 8-8-84. 3.At the separator.These are absolute values calculated from gauge pressure plus atmosphere pressure which was assumed to be 0.96 bars. 4.Determined from the collection pressure assuming liquid-vapor equilibrium (Keenan et al.,1969). 5.Steam fraction calculated using a BHT=193°C and reservoir enthalpy value of 821 kJ/kg (Keenan et al.,1969). Table 2.Chemical analyses of waters collected from Makushin Valley test well ST-1,1983", '(Concentrations in mg/l unless otherwise specified). From Webre-separator Off End of Exhaust i i 75 76 77 o 7a 75 76 7 Cations oo Na 2120 2020 2010 1900 2010 _2840 2400 2470 2420 2460 K 270 280 270 250 250 360 180 310 300 310 Ca 150 139 140 128 144 216 175 175 175 181 Mg 0.2 0.1 0.1 0.1 0.1 0.3 0.2 0.2 0.2 0.2 Li ll 11 ll 10 10 14 13 13 13 13 Sr 2.4 2.3 2.8 2.5 2.6 3.1 3.2 3.3 3.3 3.1 Cs 1.4 1.4 1.4 1.4 1.4 1.6 nd nd nd nd NH,nd nd nd nd {1 nd nd nd nd nd Total®108.5 103.5 103.0 97.0 102.6 145.6 119.6 126.0 123.7 125.7 Anions HCO,<5 <5 <5 <5 <'1.0 <5 nd nd nd nd so 91 86 85 77 80 190 nd nd nd ndf1.2 1.2 1.2 1.0 1.0 1.6 nd nd nd nd cl 3670 3540 3500 3230 3370 4870 4160 4240 4200 4220 Br 14 13 12 12 13 19 nd od nd nd Total 105.7 101.8 100.6 93.0 96.9 141.8 117.3 119.7 118.5 119.1 Balance%2.6 1.7 2.4 4.2 5.7 2.7 1.9 5.2 4.3 5.4 sio 343 335 340 306 323 450 393 395 402 3954,8 nd 2.7 1.5 nd nd nd nd nd nd nd B 68 64 65 59 62 86 74 76 77 78 Al nd nd nd nd 0.02 nd nd nd nd nd As 12 li 13 12 12 16 14 15 15 15 Fe nd nd nd nd 0.13 nd nd nd nd nd tos?6760 6500 6450 5990 6280 9070 o---o----------- pH,field®8.1 8.0 7.8 7.6 7.9 7.8 nd nd nd nd Date Sampled 8/27/83 9/1/83 9/2/83 9/2/83 9/3/83 8/24/83 9/1/83 9/2/83 9/2/83 9/3/83 a)Alaska Division of Geological and Geophysical Surveys,Fairbanks,M.A.Moorman and R.J.Motyka,analysts. b)Sampling conditions and steam fraction given in Table 1,' c)Cation and anion totals in milliequivalents/liter. d)Calculated. e)Sample 64 measured at T=50°C;all others measured after cooling to 15°C. nd=not determined Table 3.Chemical analyses of waters collected from Makushin ValleytestwellST-1,1984.”(Concentrations in mg/l unless otherwise specified). From Webre-separator?Off end of exhaustIwZWTE2E Cations Na 1910 1930 2290 2290 K 260 250 300 310 Ca 129 133 155 149 Mg 0.2 0.2 1.3 0.6 Li 10 10 12 11.5 Sr 2.7 2.7 3.2 3.2 Cs 1.4 1.3 1.6 1.5 NH,<i <1 nd nd Total®97.6 98.5 116.9 116.7 Anions HCO,26 12 nd nd so 95 97 115 112?1.2 1.2 1.4 1.4 C1 3480 3500 4180 4170 Br 12 12 14 14 Total 100.9 101.3 120.5 120.2 Balance'-3.3 -2.8 3.1 -3.0 sio --328 397 384H,8 {1 1 nd nd B --67 78 79 Al nd 0.004 nd nd As 12 ll 15 14 Fe 0.26 0.20 0.32 0.24 tos?nd 6360 .7560 7540pH,field®7.7 7.6 nd nd Date Sampled 8/4/84 8/7/84 8/4/84 8/7/84 a)Alaska Division of Geological and Geophysical Surveys,Fairbanks,R.J.Motyka and M.A.Moorman,analysts. b)Sampling conditions and steam fraction given in Table l. c)Cation and anion totals in milliequivalents/liter. d)Calculated. e)pH measured after waters cooledto 15°C. nd=not determined Table 4,Chemical analyses of 1983 waters from Makushin Valley test well ST-l,corrected to reservoir conditions. (€oncentrations in mg/l unless otherwise specified). 71 74 75 76 77 Average Cations Na 1820 1780 1780 1730 1820 1790 K 230 250 240 230 230 240 Ca 128 123 124 116 131 124 Mg 0.2 0.1 0.1 0.1 0.1 0.1 Li 9 9 10 9 9 9 Sr 2.1 2.0 2.5 2.3 2.4 2.3 Cs 1.2 1,2 1.2 1.3 1.3 1.2 NH,nd nd nd nd 1.0 1.0 Anions HCO,<5 £5 <5 <5 <1.0 <5 So 78 76 75 70 73 74?1.0 1.1 1.1 1.1 0.9 1.0 cl 3140 3130 3080 2930 3060 3070 Br 12 1l 1l . 11 12 11 Si0 294 296 300 278 293 292H,8 nd 2.4 1.3 nd nd 1.9 B 58 57 57 54 56 56 Trace Al nd nd nd nd 0.02 0.02 As 11 10 ll ll 11 10.5 Fe nd nd nd nd 0.12 0.12 TDS 5790 5750 5680 5430 5700 5670 Date Sampled 8/27/83 9/1/83 9/2/83 9/2/83 9/3/83 nd =not determined Table 5,Chemical analyses of 1984 waters collected from the Makushin Valley test well ST-1,corrected to reservoir conditions, (Concentrations in mg/l unless otherwise specified). Cations Na Anions so?t TDS Date Sampled nd=not determined 8/7/84 Average 1680. 225. 114. 0.2 9. 2.4 1.2 1 Table 6.Chemical analyses of exhaust pipe waters from Makushin Valley test well ST-1 corrected for reservoir conditions assuming 60 deg.C end point flash temperature. (Concentrations in mg/l unless otherwise specified). Cations Anions Steam Sample #Date Na K Ca Mg Li Sr Cs HCO3)SO4__-O*F cl Br $102 B As Fe TDS Fraction RM83-64 8-24-83 2120 270 160 0.2 il 2.3 1.2 nd 140 1.2 3650 14 337 64 12 nd 6780 0.252 RM83-74 9-01-83 1800 130 130 0.1 9.4 2.4 nd nd nd nd =3110 nd 294 55 11 nd 5540 0.252 RM83-75 9-02-83 1850 230 130 0.2 9.6 2.5 nd nd nd nd =3170 nd 296 57 il nd 5760 0.252 RM83-76 9-02-83 1810 230 130 0.1 9.7 2.5 nd nd nd nd =3140 nd 301 58 11 nd 5690 0.252 RM83-77 9-03-83 1840 230 140 0.1 9.7 2.3 nd nd nd nd ==3160 nd 296 58 11 nd 5740 0.252 RM84-01 8-04-84 1710 220 120 1.0 8.8 2.4 1.2 nd 86 1.0 3130 10 297 58 11 0.24 5660 0.252 RM84-02 8-07-84 1710 230 110 0.5 8.5 2.4 1.1 nd 84 1.0 3120 10 287 59 10 0.18 5640 0.252 a)Alaska Division of Geological and Geophysical Surveys,Fairbanks,Alaska,M.A.Moorman,analyst. eee ee Table 7.Makushin Valley test well ST-1,Oxygen and deuterium isotope analyses -steam and water. (Parts per mil with respect to SMOW). Sample #Water Steam pecs vuscs Date vb/u (smu)38o/!%¢smuy 180/1%0 cuscsy vn csmuy 180/4%csmuy 80/10 uses) 71 1 8/27/83 -79 9.7 -9.2 -97 -13.9 -13.45 4 8302 9/1/83 -77 10.05 -9.5 -90 -13.2 -13.05 1 3 9/2/83 -77.5 -9.95 -9.6 -90 -13.2 13.05 760 C«S 9/2/83 -77.5 -8.4 9.6 -87.3 13.15 12.85 7.OS 9/3/83 -77.6 -9.8 -9.6 -88.3 13.1 -13.0 84-1 8/4/84 -66 -10.25 -86 -11.25 - 84-2 8/7/84 -81.5 9.95 --90 -12.3 - SMU =Southern Methodist University,Stable Isotope Laboratory,R.Harmon and J.Borthwick,analysts. USGS =U.S.Geological Survey,Menlo Park,C.Janik,analyst. 1983 D/H (SMU) 185,165 (SMU) 185/165 (uses) 1984 D/H (SMU) 18/16,(SMU) Table -10.4 Makushin Valley test well ST-1,stable isotope analyses corrected to reservoir conditions. (Parts per mil with respect to SMOW). -10.2 15 16 -79 -78.5 -10.3 (-8.8)° -10.0 -9.9 a)Suspect value;not used in computing average. b)A large amount of chloride was detected in the 84-1 condensate indicating incomplete separation. Values for this sample are therefore not considered to accurately represent reservoir isotope composition. Table 9.Geothermometry for Webre separator waters from Makushin Valley test well ST-1 corrected for reservoir conditions.(Temperatures in °C). Sample #Date Qz.cond (1)Chal.cond (2)Na/K (3)Na/K (4)Na/K (5)Na-K-Ca (6)Na/Li (7) RM83-71 8-27-83 208 191 240 216 222 224 193 RM83-74 9-01-83 208 192 247 226 231 229 194 RM83-75 9-02-83,209 193 243 221 227 227 196 RM83-76 9-02-83 203 186 241 218 224 225 194 RM83- 77 9-03-83 208 191 238 213 220 223 193 RM84-01 8-04-84 nd nd 245 223 229 227 194 RM84-02 8-07-84 206 189 240 217 223 224 193 (1)Fournier,1983,improved S102. (2) (3) (4) (5) (6) ©) Fournier,1983,improved Si02. Fournier,1981,Na/K. Truesdell,1976,Na/K. Arnorsson,1983,Na/K,Basalt. Fournier &Truesdell,1973. Fouillic &Michard,1981. Table 10.Geothermometry for exhaust pipe waters from makushin Valley test well ST-1l corrected for reservoir conditions assuming 60 °C end point flash temperature. (Temperatures in °C). Sample #Date Qz.cond (1)Chal.cond (2)Na/K (3)Na/K (4)Na/K (5)Na K-Ca (6)Na/Li (7) RM83-64 8-24-83 218 204 238 214 220 224 191 RM83-74 9-01-83 208 191 (193)?(157)?(166)?(190)?194 RM83-75 9-02-83 208 192 236 211 218 222 193 RM83-76 9-02-83 210 193 236 212 218 222 196 RM83-77 9-03-83 208 192 237 213 219 222 195 RM84-01 8-04-84 209 192 241 218 224 225 192 RM84-02 8-07-84 206 189 244 222 228 228 189 (1)Fournier,1983,improved Si02. (2)Fournier,1983,improved Si02. (3)Fournier,1981,Na/K. (4)Truesdell,1976,Na/K. (5)Arnorsson,1983,Na/K,Basalt. (6)Fournier &Truesdell,1973. (7)Fouillic &Michard,1981. (a)Potassium analysis anomolously low. Table 11.Sulfate-water 180/160 isotope temperatures,Makushin Valley test well,st-1.° dDateTemp180/160-S04,180/160-H20,180/160-H20, Sample #Collected sep,C WRT SMOW WRT SMOW at sep WRT SMOW,res T1,°C°_72,°C MVTW-74 9-01-83 135 -3.8 -9.5 -9.9 245 256 MVTW-75 9-02-83 134 -3.4 -9.6 -10.0 235 245 MVTW-76 9-02-83 148 -3.4 -9.6 -9.9 235 248 MVTW-77 9-03-83 148 -3.3 -9.6 -9.9 235 244 MVTW-1W 8-04-84 130 -3.9 -10.3?-10.47 230 246 MVTW-2W 8-07-84 131 3.6 -10.0 -10.2 232 246 a)Isotope analyses performed at U.S.Geological Survey,Menlo Park,except as noted. b)Analysis performed at Southern Methodist University,Stable Isotope Laboratory. c)Temperature calculated using method described in McKenzie and Truesdell (1977)for the case of single-stop steam-loss.The separator water composition was used for 180/160 -H,0. d)Temperature calculated using the 180/160 -H,O value determined for the gessrvoir water and the equilibriumfractionationequationofMizutaniandRafter($969):1000 In=2.88 (10 /T')-4.1,T=°K. Sample Code MVTW-1 DS/CJ MVTW-2A DS/CJ MVTW-3B DS/CJ MVTW-4B DS/CJ MVTW-5A DS/CJ MVTW-1G-C RM/CJ MVTW-2G-A RM/CJ MVTW-2G-B RM/CJ DS/CJ ttRM/CJ Xg RO2 Table 12.Makushin test well,air corrected gas analyses,mole 2%. Date Sampled RO2 8-27-83 9-01-83 9-02-83 9-02-83 9-03-83 8-04-84 8-07-84 8-07-84 Xg 0.070 0.098 0.081 0.109 0.105 0.089 0.056 0.064 Ratio,moles gas to moles steam in %. C02 87.74 89.61 92.54 91.61 92.73 86.26 85.94 93.81 Ratio,oxygen in sample to oxygen in air. H2S 1,80 H2 0.28 0.46 R.Motyka,ADGGS,Fairbanks,and C.Janik.USGS,analysts. CH4 0.006 0.007 0.006 0.007 0.006 tr tr tr D.Sheppard,DSIR,New Zealand,and C.Janik,USGS,Menlo Park,analysts. NH3 0.76 Ar 0.18 0.10 0.07 0.08 0.07 0.15 0.12 0.07 N2/Ar 50.4 67.3 66.8 63.8 63.2 70.5 89.6 51.7 Table 13.Mass 2 gas content of total discharge, using 02 corrected gas analyses. Sample #Steam Fraction Mass %gas Mass %gas in Steam Total Discharge MVTW-1 DS/CJ 0.144 0.163 0.023 MVTW-2A DS/CJ 0.116 0.231 0.027 MVTW-3B DS/CJ 0.119 0.192 0.023 MVTW-4B DS/CJ 0.093 0.260 0.024 MVTW-5A DS/CJ 0.092 0.252 0.023 MVTW-1G-C RM/CJ 0.127 0.208 0.026 MVTW-2G-A RM/CJ 0.124 0.132 0.016 MVTW-2G-B RM/CJ 0.124 0.154 0.019 Table 14.Partial pressure CO2 in solution,reservoir conditions. Mole fraction CO2 Sample #in total fluid®P CO2,bars? MVTW-1 DS/CJ 8.824E-05 0.57 MVTW-2A DS/CJ 1.019E-04 0.66 MVTW-3B DS/CJ 8.881E-05 0.58 MVTW-4B DS/CJ 9.323E-05 0.61 MVTW-5A DS/CJ 8.998E-05 0.58 MVTW-1G-C RM/CJ 9.739E-05 0.63 MVIW-2G-A RM/CJ 5.972E-05 0.39 MVTW-2G-B RM/CJ 7.446E-05 0.48 a)Computed from co.=XCO,Xg_Xs where XCO,and Xg are the CO,and gas fractions from Table 8 and Xs is the steam fraction from Table l. b)Computed from the PCO,=Kh CO,where Kh is Henry's law constant (6500bars/mole fraction at"T =193°C). Gas geothermometers applied to Makushin test well.Table 15. Sample #Date Sampled T C (a)TC (b)TC (c) MVTW-1 DS/CJ 8-27-83 228 212 220 MVTW-2A DS/CJ 9-01-83 250 222 227 MVTW-3B DS/CJ 9-02-83 217 216 222 MVTW-4B DS/CJ 9-02-83 213 223 223 MVTW-5A DS/CJ 9-03-83 204 216 222 MVTW-1G-C RM/CJ 8-04-84 218 220 225 MVTW-2G-A RM/CJ 8-07-84 216 211 199 MVTW-2G-B RM/CJ 8-07-84 190 212 213 (a)Gas geothermometer of D'Amore and Panachi,1980. (b)H2S geothermometer of D'Amore and Truesdell,198. (c)CO2 geothermometer of Arnorsson and others,1983. Table 16.Makushin Valley test well ST-1,Unalaska Island,Alaska,carbon isotope analyses,co,in gas and steam. Sample #Date Collected T,°C Sep 8 Copp MVTW-1 8/27/83 120 -13.3 MVTW-3 9/02/83 134 -13.5 MVTW-4 9/02/83 148 -13.3 MVTW-5 9/03/83 148 -13.3 MVTW-1G-C 8/04/84 130 -15.1 MVTW-2G-A 8/07/84 131 -15.0 MVTW-2G-B 8/07/84 131 -15.1 a)C.Janik,U.S.Geological Survey,Menlo Park,analyst.nomeneo Table 17.180/160 in anhydrite obtained from test well core.* 180/160 -Caso4,T °c,equil?, Depth,m(ft)WRT SMOW (c)(d) 148 (486)-2.98 351 249 592.5 (1944) -1.87 319 226 593.1 (1946)-0.91 .295 208 a)Analyzed at USGS,Menlo Park. b)T °C,equil.equilibration fractionation temperature assuming 180/160 for H20 is -10.0,the current reservoir water value (USGS analysis). c)Temperature computed using Lloyd (1968)fractionation equation: 1000 Ins =3.88 (10°)/1?-2.90,T =°K. d)Temperature computed using fractionation equation of Chiba and others (1981): 1000 Ine =3.21 (10°)/t?-4.72,T =°K. Table 18.Chemical analyses of sulfate-carbonate spring waters in the Makushin geothermal area.* (Values in mg/1 unless otherwise specified). Site Name Date 1 pH?Na K Ca Mg Li Sx Hc03°$04 F Cl $102 B Fe TDS sc GV Gdl 8-11-80 97 6.4 52.4.8 12 4.0 <£0.01 0.1 37 129 0.1 10.0 94 <0.5 0.10 325 360 GV-Gd2 8-11-80 82 6.5 87 5.7 32 1 0.02 0.3 288 95 0.3 5.0 125 ¢<0.5 <0.01 504 580 GV-Gd3 7-05-81 78 4.3 62 5.2 25 8.0 0.01 0.2 3 218 <0.1 6.1 120 <0.5 nd 447 9250 GV-Ge 7-05-81 68 nd 61 3.3 260 9.6 0.04 1.1 nd 491 0.3 2.3 138 =¢0.5 0.02 nd 1400 GV-GE 8-11-80 70 6.1 78 4.5 nd nd nd nd nd 42 nd 10.0 125 nd nd nd nd GV-Gf 7-05-81 79 6.4 81 4.8 210 7.8 0.03 1.1 256 476 0.2 7.5 142 <0.5 0.21 1050 1200 GV-Gh 7-11-82 61 6.0 64 3.8 240 11 0.03 1.2 358 472 ¢1.0 5.8 145 <0.5 0.40 1120 1320 GV-Gj 7-10-82 41 6.1 53 3.4 280 Il 0.03 1.4 332 581 <1.0 6.6 120)<0.5 0.70 1220 1430 GV-G1 7-13-82 62 6.0 63 4.5 260 10 0.03 1,2 325 542 <1.0 6.6 135 <¢0.5 0.50 1190 1370 MV-Ma 7-17-82 84 6.0 54 9.0 65 13 0.02 0.3 nd 344 <1.0 nd 155 <0.5 2.5 nd nd MV-Mb 8-13-80 87 5.5 28 5.9 67 12 0.01 0.3 191 155 0.1 .5.0 140 nd 0.09 508 600 MV-Mc 7-04-81 58 5.3 24 3.2 23 5.5 0.01 0.1 nd 25 0.1 7.8 88 <0.5 0.07 nd 250 MV-Mc 7-18-82 55 6.8 32 4.3 34 6.1 <0.01 0.1 201 15 1.0 7.9 105 ¢0.5 0.10 305 351 MV-Md 8-13-80 67 5.3 14 3.4 23 8.0 0.01 0.1 116 21 0.1 5.0 88 nd 0.03 220 255 NY-Na 8-20-83 23 6.1 88 4.2 390 36 0.14 3.1 678 710 0.7 5.6 110 <0.5 nd 1680 nd GV =Glacier Valley,MV =Makushin Valley,NV =Nateekin Valley a)Alaska Division of Geological and Geophysical Surveys,Fairbanks,Alaska,M.A.Moorman,analyst. b)Determined in the field. Table 19,Chemical analyses of chloride spring waters in the Makushin geothermal area.” (Values in mg/l unless otherwise specified). b b Cations b Anions Site Name Date T pH Na K Ca Mg Li Sr HE€03 S04 F cl $i02 B Fe TDS sc DV -stream 8-21-83 14 6.9 36 3 8.8 2 0.15 <0./35 6 nd 56 43.6 0.7 nd 175 nd GV -Gm 7-20-82 39 5.9 180 19 200.0 15 0.48 1.1 463 360 ¢1.0 160 113 4.2 1.7 1290 1380 Gav -Gn 7-20-82 27 5.8 180 19 180.0 23 0.40 1.0 563 320 <1.0 140 119 4.0 1.9 1260 1760 GV -Gp 7-20-82 40 6.3 300 31 160.0 39 0.86 1.4 590 180 <1.0 380 104 9.9 2.1 1500 nd DV =Driftwood Valley,GV =Glacier Valley a)Alaska Division of Geological and Geophysical Surveys,Fairbanks,Alaska,M.A.Moorman,analyst. b)Determined in the field. Table 20.Chemical analyses of cold waters in the Makushin geothermal area.? (Values in mg/1 unless otherwise specified) b b Cations b AnionsSitenameDateTphNaKCaMegLiSr_HCO3"S04 F Cl_soiBr Si02__B As Fe TDS sc DV -stream 8-21-83 14 6.9 36 3.4 8.8 2.0 0.15 <o.1 35 6 nd 56 nd 43.6 0.7 0.10 nd 175 nd GV -Gd spring 7-05-81 5 nd 4.7 0.8 8.9 1.9<0.01 <0.1 nd 29 <0.1 5.6 nd 20.0 <0.5 nd nd nd 100 GV -Gd stream 8-11-80 7 6.0 78 4.5 nd 0.1 0.01 nd nd 418 nod 10 nd 125.0 nd nd nd nd nd GV -Gk spring 7-15-82 16 6.6 4.1 0.3 20 1,140.01 0.1 38 27 41.0 5.9 nd 9.4 <O.5 nd 0.10 88 141 GV -Gl stream 7-18-82 5 6.5 8.5 1.4 52 6.6 ¢0.01 0.1 13 150 41.0 12 nd 28.0 <0.5 nd 0.40 264 375 GV -Gn spring 7-09-83 6 6.4 5.6 0.2 6.4 1.0 <0.01 0.2 26 4 nd 5.5 nd 6.0 0.10 0.002 nd 42 nd GV -clear river month 7-19-83 7 6.4 7.5 0.5 53 1.8 0.01 <o0.1 37 14.nd 8.8 nd 14.2 0.02 0.001 nd 117 nd GV - kettle pond 8-19-84 nd nd 1.9 O.1 0.5 0.3 ¢€0.01 <0.1 nd 1 nd 2.0 O.1 3.0 0.04 ¢0.001 nd nd nd GV -muddy river mouth 7-19-83 5 6.5 6.3 0.7 12 2.2 0.01 0.1 dl 360s nd 7.0 nd 12.0 0.16 0.001 nd 82 nd MV -spring 7-19-82 6 6.6 2.6 0.2 1.8 0.6¢0.01 <0.1,Lt 3°¢1.0 3.7 nd 13.0 <0.5 nd 0.1 325 34 DV =Driftwood Valley,GV =Glacier Valley,MV =Makushin Valley a)Alaska Division of Geological and Geophysical Surveys,Fairbanks,M.A.Moorman,analyst. b)Determined in the field. Table 21.Stable isotope analyses of sulfate-carbonate spring waters in the Makushin geothermal area. Site Name Date T pb/H?180/160° GV -Ga 7-05-81 nd -83 -11.9 GV -Gb 7-05-81 nd -80 -12.2 GV -Ge 7-05-81 nd -83 -12.5 GV -Gdl 8-11-80 97 -70 -8.9 GV -Gd2 8-11-80 82 -80 - 11.6 GV -Gd3 7-05-81 78 -83 -11.9 GV -Ge 7-05-81 68 -80 -12.2 GV -Gf 7-05-81 79 -83 12.5 GV -Gh 7-11-82 61 -82 11.7 GV -G4 7-10-82 41 -79 -11.0 GV -Gl 7-13-82 62 -83 11.9 MV -Ma 7-17-82 84 -77 11.1 MV -Mb 7-04-81 nd -81 12.4 MV -Mb 8-13-80 87 -78 -11.9 MV -Me 7-04-81 58 -81 12.4 MV -Mc 7-18-82 55 -84 -11.7 MV -Md 8-13-80 67 81 12.1 NV -Na 8-20-83 23 -78 11.3 GV -Glacier Valley MV -Makushin Valley NV -Nateekin Valley a)Analyzed at Stable Isotope Laboratory,Southern Methodist U.,Dallas,Texas. b)Values are in permil with respect to SMOW. in theTable22.Stable isotope analyses of chloride springMakushingeothermalarea.* b bSiteNameDateTD/H 180/160 DV -stream 8-21-83 14 -76 -9.9 GV -Gm 7-20-82 39 -80 -11.1 GV -Gn 7-20-82 27 82 -11.1 "GV -Gp 7-20-82 40 -78 -10.9 GV -Gp 7-16-83 44 -80 -11.2 DV -Driftwood Valley .GV -Glacier Valley a)Analyzed at State Isotope Laboratory,Southern Methodist U.,Dallas,Texas. b)Values are in permil with respect to SMOW. Table 23.Stable isotope analyses of cold waters in the Makushin geothermal area, Site Name Date T p/w 180/160° DV -stream 8-21-83 14 -76 -9.9 FF 1 -stream 7-18-83 nd -81 -11.2 FF 3 -stream 7-11-83 nd 89 13.5 FF 6 -snow 7-18-82 nd -121 -15.9 FF 7 -snow melt 8-20-83 nd -88 -12.7 FF 9 -snow melt 7-11-83 nd 65 -11,.0 GV -Gd spring 7-05-81 5 -93 14.2 GV -Gd spring 8-11-80 nd -77 -11.1 GV -Gd stream 8-11-80 7 -87 -12.0 GV -Gk spring 7-15-82 16 -77 -10.0 GV -Gl stream 7-18-82 5 -88 -12.6 GV -Gn spring 7-09-83 nd -78 -11.3 GV -West Fork River 7-05-81 5 - 93 -14.2 GV -clear river mouth 7-19-83 7 -77 -11.5 GV -muddy river mouth 7-19-83 5 -85 -12.8 GV -snow melt 8-11-80 nd -76 -11.2 MV -Camp spring 7-19-82 nd -67 -9.7 MV -Mb stream 8-13-80 nd -89 -13.0 MV -Mc stream 7-04-81 nd -82 -11.9 MV -Md stream 8-11-80 nd -83 -11.3 MV -spring 7-19-82 6 -82 -11.9 NV -stream 8-20-83 nd 88 -12.7 DV -Driftwood Valley FF -Fumarole field GV -Glacier Valley MV -Makushin Valley NV -Nateekin Valley a)Analyzed at Stable Isotope Laboratory,Southern Methodist U.,Dallas,Texas. b)Values are in permil with respect to SMOW. Table 24.Analyses of tritium in waters from Makushin geothermal area. Sample code Locality Date collected TU MVTW-3 ST-1 9-02-83 0.4620.08 MVTW-5 ST-1 9-03-83 0.2920.08 RM82MV-cs cold str.,Mk.Val 7-21-82 11.340.3 RM82MV-ru hot spr.M-c 7-22-82 16.420.4 RM82GV-E hot spr.G-j 7-20-82 -36.5+0.8 RM8 2GV-wv hot spr.G-1 7-20-82 28.240.7 RM82GV-24 hot spr.G-m 7-20-82 10.5+0.3 RM82PV hot spr.G-p 7-20-82 6.1+0.2 Analyst:H.Gote Ostlund,U.of Miami,Miami,Florida. TU =Tritium units 'Table 25.Geothermometry of chloride spring waters in Makushin geothermal area. (Temperatures in °C). Site Name Date Qz.cond.(1)Chal.cond.(2)Na/K (3)Na/K (4)Na/K (5)Na-K-Ca (6)Na-K-Ca (7)Ni/Li (8) DV stream.8-21-83 96 65 210 178 187 157 71 171 GV -Gn 7-20-82 144 118 225 197 205 166 129 139 GV -Gn 7-20-82 .147 122 225 197 204 167 99 126 GV -Gp 7-20-82 139 113 221 192 200 175 64 143 DV =Driftwood Valley,GV =Glacier Valley (1)Fournier,1983,improved $102. (2)Fournier,1983,improved $i02. (3)Fournier,1981,Na/K. (4)Truesdell,1976,Na/K. (5)Arnorsson,1983,Na/K,Basalt. (6)Fournier &Truesdell,1973. (7)Fournier &Potter,1979. (8)Fouillic &Michard,1981. Table 26.Analyses of gases collected from fumaroles and hot springs,Makushin geothermal area,in mole 2%. Analyses corrected for air contamination using ratio of 02 in sample to 02 in air (R02). Gas geothermometer(c) Sample code Location Date sample RO2 Xg co2 H2S H2 CH4 NH3 N2 Ar N2/Ar C/S Tl Sodium-hydroxide charged flasks:(a) RM 83-46 FF#1 7-17-83 0.01 0.17)82.19 2,28 0.21 0.039 0.38 14.73 0.17 86.4 36.1 227 206 RM 83-GV1-A FF#3 Superheated 7-08-83 0.00 0.16 88.04 6.38 0.95 0.010 0.13 4.43 0.06 80.2 13.8 298 272 RM 83-11b FF#3 West 7-10-83 0.06 0.50 83.72 1.69 0.22 0.001 0.04 14.16 0.17 84.1 49.4 256 234 RM 83-31 -FF#3 Far west 7-13-83 0.05 0.36 88.10 4.58 0.25 0.001 0.01 6,94 0.14 51.3 19.3.273 249 RM 83-57 FF#7 8-20-83 0.01 2.63 82.15 1.81 1.10 2.482 0.18 12.21 0.08 161.9 46.7 230 210 RM 83-19 FFH9 7 11-83 0.00 0.78 91.55 3.94 0.85 0.004 0.01 3.63 0.02 146.3 23.2 294 268 DS 83 BN7 DS FF#3 superheated (98)8-29-83 0.00 0.18 88.93 6.85 0.88 0.006 0.08 22 0.03 113.1 013.302 275 DS 83 BNI3 DS FF#3 Far west 8-29-83 0.00 0.25 84.93 6.25 0.66 0.003 0.06 8.06 0.01 --13.6 299 273 RM 82-GV1 FF#3 Superheated 7-09-82 0.02 0.15 82.29 12.25 1.84 0.070 nd 3.56 0.07 54.7 6.7 313 285 RM 82-Ma sum FF#6 Summit 7-18-82 0.00 1.67 87.47 5.53 0.21 0.047 nd 6.63 0.11 60.2 15.8 235 214 RM 82-MV FF#2 FF#2 7-17-82 0.00 - 90.40 2.92 0.35 0.012 nd 6.24 0.07 87.8 30.9 252 229 RM 82 Ma west fl.FF#5 7-13-82 80.01 1.39 91.16 0.95 0.51 0.004 0.03 7,29 0.05 137.0 96.4 °(257 234 RP 81-AL3 FF#2 7-14-81 0.00 0.00 87.17.5.26 0.75 0.002 nd 6.76 0.06 120.2 16.6 308 280 RP 81-Al15 FF#3 7-05-81 0.00 0.00 87.42 1.23 1.80 0.002 nd 9.43 O.1l 86.4 70.9 309 281 RM 80-MV2 FF#l 8-13-80 0.00 0.41 91.68 2.63 0.24 0.029 nd 5.36 0.07 78.4 34.9 231 210 RM 80-MV1 FF¢2 8-13-80 0.00 0.59 87.90 2.65 0.54 0.002 nd 8.81 0.09 95.4 33.2 283 258 Uncharged,evacuated flasks:(b) RM 83 G-p Spring G-p 7-16-83)----98.22 0.02 0.005 0.052 nd 0.96 0.02 48.0 ------ RM 83 G-}j Spring G-j 7-21-83 0.04 --25.43 0.02 0.02 0.010 nd 74.13 1.02 72.4 ------ RM 82 GV UW FF#4 7-14-82 =-0.01 --92.73 0.82 1.21 0.01 nd 5.50 0.05 104.8 113.5 295 269 RM 82 Ma WF FF#5 7-13-82 0.00 --94.89 0.68 0.59 0.01 nd 3.78 0.05 77.6 139.3 268 244 RM 82 Ma Sum FF#6 7-18-82 0.00 --90.60 5.68 0.12 0.02 nd 3.43 0.01 --16.0 226 206 RM 82 GV W FF#9 7-14-82 0.00 --93.36 2.01 0.72 0.01 nd 4.33 0.04 108.3 46.4 293 267 (a)Samples RM 83 and RM 82 analyzed by R.J.Motyka,ADGGS;samples DS 83 analyzed by D.S.Sheppard,DSIR,New Zealand;samples RP 81 and RM 80 analyzed by J.Whelan,SIO,La Jolla,and R.J.Motyka,ADGGS,Fairbanks. (b)Analyzed by W.Evans,USGS,Menlo Park,and R.J.Motyka,ADGGS. (c)D'Amore and Panichi,1980.Tl uses P CO2 =1 bar;T2 uses P CO2 =0.5 bar. nd =not determined. Table 27.Makushin geothermal area,analyses of 13C/12C in C02 emanating from fumaroles and hot springs. Year Location Collected 13C,PDB Type Analyst Fum.field #1 1983 -14.3 SrC03/Na0H USGS 1983 -13.9 S$rC03/Na0H USGS Fum,field #2 1981 -12,2 §rC03/Na0H GC -12.5 $rC03/Na0H SMU 1982 -11.6 $rC03/Na0H USGS Fum.field #3,sp 1981 -11.8 SrC03/Na0H Gc -12.4 SrC03/Na0H SMU lower 1981 13.0 CO02-gas GC super heated 1982 -10.2 CO2-gas SIO 1983 -13.4 SrC03/Na0H USGS west 1983 -11.3 $rC03/Na0H USGS Fum.field #4 1982 -12.3 CO2-gas USGS Fum.field #5 1982 -12.4 $rC03/Na0H USGS -12.4 CO2-gas USGS Fum.field #6 -1982 10.0 CO2-gas USGS -11.5 $rC03/Na0H SMU Fum.field #9 1982 -12,1 CO2-gas USGS Spring G-j 1983 -15.4 CO2-gas USGS Spring G-p.1983 -13.3 CO2-gas USGS USGS =U.S.Geological Survey,Menlo Park,California. SMU Texas. GC =Global Geochemistry,Inc.,Canoga Park,California. SIO =Scripps Institute of Oceanography,Stable Isotope Laboratory, La Jolla,Claifornia. Southern Methodist University,Stable Isotope Laboratory,Dallas, Table 28.Helium isotope data,Makushin geothermal aread.* Year b c dLocationCollectedR/Ra (He/Ne)/air Re/Ra Fum.field #1 1980 6.6 110.0 6.6 Fum.field #2 1980 4.9 37.0 5.1 Fum.field #2 1981 5.0 94.0 5.1 Fum.field #3,sp 1981 3.8 24.0 4.0 Fum.field #3 1981 4.4 53.0 4.5 Fum.field #3,SH 1982 4.1 11.4 4.4 Fum.field #5 1982 5.0 50.0 5.1 Fum.field #6,SU 1982 7.8 1500.0 7.8 Fum.field #7 1983 5.9 300.0 5.9 Spring G-p 1983 (1.3)°(1.5)°(1.9)° Test well ST-1l 1983 3.6 41.0 3.7 "R.Poreda analyst,Scripps Institute of Oceanography,Stable Isotope Lab. R =3He/4He ratio in sample. Ra =3He/4He ratio in air. Re =Sample ratio corrected for air contamination using He/Ne ratios. Helium concentration in sample was extremely low. Table 29,Makushin geothermal area,miscellaneous stable isotope analyses. 13C/12C -HCO3,thermal waters.(USGS,Menlo Park,analysts). Year Location Collected 13C,PDB Spring G-h 1982 "11.1 Test well ST-1 1984 -23.0 13C/12C and 180/160 in CaCO3,calcite sinter deposited on downhole instrument cable in test well ST-1l,mid-July,1984.(SMU analysts). 13C/12C,PDB 180/160,PDB:CO2 RM84-MVTW CaCco3 -12.5 -29.3 13C/12C in methane,fumarole gases. Year Location Collected 13C,PDB Analyst Fum.field #2 1982 -42.3 USGS Fum.field #6 1982 -30.6 SIo D/H in hydrogen and methane,fumarole gases. Year Location Collected D/H -H2,SMOW D/H -CH4,SMOW Analyst Fum.field #3,sp 1981 -601 ---GC Fum.field #3, superheated 1982 -582 ---USGS Fum field #6, summit 1982 -719 -132.6 USGS caereeon Table 30.St-1 whole rock oxygen isotope data.* Sample #185/18 Description §T-1-201 4.0 Gabbro.Plagiclase altered to clays. ST-1-664 -2.7 Gabbro altered to wairakite.Steam entry. ST-1-1066 -2.0 Albite-K spar-biotite-epidote vein. ST-1-1638 +2.8 "Unaltered"gabbro.Pyroxenes altered to anthophyllite-cumingtonite. ST-1-1937 -0.1 Chloritically altered gabbro. --+6.4 Average of 11 Makushin area volcanic rocks. a)Analyzed at U.S.Geological Survey,Menlo Park,CA.,I.Barnes lab. APPENDIX A Lithologic Log and Hydrothermal Alteration at Core from the Makushin Geothermal Area,Unalaska Island,Alaska by L.D.Queen Simplified Lithology '4 6 -Vv vv VOLCANICS UNALTERED B Vv Vv Vv 200- ; ARGILLIC ALTERATION UNALASKA AND 4 FORMATION WEATHERING +BLADED400+CALCITE /)+++ 4 10/6/84 _-GABBRO DIKE Thermistor 6007 4 UNALASKA BOILING ZONE FORMATION 800 4 BLADED CALCITE-DEPTH 4 v (FEET)__.AMORPHOUS SILICA 'canpRo*QUARTZ 1000 _]++ +*DIKE +SANS ee +++ANHYDRITE 1200 7]UNALASKA FORMATION s 14004 1 10/7/84 a Kuster 1600 4 | ao 10/8/84 +++++ Kustey +¢abskot *| 1800 +HORNFELS +>na |+COMPLEX *lLower end of epidote stableOOOEee Total Depth , (1864 ft.), I |I fJ}if | 5 100 150 200 TEMPERATURE (°C) scaLET_0 pe aRTRE *COORDINATES DEFTE ze [oarsROCKTYPE&DATE BY a tEPTH STRUCTURE ALTEPLTION SULFIDES OTEER COMMENTS og Unconsolidated ash and Surface weathering. .| "=cinders,| 20 =---:-_ -!Andesite flows.Vesicular,:v v \ ™{porphyritic,highly fractured,vv ,=__-r vo :pam |;Vv & 7 ;y {;_-Vv 'fy 1 . -_viv |:: 40 =avant -_-_-- =viuv 7.ot=wy 7 yo =-vs 9 oo7'Veyl °i i i !OW 1 :a \v Vv i q ; 60 4 oy || =vy , ;::,+mv -=rT-iy i :=iy !po :Vv i i :. a "yy bo -ve Vv {:|v '::"fk tm Vv ra =- -ov :4 Ivy - _1 VY ' 100 =--VL a a -_--ow 1 : ;=ty re = ;. i : °{VW v 57VY---- =aaae ;|- ,"O20:-Lahar.Brown,indurated.5 20"|31207-Q5---- =-Jj =nae |==Unalaska volcanics.Grey- -Surface weathering.Cleys,|Scattered pyrite :-TJ}green,Porphyritic to fine',iron oxides.of xls and pyrite veing,©! 140 -grained.Phenos of flag.:Irregular quartz-epidote |=Pyrite is more =Te i veins."|abundant in clay |=a |mag:zones.7 _:vo 3 oe L Aw Ene -:it ; 4 ;PY P|=|:fd bo 160 -_----_--- _:i i . $ :si : -pj-OZ recovery,.i ::. -+7 7=_'i : _:{::_; :3 ' =:t |:: 180 = |, =; =!: _i -_- SCALE avilagayh7|eeeeeI.clay is denser and indurated, ' .REARING COORDINATES bs _BY DEPTE °"ke ©&i :ROCK TYPE &* neerssEPTHSTRUCTUREALTEPATIONSULFIDES=CO-OCENTSa°-||\ 200 E-.7 0Z recovery. :a ob ,--_-+---!;| {a ! -Aam een220 -"|i ™a"-;i"Unalaska volcanics.:Thin (1-2mm)quartz-I _p oc}-Grey green,Fine grained.. epidote veins,||yrite along fractures |"Minor andesite dikes, T TT end as veins,Veins :_:- |Bladed calcite in open ' .5 mm wide.H'nw *- i :23 20 veins/10 'ft i veins..i :240 1 - = Limonite stains on --rc™é=,i !fractures,6 /i J=2 _=ix >>=]10 veins/10 #¢oe bo,=>a |- 7 _Slightly porphyritic :; :::=eunalaska volcanics.Lightly chloritized.t ::1 °:* [Limonite on fractures._!,1 ore ere a-i - |Clay zones blue-green ;i_-om ni ?fi-10 veins/10 ft j-=|Celedonite(?)/|ot -1™ J]Fractures dip 75°or-more.|_|te et...280 ”fT ATT potwt;i ° an )Js -at --- 291-Blue-green clay>"2 20 veing/10 ft ee 1 +7h :/||_a7.ate Pos00w-aj Early qtz-chl-epi veins po -meait"|cut by calcite veins.early ,|:=;1 7.|veins'are two stage.Epi-” .i-At 312 ft breccia,Breccia:= _l chi followed by quartz.mega crateredTone6"wide,Altered.aves .#.{7 j7'2-Blue cley=Clasts angular to 4mm in diam.>eeeabenee zone around .°i-90%unalaska 10%quartz arn Altenea 0 em on both side P.-_!3%pyrite in -_320 Fragments:Dip 45°.Grain.-1 ere zone cut by S altered zone.Very ):°_Tpupported,Slickensides in +-numerous catcite veins (3mm fine,anhydral,:ry,|wide).Altered area pale .. :-tlays.a -_Possible chalcopyrite,,+-oo -green.Plag phenos alterea-hed!a pe L!to turquoise blue clay.3-i 7 S'Matrix largly clay and pyrite :340 _- -xls.Calcite veins cut pyrits Tyaiveins,Minor chlorite._|17 ¥ °4 ta _.4comeee-_---TT=_ X Mafies to chl and pyrite S va4Lightgreenaphanitic1"™Calcite-silica veins to =360 -unalaska volcanics.ae 1 cm thick,Possible light _m:Pyrite euhedral poo' 4-5 veins/10 ft " NS silcification,-|2-32 of mode,an 1.TL:Clay zones,Clays light;7 N\;|green to hwhite.White i 7 Oe fo Nee *cSeomme seme SE ee os -2 _ewes SE SS.PereSCALERELRING;vereaeg DEFTE- «COORDINATES DATE BY- Sod .ROCK TYPE &* a OO ENTSPTHSTRUCTUREALTERATIONSULFIDES7THERCOMSENT!z =/|::Zl)eee bee ae380-Hinateske volcanics.dark g y-. .384--Hematite (2)tye porphyritic,<1 Hematite in fracture.}Phenos of pyx,Pre - 1 ry - abe H43veins/10 ft i xX ,= "loom ° a{.: :Lm400_fBreccia.Clasts of Unalaska:Wi4g"4]Clasts altered.Chlorite,[=;=-25mm clasts.iL pyrite,cloudy plag.No 7 :: :7 ->|elteration envelope.An 1 :' _" Tp matrix is calcite.Open i :-_|contains calcite xls,an :=o>Ta to420==”T!Bladed calcite.wa co:a 'i :=pais -i |-_="iT i PGLightgreenbrownunelaskaCalciteveinsto8mm.Ver in .ot- :- .LY/-100%mafics to ottvolcanics.-_.=|abundant.Rock bleached,4%|fine-grained pyrite i7.ogee Mafics to chl-pyrite.Some] <j g PY an ya7 t t' ;++=|c¢lay around veins,Plag.io cies44020veins/10 ft ==Teloudy,Wi ae:= wm oe oeeatenMe-_-_--_->S r= .v5 Tbe|460.--.rwmtMediumgrainedgabbrodike,!@QOr(et so .5 Light grey,MaficS tebdular |4 "iTjtesubequil.10-15%of mode,!."T]_-_f/u°iMafics altered to chiorite..4”I 1 Some secondary k-spar(?)in'r.+.v480eins,Some clasts of unalaska +a [-_S present.eo f-_:- r.o T jen3a-=-1 / =7 Epidote i d toe500tChloritespots.Rounded.i PROKE An ground mass =|AUS2-3mm diam.Old amycales(2)=! q t:very abundant.Na=i aa!4 520 ---15 mmm wide calcite vein,-.-aa :7 .Dog tooth spar,Coarse4'_>grained. _ 7 .+:--_=Calcite-silica veins at "Waur%-Unalaska clastics ak yo boundry.Epidote increases |5 : >°t..4 toward boundry,:540 "pst a=2-3 veins/10 ft eset=:teste,:|="Ons!i ' i He shi i+;pores Small calcite veins ae=15 veins/10 ft "Alaa |=rere --560 ob Basi SCALE Be” RELNING _COORDINATE me : DEPTE"ROCK Ty =DATE BY SEPTH ETRUCTURE ALTERATION SULTIDES ATHER COSENTS ao 2d):|mal Treiry i'aoe |o wie j :_".".4)Epidote forms halos arount--ao360+ :141 many clasts..unalaska clastics.poorly Ir.an . co sorted.Clasts angular.ame J etl -a1-2 mm to several cm.os |a varying lithogy of clasts,i -!include clasts of pluton,'=i{ .oa .--oo -580 Unalaska volcanics,ip -4,.i+or i |Little alteration.:1°dike?=|-_45 .F i : =Sey |bo-eee poywerertneyan5:-ry)|e taeé00eedLA--=Unalaska clastics.ama"°0 I-!Loo :a aaTees{..i---Breccia.Clasts unaleskar yet 5 cm wide.70°dip.Coleree =Be4silicamatrix,Grain Bea.lo md1supportrd.i ;tie_-i -_-=_620 be --pe=|-noa!): en eee q 3 2 -ee Se -_-_---'Terry i :a |bal]=trey.i 74! .Fee .:°ee640, :2-3 veins/10 ft ela'aX4 areocee 2 cm wide,45 a oTmiyeksip.i jt oe , 4 _ =Ss Chlorite abundant,a 74'3 fan -_-10-15 vei 10 ft Eos .I:+veins/,22S)Calcité vein.Pale blue td !:2 white botryoida'ilica,/660 {Bladed and dogs tooth - 680 700 PPL,ELLE]LULLRELLUULLLLULL|3 veins/1C ft _calcite, Pale blue alteration of plag around calcite veins.|. Clacite-silica veins. reEe15-20°dip,.5-1,0 cm thick,2"Prin.mo silica.No alteration aedasc?.wt reel720=:i:-<envelope. aUnalaskavolcanics.Boundry”-Increase of chl toward -_--sharp.a boundry,F=ile .wo a-__-Thin steeply dipping=7 _-_-740 = -calcite veins.: 'Y pobre:0.5%pyrite. OFS Fed Ww ete ews bet GS 2"£22.B-Oe one ETE 2.2.Be oe Bras ae SCALE °RELRING «COORDINATES =. DEPTE "ROCK TYPE &Date BY EPTH STRUCTURE ALTERATION SULTIDES =CO-MENTS/|740 Hireleske volcanics.. -,4 |trace epi trace pyrite |5-10 veins/10 ft Calcite quartz vein.Dog @ 745-Clear needles in | tooth spar and small qtz .to Lt calcite vein,|[xls.Also small needles||_j | in radiating clusters i ssibly zeolites.-i 760 re 4 ;;=. 10-15 veins/10 tt Thick caleite veins.LEULULULELLE,LLitBELLELLU780 ; 10-15 veins/10 ft 800 2-5 veins/10 ft -_820. Clasts of pluton.Feldspa -l_very weathered,Clasts toTscm, 7... .840 _20 veins/10 ft a4 + a 8604in . aa 5 veins/10 ft oa. "a{ a 880 - : _ : 900 - aa = i ;5 veins 10 ft-f 7 920 + Appear to cut surroundin is|_epidote alteration. i i H i oa g i i .|1 | any di 3 a”3|3 : an Po:': cere Calcite in open veins [|': ia a1 G2)now entirely dogs tooth.j :oeee!Zz _ nay i :0 Ma?8 °eos 2 pod1Brodaa): Ltt a -,trace pyrite 7 = iano[be Ly ife+>:709 |1 i ;Adee °if 5B 2b)wa itatiLP"w=Breccia.Veins of calcitCO.peeaw4 i 848-Calcite-silicarareGranularmassive.Imm xls_|=oee es sr;vein2BFF0,oe calcite,Opal /chalcedony}"|Trace pyrite.Pyrit d =}:25%of mode,Clay at edoss 7 |a@s euhedral xis in tHin ;..i : \open calcite veins.| * § ,8 ee eo:i a-: i wo: _ -_- 4 .j e ':t /po i a i ai,z , i i rr :PNG i |: =-- i i SG|oa 2;_!-_--_..2 /.2a)|Pyrite veins,2-3 fi::mm wide.4 at"oPrge} SCALE REARINGaTaeNEPTE*COORDINATES DATE BY NEPTE o- -re eo .ROCK TYFE &-'n sop Lhe '+SEPTHSTRUCTUREALTERATIONSULFIDES7THERCOOENT!a q |320 _binalasks clastics.-rn 15 veins?10 ft eee ty .| 7 aan |SO EESa:icom:=---240 in Pale blue silica veins..;-.2-3 veins/10ft t-; - ,: ---Gabbro dike.1-2mm ave |First appearance of Ff |j :=grain size.anhydrite?7 i i :7,i t+i :tT +7!a:a360 _;Ft¢4 Gabbro epidote and chlorife |!; Ts -2-3 veins/10 ft 't+Ti altered.>i !-(+f -|¢'4 Cee q i1;. a _> t l Pot =.or 'Epidote 1-28 of mode,':t : :'0 +TS --Tes-=:7 TY Thin chlorite'veins.i Pyrite with chlorite-':5 i T+i veins baa!i tert -_--_--3 . '{er ::4s ::,1-2 veins /10ft Ir 'Calcite veins cutting sling f i -io older epidote veins,|;'Tor 4 -=1000 +tf "a -ro| bojt [osaa4to+oy oF ro =vr ,-_020 ili A ee i .Tain *|77Unalaskaclastics.Boundry,:pit Blue silica veins with Pyrite veins |;-|is indistinct,'23 2S]minor calcite.1-5mm wide,||/tL y .-_-_---_i :j_res 60 dip.-|i-_:=i : J yee e 1 |-=040 _.==:+9 cm thick medium grained-°_5 veins/10 ft wasanhydrite vein,: ;;7.Tle *1047-Calcite veins "4.sis8 :a”AS Maynebtexis ----magnetite96a!in calcite vein,i4:O374;=cts /po 060 Sess io ;=GRGYs ae- Lea a -7 ?-Breccia.-Avats_Calcite-quartz veins.7 ve =1070 Marcasite?end|vec:Quartz xls line vugs.a a zeolite in quartz25veins/10 ft 024 Quartz vugs contain zeolite -!i _veinP=end marcasite(?),Zeolite aT -oO080:Sate ;'-_-rad -needles (Mordenite ?).7 3 i :=Fractures which pass (5 gee Sidon cemented breccia lies"ithrough clasts show no --."-!along the edges of the _-"offset along fracture.|ses calcite cemented breccia.|=ee Clasts in the silica cemented |t100=4-5 veins/10 ft =.'Stportions are less altered ea 7 7 a a ithan those in the calefcic * SCALE ..?7 COORD INNATE S -v - °POCK TYPE &DATE BY ;. STRUCTURE ALTERATION SULFIDES OTRER CO-MENTS°Jbe2)e + #100 =5 ao Ly i Unalaska clastics.theHe{---l_-+1117-anhydrite veins 1120 with magnetite selvage|1J|veorarja6| 8 ' .">-"7 . : j3-4 veins/10 ft -7°3 :-*teOleidesYo)1140 *!'aeI':a.iymAitizeti146,sng.Breccia.Taha Strong chloritizetion, "TMeanetite grains 1%']153-Magnetite-anhydrite 'breccia filling.:3}Veins of fine grained calci e:scattered throughout:iY'OS ¥ee and coarse grained anhydrite. izone and in veins.inoeSeste, i 1 .q-_--:7<Some small quartz xls.=-veins it is replaced ™Iagegg a i 3 ''4&a:paar491160 25 veins /10 ft eae Be by pyrite.i)area):pyrite also replaces ::-ethloritized mafics 7 |LLLPULLILLLLU)GIL|-LLLLacon777252]pleg around veins alterd to montmorillonite,-_-_1a'Setae:$.aRoetes 1geeenvelopeaboutanhy-mt veinso 2 .ta .re :.-!__-,--veins.Thence °.Ae fe->-E pidote in altertion CH i °ve Biel:Brye&."Una leske volcanics.i 0-2 veins/10 ft ey eri Clay alterationaround si1ide//' "-:.-d veins. iarsJJJLA!aI|Jark °Pyrite with anh veins,1220}15-20 veins/10 ft eo eek, Medium grained anhydrite am an-*Surrounded by fine grained,c|) .:oes!. VA 325'veins/10 ft tert.co,calcite,A : . ae 1236-Zeolites 1240 10.veins/10 ft rt) -420veins/10 ft ase LLLpati.LI.a1i]1260 ,;Sa -rT20veins/10 ft 'ox,Cc=]oraonxo<0pafe]oa3heoOnrmewoZzradLaaIt.lyi Pyrite to 5%.0,5-2-green.Slightly foliated.---mm gréins -+_Vuggy.1-4mm vugs.Qtz xls =jot SCALE RELRINTNATEDEPTE- COORDINATES DLTE BY7ROCKTYPE& £PTH STRUCTURE ALTERATION SULFIDES =COMMENTS {I] _|1280-Unalaska volcanic280Lunslasksvolcanics,_=.:0-1 veins/10 ft =uoi-_ a OSes any foe300aysonUnalaskaclastics SRRES |totoy}ig on sea Z|poy: Ai -1320 =]Limonite in anhydrite calests >iwvvein_:iF 'o| Posy +\-rer /5340 B360-PULLEEGPLOLDLLL,LL»balU.PLUHLLU'1-2 veins/10 ft LULLpLULL1400 Breccia..LLLLJ420 440 10 veins/10 ft {AttILLUPittt4160 of clasts are of pluton, Chloritized, peas Anhydrite veins.No CO"le "th . :Bladed anhydrite. ieneeeeowGl:i-Vanalaska clastics.Majority305 i-_a.Deoccaey| 3° Silica-anhydrite veins, - ! i ' : Pyrite as veins and {anhydral grains.ay 1 i LoLo |ceceeeepc]epeeenpce-|--pola.Z 4 i ! a t ' i i t : - ! - ' |i i : ' Le: twee: i : :i ;: H : !. -_------ imi'Magnetite veins with -_! ? oon,tw, q iinoanhydrite,1-4mm i *:1616 Magnetite veins_twide veins,Magnetite:_i."jenhedral,replaced by: {pyrite.| i 4 i tod - 1620 se _ -4 COODDINATES DATE By DEPTE "-"ROCK TYPE &TA,° sEPTH STRUCTURE ALTEP,ATION SULFIDES OTRER CYSENTS vor ::1460 f°-4 4 ag feea-/{-- -|awd { 7 { _..i 1480 ra i _=|iG -_-SBE trace of epidote with -¥%;: -anhydrite vein,i i--|i t :aa foi:i 4 roo1500_7- ,=./|=|to,=:a a.|a 4 1 : 1520.1 h :-f-fr.cm anhydrite vein.|7 i 1527-silica veins17:i t ..-le ==Grey,fine-grained sili .a -CT,4 hes {anhydrite veins,:i=|i'Hematite Xls.';. 7 3 _-_1540 Magnetite-anhydrite veins.4 \71541-Silica zeoliteoeiveins.. .Trace epidote,t°>Ty ra.i 1 1557-hematite xls.-ote t-"'eo.__-_-.2 Sy _-.1560 _!7 Unalaska clastics.Clasts ee :/i :t :2 OT"j predominately plutonics.BaP Me |: "aj Clasts to 8 cm.Angular.Ze |7 a LJ Matrix is fine grained 7 |7-plag fragments and chlorite?S24 /:i ;-50 %clasts.BO i _-1580 an .j =.<a ---- .=i 7 " ”:=: 1600 LL ---=i4:-§- : =" re "=Metamorphosed unalaska.am Boundry transitional.TiGabbro dike.Boundries.4:sharp.Fine grained at edge -medium grained at edge.i 1640-0 1-24 epidote in .gabbro and_horntels,. =" SCALE ele RELNING om 7 #C00!TQINATES DATE BY DIFTE "ROCK TYPE a-ae,: PTH STRUCTURE ALTERATION SULFIDES OTRER CO-SENTS .q | "a |40 }.---| 1 os oe ja =3 3 60 1-2 veins/10 ft a yga"i;1667-Sericite?-_|White hornfels,Sericite2i.1 -_-"|;3 =,-"i I hot60+ry bt=4 Po3|ae=Lou - -a |_.-||100+Ve |Anhydrite vein,1-2 em wide !::1703-Plag altered to3Mediumgrainedgabbro,17 Pleg eltered to cley 6 cm ee :i clay |.lg =|around vein,i :: J jot P| om Pete :: 20-.-a ie -lo -7 .an ite a+Lo |.i Q a ie 7 !2-tT °on ->>it rt .i § a.-!1 |a it 174061 it40rr-'=Fiberous zeolite vein.F__Sumontite =7 -.Laumontite?Clay surrounds "9 11743 Pale green epidote7ivvein,.K i veins, ° a -*--ale green epidote veins --=-i '_+it OT fj-:°!8 -it Ty {i i 60 +.or ij fos _*.tT te: -_-_--OF,|:4 on }i_7 Ot t :=tote" °|_-1780-anhy-epi-zeolite -80 Wine ,ea!breccia.Clasts ere pluton.'A vATa Sperry anhydrite,Epidote <-s veins |: Ti!em to 5 cm,'Se +'lines all veins and open-PSe 1784 epidote veins !: a ;t4ot,tspace.eotites grow in openet --- ;+spaces,Surrounding rock '4 T+°im7't+epidote altered,Below 1781}i a : +rePidote veins with no enhy,|" LL oS ae a mo _+?)!i_-:-ow Sm |3 ' =eens FAL -_-- =aan a ao Ton ----= :-cz DB FB RE re ne SCALE .REARING »sCOOQOLNATES .. DEPTE "ROCK TYPE &. DATE BY trTA STRUCTURE ALTERATION SULFIDES OTRER COSENTS a .oJ T+4 |a ++!t 1620 J t+7 +T '=i ro+::sys.4 1828 silica veins with --_Wl Fine grained silica veins!)"!_-a ; \:..: 'epidote,3 +T +,with epidote selvage.-|4 +t1340_s 7%]Fine grained anhydrite |_|1.-'1838 anhy-silica veins oF i,t T|silica veins.;oh Lt /: a ty by =oP a TT -Ft cf ;i : bord j T a ! _a i i1860Jonou- .iT H 2 : 'fad ':'-. wwe:1864 -total depth T a.|_ 1 ::a : "L :KEY =-- 5 ANDESITIC VOLCANICS CLAY ZONES 1 PYRITE TT i 3 i Ye -- _s,;CALCITE -a _sant UNALASKA VOLCANICS W<po:a QUARTZ i Lo a ]ts --UNALASKA CLASTICS SILICA (not qtz).3 ° _ANHYDRITE Tee foo -]METAMGRPHOSED UNALASKA -.f |"HORNFELS EPIDOTE -a -to om --_7 :;3 -_GABBRO ZEOLITES %, a-_le --ar MAGNETITE Te iiil=BRECCIA ZONES Ava CHLORITE |ot Do] ).:°:: al -4 : _-': a.----- .os F j ':= "h ee -Po a= :i4; ; ' --a TT +4 ; -a F i --7 -oa - ;i nea',:i :=oo !a 5 :a =:.|a -_--_--a :[J . red APPENDIX B Lithologic log and Hydrothermal Alteration of Core from Drill Hole A-l, Makushin Geothermal Area,Unalaska Island,Alaska. by L.D.Queen "a