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HomeMy WebLinkAboutHumpback Creek Reconnaissance Report 1985CoR -\-\ 00\ ------------------------------------- r I i ~ . r Alaska Power Authority· HUMPBACK CREEK RECONNAISSANCE REPORT Augu.st 1985 ALASKA. POWER AuTHORITY 334 WEST 5th AVENUE· ANCHORAGE. ALASKA 99501 Phone: (907) 27~1 September 10, 1985 To Interested Parties: Enclosed is a copy of the Power Authority's Findings and Reconmendations for the proposed hydr'oproject on Humpback Creek. The Findings were approved by the Power Authority's Board of Directors at its meeting on September 4, 1985. This reconnaissance study is the result of Cordova Electric Cooperative's (CEC) request to the Power Authority for technical advice concerning a Federal Energy Regulatory Commission (FERC) preliminary permit for Humpback Creek initiated by the CEC. The CEC undertook the reconnaissance study of the Humpback Creek potential hydroelectric site in an effort to find a low-cost power supply when interim conclusions of state-funded studies showed that none of the options considered would markedly decrease the cost of electricity for Cordova. The reconnaissance report and investigations conducted by CEC indicate that a project at Humpback Creek could produce 3,000,000 - 4,000,000 KWH of electric energy with an installed capacity of 600-800 KW. The project would produce about 20% of the total energy required by the CEC. Most of the energy would be produced during the late spring, sunmer, and early fall which is coincident with the cannery processing loads in Cordova. The Power Authority will continue to support the efforts of the Cordova Electric Cooperative to obtain adequate data for its feasibility study and FERC preliminary permit application. Thank you for your interest, anC I hOJe this information is useful. Sincerely, . / /'" '; -A./ ./(./ /' , /1 // . ~V ~r--YN~rv Robert D. Heath Executive Oirector Attachment as stated. SGR/ RDH; fs 1047/457 Humpback Creek Reconnaissance Report August 1985 PRO~I ECT TEAM Bob Loeffler, Project Leader Project Economist Brent N. Petrie, Director Power Systems Planning Edwin L. Morris, Associate Executive Director, Planning Robert D. Heath Executive Director © 1985 ALASKA POWER AUTIiORITY Humpback Creek Reconnaissance Study Table of Contents I. I n t ro due t ; 0 n .. . • . .. . . . . . . .. .. . . . .. . . . . . . .. . . . .. . . . . .. . . .. . .. .. . . .. 1 A. Purpose of the Study ....•..•.•...••....•.......•.. 1 B. Description of the Project •..•.......•......•..... 1 II. Technical Issues A. Dam Concept ............................................. 7 B. Gravel Depth/Seepage ...••............•.......•.... 7 C. Fisheries Protection .......•.....•.•..•....•...... 8 D. Hydrology/Energy Production .•.•.............•.•.•. 8 E. Design Concepts/Cost Estimate ..•.•...••........... 8 III. Preliminary Analysis of Hydrology/Energy ....•.......... l0 IV. Economic Analysis ....................................... 15 v. Conclusion ................................................. 20 534/438 List of Tables Table No. Page 1. Summary of Project Parameters ••.••.••............. 6 2. Total Energy Available from Humpback Creek ........ ll 3 .. C F S v s KW .................................................................................. 13 4. Sample Economic Calculations ..........•........... 18 List of Figures Fi gure No. Page 1. Project Layout ................................... 2 2. Design Parameters: Energy.vs Maximum and Minimum Streamflow .......................... 12 3. Energy Production: 1974 and 1975 ................ 14 4. Expected Benefit/Cost Ratio by Construction Cost and Energy Output ...................... 16 534/438 I. Introduction A. -Purpose of the Study: Cordova Electric Cooperative, Inc. {CEC} is studying a small hydroproject on Humpback Creek near Cordova. CEC has expended significant effort analyzing the site and begin- ning the permitting process. It has been a difficult task that CEC has completed professionally and very quickly. This Reconnaissance Study has two purposes. It was begun at the request of Cordova Electric Cooperative in order to help it under- stand the problems, opportunities, and obstacles in the development of the project. It will provide a general assessment of the technical and economic opportunities of the site. It is a IIsecond opinion ll given at the request of the Cooperative to help with the remainder of its project development process. In addition, this report functions as a Reconnaissance Study, under the Alaska Statutes {44.83.177}. The Reconnaissance Study is undertaken to assure the public {through the Alaska Power Authority Board of Directors} that a project which may eventually use public funds has had substantive review by an unbiased agent of the State. Most of the base information for this study is taken from three sources: IIHumpback Creek Hydroel ectri c Project, Status Report as of July 9, 1985 11 prepared by Cordova Electric Cooperative, Inc.; from conversati ons with CEe' s General Manager, Mr. Doug Bechtel; and from a site visit by Power Authority Staff. B. Description of the Project: Humpback Creek flows into Orca Inl et approximately three mi 1 es northwest of the City of Cordova {Figure 1}. The hydroelectric development would be a run-of-river plant consisting of a diversion weir located approximately one-half mile from the river's mouth, a penstock, and a powerhouse. The powerhouse woul d be located a few hundred feet from the river's mouth at the approximate location of the upstream extent of salmon use in the river. 534/438 - 1 - 28 34 o o:Cc> ?' Soull! Rock. .Al!~;:'Knot Pt ,y ',-,' < IBM J 16 534/438 I I 23 I . I . I I /\ I 24 18 Boy Scout I 30 FIGURE 1. Humpback Creek Project Layout - 2 - Humpback Creek was the original source of electricity for Cordova. A 125 KW pel ton wheel operated on the creek from 1909 unti 1 some- time in the late 1940s or early 1950s. The intake for the system was from a log-crib dam at the 175-foot level of the creek 500 feet downstream from the proposed dam location. The old dam is 47 feet high with a crest length of 110 feet and a crest width of 10 feet. The reservoir area behind the dam is completely filled with hun- dreds of thousands of cubi c yards of course stream gravel s. The trapped gravels form a level area that extends a few hundred feet upstream. In addition, much of the ballast has eroded out between the timbers of the dam and most of the streamflow occurs not over the dam but through the gravel behind the dam and through the dam itsel f. There are two other log-crib dams on the Creek, both located up- stream from the proposed dams ite. These dams were bui It to trap gravel before it reached the intake dam and filled in the reservoir. The proposed damsite sits in an 18-foot wide notch in the steep creek canyon with vertical bedrock abutments on either side. A small dam or diversion weir (perhaps ten feet high, perhaps small- er) would channel the stream's flow into the penstock. Because the stream carries a very heavy load of sand and gravel, some means must be found to keep the materi a lout of the penstock and to regularly clean the dam. In addition, the site is only 500 feet upstream from the log-crib dam that supports the gravel plain. The proposed damsite rests on these gravels. It is not clear how deep the gravel extends --perhaps only a few feet, perhaps as much as twenty feet. It is possible that a significant part of the river's flow occurs through the gravels beneath the proposed damsite. If so, maximum water capture would require sealing the gravel below the dam. 534/438 - 3 - The penstock would probably be buried in the existing gravels from the new dam downstream to the old dam site. The next part of the project description is taken from the July 1985 Status Report prepa red by CEC, liThe pi pe woul d then be routed down the face of the existing dam to an existing notch cut in the rock on the north abutment of the Creek. This notch was cut into an otherwise sol id rock cliff when the old hydro was constructed in 1908 •... At the end of this notch in the north abutment it will be necessary to cross the Creek with an overhead cable stretched from bank to bank. The length of the span would be approximately 155 feet. There is an existing 1 or 1* inch cable that was used to support the old wood stave pipeline and can be used during construction of the pipeline across the stream bed. "O nce the pipe crosses to the south side of the stream, progress will be much easier. Most of the existing wood stave pipeline is still in place altho~gh badly rotted. There is sufficient flat area to run the pipeline without any special concern. All of the rings and wood staves would have to be removed. After approximate- ly 300 feet on the south side of the stream, the existing pipeline turns 90° to the west to proceed an additi ona 1 500 feet to the existing power plant site. liThe alternate power plant site would continue on along the bank following the course of the stream until the last 100 feet when the pipeline would drop rapidly onto a flat area several acres in size at approximate elevation 25 feet. This flat area is the same area proposed many years ago by Fish and Game as a site for a fish hatchery. II The capacity of the powerplant is not yet determined. Two concepts are 800 KW capacity from two 400 KW units, or 600 KW capacity from two 300 KW units. The exact arrangement will be determined from considerations of hydrology and cost; that is, it will be necessary 534/438 - 4 - to optimize the number and capacity of the units in the powerplant to get the greatest generation at the least cost. The final decisions cannot be made until hydrology and cost data are avail- able. In any case, the maximum output from the project will be much 1 ess than the current base load for Cordova. The project's energy will be fully absorbed at its first day of operation. Generation voltage at the powerplant would be 2,400 or 4,160 volts and would be raised to 12.47 KV for transmission to Cordova. From the Status Report, "Overhead constructi on woul d be used from the powerplant to the water's edge. A three-phase concentric neutral underwater 1 ine would be used to carry the power to the CEC sub- station at Orca". The CEC substation is at the Orca cannery. The direct underwater distance would be approximately two miles _(the cannery is approximately one mile outside of Cordova). Humpback Creek freezes up in the wi nter. Therefore, the proj ect will only operate spring, summer, and fall. A crucial part of this project is its intention to use inexpensive construction techniques and relatively inexpensive local labor. Cordova Electric Cooperative, Inc. has experience using local labor for construction projects and almost certainly has the expertise to direct its use for the hydroproject. Local labor and the low-cost nature of the project do require simple design techniques. The project, however, seems to lend itself very well to simple designs and simple construction techniques not requiring significant use of specialty equipment, helicopters, etc. 534/438 - 5 - Table 1. Summary of Project Parameters Project Type: Projected Dam Height: Projected Crest Length: Penstock Length: Gross Head: Installed Capacity Generation Voltage Transmission Voltage Transmission Line Length: Projected Energy: 534/438 - 6 - Run-of-River Hydroproject Less than 10 feet 18 Feet 2,600 Feet Approximately 185 Feet 600 KW or 800 KW 2,400 or 4,160 volts 12.47 KV Approximately 2 miles 2.5 to 3.5 million KWH/yr II. Technical ISSU2S This report is a Reconnaissance Report; part of its function is to identify the issues that must be resolved before final feasibility and design decisions can be made. A final feasibility assessment requires a rel iable cost estimate, a reliable estimate of energy production. These, in turn, require reliable design concepts. This chapter identifies a number of the technical issues that must be solved before reliable design concepts, a reliable cost esti- mate, and a reliable est"illlate of energy production can be de- termined. This chapter is not a comprehensive work program for developing the project; rather, it only highlights the most important problems. A number of these problems are interdependent; for example, resolving the problem of water seepage through the gravel may require better hydrologic information. A. Dam Concept: Because of the amount of gravel moving along Humpback Creek, the dam or weir design must prevent the gravel from blocking the penstock intake. In addition, there must be an easy method for sluicing the gravel out from behind the dam. If gravel builds up, the impoundment behind the new dam will quickly fill up like that behind the older, log-crib dams on the Creek. B. Grave 1 Depth/Seepage: There may be a s i gnifi cant amount of water flowing through the gravels beneath the proposed dam. If so, the maximum energy production may require that the gravels be sealed in some fashion. It is also possible, however, that the seepage is slow enough, the gravels are shallow enough, or there is enough water available on the surface, so that capture of the additional water would not be necessary. 534-/438 - 7 - C. Fisheries Protection: The proposed powerhouse site is near the upstream extent of salmon in the Creek.. While Power Authority staff did not see the Creek during its salmon run, the impression was that very little useable habitat exists upstream from the powerhouse site. The log-crib dam certainly limits the upstream extent of fish migration. Downstream from the dam, the creekbed is scoured by very fast-moving water and appears unsuitable for salmon spawning or rearing. It is doubtful whether the project will cause any serious harm to the fishery, but this issue w"ill have to be resolved by CEC, the Alaska Department of Fish and Game, and the U.S. Fish and Wildlife Service. D. Hydrology/Energy Production: The amount of streamflow avail- able determines the amount of electricity produced. A U.S. Geolog- ical Survey streamgage operated near the mouth of the river, at the proposed powerplant site, from October 1973 through September 1975 (during water years 1974 and 1975). The stream averaged 28 CFS during 1974 and 49 CFS during 1975. A more accurate determination of the amount of water available is needed before the penstock and generators can be sized. This information is also required for an accurate economic evaluation of the project. Because of the importance of hydrology to the estimate of the energy production and the economic evaluation, it is discussed further in the next chapter. E. Design Concepts/Cost Estimate: Cordova Electric Cooperative, Inc. has estimated the cost of the hydroproject at $2,220,000 (in 1985 dollars). Given the preliminary nature of the design, the forecast is, as intended, some\'/hat rough. A more detailed cost estimate must await a decision on the dam concept, and penstock and generator sizes. These, in turn, are at least particularly depen- dent upon better definition of the hydrology. Power Authority staff has done a limited review of the cost estimate. Staff recommends that the economic analysis be based on a $3,000,000 cost 534/438 - 8 - estimate. The increase in the cost is not based on any mistakes by CEC; rather, staff opinion was that the level of detail in the existing cost estimate justified a higher contingency. 534/438 - 9 - III. Preliminary Analysis of Hydrology and Energy Production. Good hydrologic data are necessary to make a reliable est"imate of the potential energy production from the site. Two years of streamflow data are available for Humpback Creek. Unfortunately, the data were taken at the powerplant site, not at the intake site. Staff from the Power Authority and from CEC recently visited the Creek, installed a stream-gage at the damsite, and took streamflow measurements both at the damsite and at the old gage site. Flow measured 48.3 CFS at the damsite and 47.2 CFS at the gage site. The measurements show a slight gain between the damsite and stream mouth. While a slight gain is possible, the difference between the two measurements is small enough that measurement error is also possible. In any case, the measurements indicate that the gage-site data are applicable to streamflow calculations at the intake site. In addition, the stream reach between the intake and the mouth is mostly bedrock except for a few hundred feet preceding the powerplant site. There were no significant tributaries enter- ing between the two sites and only a minimal difference in drainage area. There is unlikely to be a significant difference between the two sites. Power Authority staff estimated the energy production from the site based on the two years of data. Table 2 shows the total amount of energy available from Humpback Creek. The table was calculated from the U.S.G.S. daily mean streamflow records. It assumed a net head (i.e., head available after head losses) of 175 feet and a turbine-generator-transformer efficiency of 80%. The table shows that there was a potential to produce 5,055,500 KWH during the 1975 water year but just less than 3 million KWH during the preceding year. 534/438 -10 - Table 2. Total Energy Ava il ab 1 e from Humpback Creek (1974) (1975) Average ( K~JH) (KWH) ( KWH) October 334,292 777,641 555,966 November 71 ,272 547,281 ·309,277 December 76,027 244,881 160,454 January 46,271 79,159 62,715 Februa ry 28,617 36,391 32,504 March 20,359 27,279 23,819 Apri 1 132,976 153,136 143,056 r~ay 450,183 574,332 512,258 June 523,078 714,427 618,753 July 323,186 769,668 546,427 August 218,685 410,603 314,644 September 689,369 742,902 716,136 Total: 2,914,316 5,077,700 3,996,008 Unfortunately, not all of the energy can be captured. During floods, much of the water will run over the dam. Thus, the amount of energy captured depends on how much of the stream's flow occurs above the turbine's minimum and below its maximum flowrate. Figure 2 shows the amount of energy that can be captured at three different turbine minimum flowrates for any maximum flowrate between 50 CFS and 90 CFS. For example, if equipment installed in the Humpback Creek powerhouse could not use flows below 20 CFS, and the maximum capacity of the turbine/penstock system was 80 CFS, the system would produce approximately 3.1 million KWH. If the maximum were only 60 CFS, the turbine would produce 2.6 million KWH. If the system's minimum was only 9 CFS with a 60 CFS maximum, the system would produce 2.9 million KWH. Assuming 175 foot net head and an 80% efficiency, the relationship between CFS and KW is given in Table 3 using an 8 CFS minimum and 534/438 -11 - 4.0 I 3.9 ~ 3.8 ...... 3.7 '" >, 3.8 \ 3.5 = it 3.4 :III 3.3 -.; d';' 3.2 o d 3.1 ~ 0 3.0 0'" =:: 2.9 ~ ... o~ 2.8 ","'" 14 2.7 >, 2.6 II 2.5 '" II 2.4 d rz1 2.3 2.2 2.1 2.0 50 Figure 2 Humpback Creek Hydroproject 8 CFS Desiln Parameters: Max c!c Min Streamflow e------~16 CPS~~J.u ....a---Minimim~ ~- a----~-CPS Minimum Flow -- ------ 60 70 80 Maximum Design Flow (CPS) t:I 8 CPS Min + 16 CPS Min ¢ 20 CFS Min a 66 CFS maximum flow. Using the U.S. Geological Survey streamflow measurements, the hydroproject woul d have produced approximately 2.4 million KWH in 1974, but in 1975, it would have produced 3.6 mi 11 i on KWH. The proj ect wou 1 d have had to shut down November through part of March in 1974 and January through part of March in 1975. The monthly profile for the two years are shown in Figure 3. 534/438 -12 - 90 Table 3. KW versus CFS (assuming 175-foot net head and 80% efficiency) KW 50 75 100 150 200 300 400 500 600 700 800 900 1,000 CFS 4.2 6.3 8.4 12.6 16.9 25.3 33.7 42.1 50.6 59.0 67.4 75.9 84.3 The difference in energy production between the two years is significant and has a significant bearing on the design and econom- ic benefits of the project. It is important to estimate the long-term average streamflow and energy producti on. Fortunately, it may be possible to correlate the records from the two years with gagi ng records from a nea r-by gage wi th a 1 anger record (Power Creek) or from rainfall. In addition, the gage recently installed at the damsite by the Power Authority should provide useful infor- mation. Finally, the relationship between the U.S.G.S. record and the streamflow at the damsite must be confirmed. These tasks require a more detailed hydrologic analysis than can be accom- plished in this report. 534/438 -13 - Figure 3. Humpback Creek Hydroproject Enercy Production; 1974 and 1975 600 -r- 500 .£: 400~ V ...,""' c • I 0" ;:!Ie: 300 J / III " . 18 , Coo .£: II:fo< Water Year" it"" 200 1974 :d \ \ 100 -..; \ ) I I \ \r I " 0 ~ tp , Oct Nov nec Jan Feb liar Apr liay June July AuC Sept lionths. 1974 and 1975 Water Years 534/438 -14 - I V. Economi c Ana lys i s At Humpback Creek's current reconnaissance level of information, detailed economic analysis producing a detailed forecast of. project benefits would be misleading. The data on which to base the analysis is not yet that reliable. The exact construction cost and energy output from the project are not yet known. The economic question at this stage of the analysis is not, "What is the exact expected benefit from the project? How much will it lower energy costs, in ¢/KWH?" Rather it is the easier question, "Are the project's benefits likely to be greater than its costs? Is the project worth further study?" To these easier questions, the answer is a resounding "Yes". This section uses a range of probable construction costs and energy outputs to forecast a range of benefi t/ cost rati os and net bene- fits. That range is shown in Figure 4. The figure shows the benefit/cost ratios for different construction costs at three energy outputs: 2 mi 11 i on KWH, 3 mi 11 i on KWH, and 4 mi 11 i on KWH. Two million KWH is almost certainly less than the project will produce, 3 million is a reasonable estimate (from the current information), and 4 million seems possible, but" high. The table shows that under the 1 ike ly range of ci rcumstances, the project will produce benefits greater than its cost. If the project costs $3.0 million and averages 3 million KWH each year (a set of circum- stances that is not unlikely given the present information), the benefit/cost ratio is 1.4. If the project can be constructed for $2.5 million, the ratio will be 1.7. 534/438 -15 - .2 i 1i ~ -• J Figure 4. Expected Benefit/Cost Rations by Construction Cost and Energy Output Humpback Creek Hydroproject ·.0 Beneflt/Coet Ratio (by Coet and Energy) 3.5 3.0 2.5 2.0 1.5 1.0 --~---------- 2.000.000 kWH/yr 0.5 +--------...------'P"'"""'-----___ -------I $2.000.000 $3.000.000 $4.000.000 Construction Co" (1985 dollars) The present hydrologic information indicates that the Humpback Creek hydroproject will certainly produce more than 2 million KWH. Figure 4 shows that if production is greater than 2 million KWH, the project will produce benefits even at the unexpectedly high construction cost of $4,000,000. Only if production is 2 million KWH or less, AND the cost is more .than approximately $2.6 million will the project1s benefits be less than the cost. 534/438 -16 - An example of the calculation required to produce Figure 4 is shown in Table 4. The table calculates the benefit/cost ratio and net benefits from the project using, for this example, a $3.0 million construction cost and an average annual energy output of 3.0 million KWHs. Using those parameters, the table shows that the proj ect' s total benefi ts are $4,226,278; its net benefits are $1,226,278 (total benefits minus the construction cost); and the benefit/cost ratio is 1.4 (total benefits divided by construction cost). The calculations assume the project has a 30-year economic life and uses a (real) 3.5% discount rate. The exact mechanics of the table may require some explanation. The first column shows the year; the second shows the hydroproject's expected annua 1 opera ti on and rna i ntenance cost: $40,000. Other than the construction cost, $40,000 is the hydro's only annual cost. Columns three and four show components of CECls avoided diesel cost. Each year, if the project produces 3 mill ion KWHs (for this example), it saves CEC from generating that amount of energy using diesel. Given the diesel efficiency of 13 KWH/gallon of fuel, the hydro saves 230,769 ga 11 ons of fuel each yea r. The current, 1985, fuel cost for Cordova is 93.5¢/gallon. Power Authority parameters specify an expected 4% real decrease in fuel costs next year, flat fuel prices until 1989, 2% real increase through 2004, and flat prices thereafter. Thus, the fuel price and the value of the fuel saved changes from year to year. 534/438 -17 - COSTS Construction Cost t3,000,080 Discount Rate 3.5~ 0&/11 Total Fuel Fuel 0&" Avoided U1 EcoOOllic Li fe 30 Years Year Cost Hydro Saved Savings Savings Cost Benefits w 0&" t~0,000 Cost (gals) ($) It' It I It I +::> ......... Inflation 0~ 1986 to to to to to .., to +::> w 1987 t~0,M t~e,. 230, 769 t287,138 t30,_ t237,138 tI97,138 00 AVOIDED COST PARIV£TERS 1988 t~0,_ t~0,_ 230,769 t207, 138 t30,000 t237,138 t197,138 1985 Fuel Price $8.935 1989 t~0,_ t~0,00i 230,769 t207,138 t30,000 t237,138 tI97,138 Diesel Efficiency t13 KYi/gal 1990 t~0,_ t~0,_ 230, 769 t211, 281 t30,_ t2~1,281 t201,281 Avoided 0 & " te.01 /KYi 1991 t~0,_ t~0,. 230, 769 t215,507 t30,. t2~5,507 t205,587 Hydro Production 3,000,000 1992 t~8,000 t~,_ 230,769 t219,817 t30,808 t2~9,817 t289,817 1993 t~8,_ t~8,_ 238, 769 t22~,213 t30,000 $254,213 t21~,213 199~ t~0,_ t~0,000 230,769 t228,698 t30,000 t258,698 t218,698 Net Benefits tl,226,278 1995 "0,000 "0,_ 230,769 t233,272 t30,. t263,272 t223,272 1996 m,_ t~0,000 230,769 t237,937 t30,. t267,937 t227,937 Benefit/Cost Ratio 1. ~ 1997 "0,000 "0,000 230,769 t2~2,696 t30,000 t272,696 t232,696 1998 t~0,008 t~0,_ 230,769 t2~7,550 t30,. t277,550 t237,558 1999 "0,. "0,-230,769 t252,501 t30,. t282,501 t2~2,501 ........ 2000 t~0,_ t~0,_ 230,769 t257,551 t30,. t287,551 t2~7,551 00 2001 "0,. t~0,000 230,769 t262, 702 t30,000 t292, 702 t252, 702 2002 t~0,000 t~0,_ 230, 769 t267, 956 t30,008 t297,956 t257,956 2003 t~0,_ t~0,000 230,769 t273,315 t30,. t383,315 t263,315 298~ t~0,_ t~0,_ 230, 769 t278, 781 t30,000 t308,781 t268,781 2005 t~0,_ t~0,_ 230, 769 t28~,357 t30,. t31~,357 t27~,357 2086 t~0,_ t~0,000 230,769 t28~,357 t30,. t314,357 t2n,357 2007 "0,. t~0,000 230,769 t28~,357 t30,_ t314, 357 t2H,357 2088 t~0,000 t~0,000 23O,769 t28~,357 t30,. t314,357 t2n,357 2809 t~0,. t~0,. 230, 769 t28~,357 t30,OO0 t31~,357 t27~,357 2010 t~0,000 t~0,008 230, 769 t28~,357 t30, 000 t314,357 t2n,357 2011 t~0,. t~0,000 230, 769 t28~,357 t30,. t31~,357 t2n, 357 2012 t~0,000 t~0,000 230, 769 t28~,357 t30,. t314,357 t2n,357 2013 t~0,000 t~0,. 230,769 t28~,357 t30,. t31~,357 t2n, 357 201~ t~,000 t~0,_ 230, 769 t28~,357 t30, 000 t314,357 t2n,357 2015 t~0,_ t~0,_ 230,769 t28~,357 t30,_ t31~,357 t2n, 357 2816 t~0,_ t~0,000 230,769 t28~,357 t30, 000 t31~,357 t2n, 357 -------- Total Benefits: t~,226,278 Table 4. Fuel is not the only cost required to run a diesel; there are operation and maintenance costs (0&~1), and labor costs. The 0&~1 avoided by operating the hydroproject are expected to be O.l¢/KWH (or $30,000 for 3 million KWHs) and are in column six. The labor cost of operation and maintenance is not included as a hydro benefit, because it is assumed that the 1 abor wi 11 be used to maintain the hydroproject. The total cost that CEC avoids by not running their diesels is in column seven, Avoided Cost. It in- cludes the fuel and O&M savings. The benefits are the avoided cost mi nus the hydro cost. The total benefits at the bottom of the tab 1 e are the di scounted sum of benefits; net benefits are the total benefits minus the construction cost. 534/438 -19 - v. Conclusion On the basis of the available reconnaissance-level information, it appears that the proposed Humpback Creek Hydroproject is an excel- lent project. Its economic benefits are expected to be signifi- cantly greater than its cost. The project appears to have no serious environmental problems. The technical problems are impor- tant but certainly not insolvable. The next step is for CEC to continue refining the design concepts --working out the questions of the dam concept, gravel depth and seepage, hydrology, etc. --to arrive at a firm cost estimate and construction plans. The Power Authority should provide help to CEC as needed. Power Authority staff has begun to help with the hydrology question. A stream-gage has been installed at the damsite. This assistance should continue with an analysis to determine the available water. When a firm estimate of cost and energy production is available, the final feasibility decisions and possible construction schedules can be made. In addition, after reliabl.e cost and energy information is available, Cordova Electric Cooperative with the help of the Power Authority, if needed, can begin arranging a financing plan for the project. 534/438 -20 -