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HomeMy WebLinkAboutKingcove Oldharbor Hydro 10 of 13 1982SECTION V TOGIAK SUMMARY INTRODUCTORY NOTE: Presented in this section is the Summary from Volume E-- Reconnaissance Study for Togiak Hydroelectric Project. Included for general background information are several items from that report: Exhibit VI-1, Photographs of the Project Area; Figure VII-4, Projected Monthly Generation, Demand, and Usage; and selected project drawings which include Plate I, the General Plan, and Plate II, Alternative A - Plans and Sections. References to figures, exhibits, and plates in the summary presented here refer to items in Volume E, the full feasibility report for the Togiak Hydroelectric Project'. NBI-432-9526-ST V-1 TOGIAK SUMMARY A. GENERAL Several prior studies of alternative means of supplying the Togiak area with electrical energy had recommended a hydroelec- tric project as the best source. As a direct result of these prior studies and recommendations, the Alaska Power Authority authorized a reconnaissance -level feasibility study to investi- gate in detail the hydropower potential in the vicinity of Togiak. This report summarizes the activities conducted for the reconnaissance study. These activities included projections of energy needs, formulation of alternative hydroelectric projects and a hypothetical base case to meet the electrical energy needs of Togiak, detailed analyses of economic feasibility, and preparation of an environmental assessment of the effects of the project. The results of the technical studies conducted indicate that a 432 kilowatt (kW) hydroelectric project utilizing a 38- foot-high concrete dam could be constructed on the Quigmy River to meet the electric demands of Togiak. However, the results of the economic analyses indicate that the hydroelectric project would have only marginal feasibility. An additional project on the Kurtluk River is currently under investigation. The results of this investigtion will be presented in a subsequent report. The total cost of the proposed Togiak hydroelectric project is $7,047,200 with the 4.6-mile road option and $8,169,600 with the 11.6-mile road in January 1982 dollars. The project could be implemented and on-line by January 1, 1985, if a decisio❑ to NBI-432-9526-ST V-2 proceed with the project is made by December 1982. During an average water year, the proposed project would be capable of supplying about 99 percent of the electrical needs and about 30 percent of the space heating needs in the project area. The equivalent savings in diesel fuel in the year 2001 would be 144,000 gallons for direct electrical demand and 44,000 gallons for space heating. B. AREA DESCRIPTION Togiak is a small village located on Bristol Bay about 70 miles west of Dillingham and 400 miles southwest of Anchorage. The hydroelectric site selected for detailed study is on the Quigmy River about 12 miles west of Togiak. The smaller village of Twin Hills, four miles east of Togiak, was included i❑ the assessment of the future power needs of the area. C. POWER PLANNING Power planning for the Togiak Project was conducted using standards set forth by the Alaska Power Authority. Previously recommended potential hydroelectric sites were investigated and the project area was surveyed to evaluate potential new sites. After detailed study, a project was selected and then compared with a base case plan. The base case pla❑ consisted of a continuation of the present diesel generatio❑ system, enlarged as necessary to meet future growth. The installation of waste heat recovery equipment and wind generators was also considered as part of the base case plan. Present energy demands for Togiak for direct electrical uses and space heating were estimated and future uses in these same categories were projected. The projections were based on forecasts of increases i❑ the number of customers and increased usage rates. Population growth and employment, legislation and NBI-432-9526-ST V-3 other political influences, life style changes, and other factors can influence future energy demands but were not explicitly treated. The period of economic evaluation used was 53 years, which starts in January 1982 and extends for the 50-year life of the hydroelectric project after the estimated on-line date of January 1985. The energy demands for Togiak were increased for 20 years starting in 1982 and extending through December 2001. The demands were then held level over the remainder of the economic evaluation period. As stated, the neighboring community of Twin Hills was included in estimating future energy demands. For the proposed hydroelectric project, it was assumed that the first priority of use for the energy produced would be for the direct electrical needs of the Togiak area, and any remain- ing energy would be used for space heating. D. DESCRIPTION OF RECOMMENDED HYDROELECTRIC PROJECT Hydroelectric power plants transform the energy of falling water into electrical energy. Generally, a hydroelectric power project consists of a dam to produce the head or to divert stream flows so that they can be passed through a turbine - generator system to produce electric power. In the case of the alternative projects considered to bring hydroelectric power to Togiak, three dam configurations and two access road options were evaluated. These are described below. All three of the dams considered would divert water from the Quigmy River through an intake structure and pass the water through a tur- bine -generator system to produce electric energy. An access road would be constructed from Togiak to the project facilities and a transmission line would be constructed along the access road alignment to transmit the power generated at the plant to Togiak. NBI-432-9526-ST V-4 The general plan and features of the recommended hydroelec- tric project are presented in the plates of Appendix A. Photo- graphs of the project area are presented in Exhibits VI-1 through VI-3 of Section VI and in pages 2, 10, and 15 of Appendix E. The site selected for investigation was a narrow canyon suitable for either a concrete or rockfill dam. Since both types were apparently technically feasible, two concrete dams (38 and 28 feet high) and one rockfill dam were investigated to evaluate their economic feasibility and confirm their technical feasibility. Although the Quigmy River above the proposed dam site locations might not be a major spawning area, the preliminary designs for all three dam alternatives incorporated fish ladders to allow for fish passage. An 11.6-mile road would be required to provide access from Togiak to the proposed facilities. The Alaska State Department of Transportation and Public Facilities, Division of Aviation, is investigating the possibility of building a road along the first seven miles of the proposed access road alignment in order to reach a gravel source needed to construct an airport to serve Togiak. Two possibilities exist for obtaining an access road for the proposed hydroelectric project: 1. The entire 11.6-mile road would be built as part of the hydroelectric project. 2. The Alaska Department of Transportation would build the first seven miles of the road and the hydroelec- tric project would build the remaining 4.6 miles. The investigations conducted during this study indicate that the most favorable combination, and indeed the only one that could be economically feasible, is the 38-foot-high concrete dam with only 4.6 miles of the access road being funded by the project. NBI-432-9526-ST V-5 E. BASE CASE PLAN The base case plan formulated to meet the projected energy demands of Togiak assumed that the existing diesel system would continue to be used as the sole source of electric power. It was also assumed that the system would be modified to incorpor- ate waste heat recovery that would be used for space heating. Wind generation would also be installed as part of this plan. The existing diesel plant's capacity was judged to be adequate to meet peak demands on the Togiak system throughout the period of study. The forecasted energy demands for the base case included the requirements for Twin Hills. F. ECONOMIC ANALYSIS The economic analysis was based on the Alaska Power Authority criteria that compare the net present worth of the base case costs to the net present worth of the alternative proposed hydroelectric project costs using specified real price escalation and discount rates. Net present worth is the present value of the costs that would be incurred over a comparable economic evaluation period of 53 years for both projects. The net present worths of the base case are as follows: Base Case Only Waste Heat Credit Subtotal Wind Energy Credit Subtotal Space Heating Credit Total Alternatives A & C $11,027,600 999,400 10,028,200 540,700 9,487,500 2,463,000 $11,950,500 NBI-432-9526-ST V-6 Alternative B -.$111027,600 999,400 10,028,200 540,700 9,4879500 1 234,800 17221,300 I The space heating credit was shown as an increase in cost to the base case so that all present worths could be compared to the hydroelectric project standing alone. For the three alternative hydroelectric projects studied, the present worth of the costs is as follows: Alternative A Alternative B Alternative C W/11.6-Mile ,Road $12,758,400 13,037,400 13,257,700 W/4.6-Mile Road $11,668,600 11,947,600 12,167,900 As can be noted from the table, the only hydroelectric alternative with a lower present worth cost than the base case is alternative A, and then only if the 4.6-mile roadway can be constructed. An additional measure of project feasibility is the bene- fit/cost (B/C) ratio. The B/C ratio is the present worth of the project benefits divided by the net present worth of the project costs. For the alternative studies for this project, the calculated B/C ratios were as follows: B/C Ratio B/C Ratio W/11,6-Mile Road W/4.6-Mile Road Alternative A 0.937 1.024 Alternative B 0.822 0.897 Alternative C 0.982 _. 0.901 NBI-432-9526-ST V-7 These results indicate that Alternative A, the 38-foot-high concrete dam with 432 kW installed capacity, is marginally feasibile only if the Alaska Department of Transportation con- structs the first 7.0 miles of the required 11.6-mile access road. If the entire 11.6-mile road must be constructed, the project is a break-even proposition. G. ENVIRONMENTAL AND SOCIAL EFFECTS The study results indicate that a hydroelectric project at the Quigmy site could have potentially serious environmental impacts, but measures such as fish ladders could likely miti- gate the most serious effects. Additional studies are recom- mended to answer questions related to the downstream effects of the dam impoundment on salmon spawning; coho (silver) salmon runs; minimum water requirements for fish below the proposed dam; selection of a suitable access route; and methods to ensure safe passage of out -migrating young salmon. Additional study of fish passage facilities is also recommended. H. CONCLUSIONS AND RECOMMENDATIONS The studies conducted for this report indicate that a marginally feasible project consisting of a 38-foot-high concrete dam with 432 kW installed capacity could be con- structed at the Quigmy River site. The next step in project implementation, the preparation of a Definitive Project Report to optimize the project features, should be pursued only if the Alaska Department of Transportation constructs the initial 7.0 miles of the necessary 11.6-mile-long access road. A more detailed investigation of a much smaller hydroelec- tric site on the Kurtluk River three miles from Togiak could be pursued, but the project would meet only a small portion of the Togiak electric demands. The site is currently being investi- gated at a preliminary level and will be addressed in a subsequent letter report. NBI-432-9526-ST V-8