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Home My WebLink AboutFive Mile Hydroelectric Project - Chitina Regional Hydroelectric Investigation Report - May 2008 - REF Grant 2195456POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE i R EGIONAL H YDROELECTRIC I NVESTIGATION C HITINA , A LASKA F INAL R EPORT May 2, 2008 Prepared by polarconsult alaska, inc. 1503 West 33rd Avenue, Suite 310 Anchorage, Alaska 99503 Phone: (907) 258-2420 Prepared for ALASKA ENERGY AUTHORITY 813 West Northern Lights Blvd. Anchorage, Alaska 99503 Contracting Agency LCMF 615 East 82nd Ave., #200 Anchorage, Alaska 99518 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE i TABLE OF CONTENTS ACRONYMS AND TERMINOLOGY.....................................................................................................III EXECUTIVE SUMMARY.......................................................................................................................... 1 1.0 INTRODUCTION.......................................................................................................................... 3 1.1 PROJECT EVALUATION PROCESS .................................................................................................. 3 1.2 SUMMARY OF INVESTIGATIONS .................................................................................................... 4 1.3 CHITINA PROJECTED ELECTRICAL REQUIREMENTS ...................................................................... 5 1.4 COMMUNITY BACKGROUND ......................................................................................................... 6 2.0 PREVIOUS STUDIES................................................................................................................... 7 2.1 LIBERTY CREEK ........................................................................................................................... 7 2.2 FIVEMILE CREEK .......................................................................................................................... 7 2.3 TROUT LAKE ................................................................................................................................ 8 2.4 FOX CREEK .................................................................................................................................. 8 2.5 O'B RIEN CREEK............................................................................................................................ 8 3.0 SELECTED PROJECT ANALYSIS..........................................................................................10 3.1 O'B RIEN CREEK, LOW HEAD PROJECT ....................................................................................... 10 3.2 O'B RIEN CREEK, HIGH HEAD PROJECT ......................................................................................12 3.3 FIVEMILE CREEK ........................................................................................................................ 15 3.4 CONCEPTUAL DESIGN ................................................................................................................ 16 4.0 ECONOMIC ANALYSIS............................................................................................................19 5.0 CONCLUSION AND RECOMMENDATIONS........................................................................21 6.0 REFERENCES.............................................................................................................................23 TABLES TABLE 1 - PROJECT CONFIGURATIONS AND MINIMUM OUTPUTS .................................................................... 9 TABLE 2 - O'BRIEN CREEK LOW HEAD COST ESTIMATE ............................................................................... 11 TABLE 3 - O'BRIEN CREEK LOW HEAD PROJECT SUMMARY .........................................................................11 TABLE 4 - O'BRIEN CREEK, HIGH HEAD COST .............................................................................................. 14 TABLE 5 - O'BRIEN CREEK, HIGH HEAD CONFIGURATION ............................................................................14 TABLE 6 - FIVEMILE CREEK PROJECT SPECIFICATIONS ................................................................................. 16 TABLE 7 - FIVEMILE CREEK COST ESTIMATE ................................................................................................18 TABLE 8 - ECONOMIC SUMMARY .................................................................................................................. 19 FIGURES FIGURE 1. VICINITY MAP ............................................................................................................................... 2 FIGURE 2. O'B RIEN CREEK, LOW HEAD PROJECT MAP .................................................................................. 3 FIGURE 3. O'B RIEN CREEK, HIGH HEAD PROJECT MAP ................................................................................. 4 FIGURE 4. FIVEMILE CREEK PROJECT MAP .................................................................................................... 5 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE ii PROJECT PHOTOS PHOTO 1. O'BRIEN CREEK, LOW HEAD PROJECT INTAKE SITE PHOTO 2. O'BRIEN CREEK CANYON AT FOX CREEK. PHOTO 3. O'BRIEN CREEK, HIGH HEAD INTAKE PHOTO 4. O'BRIEN CREEK, HIGH HEAD INTAKE PHOTO 5. O'BRIEN CREEK, HIGH HEAD INTAKE LOCATION BEFORE FLOOD PHOTO 6. O'BRIEN CREEK, HIGH HEAD INTAKE AREA AFTER FLOODING PHOTO 7. O'BRIEN CREEK, HIGH HEAD INTAKE AREA AFTER FLOODING PHOTO 8. BANK EROSION NEAR FROM INTAKE PHOTO 9. DOWNSTREAM VIEW OF UPPER RIDGE ON O'BRIEN CREEK PHOTO 10. UPSTREAM VIEW OF UPPER RIDGE ON O'BRIEN CREEK PHOTO 11. VIEW OF SECOND RIDGE ON O'BRIEN CREEK PHOTO 12. SECOND RIDGE ON O'BRIEN CREEK PHOTO 13. O'BRIEN CREEK POWERHOUSE SITE, HIGH HEAD PROJECT PHOTO 14. SLIDES ALONG COPPER RIVER HIGHWAY PHOTO 15. SLIDES ALONG COPPER RIVER. PHOTO 16. ROAD ADJACENT TO FIVEMILE CREEK PHOTO 17. EXPOSED ROCK FORMATION, FIVEMILE PROJECT PHOTO 18. FIVEMILE AERIAL PHOTO. PHOTO 19. FIVEMILE CREEK, POSSIBLE INTAKE SITE. APPENDICES APPENDIX A, HYDROLOGY ANALYSIS APPENDIX B, GEOTECHNICAL REPORT, SHANNON WILSON APPENDIX C, SUMMARY OF FLOODING IN SOUTHCENTRAL ALASKA, OCTOBER, 2006. USGS POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE iii ACRONYMS AND TERMINOLOGY AEA Alaska Energy Authority APA Alaska Power Administration ATV All terrain vehicle cfs cubic feet per second CVEA Copper Valley Electrical Association EPS Electric Power Systems, Inc. ft feet HDPE high-density polyethylene in inch kVA kilovolt-amp kW kilowatt kWh kilowatt-hours LCMF LCMF, LLC LIDAR Light Detection and Ranging mi mile PCE Power Cost Equalization Program Polarconsult Polarconsult Alaska, Inc. USGS United States Geological Survey POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 1 EXECUTIVE SUMMARY This report has been prepared at the request of Alaska Energy Authority (AEA), Rural Energy Group. Its purpose is to assist in the evaluation of hydropower resources available to the community of Chitina, Alaska. Based on field investigations, analysis of resource suitability, and community power needs, recommendations have been provided for additional investigation and development activities. The continued investigation of O’Brien Creek was the initial intent of this project and required field activities to select a project configuration among the alternatives presented in the O’Brien Creek Hydroelectric Conceptual Design Report (Polarconsult, 2005). A record flood in 2006 (USGS, 2006) caused drastic changes to the stream bed, resulted in slope stability problems, and caused landslides along the proposed penstock alignment and Copper River Highway effectively cutting off access to the project. In addition, discontinuous permafrost was found along the penstock and access alignment. It became apparent that a re-evaluation of the conceptual design and cost assumptions was required. The primary focus of this report is the continued evaluation of the O’Brien Creek resource and a preliminary review of Fivemile Creek and other creeks to determine the best potential hydro project alternative. The end result is a more comprehensive review of the hydropower alternatives for Chitina. Fivemile Creek was originally not pursued as a project alternative because a 4 mile transmission line was required and it was reported that there was little or no discernable stream flow in the winter time. Since the 2005 analysis, an extension of the power line from Chitina to a new diesel powerhouse located at the airport (immediately adjacent to Fivemile Creek) is planned and will be completed in the near future. As a result, the economic viability of the Fivemile project is improved and prompted further consideration during this investigation. Field reconnaissance of the Fivemile project in 2007 suggests that it is a favorable alternative to the O’Brien Creek project in several respects. The benefits include existing access, better soil conditions, and a nearby interconnection point to the electric grid. In addition, the smaller size of the project makes it a better fit for Chitina’s current electric requirements. The project is currently envisioned as having a design output of 300 kW and a minimum winter output of 110 kW. An economic analysis of the project indicates is has a benefit to cost ratio of 2.0 in a “growth” scenario and 1.3 in a “no growth” scenario. Given the current economic and technical difficulties of constructing a project on O'Brien Creek, investigative efforts would be more efficiently spent evaluating a project on Fivemile Creek. It is concluded that further evaluation of the potential for hydropower on Fivemile Creek is warranted. Further investigative activities on Fivemile Creek should include: Installation of a stream gauge near the intake location Stream flow measurement to correlate weir readings at the culvert POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 2 A Light Detection and Ranging (LIDAR) survey of the area suitable for project layout Preliminary geotechnical investigation Identification of regulatory requirements Preparation of a conceptual design report Development of a project cost estimate Refinement of project economics The cost to perform these investigative activities is estimated to be $100,000-$150,000 and will be used to prepare a conceptual design report and refine the project cost estimate. POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 3 1.0 INTRODUCTION The Alaska Energy Authority (AEA), Rural Energy Group is pursuing the evaluation of hydroelectric projects for the community of Chitina, Alaska, in order to lower energy costs. The increasing costs are the result of escalating costs of diesel generation upon which the community currently depends. Through the use of a renewable hydroelectric resource, the community will benefit from long-term independence from the escalating costs of diesel. To achieve this goal, AEA has taken steps to identify the most suitable hydroelectric projects available to the community. This has required the review of existing studies of alternatives, a conceptual evaluation of desirable project alternatives, initial field investigations, and finally a more detailed evaluation of those projects that are most likely to satisfy the electrical generation needs of the community. Each of these evaluations required a careful review of project configurations, costs, and benefits to make an equitable comparison between projects, resulting in a determination of the project most appropriate and economical for Chitina. This report details previous studies, field investigations, analysis of project configurations and resource availability, and a review of community power needs. The summary of previously investigated projects provides a comprehensive understanding of the alternatives that had been explored. The investigative work has been an iterative effort to further identify the best hydro resource available to the community. The initial project focus was the continued investigation of potential hydro projects on O’Brien Creek due to its large water resource and its capability to meet the long-term electrical needs of the community. The report provides detailed characteristics of the O’Brien and Fivemile Creek projects and a detailed hydrology analysis. In addition, recommendations have been provided to guide the additional investigation and activities necessary to proceed with the development of a hydroelectric project to meet Chitina's needs. Figures attached with the report include a vicinity map (Figure 1) that shows the location of Chitina, the drainage basins being considered for hydro development, and the nearby United States Geological Survey (USGS) stream flow gauging sites. Figures 2 through 4 show the location of each of the most favorable project alternatives. Polarconsult Alaska, Inc. prepared this report under the August 30, 2007 proposal, September 21, 2007 notice to proceed, and subsequent changes in scope requested by AEA. The work was coordinated through the term contract between LCMF, LLC and AEA. 1.1 PROJECT EVALUATION PROCESS The selection and evaluation of hydro projects suitable for construction is an iterative process that involves several steps. Evaluation of prospective hydro projects began with the selection of superior projects by using existing data and reports. This effort primarily was based on finding a project that could provide sufficient power to meet the energy needs of the community and then considering the technical feasibility and associated cost of the project. Those projects that could provide sufficient power and could be constructed within reasonable economic limitations were submitted to AEA for further POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 4 consideration. Numerous potential projects that initially appeared feasible have been conclusively eliminated through this process. The process resulted in the recommendation to further evaluate O’Brien Creek for its hydroelectric potential. In coordination with AEA, several data gathering and review iterations were necessary to evaluate the O’Brien Creek project configurations with the best potential to provide hydropower to the community. As a part of this process, AEA requested the scope of the investigation be expanded to include the evaluation of Fivemile Creek. 1.2 SUMMARY OF INVESTIGATIONS The initial review and analysis of a potential hydro project on O'Brien Creek began in September 2004. A review of existing studies, maps, and potential project configurations was undertaken. Potential projects were identified and an aerial field trip via helicopter was arranged in October 2004 to visually investigate the terrain conditions. Following the 2004 field trip, Polarconsult coordinated the collection of Light Detection and Ranging (LIDAR) data for the project area to further evaluate project options including access, penstock, and transmission routes. LIDAR data provides a detailed image of the ground topography. Due to the vast area of the site, this data was used to cost-effectively evaluate the surface conditions. In December of 2004, the LIDAR data was used to develop a more detailed and reliable evaluation of project alternatives. A Conceptual Design Report (Polarconsult, 2005) was completed that outlined the various project options based on the selection of the preferred project intake site. The project configurations being considered offered alternatives for site access, power house location, and transmission considerations. The report included a project cost estimate and recommendations for further work that included selection among these alternatives along with stream flow and geotechnical investigations. In April of 2005, a field trip was conducted to assess the minimum stream flow available at the preferred project intake site. The measurement of the minimum stream flow is critical to evaluating the ability of the project to meet the power needs of the community. This trip also afforded the opportunity to evaluate the terrain near the intake site as well as along the proposed project routes by helicopter. The visual assessment during this field trip also served to validate the LIDAR data. Subsequent to the 2005 field trip, local reports of severe landslides along the Copper River Highway prompted a reconsideration of the option that sited the powerhouse and the project access route near Eskilida Creek. The extensive nature of the slides eliminated those options and forced a reassessment of the project and associated costs. In October of 2007, a geotechnical and more detailed investigation of the remaining project options was undertaken. As part of this work, a comprehensive review of project alternatives for O’Brien Creek was conducted. During this investigation, significant changes in the site conditions were identified resulting from a severe flood in 2006 (USGS, 2006). The flood resulted in landslides and slope stability concerns near the proposed intake and along the first mile of the penstock route. The landslides along the Copper River Highway required the penstock to bridge O’Brien Creek near the POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 5 powerhouse. In addition, the discovery of permafrost conditions along the penstock route required another reassessment of the project and associated costs. During the same field investigation, a brief evaluation of Fivemile Creek was conducted. This change in project scope was performed in recognition of the fact that the feasibility of a hydro project on Fivemile would avoid many of the difficulties encountered on O’Brien Creek. Although a Fivemile Creek project is significantly smaller than O’Brien Creek, it was recognized to have the potential to meet the current power needs of the community for a much lower cost. The decision was made by AEA to utilize the mobilized design team and available helicopter to evaluate the feasibility of developing a hydro project on Fivemile Creek. The findings of the O’Brien fieldwork were summarized in a brief report (Polarconsult, 2007a) that enumerated the significant construction challenges and the anticipated increases in project costs associated with developing a hydro project on O'Brien Creek. As a result, other more favorable hydro alternatives were focused on. A separate and similarly brief report summary of the Fivemile Creek project was also prepared that included some basic hydrology information and field observations. It was concluded that the low winter stream flow in Fivemile Creek was critical to assessing the potential value of the project. In order to progress in a timely manner with the new focus on Fivemile Creek, a plan involving local residents constructing and monitoring a weir to verify winter low stream flows on Fivemile Creek was undertaken during the winter of 2007 and 2008. The results of the 2007 investigations of the O’Brien Creek project, Fivemile Creek project, and other relevant previous work are presented in this report. 1.3 CHITINA PROJECTED ELECTRICAL REQUIREMENTS The current and projected electrical requirements for Chitina were required to determine the adequacy of the proposed hydroelectric project to meet the electrical needs of the community. A projection was summarized in the Chitina Rural Power System Upgrade report (LCMF, 2005). The findings of this report and current information have been provided in this summary. The findings of the LCMF report indicated a 189 kW absolute peak demand at the end of FY2015. This was based on an increase in the demand based on 6-year historical population growth for Chitina of 3.26% plus a step increase in demand of 68 kW (peak) related to the tie-in of the Chitina Airport to the existing community. These conclusions are augmented by information provided by the Fiscal Year 2007 Statistical Report of the Power Cost Equalization Program (PCE) which provides data for the period from July 1, 2006 to June 30, 2007, and by information from Mr. Martin Finnesand, the power plant operator for Chitina Electric. The 2007 PCE report shows that the community used 33,789 gallons of fuel at an average cost of $2.52 per gallon. Each gallon of fuel produced 13.34 kWh of electricity. The total generation was about 450,086 kWh which is equivalent to a continuous power output of 51.4 kW. For a community load profile, the absolute peak demand overestimates power usage. The calculation of the probable peak was made to anticipate long-term peak loads. POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 6 Discussions with Mr. Finnesand indicated that the current peak demand is approximately 75 kW. This does not include the additional loads that will come when the power line extension is constructed to the airport, which is expected to be approximately 30 kW (factored peak) for the clinic and DOT maintenance facility. Applying the 3.26% growth factor applied to the current 75 kW peak demand plus an estimated 30 kW peak results in a 124 kW probable peak for FY2015. The peak demand in Chitina occurs during the summer and winter. The summer peak is caused by the seasonal increase in population and the increased refrigeration loads to freeze salmon caught by the residents and summer visitors. The timing of the summer peak load is ideal for a run-of-river hydroplant, as it has more than sufficient capacity since water flows increase greatly during the summer. 1.4 COMMUNITY BACKGROUND Chitina is located on the west bank of the Copper River at its confluence with the Chitina River, at mile 34 of the Edgerton Highway, 53 miles southeast of Copper Center. Chitina was established in the early 1900s as a support town for mining in Kennicott but was nearly abandoned after the mine shut down in 1938. The 2000 census population was 123. The climate in Chitina is characterized by long, cold winters and relatively warm summers. Total annual precipitation averages 12 inches. Temperature extremes from a low of -58 to a high of 91 degrees Fahrenheit have been recorded (Alaska Community Database, 2008). During the summer, subsistence dipnetting for salmon on the Copper River brings a large number of Alaskans from Anchorage and other areas of the state. Employment is primarily with the village council, village corporation, or the National Park Service. Many residents are self-employed or work in retail establishments. The summer influx of fishermen, tourists, and campers provides some cash income through fish guiding and other services. The terrain near Chitina is rugged, with the Chugach Mountains rising steeply from the banks of the Copper River. A series of small lakes is located in the narrow valley along the Edgerton Highway between the townsite and the airport. A bridge crosses the Copper River at the townsite leading into the Wrangell St. Elias National Park and the road to McCarthy and the Kennicott Mine. The park on the east side of the Copper River near the bridge consists of National Wilderness and Preserve areas. South of Chitina, the Edgerton Highway becomes the Copper River Highway. This is an unimproved trail accessible by four wheel drive and all terrain vehicles (ATVs). In the 1920s, it was the alignment of a railroad track that extended to Cordova, crossing the Copper River via the Million Dollar Bridge. The old railroad grade has not been maintained and recent flooding has taken out bridges and caused landslides that have effectively blocked travel between O’Brien and Eskilida Creeks. Chitina is accessible by road system and the small airport. The driving distance from Valdez to Chitina is 116 miles. Driving distance from Anchorage is 247 miles. The Chitina Airport has a 2,850-foot gravel runway. POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 7 2.0 PREVIOUS STUDIES Previous reports considered many possible configurations and locations for hydroelectric projects near Chitina. The U.S. Department of Energy and the Alaska Power Administration (APA) performed a study in 1981 evaluating four potential hydroelectric sites within 10 miles of Chitina (APA, 1981). The study included an evaluation of the feasibility of an intertie between Chitina and the Copper Valley Electrical Association (CVEA) system at Tonsina as well. The APA study concluded that there were no reasonably developable small hydro sites in Chitina given the combined economics of providing transmission and distribution and the low power demand. The study suggested that a more favorable solution was to construct a larger hydro (500 kW) on Fivemile or Liberty Creek along with the intertie. The excess energy from the hydro would be sold back to CVEA during the summer to offset the cost of the hydro and local distribution system. A study of an intertie was performed by Electric Power Systems, Inc. (EPS) to determine the possible routing and estimated costs for a single-phase overhead tieline from Lower Tonsina to Chitina along the Edgerton Highway (EPS, 2003a). This intertie would connect Chitina’s existing distribution system to CVEA’s single-phase distribution line. The total cost to construct this line was estimated at $2,190,960 (EPS, 2003a). The cost of the line was compared to the cost of a replacement generation plant and was concluded to be cost prohibitive. The following is a summary of several different projects that have been considered for hydro development. 2.1 LIBERTY CREEK The APA report examined a project on Liberty Creek below the falls. This project was configured with 250 feet of head with the pipe suspended from the canyon walls. Minimum winter production would be approximately 60 kW. The presence of a State Recreation Site at Liberty Falls is anticipated to be a substantial impediment to obtaining approval to build a project. To permit the project, the falls would have to be avoided, limiting design options. A project could be entirely located upstream of the falls, but the creek is in a deeply incised canyon for several miles making construction and access a significant difficulty. Another option that was not considered in the APA report was to lengthen the penstock and place the powerhouse on the banks of the Copper River, netting approximately 550 feet of head. This configuration would produce about 130 kW in the winter and have a capacity of 300 kW. This option would have a 6,500-foot pipeline with a 6-mile transmission line. The high cost of the transmission line alone is expected to result in the project not being economically viable. 2.2 FIVEMILE CREEK APA found that Fivemile Creek could support a hydro plant in the summer but did not expect enough water in the winter to make development worthwhile. Additionally, at the POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 8 time of the report, a 4-mile transmission line would have been required to connect to Chitina Electric. The project considered by APA had 300 feet of head. Such a project would have a minimum winter power production of 30 kW. This would require the diesel plant to run most of the winter to handle peak loads. Another alternative for Fivemile Creek was a high head configuration. This configuration utilizes an intake at an elevation of about 1,570 feet and a powerhouse located at about 530 feet. This option would produce a minimum power output of about 110 kW in the winter and would be designed for a maximum output of about 300 kW. This is the option that is more thoroughly investigated, and ultimately recommended, later in this report. 2.3 TROUT LAKE The existing hydroelectric project on Trout Lake has never been fully operational due to problems keeping the siphon portion of the penstock from leaking air. EPS prepared the Chitina Hydro Evaluation report (EPS, 2003c). This report details the investigation of the existing hydro and evaluates the feasibility of bringing the system back into service. EPS initially recommended bringing the project online if the costs to do so were minimal. The EPS report states that the Francis turbine output is 63 to 85 kW at a net head of 82 to 121 feet and flow of 11.3 to 12.7 cubic feet per second (cfs). The actual output of the Trout Lake hydro under full output was found to be 52 kW. The report found the cost to restore operation of the hydro to be approximately $50,000. This was under the assumption that the penstock air leaks could be easily repaired. After consideration of the EPS report, the conclusion reached by LCMF was that the Trout Lake project was not worth pursuing as a possible hydropower resource for Chitina. The capacity of the turbine on Trout Lake, about 60 kW, is not indicative of the ultimate value of this resource. The amount of water on a yearly basis is very limited due to the small drainage area. Coupled with the very poor efficiency of a Francis turbine at low operational flows, the potential winter power production is essentially zero. The limited output and other operational considerations combined with the relatively high cost and uncertainty of restoring operation warrant, as a minimum, delaying any investment into this project until further analysis of the Fivemile project is completed. 2.4 FOX CREEK APA also investigated the potential for a project on Fox Creek. Helicopter over flights, and later review of LIDAR data, confirmed the conclusion by APA investigators that the canyon was too steeply incised to effectively construct a project there. 2.5 O'BRIEN CREEK The APA report considered a project located along the lower reaches of O'Brien Creek. This project sited the intake location above the Fox Creek discharge and the powerhouse downstream from the Fox Creek discharge. Net head was estimated to be approximately 300 feet with a 2,700-foot-long pipeline. Polarconsult reviewed this project using LIDAR data and found that approximately 5,300 feet of pipeline would be required to obtain 300 feet of head. The intake elevation would POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 9 be at approximately 850 feet, with the powerhouse at 550 feet. This option would generate 220 kW in the summer and have a minimum power output of about 80 kW in the winter. The transmission line associated with this project would be about 2.3 miles long. Polarconsult evaluated other design configurations for hydropower on O'Brien Creek (Polarconsult, 2005). These were high head options that considered the intake sited at an elevation of about 1,950 feet and powerhouse located on either the Copper River or somewhere along the lower reaches of O'Brien Creek. These options would have the ability to produce significantly more power than the low head options. Depending on the turbine size selected, this option could generate 470 kW in the summer and have a minimum power output of about 390 kW in the winter. The higher head option, with a substantial amount of extra energy available, was the primary focus of investigations upon which this report is based. The LIDAR data indicated that such a project appeared feasible and would be accessible via a road access located about 2 miles south of the O'Brien Creek mouth near Eskilida Creek. Both options on O'Brien Creek are discussed in more detail in the sections to follow. Table 1 compares the various project configurations. Table 1 - Project Configurations and Minimum Outputs Location Basin area Head Min. Flow Min. Output (sq mi) (ft) (cfs) (kW) O'Brien low head 34.0 300 4.43 80 O'Brien high head 31.8 1500 4.13 390 Liberty Creek 27.9 550 3.63 130 Fivemile low head 13.2 300 1.73 30 Fivemile high head 12.6 1040 1.65 110 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 10 3.0 SELECTED PROJECT ANALYSIS Several hydro projects were considered for further analysis based on the potential to meet the power needs of the community and be economically viable. The selected projects were analyzed to determine if further investigation was appropriate. The projects considered under this section are low head and high head project configurations on O'Brien Creek and an analysis of a high head project on Fivemile Creek. 3.1 O'BRIEN CREEK, LOW HEAD PROJECT A low head project that located the intake and powerhouse in the canyon near the discharge of Fox Creek was considered by APA. The project envisioned by APA, and considered here, is described using the LIDAR data gathered and differs slightly from the APA report due to more accurate topographic information (Figure 2). The intake location for this project is at an elevation of about 850 feet. Siting the intake another 600 feet further upstream could net additional head; however, the bank on the west side gets very steep and a large outcropping exists that imposes a practical limitation for access. The APA report placed the powerhouse near Fox Creek at an elevation of 620 feet. Since a road is required for intake access, a better solution is to locate the powerhouse further downstream at an elevation of about 550 feet. This adds about 2,300 feet of penstock but reduces the transmission line length. The field visit in 2007 afforded only a brief aerial look into this option. Based on pictures and video, the intake site is rocky and gravelly with what appears to be a significant amount of talus material coming off both banks. Construction of an access road on the west bank will encounter the same soil conditions that were found higher up in the drainage, namely unstable glacial till. Such soil conditions will make long-term maintenance of and access to the intake difficult. The intake location may present the problem of establishing an effective water cutoff due to the potential for significant amounts of permeable material at the base of the creek bed (Photo 1). This can make the collection of low water flows difficult. The pipeline and access road would need to be adequately protected from slides and erosion of the embankment (Photo 2). Enough loose material exists so that trenching appears feasible; however, the material may not be suitable for backfill without screening. A culvert or bridge over Fox Creek will be required as well. The powerhouse site has enough area to adequately be located above flood stage and is not on a steep slope. The transmission line would likely follow the access road. Overall, this low head option for O'Brien Creek is more economical than the higher head options evaluated. However, the project is expected to be more expensive and would likely have a higher maintenance cost than a project on Fivemile Creek due to the narrow and difficult canyon conditions and transmission line costs. Additionally, it is expected to produce less power than Fivemile Creek. Should conditions on Fivemile Creek turn out not to be very favorable, then a closer look at this project is worthwhile. POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 11 In comparison to the high head option on O'Brien Creek, this lower head project would be better for just meeting Chitina's current energy needs. Table 2 - O'Brien Creek Low Head Cost Estimate Description Cost Materials Pipe $ 238,500 Turbine $ 150,000 Controls $ 70,000 Intake $ 85,000 Powehouse $ 80,000 Transmission $ 287,500 Access $ 50,000 Labor $ 250,000 Equipment $ 150,000 Shipping $ 150,000 Subtotal $1,511,000 Contingency (25%) $ 380,000 Subtotal $1,891,000 Profit/Overhead (25%) $ 470,000 Engineering $ 210,000 Administrative $ 70,000 Total $2,641,000 Table 3 - O'Brien Creek Low Head Project Summary Basin Area 34.1 sq mi Winter Minimum Flow 4.6 cfs Design Flow 17.0 cfs Pipeline Length 5,300 ft Nominal Pipeline Dia 18 in Transmission Length 12,350 ft Intake Elevation 850 ft Powerhouse Elevation 550 ft Static Head 300 ft Dynamic Head 220 ft Design Power Output 220 kW Winter Power Output 80 kW POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 12 3.2 O'BRIEN CREEK, HIGH HEAD PROJECT Several high head project configurations have been proposed for O’Brien Creek. The Polarconsult 2005 report recommended a project where the powerhouse was located along the banks of the Copper River about 1½ mile downstream from the mouth of O'Brien Creek (Figure 3). An access road was to be constructed 0.5 miles to the south that was to follow an existing ATV trail. Access to the project and the transmission route required the use of the Copper River Highway. Given the large amount of power that was available with the high head project, this option appeared to be the most favorable. Since the field investigation in 2005, extensive slide activity has occurred on the Copper River Highway between the mouth of O'Brien Creek and the proposed powerhouse location. The slide has been described as a major obstacle that will remain unstable for a considerable time. The high cost and dangerous conditions* associated with the slide have, for the time being, precluded further consideration of this alternative. For this reason, a closer look at other options was undertaken in 2007. *"…repairing the original slide was going to cost an estimated $10 million and it’s gotten a lot worse since — it’s not safe to work on the road. 'We had a hydrologist go look at it, and he said the whole mountain is unstable,' Thies said. 'I don’t see any way you can put that thing back in shape.' " Fairbanks Daily News-Miner, March 12, 2007. The fieldwork in 2007 primarily focused on finding a new powerhouse location and project access route to avoid the slide area. The other alternatives considered locating the powerhouse somewhere along the lower reach of O'Brien Creek with access ascending in the same area. Additional work during the field trip involved evaluating soil conditions, intake locations, and construction issues. During the 2007 field trip, several conditions were encountered that affected previous project concept design and cost assumptions: 1. It was discovered that the flood event of 2006 (USGS, 2006) completely reshaped the intake area (Photos 4-8) and caused new landslides and slope stability problems along the proposed pipeline route (Shannon Wilson, 2007). 2. The soil conditions along the penstock route were found to be poor with broad areas of bog and discontinuous permafrost requiring more costly construction methods. 3. The steep initial ascent of the access road would require the use of a winch line and a helicopter to move personnel, equipment, and materials, resulting in additional costs to access the project during construction and future maintenance. Relocation of the powerhouse required crossing O'Brien Creek with the high pressure pipe over a bridge able to withstand the 2006 flood and increasing the total pipeline length by about 3,000 feet for a total of 18,500 feet. The transmission line would be reduced by 1.3 miles for a total length of about 2.0 miles. The project cost estimate was also affected by the presence of permafrost soils identified along the penstock and access route (Shannon Wilson, 2007). Once disturbed, these soils can thaw, creating pools of water and areas of active soil movement. If widespread, the permafrost will dramatically slow the progress of pipeline installation. Where there is POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 13 permafrost, anchors need to be installed to keep the pipe from floating when empty and to provide restraint at bends and on slopes. A separate maintenance access route may be necessary after initial construction to avoid subsequent bogs and poor soil strength where the pipeline disturbance has melted the permafrost. Both the additional access difficulties and the presence of poor soils significantly complicated the design, construction, and maintenance aspects of the project. The consequence of this is a large increase in the planning, engineering, and administrative efforts. Similarly, due to unforeseen construction risk, the contingency costs also increase substantially. The extensive erosion, landslides, and slope stability concerns resulting from the 2006 flood also affect the project costs. The intake area was found to be inundated with alluvial material. As a result, it is expected to be more difficult to capture low stream flows. The floods caused undercutting and large landslides along the side hill that the original design called for benching the pipeline in. The unstable slopes dictate that the pipe should now be buried at the base of the side hill along the edge of the creek. This will require thicker wall high-density polyethylene (HDPE) pipe buried at a greater depth in the flood prone area to withstand higher pressures and boulders in the backfill. To maintain the same project power output, the pipe diameter will need to be increased to compensate for the thicker walls. As a result of these findings, the construction cost of a high head project is significantly higher than previously estimated. An estimate of the total project cost for the high head project with the powerhouse located on O'Brien Creek is presented in Table 4 with the project specifications shown in Table 5. The development of a high head project is not economical based on the cost and current power requirements of Chitina. If a market for significantly more power were available, this project would warrant further consideration. Such a project may have a rated capacity anywhere between 900 kW and 2500 kW. POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 14 Table 4 - O'Brien Creek, High Head Cost Description Cost Diversion / Intake / Desander $150,000 Penstock $600,000 Powerhouse/Turbine/Generator $300,000 Access and Bridge $75,000 Power Transmission System $420,000 Equipment $560,000 Labor $375,000 Shipping $200,000 Subtotal Direct Costs $2,680,000 Contingency (25%) $670,000 Subtotal Estimated Cost $3,351,000 Overhead & Profit (25%) $838,000 Total Construction Cost $4,188,000 Engineering $350,000 Construction Management $165,000 Total Project Cost $4,703,000 Table 5 - O'Brien Creek, High Head Configuration Basin Area 31.8 sq mi Winter Minimum Flow 4.1 cfs Design Flow 6.5 cfs Pipeline Length 18,500 ft Nominal Pipeline Dia 12 in Transmission Length 17,600 ft Intake Elevation 1,950 ft Powerhouse Elevation 450 ft Static Head 1,500 ft Dynamic Head 1,130 ft Design Power Output 470 kW Winter Power Output 390 kW POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 15 3.3 FIVEMILE CREEK A project on Fivemile Creek was evaluated and is presented as the recommended project for further investigation (Figure 4). The initial review presented in the APA report indicated that a Fivemile Creek project lacked sufficient water to generate enough power for local needs during the winter. In addition, the project required a 4-mile extension of the transmission line to connect with the community. The impediments to developing Fivemile Creek were considered in 2005 and prompted the investigation of a project on O’Brien Creek. O’Brien Creek was known to have more than enough water to meet the power generation needs for Chitina, even during the lowest flows of spring. At that time, the presumed location for the new diesel power plant was in the town of Chitina, which would have required a 4-mile transmission line to connect Fivemile to the city grid. As a result, a project on O'Brien Creek was considered to be more feasible. The high cost of developing O'Brien Creek and the decision to locate the new diesel power plant near the airport prompted a more detailed review of the Fivemile Creek project. During the 2007 field trip, an aerial reconnaissance of the Fivemile project area was performed and a short excursion was undertaken to search for a possible intake location and pipeline route out of the steeply incised canyon. Analysis of the project indicated that a high head option for the project was the only way to provide sufficient power to justify development of the project. This required placement of the intake site near the 1,570-foot elevation contour. Aerial inspection of the site indicated the possibility of mild side slopes suitable for a penstock route that was not apparent during the prior review of topographic maps. Considering Fivemile Creek as a potential alternative location for a hydroelectric facility focused on the availability of water for power generation. Based on the findings of the hydrological investigation (Appendix A), there appears to be enough water to make a project viable on Fivemile. The field inspection focused on a project with an intake elevation of 1,570 feet and a powerhouse located near the Copper River at an elevation of about 530 feet. The choice of intake location was based on review of the USGS contour map and a brief aerial observation that confirmed more suitable terrain at the higher elevations. A handheld GPS and altimeter was used to locate the possible intake location. An existing four wheel drive trail that ascends the drainage on the ridge on the north side of the creek was used to ascend to an elevation of approximately 1,450 feet followed by a foot survey to the creek. The terrain encountered included flat benches with soil and medium-sized spruce trees and rock cliffs. The predominant terrain was a slight to moderate side hill (slopes of about 2.5:1) with dense spruce and dead fall over soil. Active erosion, landslides, or slope instability were not observed. POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 16 It was concluded that a good probability of finding a penstock alignment could be benched to avoid significant rock excavation. However, this initial impression is based on visual observation and needs to be verified. Below the intake site, Fivemile Creek flows through a confined canyon that becomes more incised in the downstream direction. At the intake site, the creek is confined tightly on the south side (opposite the pipeline side) by canyon-like cliffs and steep slopes. The north bank at the intake, which is where the pipeline would traverse, had some exposed rock but did have a stretch of flat to slightly sloped ground that may have consisted of large alluvial material. The flat ground gave way to a steep slope and some cliffs about 100 feet away from the creek. Above the intake site, the north bank of the creek rises steeply again then appears to flatten out again. Just downstream from the intake site, the north bank appears to remain relatively flat and accessible for some distance. The Fivemile Creek project would be high head with about 1,040 feet of elevation drop between the intake and powerhouse. This project is able to produce 300 kW of electricity at a flow of 5 cfs. The Fivemile Creek Project specifications are presented in Table 6. Table 6 - Fivemile Creek Project Specifications Basin Area 12.65 sq mi Winter Minimum Flow 1.65 cfs Design Flow 5.0 cfs Pipeline Length 8,500 ft Nominal Pipeline Diameter 12 in Transmission Length 2,000 ft Intake Elevation 1,570 ft Powerhouse Elevation 530 ft Static Head 1,040 ft Dynamic Head 940 ft Design Power Output 300 kW Winter Minimum Output 110 kW Annual Potential Energy 2.04 GWh Estimated Cost* $2,010,000 *Approximate estimate of costs based on assumed site conditions to be verified by further investigation. 3.4 CONCEPTUAL DESIGN The Fivemile Creek intake area is fairly narrow and appears to be confined in a bedrock channel that will allow for a relatively simple diversion to capture flows. Although the total project flow is only 5 cfs, the small dam and intake will require a design to support the occasional extreme flood with large trees and boulders being carried downstream. However, site conditions suggested that the area withstood the 2006 floods without significant bed or bank changes and channel meandering. Additionally, in the winter, a substantial amount of glaciation is anticipated. As such, the dam and intake will be subject to significant ice loads. Additional design features should include a pool deep enough to prevent freezing of the slow moving water down to the streambed and insulation to minimize heat loss. POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 17 A significant amount of dead wood and spruce needles should be expected in the stream flow. A self-cleaning screen system will be required to keep debris from entering the pipeline. Power at the intake site is required to operate screening systems. A head level control system will be required to monitor water availability. The section of penstock extending approximately 3,200 feet from the intake is envisioned to traverse the hillside until it crosses the existing four wheel drive trail. As described above, the embankment on the north side of the intake is relatively flat, leaving sufficient room to establish an access trail and pipeline bench. Collection of topographic survey data will determine the best location for the pipeline and access route and, subsequently, the intake location. An inspection of the soil conditions was made along the four wheel drive access trail that ascends from the Edgerton Highway up to the peak of the mountain on the north side of Fivemile Creek. This trail leads to an abandoned mine. Only a few sections of the trail, primarily close to the highway, have appreciable topsoil. Most of the trail was rocky with large cobbles and occasional patches of exposed bedrock. The bedrock appeared competent. If insufficient soil or loose rock is found along the pipeline route then burial may be quite difficult. However, a gravel pit is located along the trail approximately ½ mile from the highway (per discussions with Martin Finnesand), and may serve as a source of material for bedding, padding, and mounding the pipeline. Sufficient burial is important for this project in order to obtain low-cost pipeline protection from movement and insulation to guard against freezing. HDPE pipe could be used for the 3,200-foot low pressure section. Steel pipe is required for the remaining high pressure section. Once the traverse is completed out of the creek canyon, there are several pipeline route options. The topography is at a 12% to 18% grade. This large potential area will dictate a thorough investigation to find the best route to minimize construction and maintenance costs. A LIDAR survey of the area is recommended to avoid terrain features shown on the low resolution USGS quad map. A future geotechnical investigation along the proposed pipeline route should be done with the intent of minimizing rock excavation and identifying good natural bedding conditions. This route almost certainly will not coincide with the existing four wheel drive trail. Crossing the Edgerton Highway will also be required. It is expected that the pipeline will be buried under the highway. The suggested powerhouse location was chosen to maximize the static head while avoiding airport property. The final location selected should address these considerations along with long-term erosion potential of the banks of the Copper River, vehicle access to the powerhouse, pipeline alignment, transmission line length, and the pipeline crossing location of the Edgerton Highway. The State of Alaska Department of Fish and Game does not list Fivemile Creek as an anadromous stream. Visual inspection of the mouth of the creek also indicates that this stream is not suitable fish habitat. Therefore, the tailrace does not need to drain back into Fivemile Creek. This will also simplify permitting requirements. POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 18 Table 7 - Fivemile Creek Cost Estimate Item Amount Materials Pipe $ 220,000 Turbine $ 150,000 Controls $ 70,000 Intake $ 50,000 Powerhouse $ 60,000 Transmission $ 50,000 Labor $ 200,000 Equipment $ 150,000 Shipping $ 150,000 Subtotal $1,100,000 Contingency (25%) $ 280,000 Subtotal $1,380,000 Profit/Overhead (25%) $ 350,000 Engineering $ 210,000 Administrative $ 70,000 Total* $2,010,000 *Approximate estimate of costs based on assumed site conditions to be verified by further investigation. POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 19 4.0 ECONOMIC ANALYSIS A comparative analysis of the O’Brien high head project and the Fivemile Creek high head project alternatives were made against the projected diesel generation costs. Based on this comparison, the Fivemile Creek project is superior to the O’Brien Creek project. Further, the Fivemile Creek project will more than pay for itself in savings in fuel that would otherwise have been used in the diesel plant. The following assumptions were used to make this analysis: Item Value Fuel use in FY2007 33,789 gallons (AEA, 2008) Fuel cost for 2008 $3.70 per gallon (Data from Martin Finnesand) Increased demand on Airport tie-in 30 kW* TotalYearly Energy from Airport 25,000 kWh * Current peak demand for community 75 kW (Data from Martin Finnesand) Power generated in FY2007 450,586 kWh/yr (AEA, 2008) Annual increase in energy growth 3.26%/year (LCMF, 2005) Loan payment period 30 years Real discount rate 3%(AEA Alternative Energy RFP, Dec. 6, 2007) * Energy usage is estimated. A 25-kW genset can carry the DOT State Maintenance Facility Loads, and 5 kW is the estimate for the Clinic. Assumed average load is about 3 kW. Based on conversation with Martin Finnesand. For the purposes of this comparison, the analysis used the current peak demand of 75 kW plus the 30 kW probable demand for the Chitina Airport tie-in. Based on load growth projections, the calculation for peak demand growth was made with the 75 kW demand escalating for 30 years at a rate of 3.26% per year (LCMF, 2005). The total energy demand used in these calculations is the FY2007 power generated (450,586 kWh) plus the assumed static demand of 25,000 kWh from the airport and clinic. Daily peak load requirements and subsequent diesel use were factored in as well. Present worth values were then calculated based on the value of fuel displaced for diesel generation by the respective hydro project. The following table summarizes the construction costs, projected value of fuel saved, and the benefit to cost ratio under different growth scenarios. Table 8 - Economic Summary Project Construction Cost No Growth 3.26% Growth Savings PV* B/C** Savings PV* B/C** O'Brien, High Head $ 4,703,000 $ 2,600,000 0.6 $ 4,100,000 0.9 O'Brien, Low Head $ 2,641,000 $ 2,500,000 0.9 $ 3,500,000 1.3 Fivemile*** $ 2,010,000 $ 2,600,000 1.3 $ 3,900,000 1.9 * PV = Present value at real discount rate. ** B/C Benefit to cost ratio. ***Approx. est. of costs based on assumed site conditions to be verified by further investigation. POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 20 This analysis did not include the potential benefits gained by using excess electricity for heating or other purposes. The heating value of surplus electricity produced by the projects can positively affect their economic values, offsetting local use of heating fuel. POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 21 5.0 CONCLUSION AND RECOMMENDATIONS The 2007 field investigation provided additional information to evaluate the O’Brien Creek hydro project alternatives. The field investigation also included the Fivemile Creek project. This report includes a summary of previous projects in the area as well as further evaluation of the O’Brien and Fivemile Creek alternatives. Previously unidentified field conditions resulted in a significant change in the design concept and cost assumptions for the proposed configurations on O’Brien Creek. These changes were the result of a record flood in 2006 (USGS, 2006) that caused drastic changes to the stream bed, resulted in slope stability problems, and caused landslides along the proposed penstock alignment and Copper River Highway. The landslides along the highway effectively cut off access to the project. In addition, discontinuous permafrost was found along the penstock and access alignment. These conditions required a re-evaluation of the conceptual design and negatively affected the project economics and construction risks. A preliminary investigation of Fivemile Creek was conducted to evaluate the hydroelectric potential of the resource. A previous analysis of the Fivemile project required the construction of a 4-mile-long power line to Chitina. Since the 2005 analysis, an extension of the power line from Chitina to a new diesel powerhouse located at the airport (immediately adjacent to Fivemile Creek) is planned and will be completed in the near future. As a result, the economic viability of the Fivemile project is improved and prompted further consideration during this investigation. Field reconnaissance of the Fivemile project suggests that it is a favorable alternative to the O’Brien Creek projects in several respects. The benefits include existing access, better soil conditions, and a nearby interconnection point to the electric grid. In addition, it is the lowest estimated cost and the best fit for Chitina’s current electric requirements. This results in favorable economics and significantly reduced construction risks. A comparative analysis of the project alternatives was made against the projected diesel generation costs. Based on this comparison, the Fivemile Creek project is superior to the both O’Brien Creek projects. Further, should the electrical load increase as predicted by LCMF, the Fivemile project remains the superior project in terms of economics and ability to meet Chitina's energy needs. The project on Fivemile Creek is currently envisioned as having a design output of 300 kW and a minimum winter output of 110 kW. The construction cost of the Fivemile Creek project is $2,010,000. The Fivemile Project has a benefit to cost ratio of 2.0 in a “growth” scenario and 1.3 in a “no growth” scenario. Continued investigative efforts should focus on evaluating the potential of a hydro project on Fivemile Creek. POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 22 Further investigative activities on Fivemile Creek should include: Installation of a stream gauge near the intake location Stream flow measurement to correlate weir readings at the culvert A Light Detection and Ranging (LIDAR) survey of the area suitable for project layout Preliminary geotechnical investigation Identification of regulatory requirements Preparation of a conceptual design report Development of a project cost estimate Refinement of project economics The cost to perform these investigative activities is estimated to be $100,000-$150,000 and will be used to prepare a conceptual design report and refine the project cost estimate. POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 23 6.0 REFERENCES AEA(Alaska Energy Authority). 2008.Statistical Report of the Power Cost Equalization Program, Fiscal Year 2007. February. Alaska Community Database, Community Information Summaries (CIS). 2008. http://www.dced.state.ak.us/dca/commdb/CF_CIS.cfm?Comm_Boro_Name=Chitina APA (U.S. Department of Energy and Alaska Power Administration). 1981. Preliminary Evaluation of Hydropower Alternatives for Chitina, Alaska. February. EPS (Electric Power Systems, Inc.). 2003a.Chitina Electric Power Generation and Delivery System Inspection. March. EPS. 2003b.Lower Tonsina to Chitina Single Phase Overhead Tieline Feasibility Report. July. EPS. 2003c.Chitina Hydro Evaluation. August 28. Fairbanks, Morse & Co. 1981. Hydraulic Handbook. First Edition. LCMF. 2005. Conceptual Design Report, Chitina Rural Power System Upgrade, Draft Revision 1. September 6. Polarconsult (Polarconsult Alaska, Inc.). 2005.O’Brien Creek Hydroelectric Conceptual Design. March 21. Polarconsult. 2007a. O’Brien Creek Hydroelectric. October 31. Polarconsult. 2007b. Fivemile Creek Inspection and Concept Design. October 31. Shannon Wilson. 2007. O’Brien Hydroelectric Project, Geotechnical Report. November 14. USGS (United States Geological Survey). 2006. Summary of Flooding in Southcentral Alaska. October.http://ak.water.usgs.gov/flood/2006October/index.php POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 FIGURES POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PROJECT PHOTOS POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 1 PROJECT PHOTOS PHOTO 1. O'BRIEN CREEK, LOW HEAD PROJECT INTAKE SITE ..............................................................................2 PHOTO 2. O'BRIEN CREEK CANYONAT FOX CREEK...............................................................................................3 PHOTO 3. O'BRIEN CREEK, HIGH HEAD INTAKE ....................................................................................................4 PHOTO 4. O'BRIEN CREEK, HIGH HEAD INTAKE ....................................................................................................4 PHOTO 5. O'BRIEN CREEK, HIGH HEAD INTAKE LOCATIONBEFORE FLOOD ..........................................................5 PHOTO 6. O'BRIEN CREEK, HIGH HEAD INTAKE AREA AFTER FLOODING...............................................................6 PHOTO 7. O'BRIEN CREEK, HIGH HEAD INTAKE AREA AFTER FLOODING...............................................................7 PHOTO 8. BANK EROSION NEAR FROM INTAKE......................................................................................................8 PHOTO 9. DOWNSTREAM VIEW OF UPPER RIDGE ON O'BRIEN CREEK ..................................................................9 PHOTO 10. UPSTREAM VIEW OF UPPER RIDGE ON O'BRIEN CREEK ....................................................................10 PHOTO 11. VIEW OF SECOND RIDGE ON O'BRIEN CREEK ....................................................................................11 PHOTO 12. SECOND RIDGE ON O'BRIEN CREEK ...................................................................................................12 PHOTO 13. O'BRIEN CREEK POWERHOUSE SITE, HIGH HEAD PROJECT ..............................................................13 PHOTO 14. SLIDES ALONG COPPER RIVER HIGHWAY...........................................................................................14 PHOTO 15. SLIDES ALONG COPPER RIVER...........................................................................................................15 PHOTO 16. ROAD ADJACENT TO FIVEMILE CREEK ...............................................................................................16 PHOTO 17. EXPOSED ROCK FORMATION, FIVEMILE PROJECT..............................................................................17 PHOTO 18. FIVEMILE AERIAL PHOTO. ..................................................................................................................18 PHOTO 19. FIVEMILE CREEK, POSSIBLE INTAKE SITE...........................................................................................19 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 2 Photo 1. O'Brien Creek, Low Head Project Intake Site Taken from a screen capture of a video recording, this is a view looking upstream towards the assumed location of the intake for the low head project on O'Brien Creek. Note the fractured rocky embankment and unstable slopes. Capturing low water flows will be difficult due to substrate permeability. (2007 Polarconsult) POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 3 Photo 2. O'Brien Creek Canyon at Fox Creek. View upstream along the pipeline route of the low head O'Brien Creek project. Access and penstock bench would be located along the right side of the stream. (2007 Polarconsult) POLARCONSULTALASKA, INC. REGIONALHYDROELECTRICINVESTIGATIONCHITINA, ALASKAFINALREPORTMAY2,2008 PAGE4Photo 3. O'Brien Creek, High Head IntakeCreek bed and banks during flow measurement at intake area before flood. Photo taken just upstream from the intake and is looking downstream. (2005 Polarconsult)Photo 4. O'Brien Creek, High Head IntakePhoto was taken just downstream from the intake and is looking downstream. (2007 Polarconsult) POLARCONSULTALASKA, INC. REGIONALHYDROELECTRICINVESTIGATIONCHITINA, ALASKAFINALREPORTMAY2,2008 PAGE5Photo 5. O'Brien Creek, High Head intake location before floodIntake was presumed to be located at the 1950' elevation that is near the bottom middle of the photo on the curve of the stream. Stream flow is from left to right. (2005 Polarconsult) POLARCONSULTALASKA, INC. REGIONALHYDROELECTRICINVESTIGATIONCHITINA, ALASKAFINALREPORTMAY2,2008 PAGE6Photo 6. O'Brien Creek, High Head intake area after floodingView looking downstream at intake location that is near the upper middle of the photo where the creek jogs to the left. The first ridge crossing can be seen about a 1/4 mi further downstream at near the top middle of the photo. (2007 Polarconsult) POLARCONSULTALASKA, INC. REGIONALHYDROELECTRICINVESTIGATIONCHITINA, ALASKAFINALREPORTMAY2,2008 PAGE7Photo 7. O'Brien Creek, High Head intake area after floodingPhoto shows debris and boulders moved during the 2006 flood event. (2007 Polarconsult) POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 8 Photo 8. Bank Erosion Near from Intake Along the east embankment of O'Brien Creek just upstream from the intake. Due to slope stability concerns, the pipeline and access would have to be located at the toe of the slope. (2007 Polarconsult) POLARCONSULTALASKA, INC. REGIONALHYDROELECTRICINVESTIGATIONCHITINA, ALASKAFINALREPORTMAY2,2008 PAGE9Photo 9. Downstream View of Upper Ridge on O'Brien CreekThis photo shows the first (upper) ridge crossing for the O'Brien Creek project. The required cut through the ridge is approximately 25 feet. Geologist indicates that this cut will likely not encounter rock. (2007 Polarconsult) POLARCONSULTALASKA, INC. REGIONALHYDROELECTRICINVESTIGATIONCHITINA, ALASKAFINALREPORTMAY2,2008 PAGE10Photo 10. Upstream View of Upper Ridge on O'Brien CreekView of the first ridge crossing on O'Brien Creek. Active erosion is visible indicating loose material. Competent rock plane is visible on the right side of the ridge. (2007 Polarconsult) POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 11 Photo 11. View of Second Ridge on O'Brien Creek This photo is taken from the top of the first ridge looking downstream. The pipeline and access route would be located along the creek bed because unstable slopes prevent benching (numerous areas of erosion are visible). The second ridge crossing is visible in the top middle of the picture as the low spot along the hill crest. (2007 Polarconsult) POLARCONSULTALASKA, INC. REGIONALHYDROELECTRICINVESTIGATIONCHITINA, ALASKAFINALREPORTMAY2,2008 PAGE12Photo 12. Second Ridge on O'Brien CreekThis is a closeup of the second ridge and the basin divide looking downstream from the upper ridge. As evidenced by the erosion, the ridge appears to consist of loose material. The cut through this ridge would be about 25 feet. (2007 Polarconsult) POLARCONSULTALASKA, INC. REGIONALHYDROELECTRICINVESTIGATIONCHITINA, ALASKAFINALREPORTMAY2,2008 PAGE13Photo 13. O'Brien Creek Powerhouse Site, High Head Project(2007 Polarconsult) POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 14 Photo 14. Slides Along Copper River Highway (2007 Polarconsult) POLARCONSULTALASKA, INC. REGIONALHYDROELECTRICINVESTIGATIONCHITINA, ALASKAFINALREPORTMAY2,2008 PAGE15Photo 15. Slides Along Copper River.This photo shows slides that occurred along the Copper River between O'Brien Creek and Eskilida Creek. This area was the presumed access route recommended in the 2005 report. (2007 Polarconsult) POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 16 Photo 16. Road adjacent to Fivemile Creek The road was constructed for mine access and goes to the top of the peak just south of Liberty Creek. (2007 Polarconsult) POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 PAGE 17 Photo 17. Exposed Rock Formation, Fivemile Project This exposed rock formation was found during the traverse to the intake site and appears to be visible in the aerial photo. (2007 Polarconsult) POLARCONSULTALASKA, INC. REGIONALHYDROELECTRICINVESTIGATIONCHITINA, ALASKAFINALREPORTMAY2,2008 PAGE18Photo 18. Fivemile Aerial Photo.This aerial shows the low pressure pipe area. The creek does not become steeply incised until well below the intake site. POLARCONSULTALASKA, INC. REGIONALHYDROELECTRICINVESTIGATIONCHITINA, ALASKAFINALREPORTMAY2,2008 PAGE19Photo 19. Fivemile Creek, Possible intake site.Note basement rock outcrop on left and narrow stream section. Stable stream banks and spruce tree on right suggest insignificant damage to site from the 2006 flood. (2007 Polarconsult) POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 APPENDIXA- HYDROLOGY ANALYSIS POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS APRIL 11,2008 1 C HITINA H YDROLOGY A NALYSIS April 11, 2008 prepared by polarconsult alaska, inc. 1503 West 33rd Avenue, Suite 310 Anchorage, Alaska 99503 Phone: (907) 258-2420 POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS APRIL 11,2008 1 TABLE OF CONTENTS TABLE 1 -HYDROLOGIC BASIN SIZE, ELEVATION,AND LOCATION........................................................................2 FIGURE 1 - USGS MEDIAN DAILY UNIT FLOW DATA (CFS/SQMI)..........................................................................3 TABLE 2 - FLOW MEASUREMENTS ..........................................................................................................................4 TABLE 3 - WINTER HYDROGRAPH FACTORS ..........................................................................................................4 FIGURE 2 - O'BRIEN CREEK SUMMER FLOWS CORRELATED TO USGS GAUGE SITES ..........................................5 FIGURE 3 - LITTLE TONSINA MEDIAN UNIT FLOW AND CHITINA ESTIMATED UNIT FLOW....................................6 FIGURE 4 - FIVEMILE CREEK POWER OUTPUT .......................................................................................................6 PHOTO 1 - O'BRIEN CREEK FLOW MEASUREMENT 1, ~0.7 MI ABOVE INTAKE SITE...............................................7 PHOTO 2 - O'BRIEN CREEK FLOW MEASUREMENT LOCATION 2,AT INTAKE SITE..................................................8 FIGURE 5 - O'BRIEN CREEK FLOW MEASUREMENTS MAP.....................................................................................8 FIGURE 6 - FIVEMILE CREEK WEIR DESIGN .........................................................................................................10 PHOTO 3 - INSTALLED WEIR,EARLY IN WINTER ...................................................................................................11 PHOTO 4 - VIEW OF WATER SPILLING OVER WEIR .................................................................................................11 PHOTO 5 - VIEW OF WEIR,LATER WINTER ............................................................................................................12 TABLE 4 - WEIR/FLOW MEASUREMENTS..............................................................................................................12 POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS APRIL 11,2008 2 An analysis of the hydrology in the Chitina area was conducted to estimate the quantity of water available to the projects being evaluated. The stream flow characteristics directly affect the power production and associated economic viability of the respective projects. None of the creeks in the Chitina area have continuous stream flow data available. The USGS performed numerous summer and fall flow measurements looking for high flows in O'Brien Creek but only performed one low flow measurement in April. This information is presented in a study performed by APA in 1981. These measurements were made near the mouth of O'Brien Creek just upstream of the bridge. The study further stated that local residents indicate the stream runs year-round. The 1981 study made an effort to forecast the low winter flow and power production using data from Squirrel Creek. The resulting low flow was estimated to be between 3.4 and 2.2 cfs. The USGS has gauging data for the Little Tonsina River, Tebay River, and Squirrel Creek, all of which are situated at latitudes similar to O'Brien Creek and Fivemile Creek. The following table summarizes the various locations, basin sizes, and elevations for the project locations discussed and the three USGS sites. Table 1 - Hydrologic Basin Size, Elevation, and Location Location USGS Site No Basin size (sq mi) Elevation (ft) Latitude (dd.dd) Longitude (dd.dd) Begin Date End Date No of Records O'Brien Mouth 46.3 450 61.4817 -144.4556 O'Brien Intake, APA 34.0 920 61.4733 -144.4906 O'Brien Intake, PCA 31.8 1950 61.4608 -144.5408 Fivemile Culvert 13.3 620 61.5822 -144.4375 Fivemile Intake, APA 13.2 890 61.5811 -144.4475 Fivemile Intake, PCA 12.6 1550 61.5781 -144.4819 Little Tonsina River 15207800 22.7 1850 61.4800 -145.1500 9/1/1972 9/30/1978 2221 Tebay River 15211500 55.4 1796 61.2300 -144.2000 7/1/1962 6/30/1965 1096 Squirrel Creek 15208100 70.5 1520 61.6700 -145.1800 7/1/1965 9/30/1975 3744 All data from each USGS site was averaged for each day and divided by the basin area to get the average daily flow per square mile for each of the gauged sites. The following chart shows the results. POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS APRIL 11,2008 3 Figure 1 - USGS Median Daily Unit Flow Data (cfs/sqmi) As shown in Figure 1, there is an extreme amount of variability, both in the summer and winter. Squirrel Creek has significantly lower flows than both the Tonsina and Tebay on discharge per unit area basis. This is probably due to the fact that it is further north and most of the basin lies on the north flank of the Chugach Range. Squirrel Creek probably lacks precipitation due to down sloping effects under the predominant southerly flow regimes. On a discharge per unit area basis, both the Little Tonsina River and the Tebay River exhibit very similar winter flow characteristics. The summer flows, which differ significantly, are not relevant for the size of project that is being considered in Chitina. Because of the climate conditions in Chitina, the stream flow in all of the creeks in the area tends to drop off rapidly at the onset of winter. It quickly reaches a low flow that is relatively constant until the spring thaw. For purposes of providing power year round, this low flow period is critical for determining the project economics. Generally, all of the projects in this report and in the APA report easily exceed Chitina's power requirements in the summer. The APA report recognized the importance of this low flow period and, rightfully, made it one of their primary concerns in evaluating the various project options. The following table is a list of actual low flow measurements made on O'Brien and Fivemile Creeks. This data is compared with averages and minimums on the USGS sites. 0 1 2 3 4 5 6 7 8 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecUnit Flow (cfs/sqmi)Tebay L Tonsina Unit Flow Squirrel POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS APRIL 11,2008 4 Table 2 - Flow Measurements Location Date Flow (cfs) Unit Flow (cfs/sq mi) O'Brien Mouth 4/23/1976 4.00 0.086 O'Brien Intake, PCA 4/15/2005 4.00 0.126 Fivemile Culvert 1/7/2008 2.44 0.183 Fivemile Culvert 2/6/2008 2.26 0.170 Fivemile Culvert 2/20/2008 2.10 0.157 Fivemile Culvert 3/5/2008 1.93 0.145 Little Tonsina River, Median Min 3/9 4.50 0.198 Tebay River, Median Min 4/15 16.00 0.289 Squirrel Creek, Median Min 3/8 11.50 0.163 Little Tonsina River, Min 4/1/1974 3.00 0.132 Tebay River, Min 4/15/1964 14.00 0.253 Squirrel Creek, Min 4/5/1967 9.00 0.128 As stated in the APA report, the USGS measured a stream flow of 4.0 cfs on 4/23/1976. On the same date (4/23/1976) that the USGS measured the O'Brien flow, the USGS gauge data at Little Tonsina River was 6 cfs, whereas the median for that day is 5.5 cfs. The lowest Tonsina record is 3 cfs. No similar comparison data is available for the flow measurements done in 2005 and 2008. The first three readings taken at the Fivemile Creek culvert were not collected in the springtime when the absolute minimum flow is likely to occur; however, the final measurement made on 3/5/08 nearly coincides with the minimum spring flow on the Little Tonsina. All of the above spring flow measurements at O'Brien and Fivemile Creeks indicate the springtime unit stream flows near Chitina are lower than the median values at the gauged USGS sites. The USGS reading done on 4/23/1976 at the O'Brien mouth is significantly less than that measured by Polarconsult on O'Brien and Fivemile Creeks. A possible explanation for this is that a significant portion of the stream flow occurs as groundwater flow. The USGS measurement was taken at the mouth, where the streambed consists of a gravel outwash plane that would allow for such an occurrence. The 4/23/76 flow measurement at the O'Brien mouth will be discarded as an outlier. Therefore, choosing the Little Tonsina River as the basis for a unit winter hydrograph, the following data points are used to obtain an appropriate scale factor. Table 3 - Winter Hydrograph Factors Location Date Flow Unit Flow L Tonsina Unit Flow Ratio Predicted Flow % Diff O'Brien Intake, PCA 4/15/2005 4.00 0.126 0.220 57% 4.60 15% Fivemile Culvert 1/7/2008 2.44 0.183 0.264 69% 2.32 -5% Fivemile Culvert 2/6/2008 2.26 0.170 0.264 64% 2.32 2% Fivemile Culvert 2/20/2008 2.10 0.157 0.242 65% 2.12 1% Fivemile Culvert 3/5/2008 1.93 0.145 0.198 73% 1.74 -10% Average 65.7% POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS APRIL 11,2008 5 As shown, the resulting average ratio is 65.7%. This factor was applied to the winter portion of the Little Tonsina data set to obtain daily average flow values that directly convert to project output. The predicted flows for the dates that actual flows were measured are shown in the table also. The remainder of the unit hydrograph, early summer through early winter, is obtained from the Little Tonsina River flow record as well. A comparison with the Little Tonsina and Squirrel Creek basins was performed using the stream flow measurements done by the USGS at O'Brien Creek that are presented in the APA report. (The APA report data is included on page A-13.) The following chart clearly indicates that O'Brien Creek flows correlate well with the Little Tonsina River (88%) and not very well with Squirrel Creek (52%). Figure 2 - O'Brien Creek Summer Flows Correlated to USGS Gauge Sites Based on the above, a unit hydrograph is developed using the median unit flows of the Little Tonsina winter data scaled by a factor of 65.7%. The graph is then scaled up linearly from the middle of April through the end of May to match the Little Tonsina River (on a cfs/sqmi basis). From the end of May until the end of September, the graph is simply the Little Tonsina River median record scaled by basin area. Then the graph is scaled back down linearly from the beginning of October through November using the 65.7% winter production factor. The following chart shows the Little Tonsina River median hydrograph, the scale factor used, and the resulting O'Brien/Fivemile Creek (Chitina) hydrograph. 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 05/14/7010/01/7006/07/7106/09/7208/16/7209/29/7206/07/7306/19/7407/26/7406/25/7507/01/7509/04/7504/23/7606/26/7607/13/7608/24/7605/24/7707/06/7708/09/7709/28/7707/06/7805/03/7905/25/79DateUnit Flow (cfs/sqmi)O'Brien Little Tonsina Squirrel POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS APRIL 11,2008 6 Figure 3 - Little Tonsina Median Unit Flow and Chitina Estimated Unit Flow The resulting estimated median minimum springtime flow for the O'Brien Creek intake (PCA) is 4.1 cfs, and for the Fivemile Creek intake, 1.6 cfs. Using a maximum flow of 5 cfs, the following chart shows the estimated power output for a project on Fivemile Creek along with the assumed stream flows. The stream flow should be verified through physical measurements and the installation of a stream gauge. Figure 4 - Fivemile Creek Power Output 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 1/12/13/14/15/16/17/18/19/110/111/112/1Unit Flow (cfs/sqmi)0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%Chitina Scale FactorL Tonsina Unit Flow Chitina Unit Flow Chitina Scale Factor 50 100 150 200 250 300 350 1/12/13/14/15/16/17/18/19/110/111/112/1Power (kW) POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS APRIL 11,2008 7 FLOW MEASUREMENT DATA AT O'BRIEN INTAKE SITE, 4/15/2005 Location 1 (~0.7 mi upstream of intake site) N61°27.8536' W144°33.6790' 4/15/2005 13:00 Flow 4.1 s d v q 2 0.00 0.00 0.00 3 1.05 0.00 0.00 4 1.20 0.30 0.36 5 1.18 0.25 0.30 6 1.62 0.40 0.65 7 1.17 0.60 0.70 8 0.93 0.60 0.56 9 1.09 0.45 0.49 10 1.05 0.50 0.53 11 0.98 0.40 0.39 12 0.57 0.28 0.16 13 0.70 0.00 0.00 14 0.00 0.00 0.00 Location 2 (intake site) N61°27.6543' W144°32.5137' 4/15/2005 15:00 Flow 3.9 s d v q 2 0.00 0.00 0.01 3 0.55 0.20 0.11 4 0.41 0.55 0.23 5 0.78 0.55 0.43 6 0.37 0.00 0.00 7 0.58 0.00 0.00 8 0.91 0.00 0.00 9 0.75 0.35 0.26 10 1.16 1.00 1.16 11 1.08 1.20 1.30 12 0.82 0.50 0.41 13 0.00 0.00 0.00 14 0.00 0.00 0.00 Photo 1 - O'Brien Creek Flow Measurement 1, ~0.7 mi above intake site POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS APRIL 11,2008 8 Photo 2 - O'Brien Creek Flow Measurement Location 2, at intake site Figure 5 - O'Brien Creek Flow Measurements Map POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS APRIL 11,2008 9 FLOW MEASUREMENT DATA AT FIVEMILE CREEK CULVERT Measurements at Fivemile Creek were performed by installing a weir at the outlet of the culvert that goes under the Edgerton Highway. The following drawing and pictures detail the weir design and installation. Measurements and installation were performed by Martin Finnesand of Chitina Electric and reported to Polarconsult. The table following the photographs summarizes the measurements and the flow values. POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS APRIL 11,2008 10 Figure 6 - Fivemile Creek Weir Design POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS APRIL 11,2008 11 Photo 3 - Installed Weir, early in winter Photo 4 - View of water spilling over weir POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS APRIL 11,2008 12 Photo 5 - View of weir, later winter Water Height Measurements (above crest): Table 4 - Weir/Flow Measurements Date Height (ft) Flow (cfs) 1/7/2008 0.44 2.44 2/6/2008 0.42 2.26 2/20/2008 0.40 2.10 3/5/2008 0.38 1.93 POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS APRIL 11,2008 13 The following USGS flow measurements performed at O'Brien Creek were presented in the Preliminary Evaluation of Hydropower Alternatives for Chitina, Alaska (U.S. Department of Energy and Alaska Power Administration, 1981). POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 APPENDIX B - GEOTECHNICAL REPORT, SHANNON WILSON POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY 2,2008 APPENDIX C - SUMMARY OF FLOODING IN SOUTHCENTRAL ALASKA, OCTOBER, 2006. USGS October 2006 Flooding in the Seward- Prince William Sound areas, Alaska USGS Home Contact USGS Search USGS Summary of flooding in Southcentral Alaska, October 2006 / Alaska Science Center / Water Office / National Water Information System (NWIS) / Contacts / PROVISIONAL FLOOD PEAKS AND RECURRENCE INTERVALS STATION NUMBER STATION NAME PERIOD OF RECORD PREVIOUS PEAK DISCHARGE (FT3/S) DATE OF PREVIOUS PEAK NUMBER OF PEAKS HIGHER THAN OCTOBER 2006 PEAK DISCHARGE (FT3/S) DATE AND TIME OF PEAK 15200280 Gulkana River at Sourdough 1973-78; 1989-2004 12,700 9/12/1990 none 15,300 10/ ? /2006 15207800 Little Tonsina R near Tonsina 1972-78 214 7/20/1977 none 570 est 10/9-10/2006 15208000 Tonsina River at Tonsina 1950-82 8,490 6/17/1962 none b14,000 est 10/9-10/2006 15208100 Squirrel Cr at Tonsina 1964-82 1,200 6/ /1964 1 in 19 yr c1,100 est 10/9/2006 15208200 Rock Cr nr Tonsina 1966-95 225 5/29/1989 1 in 29 yr 200 10/9/2006 15210025 McCarthy Creek nr McCarthy 1994-current 4,000 9/27/2000 none 7,100 est 10/9-10/2006 15211700 Strelna Cr near Chitina 1971-96 670 8/12/1985 unknown unknown 10/9-10/2006 15211900 O'Brien Creek near Chitina 1970-82, 84- 96 1,950 6/6/1990 unknown unknown unknown 15212000 Copper River nr Chitina 1950, 52-53, 56-90 380,000 8/8/1981 1 in 38 yr 334,000 10/10/2006 15212500 Boulder Creek nr Tiekel 1964-current 1,330 8/7/1981 none 1,700 10/9-10/2006 Page 1 of 3USGS ASC Summary of flooding in Southcentral Alaska, October 2006 4/9/2008http://ak.water.usgs.gov/flood/2006October/index.php Last revised 6/22/2007 (revised) 15212800 Ptarmigan Creek Trib nr Valdez 1965-70, 95- current 85 9/ /1965 none 184 10/9/2006 15214000 Copper R. @ Million Dollar Bridge 1913, 1988- 95 415,000 9/23/1995 none 447,000 10/11/2006 16:00 15215990 Nicolet Creek near Cordova 1990-current 988 11/3/1994 8 in 15 yr 557 10/9/2006 11:00 15225997 Solomon Gulch Top of Falls 1986-current 3,280 10/11/1986 none 3,350 10/9/2006 11:15 15226600 Lowe River in Keystone Canyon near Valdez 1976-77, 1995 18,700 9/22/1995 none 42,000 10/10/2006 15227500 Mineral Creek near Valdez 1990-current 5,570 6/ /1976 5 in 16 yr 3,500 10/9/2006 15236200 Shakespeare Creek at Whittier 1970-80, 84- current 690 9/20/1995 13 in 33 yr 491 10/9/2006 15237550 Mt. Alice Creek nr Seward 1990-95 1,340 10/11/1986 2 in 7 yr 600 est 10/9/2006 15237730 Grouse Cr. at Lake Outlet near Seward 1997-current 478 2/5/2003 none 901 10/9/2006 13:15 15238010 Salmon Creek near Seward 1990-95 8,500 10/11/1986 1 in 6 yr 6,200 est 10/9/2006 15238600 Spruce Creek near Seward 1967-current 13,600 10/11/1986 1 in 40 yr 3,640 10/9/2006 15239050 Middle Fork Bradley R near Homer 1979-current 1,470 9/20/1995 1 in 26 yr 1,350 10/9/2006 11:00 15243950 Porcupine Creek near Primrose 1963-89, 2003 4,000 10/11/1986 1 in 28 yr 3,800 est 10/9/2006 15248000 Trail River near Lawing 1947-77, 87, 2003 8,200 10/24/2002 15 in 31 yr 4,000 10/9/2006 15250000 Falls Creek near Lawing 1963-76 693 9/15/1966 2 in 9 yr 500 est 10/9/2006 * note, recurrence intervals have not been adjusted using 2006 peaks Accessibility FOIA Privacy Policies and Notices Page 2 of 3USGS ASC Summary of flooding in Southcentral Alaska, October 2006 4/9/2008http://ak.water.usgs.gov/flood/2006October/index.php