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Home My WebLink AboutChitina Final Report 2008REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT May 2, 2008 Prepared for ALASKA ENERGY AUTHORITY 813 West Northern Lights Blvd. Anchorage, Alaska 99503 Contracting Agency LCMF 615 East 82ndAve., #200 Anchorage, Alaska 99518 Prepared by polarconsult alaska, inc. 1503 West 33rd Avenue, Suite 310 Anchorage, Alaska 99503 Phone: (907) 258-2420 POLAR CONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT TABLE OF CONTENTS ACRONYMS AND TERMINOLOGY ..................................................................................................... 111 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'BRIEN CREEK ............................................................................................................................ 8 3.0 SELECTED PROJECT ANALYSIS .......................................................................................... 10 3.1 O'BRIEN CREEK, Low HEAD PROJECT ....................................................................................... 10 3.2 O'BRIEN 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 TABLE4-O'BRIEN CREEK, HIGH HEAD COST .............................................................................................. 14 TABLES-O'BRIEN CREEK, HIGH HEAD CONFIGURATION ............................................................................ 14 TABLE 6 -FIVE MILE 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'BRIEN CREEK, LOW HEAD PROJECT MAP .................................................................................. 3 FIGURE 3. O'BRIEN CREEK, HIGH HEAD PROJECT MAP ................................................................................. 4 FIGURE 4. FIVEMILE CREEK PROJECT MAP···································································································· 5 MAY2,2008 PAGEi POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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 II. 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, SL"MMARY OF FLOODING IN SOUTH CENTRAL ALASKA, OCTOBER, 2006. USGS MAY2,2008 PAGEii POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT ACRONYMS AND TERMINOLOGY AEA APA ATV cfs CVEA EPS ft HDPE m kVA kW kWh LCMF LIDAR mi PCE Polarconsult USGS MAY2,2008 Alaska Energy Authority Alaska Power Administration All terrain vehicle cubic feet per second Copper Valley Electrical Association Electric Power Systems, Inc. feet high-density polyethylene inch kilovolt-amp kilowatt kilowatt-hours LCMF, LLC Light Detection and Ranging mile Power Cost Equalization Program Polarconsult Alaska, Inc. United States Geological Survey PAGE iii POLARCONSULT ALASKA, INC. EXECUTIVE SUMMARY REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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 PAGEl POLARCONSUL T ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT • 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. MA¥2,2008 PAGE2 POLARCONSUL T ALASKA, INC. 1.0 INTRODUCTION REGIONAL HYDROELECTRIC INVESTIGATION CHlTINA, ALASKA FINAL REPORT 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 fmally 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 MAY PAGE3 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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 MAY2,2008 PAGE4 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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 fmdings 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. MAY2,2008 PAGES POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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. PAGE6 POLARCONSUL T ALASKA, INC. 2.0 PREVIOUS STUDIES REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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 (AP A, 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 ofthe 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 AP A 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 AP A 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 MAY2,2008 PAGE7 Douglas Ott From: Douglas Ott Sent: Wednesday, April16, 2008 10:08 AM Alan Fetters To: Cc: Subject: Lenny Landis; Peter Crimp Chitina Hydro Investigation Alan, I have reviewed the draft report prepared by Polarconsult entitled Regional Hydroelectric Investigation, Chitina, Alaska. I concur with the general conclusion that O'Brien Creek should not be further investigated at this time for hydroelectric development However, I do not believe the high head configuration of Fivemile Creek is necessarily the best hydro option for Chitina. My review comments are as follows: 1. Page 9: Table llists two configurations for Fivemile Creek, but the narrative does not discuss the low head option. I would like to see this narrative provided in the report. 2. Page 18: I have low confidence in the Table 7 cost estimate. The cost estimate does not have any line item cost identified for construction of the pioneer road needed to install the 8500 feet of penstock required under this hydro concept Additionally there is no cost attributed for rock excavation at either the intake structure or to bury the penstock. There is also no cost identified for the power line needed at the intake site to operate the screening system. Nor is there any cost listed for the Edgerton Highway pipeline crossing. 3. Page 20: The economic analysis should probably only consider a no-growth option for Chitina. If any trend is considered it might even be for negative growth, since the general trend is for population growth in the larger communities of rural Alaska due to out-migration from the smaller communities. 4. Page 20: The B/C ratio for Fivemile Creek will go down when the costs of my comment 2 items are factored into its construction cost, very possibly bringing into question the viability of this option. 5. The low head option of Fivemile Creek (or some intermediate head option) would be better matched to Chitina's limited power needs. The creek flow data measurements taken in early 2008 were encouraging. The hydro project would be more inexpensive in this configuration and have less economic risks of construction cost overruns. Operationally, the hydro in this configuration could provide most of the power needs of Chitina except for a few months of the year when it would be supplemented by diesel generators. * * * * -:fi~P~~ /lete'UUttWe &~ad&~ &~ ~ 1~ V~pue.tt ad &xtzMt A~ S"/3 71/e<~t~ LitJiu ?J~ A~. J'fJ: 99503 tzk (907) 771-3067 tx ( 907) 771-3044 1 ~T~ear,kl::l$(;ai,](IQ!1tl\.l·.l;al!.o~rxe~r·f ,~, M~ntn''':~<rJi\Cfilnmu!Jijy,;~-j~mes$1\:KWHi~en.;ole$elj. r!lel};t:lsedlOles~I>'J:~~»>ti~$al'•i.:~· {k~~m,4l~;,M~Wbll~~~~~,E ~~)f:::~~~~"J.d~~~~:~¢?~e!!tfl dfcost ... ·I 2007 1 2006 July Chitina 43439 3375 12.87 300 87600 44161 1 0 2 2006 August Chitina 41255 3118 13.23 300 87600 46345 1 0 2007 3 2006 September Chitina 36798 2882 12.77 300 87600 0 2007 4 October Chitina 38789 3079 12.60 300 87600 48811 1 0 2007 5 2006 November Chitina 41382 3021 13.70 200 58400 17018 0 0 2007 6 2006 DecemberChitina 40557: 2876 14.10 110 32120 -8437 0 632.46 2340.097 2007 7 2007 January Chitina 40332 2816 14.32 110 32120 -8212 0 615.59 2277.691 2007 8 2007 February Chitina 32384 14.04 110 32120 -264 0 19.79 73.22339 2007 9 2007 March Chitina 34850 13.65 110 32120 -2730 0 204.65 757.1964 2007 10 2007 April Chitina 29957 2265 13.23 110 32120 2163 0 2007 11 2007 May Chitina 34477. 2742 12.57 200 58400 23923 1 2007 12 2007 June Chitina 36406 13.21 300 87600 51194 450626 13.34 264774 1 1472.488756 5448.208 2008 1 2007 July. Chitina 40222 12.90 2008 2 AugustChitina 37407 3164 11.82 2008 3 2007 September Chitina 32804 2829 11.60 2008 4 October 34300 2919 11.75 2008 5 2007 November Chitina 33840 2897: 11.68 2008 6 2007 December Chitina 37615 3129 12.02 2008 7 2008 January Chitina 36730 3099 11.85 2008 8 2008 February Chitina 36768 3148 11.68 1190938 91881 12.96 FY 2007 1 Jul-06 2 Aug 3 Sep 4 Oct 5 nov 6 Dec 7 Jan-07 8 Feb 9 Mar 10 Apr 11 May 12 Jun POLARCONSUL T ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITrNA, ALASKA FrNAL REPORT 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 of30 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 I ,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 MAY2,2008 PAGES POLARCONSULT ALASKA, !NC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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 MAY2,2008 PAGE9 POLARCONSULT ALASKA, INC. 3.0 SELECTED PROJECT ANALYSIS REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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 AP A 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 AP A 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. MAY 2,2008 PAGEIO POLARCONSUL T ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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 sqm1 Winter Minimum Flow 4.6 cfs Design Flow 17.0 cfs Pipeline Length 5,300 ft Nominal Pipeline Dia 18 m 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 MAY2,2008 PAGE 11 POLARCONSUL T ALASKA, INC. 3.2 O'BRIEN CREEK, HIGH HEAD PROJECT REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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 1 Y2 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 MAY 2,2008 PAGE12 POLARCONSUL T ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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. MAY2,2008 PAGE 13 POLARCONSULT ALASKA, INC. Table 4-O'Brien Creek, High Head Cost Description Diversion I Intake I Desander Penstock Powerhouse/Turbine/Generator Access and Bridge Power Transmission System Equipment Labor Shipping Subtotal Direct Costs Contingency (25%) Subtotal Estimated Cost Overhead & Profit (25%) Total Construction Cost Engineering Construction Mana~ement Total Project Cost Cost $150,000 $600,000 $300,000 $75,000 $420,000 $560,000 $375,000 $200,000 $2,680,000 $670,000 $3,351,000 $838,000 $4,188,000 $350,000 $165,000 $4,703,000 REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT Table 5 -O'Brien Creek, High Head Configuration Basin Area 31.8 sqmt Winter Minimum Flow 4.1 cfs Design Flow 6.5 cfs Pipeline Length 18,500 ft Nominal Pipeline Dia 12 m 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 PAGEI4 POLARCONSULT ALASKA, INC. 3.3 FIVEMILE CREEK REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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 fmdings 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. PAGElS /? {IrA.)"-/ ~(I+Jjrt WloPs. 35500 I Fiscal= Year I Fiscai_Month I Calendar Year I Month I Communitt,.Names I KWH Gen Diesel I Fuel Used,.Diesel j kwh/gal I P (kW) I E (kWh) I Excess E (kWhll Excess% I diesel fuel need I df cost I 2007 1 2006 July Chitina 43439 3375 12.87 300 87600 44161 1 0 2007 2 2006 August Chitina 41255 3118 13.23 300 87600 46345 1 0 2007 3 2006 September Chitina 36798 2882 12.77 300 87600 50802 1 0 2007 4 2006 October Chitina 38789 3079 12.60 300 87600 48811 1 0 2007 5 2006 November Chitina 41382 3021 13.70 200 58400 17018 0 0 2007 6 2006 December Chitina 40557 2876 14.10 110 32120 -8437 0 632.46 2340.097 2007 7 2007 January Chitina 40332 2816 14.32 110 32120 -8212 0 615.59 2277.691 2007 8 2007 February Chitina 32384 2306 14.04 110 32120 -264 0 19.79 73.22339 2007 9 2007 March Chitina 34850 2554 13.65 110 32120 -2730 0 204.65 757.1964 2007 10 2007 April Chitina 29957 2265 13.23 110 32120 2163 0 2007 11 2007 May Chitina 34477 2742 12.57 200 58400 23923 2007 12 2007 June Chitina 36406 2755 13.21 300 87600 51194 450626 33789 13.34 264774 1 1472.488756 5448.208 2008 1 2007 July Chitina 40222 3118 12.90 2008 2 2007 August Chitina 37407 3164 11.82 2008 3 2007 September Chitina 32804 2829 11.60 2008 4 2007 October Chitina 34300 2919 11.75 2008 5 2007 November Chitina 33840 2897 11.68 2008 6 2007 December Chitina 37615 3129 12.02 2008 7 2008 January Chitina 36730 3099 11.85 2008 8 2008 February Chitina 36768 3148 11.68 1190938 91881 12.96 FY 2007 1 Jul-06 2 Aug 3 Sep 4 Oct 5 nov 6 Dec 7 Jan-07 8 Feb 9 Mar 10 Apr 11 May 12 Jun POLARCONSUL T ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CH!TTNA, ALASKA FINAL REPORT 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, Fivernile 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 sqmt Winter Minimum Flow 1.65 cfs Design Flow 5.0 cfs Pipeline Length 8,500 ft Nominal Pipeline Diameter 12 m 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. MAY2, PAGE16 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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 ~ 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. MAY2,2008 PAGEI7 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT Table 7 -Fivemile Creek Cost Estimate Item Materials Pipe Turbine Controls Intake Powerhouse Transmission Labor Equipment Shipping Subtotal Contingency (25%) Subtotal Profit/Overhead (25%) Engineering Administrative Total* Amount $ 220,000 $ 150,000 $ 70,000 $ 50,000 $ 60,000 $ 50,000 $ 200,000 $ 150,000 $ 150,000 $1,100,000 $ 280,000 $1,380,000 $ 350,000 $ 210,000 $ 70,000 $2,010,000 *Approximate estimate of costs based on assumed site conditions to be verified by further investigation. MAY2,2008 PAGE18 POLARCONSUL T ALASKA, INC. 4.0 ECONOMICANALYSIS REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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 30kW* Total Yearly Energy from Airport 25,000kWh * Current peak demand for community 75 kW (Data from Martin Finnesand) Power generated in FY2007 450,586 kWh/_l! (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 ofthis comparison, the analysis used the current peak demand of75 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 O'Brien, High Head $ 4,703,000 O'Brien, Low Head $ 2,641,000 Fivemile*** $ 2,010,000 * PV = Present value at real discount rate. ** B/C Benefit to cost ratio. No Growth Savings PV* B/C** $ 2,600,000 0.6 $ 2,500,000 0.9 $ 2,600,000 1.3 3.26% Growth Savings PV* B/C** $ 4,100,000 0.9 $ 3,500,000 1.3 $ 3,900,000 1.9 *** Approx. est. of costs based on assumed site conditions to be verified by further investigation. MAY2, 2008 PAGE19 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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. MAY2,2008 PAGE20 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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. MAY2,2008 PAGE2l POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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 1 , i.J; The cost to perform these investigative activities is estimated to be $100,000-$150,00d\_. \'1 1w and will be used to prepare a conceptual design report and refine the project cost estimate. MAY2,2008 PAGE22 POLARCONSUL T ALASKA, INC. 6.0 REFERENCES REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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/dcalcommdb/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/20060ctober/index.php MAY2,2008 PAGE23 POLARCONSULT ALASKA, INC. MAY2,2008 FIGURES REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT PROJECT VICINITY ~AP PROJECT REGIONAL HYDROELECTRIC INVESTIGATION CHITINA. ALASKA 1 O'BRIEN CREEK DRAWN: DH CHECKED: ___ Ill. polarconeult alaeka. Inc. SCALI: 1"•& WII.!S Fll.E: ----=1 1003 W1!:ST 33RD AVB. SU1TI 310 PHONE (80'7) 2015-2420 ANCH ORAGE, ALASKA VV~03 FAX 2~8-IUUI PROJECT REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA 2 DRAWN: __ ....J!!! CHECKED: ___ 011 SCAlf: 1"•6 IIUS Rl£: __ __!!!!IW'q ..... , O'BRIEN CREEK HIGH HEAD PROJECT WAP polarconault alaaka. Inc. maRCY BTB"''D(I • mniiiOJifiUNT.Q. lfD'YICKB • IDIGIJGDUNG H81CN UIOll WIIIIT 33RD AVII, surrB 310 PHONE (H7) 21111 -2420 ANCHORAGE, ALASU VV303 P'AX (V07) 2311-UUt PROJECT REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA 3 4 llo\TE: 4/8/2008 c DESIGNED: __ DH ~-::::::::=::=;=:=:=::=::=::=:=:=:::::===:=:::::==:==F'=IV=E=._.~I=LE==C~R~EE:;K:=P=R=O=J~E~C~T~._.;;A~P~=:::;:;:::::;;:::::::=======~ DRAWN: DH polarconault alaska Inc PROJEcT CHECKED: __ Do\ • " IDfDIOrr ..,..,..,. •• BJmiiOJOIICNTAL ""'""'"" •• NG!NDR!N~ DIBIGN REGIONAL HYDROELECTRIC INVESTIGATION SCALE: 1"=6 NILES CHITINA, ALASKA FlGURE FILE: __ __!!!!!YAI'q 1603 W'l!:ST 33RD AVB. SUITl!: 310 PHONE (P07) 268-2.20 ANCHORAGE, AL.\SJtA Vlit~03 P'AX (&07) 2C!IB-2418 POLARCONSUL T ALASKA, INC. MAY2,2008 REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT PROJECT PHOTOS POLAR CONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT PROJECT PHOTOS PHOTO 1. O'BRIEN CREEK, LOW HEAD PROJEC! INTAKE SITE .............................................................................. 2 PHOTO 2. O'BRIEN CREEK CANYON AT 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 LOCATION BEFORE 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. SECONDRIDGEON0'BRIENCREEK ................................................................................................... 12 PHOTO 13. O'BRIEN CREEK POWERHOUSE SITE, HIGH HEAD PROJECT .............................................................. 13 PHOTO 14. SLIDESALONGCOPPERRIVERHIGHWAY ........................................................................................... 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. FIVEMILEAERIAL PHOTO ................................................................................................................... 18 PHOTO 19. FIVEMILE CREEK, POSSIBLE INTAKE SITE ........................................................................................... 19 MAY2,2008 PAGE 1 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPoRT 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) MAY 2 ,2008 PAGE2 POLARCONSULT ALASKA, INC . REGIONAL H YDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPoRT 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) MAY2,2008 PAGE3 POLARCONSULT ALASKA, INC. Photo 3. O'Brien Creek, High Head Intake REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT Creek 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 Intake Photo was taken just downstream from the intake and is looking downstream. (2007 Polarconsult) MAY2,2008 PAGE4 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT Photo 5. O'Brien Creek, High Head intake location before flood Intake 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) MAY2,2008 PAGE5 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT Photo 6. O'Brien Creek, High Head intake area after flooding View looking downstream at intake location that is near the upper mid dle of the p hoto where the creek jogs to the left. The first ridge crossing can be seen about a 114 mi further downstream at near the top middl e of the photo. (2007 Po larconsu lt) MAY2,2008 PAGE6 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT Photo 7. O'Brien Creek, High Head intake area after flooding Photo shows debris and boulders moved during the 2006 flood event. (2007 Polarconsult) MAY2,2008 PAGE7 POLARCONSULT ALASKA, INC . REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT Photo 8. Bank Erosion Near from Intake Along the east embankment of O'B rien Creek just upstream from the intake. Due to slope stability concerns, the p ipeline and access would have to be located at the toe of the slope. (2007 Polarconsult) MAY2,2008 PAGE8 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, A LASKA FINAL REPORT Photo 9 . Downstream View of Upper Ridge on O'Brien Creek This photo shows the first (upper) ridge crossing for the O'Brien Creek project. The requ ired cut through the ridge is approximately 25 feet. Geologist indicates that this cut will likely not encounter rock. (2007 Polarconsult) MAY2,2008 PAGE9 POLARCONSULT ALASKA, INC. Photo 10. Upstream V iew of Upper Ridge on O'Brien Creek REGIONAL HYDROELECTRIC INVESTIGATION CmTINA, ALASKA FINAL REPORT View 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) MAY2,2008 PAGE 10 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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) MAY2,2008 PAGE ll POLARCONSULT ALASKA, INC. Photo 12. Second Ridge on O'Brien Creek REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT This 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 ofloose material. The cut through this ridge would be about 25 feet. (2007 Polarconsult) MAY2,2008 PAGE 12 POLARCONSULT ALASKA, INC. MAY2,2008 REGIONAL HYDROELECTRIC INVESTIGATION ClnTINA, ALASKA FINAL REPORT Photo 13. O'Brien Creek Powerhouse Site, High Head Project (2007 P olarconsult) PAGE 13 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT MAY2,2008 Photo 14. Slides Along Copper River Highway (2007 Polarconsult) PAGE 14 POLARCONSULT ALASKA, INC. Photo 15. Slides Along Copper River. REGIONAL HYDROELECTRIC INVESTIGATION CmTINA, ALASKA FINAL REPoRT 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) MAY2,2008 PAGE 15 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITlNA, ALASKA FINAL REPORT 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) MAY2,2008 PAGE 16 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT 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) MAY2,2008 PAGE 17 POLARCONSULT ALASKA, INC. CONTOURS FROM USGS DEM DATA. AERIAL PHOTO IS NOT ORTHORECTIFIED. ~' ~ ~ESTIMATED LOCATION Photo 18. Fivemile Aerial Photo. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPoRT This aerial shows the low pressure pipe area. The creek does not become steeply incised until well below the intake site. MAY2,2008 PAGE 18 POLARCONSULT ALASKA, INC. Photo 19. Fivemile Creek, Possible intake site. REGIONAL HYDROELECTRIC INVESTIGATION CmTINA, ALASKA FINAL REPORT Note basement rock outcrop on left and narrow stream section . Stab le stream banks and spruce tree on right suggest insignificant damage to site from the 2006 flood. (2007 Polarconsult) MAY2,2008 PAGE 19 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT APPENDIX A-HYDROLOGY ANALYSIS MAY2,2008 CHITINA HYDROLOGY ANALYSIS 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 TABLE OF CONTENTS TABLE 1 -HYDROLOGIC BASIN SIZE, ELEVATION, AND LOCATION ........................................................................ 2 FIGURE 1-USGS MEDIAN DAILYUN1T FLOWDATA(CFS/SQt\11) .......................................................................... 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 !NT AKE SITE .................................................. 8 FIGURE 5 -O'BRIEN CREEK FLOW MEASUREMEI'>TS MAP ..................................................................................... 8 FIGURE 6 -FIVEMILE CREEK WEIR DESIGN ......................................................................................................... 10 PHOTO 3 -lNST ALL ED WEIR, EARLY IN WINTER ................................................................................................... 11 PHOTO 4 -VIEW OF WATER SPILLING OVER WEIR ................................................................................................. 11 PHOTO 5 -VIEW OF WEIR, LATER WINTER ............................................................................................................ 12 TABLE4-WEIRIFLOWMEASUREMENTS .............................................................................................................. 12 APRIL 11 , 2008 POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS 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 AP A 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 USGS Site Basin size Elevation Latitude Longitude Begin No of Location No End Date 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 T onsina 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 Sguirrel 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. APRIL ll, 2008 2 POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS Figure 1 -USGS Median Daily Unit Flow Data (cfs/sqmi) 8 -' ·e -Tebay C' 7 ~ -L Tonsina Unit Flow .1!! -Squirrel .£. 6 ~ 0 iL 5 :: c ::J 4 3 2 1 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 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 regnnes. 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 AP A report easily exceed Chitina's power requirements in the summer. The AP A report recognized the importance of this low flow p eriod 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. APRIL 11 , 2008 3 POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS Table 2-Flow Measurements Location O'Brien Mouth O'Brien Intake, PCA ------·Date __ Fio~jfisl __ .:;;_U.:_:_ni-'-t _F:...:.Io ...... w_,(""-cf=s:_::./s_:Jq_mc..c.i'-) _ Fivemile Culvert Fivemile Culvert Fivemile Culvert Fivemile Culvert Little Tonsina River, Median Min Tebay River, Median Min Squirrel Creek, Median Min Little T onsina River, Min Tebay River, Min Squirrel Creek, Min 4/23/1976 4.00 0.086 4/15/2005 4.00 0.126 1/7/2008 2.44 0.183 2/6/2008 2/20/2008 3/5/2008 3/9 4/15 3/8 4/1/1974 4/15/1964 4/5/1967 2.26 2.10 1.93 4.50 16.00 11.50 3.00 14.00 9.00 0.170 0.157 0.145 0.198 0.289 0.163 0.132 0.253 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% APRIL 11, 2008 4 POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS 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 fl ow 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 AP A report. (The AP A 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 14.0 _,-------~-~----------~------, 12.0 e 1o.o CT 1/) i 8.0 u -~ 6.0 u:: :!::: t: :J 4.0 2.0 0.0 ~- 0 0 ..-,.... ,.... ,.... .._ .._ .._ '<t ..-,.... ..-0 0 .._ 1.0 0 .._ co 0 ..-0 N N N ('I) '<t '<t 1.0 t::: ,.... ,.... ,.... ,.... ,.... ,.... (0 .._ .._ 05 .._ .._ O'l O'l ,.... co 1.0 0 ..-N 0 ..-N N .._ .._ .._ .._ (0 .._ .._ co CX) O'l co ,.... co 0 0 0 0 0 0 0 1.0 1.0 co co co co ,.... ,.... ,.... ,.... CX) O'l O'l ,.... ,.... ,.... t::: ,.... ,.... ,.... ,.... ,.... ,.... ,.... ,.... t::: .._ .._ .._ .._ .._ .._ .._ .._ .._ (0 .._ ..-'<t ('I) co ('I) '<t '<t co O'l CX) ('I) 1.0 0 0 N N ..-N ~ 0 0 N 0 0 ~ .._ .._ .._ (0 .._ .._ .._ .._ .._ .._ .._ ,.... O'l '<t ,.... CX) ,.... CX) O'l ,.... 1.0 0 0 0 0 0 0 0 0 0 0 0 0 0 Date 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 Cre ek (Chitina) hydrograph. APRIL 11 , 2008 5 POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS Figure 3-Little Tonsina Median Unit Flow and Chitina Estimated Unit Flow 4.5 4 3.5 - 3 2.5 -·e C" 2 ~ !II -J! C.) - 1.5 ~ ~ IL. :!::: 1 c: ::J -L Tonsina Unit Flow -Chitina Unit Flow 0.5 -Chitina Scale Factor 0 ..... ..... ..... ..... ---..... N ("I) 0 ..... 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. 350 -~ -300 ... Gl ~ 0 D.. 250 200 150 100 50 ..... ..... --..... N APRIL 11, 2008 ..... ..... ..... ..... -("I) co 05 0 ..... Figure 4 -Fivemile Creek Power Output ..... -..... ..... ..... C\i ..... 6 POLARCONSULT ALASKA, I NC. CHITINA HYDROLOGY ANALYSIS FLOW MEASUREMENT DATA AT O'BRIEN INTAKE SITE. 4/15 /2005 Location 1 (-0.7 mi upstream of intake site) Location 2 (intake site) N61 °27 .8536' W144 °33. 6790' N61°27.6543' W144°32.5137' 4/15/2005 13:00 Flow 4.1 4/15/2005 15:00 Flow 3.9 s d v q s d v q 2 0.00 0.00 0.00 2 0.00 0.00 0.01 3 1.05 0.00 0.00 3 0.55 0 .20 0.11 4 1.20 0.30 0.36 4 0.41 0 .55 0.23 5 1.18 0 .25 0.30 5 0.78 0 .55 0.43 6 1.62 0.40 0.65 6 0.37 0 .00 0.00 7 1.17 0.60 0.70 7 0.58 0.00 0.00 8 0.93 0.60 0.56 8 0.91 0 .00 0.00 9 1.09 0.45 0.49 9 0.75 0.35 0.26 10 1.05 0.50 0.53 10 1.16 1.00 1.16 11 0.98 0.40 0.39 11 1.08 1.20 1.30 12 0.57 0 .28 0.16 12 0.82 0.50 0.41 13 0.70 0.00 0.00 13 0.00 0.00 0.00 14 0.00 0.00 0.00 14 0.00 0 .00 0.00 ~ I I Photo 1-O'Brien Creek Flow Measurement 1, -0.7 mi above intake site APRIL 11 , 200 8 7 POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS Photo 2 -O'Brien Creek Flow Measurement Location 2, at intake site :-. :"1-~e k . '-=--~-~~· .,.,....... ... 33 FLOW MEASUR MENT .1 --;:5'· --------~~---~-~~?-~~¥~--~-;~~~~~~~~~~~---~~~~~~~~ Figure 5 -O'Brien Creek Flow Measurements Map APRIL 11,2008 8 POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS 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. APRIL II, 2008 9 POLARCONSULT ALASKA, INC. CHITINAHYDROLOGY ANALYSIS FACE OF CULVERT r \\ 2~ ' ' WEIR fORMULA, Q "' · L ,. ,~ .. MIN ~" -----<--~ I ~------------5'------------~ ~------------------------s·--------------------~-4 C0 WEIR ELEVATION SCALE: 3/4" = 1' 1----------1'± -----1 3/4"t~x4" BOLT IN 7/8" HOLE 1----6" ----1 BENT OR WELDED 1/4" PLATE, 2" WIDE TACK WELD NUT AND STUD 0. WEIR SECTION SCALE: 3" = 1' WATER SURFACE (ESTIMATED) 2 LAYERS 1" EXTERIOR RATED PLYWOOD . GLUE AND SCREW TOGETHER (POLYURETHANE GLUE) 1/4" THICK RUBBER SEAL {GLUE TO PLYWOOD) 8.5" All THREAD FLAT WASHER Figure 6 -Fivemile Creek Weir Design APRIL II, 2008 10 POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS Photo 3 -Installed Weir, early in winter Photo 4 -View of water spilling over weir APRIL 11,2008 II POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS Photo 5 -View of weir, later winter Water Height Measurements (above crest): Table 4 -Weir/Flow Measurements Date 1/7/2008 2/6/2008 2/20/2008 3/5/20 08 Height (ft) Flow (cfs) 0.44 2.44 0.42 2.26 0.40 2.10 0.38 1.93 APRIL II , 2008 PUMP TESTING 209 Following are sketches of various weir types, with formulas for calculation of flow over each : Rectangular Su;>presse:l ~-------8------~ Francis Formula, Q = 3.33Bh3'~ or the more accurate Rehbock Formula, Q = ( 3.228 + 0.435 h.) B!J ;I • z ~.- V -Notch Thompson Formula, Q = 2.54h'l• Rectangu'ar Contracted 8 Francis Formula, Q = 3.33h8/~ (B-0.2h) Cipolletti Sides Slope 1 :4 Cipolletti Formula, Q = 3.367Bh'i ' 12 POLARCONSULT ALASKA, INC. CHITINA HYDROLOGY ANALYSIS 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 ). O'Brien Creek Hydrology -USGS data Drainage Area a = 44.8 sq. mi. Year Recording date Gage Ht.-ft 19fcl 1971 1972 7/71 8/72 6/9/72 9/29/72 1973 7/73 1974 6/74 1975 7/1/75 1976 8/76 7.32 5.16 4.34 3.66 4.47 3.87 Miscellaneous data from USGS report 1976, Page 260 5/14/70 8/18/70 8/18/70 10/01/70 6/7/71 6/9/72 8/16/72 9/29/72 6/7/73 6/19/74 7/26/74 6/25/75 9/4/75 4/23/76 7/13/76 8/24/76 1977 7/77 1978 6/12/78 Unpublished USGS data APRIL 11, 2008 5/24/77 7/6/77 8/9/77 9/28/77 7/6/78 5/3/79 5/25/79 6/26/76 4.12 unknown cfs 310 1670 830 192 36 492 317 530 440 93 231 74 36 137 192 111 36 101 80 69 291 46 4.0 153 58 770 102 or more 107 576 210 74 182 47 86 180 13 POLARCONSUL T ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT APPENDIX B-GEOTECHNICAL REPORT, SHANNON WILSON MAY2,2008 November 14, 2007 Polarconsult Alaska, Inc. 1503 West 33rd Avenue, Suite 310 Anchorage, Alaska 99503 Attn: Mr. Earle Ausman, P.E. SEA TILE RICHLAND PORTLAND FAIRBANKS ANCHORAGE DENVER SAINT LOUIS Phone: (907) 258-2420 RE: O'BRIEN CREEK HYDROELECTRIC PROJECT, CHITINA, ALASKA This letter report documents the results of reconnaissance studies by Shannon & Wilson, Inc. for the O'Brien Creek Hydroelectric Project near Chitina, Alaska. The project includes the development of a pipeline along O'Brien Creek approximately 3 miles long. The pipeline will stretch between a water intake structure and a power house on O'Brien Creek approximately 4 and lf4 miles, respectively, upstream from its confluence with the Copper River. At the time of our site visit, the exact locations of the project structures and the alignment had not been finalized. The purpose of this study was to visit the various portions of the project with the design team and the Alaska Energy Authority (AEA) and observe the soil and rock conditions visible from the surface. The observations made during our reconnaissance are to be used in developing preliminary, conceptual design of the project features, and in feasibility studies. Presented in this letter is a description of our reconnaissance efforts, field observations made during reconnaissance, and opinions about further development of the project. Shannon & Wilson performed this work in accordance with our agreed-upon scope which included approximately three days for the field reconnaissance and eight hours for preparation of this summary letter report. Mr. Earle Ausman of Polarconsult Alaska, Inc. authorized the work verbally on September 28, 2007. Field Reconnaissance The reconnaissance effort took place between October 3 and 5, 2007, and was conducted by Mr. Kyle Brennan, P.E., a geotechnical engineer from our Anchorage office. Our field explorations included aerial observations, hand-excavated test pits, and surface observations along the project alignment. Reconnaissance was conducted with helicopter support provided by Era Helicopters from Valdez, Alalska. . We made observations along the project corridor at discrete locations that we recorded using a handheld Global Positioning System (GPS) unit. The notes collected during our reconnaissance are summarized in the attached spread sheet and 5430 FAIRBANKS STREET ·SUITE 3 ANCHORAGE, ALASKA 99518 907·561·2120 FAX 907·561·4483 32-1-01942 O'Brien Creek Hydroelectric Project, Chitina, Alaska November 14, 2007 Page2 SHANNON &WILSON, INC. selected photographs are included on the attached photo pages. Approximate locations of the observation stations are plotted on a United States Geophysical Survey (USGS) quadrangle map included as Figure 2. Observations After conducting our site visit, it is our opinion that the project area traverses four distinct regions, each with its own unique characteristics. These four regions are indicated on the attached site plan (Figure 1) and are referred to in this report as the Intake, Upper Pipeline, Middle Pipeline, and Lower Pipeline Areas. The Intake Area includes Observation Points OP-01 through OP-06. This area of O'Brien Creek appears to be in an erosional state as the main channel is lined by terraced benches of sand and gravel on its south side. The channel bottom meanders through this area and we observed log and debris jams frequently in this area. The soil slopes on the south side of the river appear to be relatively stable and vegetation (alders and willows) appear to be well established, except for a few isolated circular slide features. This portion of the channel appears that it could be a relatively high energy area during high flow events as we observed boulders up to 8 feet in diameter. At the east end of this area, the creek rounds a sharp rock knob and moraine ridge (effectively damming the river and forcing it to flow around the rock knob) extends from the knob to the south. The ridge is shown on Photos 5 and 8 and appears to comprise till material which we estimate, from limited surface exposure, that it likely includes silt, sand, and gravel with scattered cobble and boulder-sized material. The Upper Pipeline Area is the portion of the project that includes Observation Points OP-7 through OP-12. This portion of the alignment traverses a north-facing soil slope above O'Brien Creek. Photographs 9, 13 and 17 show the typical signs of instability along the slope and suggests that the slope is active and in an oversteepened and erosional state. The soils exposed in the slides were consistent with typical glacial till soils and tended to consist of gravelly, silty sand with scattered areas of cobbles and boulders. The failure areas appeared to consist of mostly circular slumps that, on average, appeared to propagate 1 0 to 20 feet into the subsoils. The exposed scarps were typically 35 to 40 degree slopes and we observed tension cracks above crests of most of the scarps in the undisturbed portion of the slopes. The creek area at the bottom of the slopes is somewhat wider than in the Intake Area and is choked in areas with logs and other debris. The creek appears to be in an erosional state here also as it is meandering on the valley floor and eroding the toe of the soil slope to the south. 32-1-01942 O'Brien Creek Hydroeiectric Project, Chitina, Alaska November 14,2007 Page3 SHANNON &WILSON, INC. The Middle Pipeline Area includes the portion of the project covered with Observation Points OP-13 through OP-15. In this area, the project traverses off the steep slopes above O'Brien Creek and onto a flat, gently sloping table land. The ground cover in this area ranges from alders and willow trees to spruce stands with boggy areas. We excavated two hand-dug test pits in this area (near Observation Points OP-13 and OP-15). Near Observation Point OP-13 we encountered approximately 1. 7 feet of peat overlying gray, silty, clayey sand. Below 1.5 feet in this test pit, the soils were frozen. Near Observation Point OP-15, we encountered 3.5 feet of peat and organic silt over silty, gravelly sand with no frozen soil. Given the project vicinity and our observations in the test pits, we believe that this portion of the project likely contains discontinuous permafrost that is likely ice rich and not thaw stable. In addition, we observed only one area along this portion of the project where rock outcropped at the ground surface and that was just northeast of Observation Point OP-14. We anticipate that much of this area is covered with peat soils that likely average around 5 feet thick overlying silty, moraine soils. Bedrock is likely deeper than 5 to 10 feet below the ground surface over most of this portion of the project. The Lower Pipeline Area comprises Observation Points OP-16 and OP-17 and marks the area where the slope begins to steepen as the project approaches O'Brian Creek and the potential power house location. In general, slopes in this area range from 25 to 35 degrees and vegetation is well established. Much of this area is covered with peat ori the ground surface, except for the final slope into the O'Brien Creek channel (between Observation Points OP-16 and OP-17) where bedrock appears to be covered with only 6 to 12 inches of organic silt soil. The bedrock consists of black shale that is platy'in nature and strongly bedded. The slope in this area appears to follow the orientation of the bedding of the bedrock and where exposed, the rock is slippery and has a greasy texture. Conclusions In general, the design and construction of the proposed project facilities should present some significant challenges. Much of the mineral soil along the project is glacial moraine and by virtue of its gradation, will likely be difficult to handle during construction. These types of soils are typically dense or very dense in place and will need to be excavated with relatively large earth-moving equipment. Also, they are moisture sensitive and once they are disturbed and exposed to moisture, they will likely tend to . loose strength and be difficult to place with compaction control. Additionally, these soils tend to be frost sensitive and tend to heave when frozen in the presence of excess water.. Organic soils also persist over much of the project and 32-1-01942 # O'Brien Creek Hydroelectric Project, Chitina, Alaska November 14, 2007 Page4 SHANNON &WILSON, INC they too provide some of the same challenges in handling during construction. Organic soils also compress under loading and may not be able to reliably support construction equipment. The slopes on the south side of O'Brien Creek in the Upper Pipeline Area are active slopes and are in a cycle that includes periodic sliding, erosion of the slope toe by the creek, subsequent over-steepening, and additional sliding. Construction on these slopes will be hazardous and disturbance of the slops and vegetative mats will allow additional moisture to penetrate into the ground and reduce overall stability. It is our opinion that these slopes should not be host to a buried water line and they should be avoided during construction. On slopes that are not currently sliding, but are above unstable slopes, setbacks should be established and the final design should include some sort of drainage provision that would not allow water to load the slope from the pipeline trench and other features that mitigate slope disturbance and destabilization. Features that are located in the flood channel of O'Brien Creek should be designed to withstand flood events and the associated erosion and deposition of stream sediments. Our observations indicate that much of the creek is in an erosional state and that the main channel meanders in the relatively narrow canyon bottom. Given the narrow width of the channel and steep side slopes, we believe that the river system may be prone to damming by debris slides and break-out floods that can carry large amounts of sediment down-stream. In general, the rock conditions along the project {where exposed) appear to be favorable for use in development of the project. The rock, while shaley and platy in nature, should provide support for rock anchors if used in the design of this project. Further observation and analysis should be conducted to establish the type and depth of penetration for these anchors. Additionally, given our observations, we believe that the bedrock will likely be rippable to several feet or more below the soiVrock horizon depending on how fractured or platy the rock is. We recommend that further explorations and analysis be conducted once a more developed design is established. Additional explorations can consist of hand borings or hand dug test pits along a defined pipeline alignment, more detailed rock exposure mapping in areas that will require working with bedrock (if needed), and detailed slope analyses to establish needed setbacks from slope scarps and recommendations for slope mitigation. We are available to review conceptual and preliminary designs of the project to assist you in detecting potential problem areas related to geotechnical issues. 32-1-01942 O'Brien Creek Hydroelectric Project, Chitina, Alaska November 14,2007 Page 5 CLOSURE AND LIMITATIONS SHANNON &WILSON, INC. The analyses and conclusions contained in this report are based on site conditions as they presently exist. It is assumed that the reconnaissance is representative of the surface and subsurface conditions throughout the site, i.e., the conditions everywhere are not significantly different from those disclosed by the explorations. Unanticipated conditions are commonly encountered during construction and cannot fully be determined by merely conducting reconnaissance or excavating hand-dug test pits. Such unexpected conditions frequently require that additional expenditures be made to attain a properly constructed project. This information should be used in preliminary design and feasibility studies only and once a preferred route is selected, additional explorations should be conducted to characterize the subsurface conditions along the preferred alignment. Shannon & Wilson has prepared the attachment Important Information About Your Geotechnical/Environmental Report to assist you and others in understanding the use and limitations of the reports. Sincerely, SHANNON & WILSON, INC. Prepared By: :?2~ Kyle Brennan, P.E. Senior Geotechnical Engineer Attachments: Figure 1: Vicinity Map Figure 2: Site Plan Figure 3: Field Notes Photo Pages Approved By: ~~dm~ Senior Associate Important Information About Your Geotechnical/Environmental Report 32-1-01942 Project Location ! 1 0 1100 2200 4800 APPROXIMATE SCALE IN MILES Alaska O'Brien Creek Hydroelectric Project Chitina , Alaska VICINITY MAP November 2007 32-1-01942 = IIJ SHANNON & WILSON , INC. Fi g. 1 _, Geotedmical & Environmental Consuttants ~ ~ I .. ! 6i -o D D D ~OXI MATI!: LOCATION OF 08SERVA.TI DN POINT OP-01 VISITED BY SHANNON & W ILSON, 0CTOIIER 3 Tl1ROUGH 5, Z007 INLET AREA UP'PER PI .. EUNE AREA MIDDLE PII"EliNE AREA Adapt..:t tn:m uses VoldN 8-2 OuoO-onQI• ~ 1,000 2.000 APPROXIWA 1E SCALE IN FEET 4,000 - O'BRIEN CREE~ HYDROELECTR IC PROJECT CHinNA, Al..ASitA S ITE PLAN 1 ... 11 !J'IIsf_ll;' ~co1 ~2 .("q.: .. i "'-"1 LOWER PIPELI NE AREA = Ill SHANNON !I WILSC!\, II'.C. FIG. 2 ~ ~ _, ....___.~~-- ~= _ _. !Ill § .. @ ;r ~ ! ~ i ~ I FIGURE 3 --FIELD NOTES Point# Site Description OP-01 Landing zone near approximate location of intake structure. Slide on south side off channel approximately 60 feet high, 20 feet wide, OP-02 and 10 feet deep. Slide debris indudes gravelly, silty sand and scattered boulders. Narrow section of O'Brien Creek. Well pronounced, alluvial benches OP-03 extend laterally from the creek to the south. Steep rock slopes extend to the north. Upstream from a morainal ridge extending south from a rock knob. OP-04 Pipeline will likely cut approximately 20 feet into the saddle formed by the ridge. On top of moraine ridge. Appears to be a boulder moraine/ridge extending from a rock mass near stream. Looking back up the valley - OP-05 the south side looks like a thick moraine and the north side is more shear/rocky. Looking at the downstream side, there are some over- steepened slopes displaying active erosion. On a moraine slope that is exhibiting recent failure. Slope angles 35 to OP-06 38 degrees. There are pronounced tension cracks above the crest of the failure scarp. Gentle slope down to the north above O'Brien Creek. Ground is covered OP-07 with peat and vegetation indudes dense willow, alder, and spruce trees. Ground surface is wet and spongy. A running surface drainage flowing downslope into O'Brien Creek. OP-08 Boulders and cobbles are in the streambed and silty, clayey, gravelly sand exposed in the banks. On O'Brien Creek at the base of major slides. Pipe will cut right above OP-09 existing slide scarp crest. Scarp face is approx. 40 degrees and natural slope is approx. 35 degrees. Scarp face is 60 to 70 feet high. Exposed, recent slide on O'Brien Creek side of medial moraine. Natural (pre-slide) slope appears to be approximately 40 degrees. Slide is OP-10 approximately 60 feet wide and 10 feet deep with a 30-foot runout but continues in isolated flows almost all the way to O'Brien Creek. On top of Ridge on the south side of O'Brien Creek. The feature is narrow (10 to 20 feet wide at the top) and is likely a lateral or medial OP-11 moraine, steep on both sides. Slopes down to O'brien Creek @ 40 to 45 degrees for about 40 feet then levels out to 30 degrees. Signs of active erosion and slides. On the same moraine ridge as OP-11, to the northeast. Clayey, silty, OP-12 gravelly sand with cobbles and boulders. Slopes down to O'Brien creek exhibit active erosion. Pipeline will likely cut 20 to 30 feet down into the moraine ridge. Spruce stand with muskeg bottom ground cover on a north facing slope. OP-13 Frozen soil conditions detected about 1.5 feet bgs. Peat to about 1. 7 feet. Mineral soils beneath the peat comprise gray, silty, clayey sand with gravel. Bog area with standing water on the ground surface. A hand-dug test pit OP-14 reveals approximately 2 feet of peat over gray silt. Water fills the hole rapidly and it is difficult to tell if the ground is frozen. Landing zone area. A hand dug test pit reveals approximately 3.5 feet of OP-15 peat and organic silt over silty, gravelly sand; moist. No noticeable frozen I around or groundwater. On top of steeply sloping "gully" that will likely provide a corridor for the pipeline. Slope is covered with dense alders and willows and bedrock OP-16 appears to be covered with approximately 6 to 12 inches of organic silt overburden. Bedrock consists of black, shaley material with strong bedding that is oriented approximately parallel with the overall slope orientation. OP-17 On O'Brien Creek near the proposed location of the new powerhouse. Pipeline will likely come down the slope from the south. O'Brien Creek Hydroelectric Project Chitina, Alaska November 2007 SHANNON & WILSON, INC. WGS83 Datum Northing Easting 61.46143 -144.54069 61.46141 -144.53982 61.46128 -144.53746 61.46107 -144.53526 61.46098 -144.53404 61.45997 -144.53450 61.45854 -144.52743 61.45997 -144.52355 61.46189 -144.41990 61.46106 -144.51723 61.46081 -144.51717 61.46115 -144.51649 61.46960 -144.48667 61.46994 -144.48626 61.47954 -144.46627 61.48538 -144.46914 61.48595 -144.46513 Photo 1 2 3.4 5 6,7,8 9 10 NA 17 13 11 12 15 14 16 NA 18 Figure 3 Field Notes 32-1-01942 ATTACHMENT PHOTO PAGES SHANNON & WILSON, INC. 32-1-01942 Photo 1: At OP-01 looking downstream at the approximate location of the intake structure. Photo 2: At OP-02 looking downstream. Note terraced bench in background. O'Brien Creek Hydroelectric Project Chitina, Alaska PHOTOS 1 AND 2 November 2007 32-1-019042 =111 SHANNON & WILSON, INC. Fig. 4 .. Geotechnical & Environmental Consultants Photo 3: At OP-03 at recent erosion in the alluvial bench on the south side of O'Brien Creek. Photo 4: At OP-03 exposed shale bedrock on the north side of O'Brien Creek. O'Brien Creek Hydroelectric Project Chitina, Alaska PHOTOS 3 AND 4 November 2007 32-1..019042 =111 SHANNON & WILSON , INC. Fig. 5 -Geotechnical & Environmental Consultants Photo 5: At OP-04 looking downstream . Morainal ridge is visible in the background. Photo 6: At OP-05 looking upstream. O'Brien Creek Hydroelectric Project Chitina, Alaska PHOTOS 5 AND 6 November 2007 32-1-019042 1 =11·1 SHANNON & WILSON, INC. I Fig. 6 Geotechnical & Environmental Consultants Photo 7: At OP-05 looking downstream . Slides on south side of creek are visible in background. Photo 8: At OP-05 looking south along morainal ridge . O'Brien Creek Hydroelectric Project Chitina, Alaska PHOTOS 7 AND 8 November 2007 3 2-1-019042 l!!!tl'l SHANNON & WILSON, INC. Fig. 7 iiiiil' Geotechnical & Environmental Consultants Photo 9: At OP-06 looking east down slide scarp. Photo 10: At OP-07 looking south up small drainage. O'Brien Creek Hydroelectric Project Chitina, Alaska PHOTOS 9 AND 10 November 2007 32-1-019042 =1111 SHANNON & WILSON, INC. Fig. 8 I -Geotechnical & Environmental Consultants Photo 11: At OP-011 looking west along morainal ridge. Photo 12: At OP-12 looking east along morainal ridge. O'Brien Creek Hydroelectric Project Chitina, Alaska PHOTOS 11 AND 12 November 2007 32-1-019042 =111 SHANNON & WILSON, INC. Fig. 9 ~ Geotechnical & Environmental Consultants Photo 13: At OP-10 looking south at slide scarp. Photo 14: At OP-14 looking southwest over muskeg bog. O'Brien Creek Hydroelectric Project Chitina, Alaska PHOTOS 13 AND 14 November 2007 32-1-019042 =111 SHANNON & WILSON, INC. Fig. 10 . Geotechnical & Environmental Consultants Photo 15: At OP-13 at the hand-dug test pit in frozen permafrost. Photo 16: At OP-15 looking east near hand-dug test pit. Clearing is a recently cleared landing zone. O'Brien Creek Hydroelectric Project Chitina, Alaska PHOTOS 15 AND 16 November 2007 32-1-019042 ~II SHANNON & WILSON, INC. Fig.11 iii I Geotechnical & Environmental Consultants Photo 17: At OP-09 toe of typical active slope along south side of O'Brien Creek. Photo 18: At OP-17 looking east, downstream on O'Brien Creek. Note the wide valley floor and terraced river banks . O'Brien Creek Hydroelectric Project Chitina , Alaska PHOTOS 17 AND 18 November 2007 32-1-019042 ~II SHANNON & WILSON, INC. Fig. 12 iii I Geotechnical & Environmental Consultants SHANNON & WILSON, INC. ATTACHMENT IMPORTANT INFORMATION ABOUT YOUR GEOTECHNICAL/ENVIRONMENTAL REPORT 32-1-01942 SHANNON & WILSON, INC. Geotechnical and Environmental Consultants Attachment to 32-1-01942 Date: November 2007 To: Polarconsult Alaska, Inc. Re: O'Brien Creek Hydroelectric Project, Alaska Important Information About Your Geotechnical/Environmental Report CONSULTING SERVICES ARE PERFORMED FOR SPECIFIC PURPOSES A.'ID FOR SPECIFIC CLIENTS. Consultants prepare reports to meet the specific needs of specific individuals. A report prepared for a civil engineer may not be adequate for a construction contractor or even another civil engineer. Unless indicated otherwise, your consultant prepared your report expressly for you and expressly for the purposes you indicated. No one other than you should apply this report for its intended purpose without first conferring with the consultant. No party should apply this report for any purpose other than that originally contemplated without first conferring with the consultant. THE CONSULTANT'S REPORT IS BASED ON PROJECT-SPECIFIC FACTORS. A geotechnicaVenvironmental report is based on a subsurface exploration plan designed to consider a unique set of project-specific factors. Depending on the project, these may include: the general nature of the structure and property involved; its size and configuration; its historical use and practice; the location ofthe structure on the site and its orientation; other improvements such as access roads, parking lots, and underground utilities; and the additional risk created by scope-of-service limitations imposed by the client. To help avoid costly problems, ask the consultant to evaluate how any factors that change subsequent to the date of the report may affect the recommendations. Unless your consultant indicates otherwise, your report should not be used: ( 1) when the nature of the proposed project is changed (for example, if an office building will be erected instead of a parking garage, or if a refrigerated warehouse will be built instead of an unrefrigerated one, or chemicals are discovered on or near the site); (2) when the size, elevation, or configuration ofthe proposed project is altered; (3) when the location or orientation ofthe proposed project is modified; (4) when there is a change of ownership; or (5) for application to an adjacent site. Consultants cannot accept responsibility for problems that may occur if they are not consulted after factors, which were considered in the development of the report, have changed. SUBSURFACE CONDITIONS CAN CHANGE. Subsurface conditions may be affected as a result of natural processes or human activity. Because a geotechnicaVenvironmental report is based on conditions that existed at the time of subsurface exploration, construction decisions should not be based on a report whose adequacy may have been affected by time. Ask the consultant to advise if additional tests are desirable before construction starts; for example, groundwater conditions commonly vary seasonally. Construction operations at or adjacent to the site and natural events such as floods, earthquakes, or groundwater fluctuations may also affect subsurface conditions and, thus, the continuing adequacy of a geotechnicaVenvironmental report. The consultant should be kept apprised of any such events, and should be consulted to determine if additional tests are necessary. MOST RECOMMENDATIONS ARE PROFESSIONAL JUDGMENTS. Site exploration and testing identifies actual surface and subsurface conditions only at those points where samples are taken. The data were extrapolated by your consultant, who then applied judgment to render an opinion about overall subsurface conditions. The actual interface between materials may be far more gradual or abrupt than your report indicates. Actual conditions in areas not sampled may differ from those predicted in your report. While nothing can be done to prevent such situations, you and your consultant can work together to help reduce their impacts. Retaining your consultant to observe subsurface construction operations can be particularly beneficial in this respect. Page 1 of2 3/2004 A REPORT'S CONCLUSIONS ARE PRELIMINARY. The conclusions contained in your consultant's report are preliminary because they must be based on the assumption that conditions revealed through selective exploratory sampling are indicative of actual conditions throughout a site. Actual subsurface conditions can be discerned only during earthwork; therefore, you should retain your consultant to observe actual conditions and to provide conclusions. Only the consultant who prepared the report is fully familiar with the background information needed to determine whether or not the report's recommendations based on those conclusions are valid and whether or not the contractor is abiding by applicable recommendations. The consultant who developed your report cannot assume responsibility or liability for the adequacy of the report's recommendations if another party is retained to observe construction. THE CONSULTANT'S REPORT IS SUBJECT TO MISINTERPRETATION. Costly problems can occur when other design professionals develop their plans based on misinterpretation of a geotechnicaVenvironmental report. To help avoid these problems, the consultant should be retained to work with other project design professionals to explain relevant geotechnical, geological, hydrogeological, and environmental findings, and to review the adequacy oftheir plans and specifications relative to these issues. BORING LOGS AND/OR MONITORING WELL DATA SHOULD NOT BE SEPARATED FROM THE REPORT. Final boring logs developed by the consultant are based upon interpretation of field logs (assembled by site personnel), field test results, and laboratory and/or office evaluation of field samples and data. Only final boring logs and data are customarily included in geotechnicaVenvironmental reports. These final logs should not, 1m.der any circumstances, be redrawn for inclusion in architectural or other design drawings, because drafters may commit errors or omissions in the transfer process. To reduce the likelihood of boring log or monitoring well misinterpretation, contractors should be given ready access to the complete geotechnical engineering/environmental report prepared or authorized for their use. If access is provided only to the report prepared for you, you should advise contractors of the report's limitations, assuming that a contractor was not one of the specific persons for whom the report was prepared, and that developing construction cost estimates was not one of the specific purposes for which it was prepared. While a contractor may gain important knowledge from a report prepared for another party, the contractor should discuss the report with your consultant and perform the additional or alternative work believed necessary to obtain the data specifically appropriate for construction cost estimating purposes. Some clients hold the mistaken impression that simply disclaiming responsibility for the accuracy of subsurface information always insulates them from attendant liability. Providing the best available information to contractors helps prevent costly construction problems and the adversarial attitudes that aggravate them to a disproportionate scale. READ RESPONSIBILITY CLAUSES CLOSELY. Because geotechnicaVenvironmental engineering is based extensively on judgment and opinion, it is far less exact than other design disciplines. This situation has resulted in wholly unwarranted claims being lodged against consultants. To help prevent this problem, consultants have developed a number of clauses for use in their contracts, reports and other documents. These responsibility clauses are not exculpatory clauses designed to transfer the consultant's liabilities to other parties; rather, they are definitive clauses that identity where the consultant's responsibilities begin and end. Their use helps all parties involved recognize their individual responsibilities and take appropriate action. Some of these definitive clauses are likely to appear in your report, and you are encouraged to read them closely. Your consultant will be pleased to give full and frank answers to your questions. The preceding paragraphs are based on information provided by the ASFE/Association of Engineering Firms Practicing in the Geosciences, Silver Spring, Maryland Page 2 of2 3/2004 POLARCONSULT ALASKA, INC. REGIONAL HYDROELECTRIC INVESTIGATION CHITINA, ALASKA FINAL REPORT APPENDIX C -SUMMARY OF FLOODING IN SOUTH CENTRAL ALASKA, OCTOBER, 2006. USGS MAY2,2008 USGS ASC Summary of flooding in Southcentral Alaska, October 2006 Page 1 of3 USGS Home Contact USGS Search USGS Summary of flooding in Southcentral Alaska, October 2006 1 Alaska Science Center I Water Office I National Water Information System (NWIS) I Contacts I October 2006 Flooding in the Seward- Prince William Sound areas, Alaska PROVISIONAL FLOOD PEAKS AND RECURRENCE INTERVAl NUMBER OF PREVIOUS DATE OF PEAKS PEAK STATION PERIOD OF PEAK HIGHER DISCHARGE DATE ANI NUMBER STATION NAME RECORD DISCHARGE PREVIOUS THAN (FT3/S) TIME OF PE (FT3/S) PEAK OCTOBER 2006 15200280 Gulkana River at 1973-78; 12,700 9/12/1990 15,300 10/? /2( Sourdough 1989-2004 none 15207800 Little Tonsina R near 1972-78 214 7/20/1977 none 570 est 10/9-1 0/~ Tonsina 15208000 Tonsina River at 1950-82 8,490 Tonsina 6/17/1962 none b14,000 est 10/9-10/~ 15208100 Squirrel Cr at Tonsina 1964-82 1,200 6//1964 1 in 19 yr c1, 100 est 10/9/20 15208200 Rock Cr nr Tonsina 1966-95 225 5/29/1989 1 in 29 yr 200 10/9/20 15210025 McCarthy Creek nr 1994-current 4,000 9/27/2000 none 7,100 est 10/9-1 0/~ McCarthy 15211700 Strelna Cr near Chitina 1971-96 670 8/12/1985 unknown unknown 10/9-1 0/~ 15211900 O'Brien Creek near 1970-82, 84-1,950 6/6/1990 unknown unknown unknov Chitina 96 15212000 C R' ChT 1950, 52-53, opper 1ver nr 1 ma 56 _90 380,000 8/8/1981 1 in 38 yr 334,000 10/1 0/2( 15212500 Boulder Creek nr Tiekel 1964-current 1,330 8/7/1981 none 1,700 10/9-1 0/~ http:/ /ak. water. usgs.gov /flood/20060ctober/index. php 4/9/2008 USGS ASC Summary of flooding in Southcentral Alaska, October 2006 Page 2 of3 (revised) 15212800 Ptarmigan Creek Trib nr 1965-70, 95-85 9//1965 none 184 10/9/20 Valdez current 15214000 Copper R. @ Million 1913, 1988-415,000 9/23/1995 none 447,000 10/11/2006 Dollar Bridge 95 15215990 Nicolet Creek near 1990-current 988 11/3/1994 8 in 15 yr 557 10/9/2006 Cordova 15225997 Solomon Gulch Top of 1986-current 3,280 10/11/1986 none 3,350 10/9/2006 Falls 15226600 Lowe River in Keystone 1976-77, 18,700 9/22/1995 none 42,000 10/10/2( Canyon near Valdez 1995 15227500 Mineral Creek near 1990-current 5,570 6//1976 5 in 16 yr 3,500 10/9/20 Valdez 15236200 Shakespeare Creek at 1970-80, 84-690 9/20/1995 13 in 33 yr 491 10/9/20 Whittier current 15237550 Mt. Alice Creek nr 1990-95 1,340 10/11/1986 2 in 7 yr 600 est 10/9/20 Seward 15237730 Grouse Cr. at lake 1997 -current 478 2/5/2003 none 901 10/9/2006 Outlet near Seward 15238010 Salmon Creek near 1990-95 8,500 10/11/1986 1 in 6 yr 6,200 est 10/9/20 Seward 15238600 Spruce Creek near 1967 -current 13,600 10/11/1986 1 in 40 yr 3,640 10/9/20 Seward 15239050 Middle Fork Bradley R 1979-current 1,470 9/20/1995 1 in 26 yr 1,350 10/9/2006 near Homer 15243950 Porcupine Creek near 1963-89, 4,000 10/11/1986 1 in 28 yr 3,800 est 10/9/20 Primrose 2003 15248000 T .1 R" L . 1947-77, 87, ra1 1ver near awmg 2003 8,200 10/24/2002 15 in 31 yr 4,000 10/9/20 15250000 Fails Creek near 1963-76 693 9/15/1966 2 in 9 yr 500 est 10/9/20 Lawing * note, recurrence intervals have not been adjusted using 2006 peaks Last revised 6/22/2007 Accessibility FOIA Privacy Policies and Notices http://ak.water.usgs.gov/flood/20060ctober/index.php 4/9/2008