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HomeMy WebLinkAboutHoonah-IPEC Hydro Project Reconnaissance Report of Three Potential Sites - Jun 2002 - REF Grant 7030019ri. r n� Y � e ✓ k ry RECONNAISSANCE OF THREE POTENTIAL HYDROELECTRIC SITES NEAR HOONAH, ALASKA L INTRODUCTION On October 12, 2001, the City of Hoonah (the City) issued a Request for Proposal (RFP) for a consultant to perform a preliminary feasibility study of three potential hydropower sites near Hoonah, Alaska. On December 17, 2001, the City selected HydroWest Group LLC (HydroWest) for the study in response to a proposal dated November S, 2001. HydroWest is a wholly -owned subsidiary of Alaska Power & Telephone Co. (AP&T), which has developed and operates several small hydroelectric projects in Southeast Alaska. This report summarizes HydroWest's findings. The impetus for considering hydroelectric development is primarily the desire to reduce electric rates paid by Hoonah residents, which currently are about 37 0/kWh. Many communities in Southeast Alaska are supplied with power by hydroelectric developments, and enjoy much lower rates. Hoonah's power is currently supplied by Tlingit-Haida Regional Electric Authority (T- HREA), which relies on diesel generation. T-HREA's relatively high rate is a result of the cost of diesel fuel, capital expenses in other parts of the T-HREA system, and high overhead costs relative to the number of customers. There can be other advantages to hydropower, in particular a reduction in air and noise pollution from the diesel generating units. A site visit was conducted on May 31, 2002 by HydroWest employees Larry Coupe (Senior Engineer) and Glen Martin (Environmental Specialist). The site visit was scheduled late in the spring so that one of the three sites identified in the RFP could be visited, since it appeared from its description that it was at a high elevation and thus snow-covered until the late spring. Based on helicopter and ground reconnaissance, HydroWest proposed and the City agreed to substitutions for two sites. The old and new sites are described below: Table 1 ORIGINAL AND SUBSTITUTED SITE LOCATIONS Site Proposed in.the Oct. 12, 2001 RFP Gartina Creek at a 50-feet high falls in Sec. I 1 of T44S, R62E A tributary of Gartina Creek located in the northwest comer of Sec. 24, T44S, R62E A tributary of Game Creek located in the southeast corner of Sec.21, T44S, R61E Substituted Site No substitution A tributary of Gartina Creek Iocated in Sections 14 and 15 of T44S, R62E (referred to herein as Water Supply Creek) A tributary of Gartina Creek located in Sections 11 and 12 of T44S, R62E (referred to herein as Elephant Falls) Hydro West's proposed scope of work includes a site reconnaissance and preliminary evaluations of each site's hydrology, power output, arrangement, construction cost, cost of power, and permitting and environmental issues. The scope also includes a teleconference to discuss the study results with the City. The study results for each of the three sites are presented separately HydroWest Group LLC June, 2002 Reconnaissance of Three Potential Hydroelectric Sites near Hoonah, Alaska in the following sections, followed by a comparison and Hydro West's conclusions and recommendations. II. GARTINA FALLS A. Site Description Gartina Creek drains to the north off a ridge of mountains south of Hoonah, and eventually drains into Port Frederick at Hoonah, as shown in Figure 1. Approximately 3 miles upstream from tidewater, the stream flows over a waterfall approximately 50 feet high, which is referred to herein as Gartina Falls (see Photos 1 and 2). At the head of the falls are the remains of a log crib dam and a viewing platform.. The stream is split by rock ridge into two distinct cascades, as shown in Photo 3, with the majority of the flow going over the eastern branch. The stream above and below the falls has a moderate gradient. The stream is entrenched into the broad relatively flat alluvial plain to depths of about 75 feet below the falls and 25 feet above. Portions of the Gartina Creek drainage have been or are being logged, however the immediate area around the falls appears to be old -growth forest. The land that would be occupied by the project structures is owned by Sealaska Corporation. Below the falls, Gartina Creek supports runs of pink, chum, and coho salmon, Dolly Varden, and possibly steelhead and cutthroat trout. There are also resident cutthroat trout and Dolly Varden above the falls. Brown bear and deer are common in the area, and the falls can be a popular location for viewing bears that come to the creek to feed on salmon. The Gartina Falls site has been the subject of previous feasibility studies, but no hydroelectric development has been seriously pursued. It is our understanding that the old log crib dam at the head of the falls was used in the past to divert the City's domestic water. B. General Arrangement The suggested general arrangement for the Gartina Falls site includes the following principal features: A concrete and rockfill diversion dam at the head of the falls that raises the water surface 15 feet. The diversion dam would have a reinforced concrete core wall keyed into bedrock, and grouted rockfill on both sides of the core wall to provide stability. 4n the right (east) abutment, the core wall and rockfill would be about 6 feet higher to create a central overflow spillway. The grouted rockfill would effectively dissipate much of the excess energy of the spill flows, so no stilling basin would be required. • A concrete intake structure and sluiceway on the left (west) abutment of the diversion dam. The sluicegate in the sluiceway would be opened during high flows to pass accumulated sediment downstream. The flow diverted to the power plant would first enter the sluiceway, then be drawn through a trashrack into the bellmouth intake. With this arrangement, when the sluicegate is open, the sluicing flows would flush material from the face of the trashrack. • A 54-inch diameter steel pipeline about 200 feet long from the intake structure to the powerhouse. The initial 150 feet of the pipeline would have a mild slope and be located on a bench cut into the hillside roughly parallel to the stream. The final 50 feet would drop steeply down the hillside to the powerhouse. HydroWest Group LLC 2 June, 2002 Reconnaissance of Three Potential Hydroelectric Sites near Hoonah, Alaska • A two -level powerhouse approximately 20 feet by 20 feet in plan dimension and 25 feet high. The powerhouse would be constructed from reinforced concrete with a removable roof panel for equipment access. The powerhouse would contain one double -cell Ossberger-type impulse turbine connected to a horizontal -axis synchronous generator through a speed increaser. The turbine would be rated for a flow of 140 cfs at a net head of 61 feet. The generator would be rated at 600 kW. Rotational speeds would be 193 rpm for the turbine and 1200 rpm for the generator. The powerhouse would contain all necessary auxiliary equipment and systems for remote control and unattended operation. This powerhouse arrangement has been selected to reduce the footprint of the structure as much as possible and to minimize the cost of the generating unit. A double -regulated Kaplan turbine would have a higher efficiency than the Ossberger turbine, and therefore more power output. However, preliminary price quotations frorn turbine manufacturers indicated a cost premium of almost $1 million for a Kaplan turbine, which cannot be justified by the higher efficiency. • A tailrace consisting of a rock weir and a reinforced concrete diffuser structure. The diffuser structure would prevent fish from entering the powerhouse where they could be injured by the turbine. The rock weir would be located downstream of the diffuser structure to provide a pool from the powerhouse to the base of the falls to maintain important existing fish habitat. • A small switchyard would be located adjacent to the powerhouse, consisting of a pad - mounted disconnect switch and transformer. • A 12.5 kV transmission line about 4 miles long to transmit the power from the switchyard to an interconnection near the Hoonah airport. The transmission line would have single wood poles spaced approximately every 300 feet, and would generally follow the alignment of the City's water line. + An access road about 0.3 miles long connecting the intake structure to the existing Forest Service road 8503. Near the stream, a spur of the road would drop into the canyon to provide access to the powerhouse. I C. Hydrology No stream gage records are available for Gartina Creek or any other creek in the vicinity of Hoonah. Two methods of estimating the streamflows at the Gartina Falls site have been considered. The first method is to use the flow record for Falls Creek near Gustavus that was developed by correlating about three years of flow data at that site with the longer -term record of the Kadashan River near Tenakee. As noted in Hydro West's proposal, the Falls Creek correlated record has been reviewed and approved by several government agencies, and is considered to be the best available for that site. However, a map of average annual precipitation contained in the USGS Report 93-4179 (Magnitude and Frequency of Floods in Alaska and Conterminus Basins in Canada) indicates that the Falls Creek drainage basin receives less precipitation than the Gartina Creek basin (80 inches per year vs. 100 inches per year). Therefore, if the Falls Creek record were to be used, it would need some adjustment to account for the higher precipitation. The average annual precipitation map noted above also shows that the Kadashan River basin has nearly the same precipitation as the Gartina Creek basin. Therefore, the second method of flow record development is direct transposition of the gaged record for the Kadashan River near Tenakee. Both basins drain to the north, the drainage area above Gartina Falls is 10.1 mil, nearly HydroWest Group LLC 3 June, 2002 Reconnaissance of Three Potential Hydroelectric Sites near Hoonah, Alaska identical to the drainage area at the Kadashan River gage (10.2 mi2), and the average basin elevations are nearly the same (1250 feet for Gartina Falls, 1000 feet for the Kadashan River). Because of these similarities, direct transposition of the Kadashan River gage data to the Gartina Falls site is the recommended method of estimating streamflows, with a minor adjustment for the small difference in drainage area. Based on this method, the average annual flow at the Gartina Falls site is estimated to be 66 cfs. Previous studies of the Gartina Falls site estimated the average annual flow to be 77 cfs. The cause for the difference is not known at this time; however, variations of this magnitude are not unexpected considering the Iack of site -specific information. Establishment of a stream gage at the site will be necessary to confirm the hydrology estimate provided herein. D. Power Output The power output of the Gartina Falls site has been estimated by a flow -duration method, which is suitable for preliminary evaluation of run -of -river projects. With this method, the streamflow at each 5% increment of the annual flow --duration curve was determined. Then, the divertible flow, net head, and power for each of these streamflow points were calculated based on assumed efficiencies for the generating equipment. Finally, the calculated power values were numerically integrated to determine the average annual energy. For Gartina Falls, the maximum divertible flow was set at 140 cfs, equal to the flow that is exceeded 10% of the time. A 10% exceedence value is not uncommon for run -of -river projects, but could be adjusted in more detailed feasibility or design studies. At the hydraulic capacity of 140 cfs, the net head would be about 61 feet and the maximum output of the generator would be about 600 kW. The average annual generation would be about 1,880,000 kWh. The generation values shown above are based on the assumption that no instream flows would be required to maintain the aesthetics of the falls or preserve fish habitat between the diversion structure and the powerhouse. The following table demonstrates the impact that imposition of instream flow requirements would have on the project generation. Table 2 EFFECT OF INSTREAM FLOWS ON GENERATION GARTINA FALLS SITE Instream Flow Average Annual Dectease.in Annual Requirement (constant cfs) Generation (kWh) Generation. (kWh and %) 0 1,880,000 - 5 1,750,000 130,000 (7%) 10 3f 1,620,000 260,000 (14%) 20 1 1,370,000 510,000 (27%) Note that these instream flow requirements are assumed to be constant throughout the year. Fisheries agencies often want the instream flows to vary by month to mimic a natural flow pattern. HydroWest Group LLC 4 June, 2002 Reconnaissance of Three Potential Hydroelectric Sites near Hoonah, Alaska E. Construction Cost and Schedule The estimated construction cost for the Gartina Falls site is $3,750,000. The cost estimate is based on Hydro West's experience with similar construction, limited quantity takeoffs from the preliminary site arrangement, budgetary quotes from equipment manufacturers, and an estimated on-line date of January 2007. A summary of the construction cost estimate is shown in Table 3. The estimate includes a contingency allowance of 25%, which is considered to be reasonable for this early stage of analysis. The contingency allowance is to account for minor items not explicitly estimated, normal contracting variations in cost, environmental mitigation costs, and costs for unknown conditions that may occur. The estimate also includes $400,000 for permitting costs and $375,000 for engineering costs., which are based on HydroWest's experience and current understanding of the probable permitting process. Table 3 ESTIMATED CONSTRUCTION COST GARTINA FALLS SITE ITEM AMOUNT r32. ACCESS ROADS $73,000 DIVERSION STRUCTURE 560,000 0, POWER CONDUIT 167,000 4. POWERHOUSE 4.1 Structures and Improvements 292,000 4.2 Generating Equipment .250000 9 4.3 Control System 375,000 5. TRANSMISSION 290,000 SUBTOTAL $1,997,000 Contingency (25%) 499,000 Permitting & Design 775 000 CONSTRUCTION COST (2002 bid level) $3,271,000 Escalation (at 3%) 303,000 CONSTRUCTION COST (2005 bid level) $3 574 000 , , Financing Cost (5%) 176,000 TOTAL CAPITAL COST. $3,750,000 The January 2007 on-line date noted above is based on the following basic schedule. This schedule is based upon having funds readily available for the initial consultation and study planning work. If funds are not readily available, this schedule would start at the time funding is secured. HydroWest Group LLC 5 June, 2002 Reconnaissance of Three Potential Hydroelectric Sites near Hoonah, Alaska Table 4 PRELIMINARY DEVELOPMENT SCHEDULE GARTINA FALLS SITE Task/Milestone Initial consultation and study planning Studies and permit applications Permit processing Construction On --line F. Cost of Power Dates July, 2002 — December, 2002 January, 2003 — December, 2004 January, 2004 — April, 2005 June, 2005 — December, 2006 January, 2007 The annual cost for a hydroelectric project includes the cost of debt service and various operation and maintenance costs. Because of the relatively high cost of construction for a hydro project, the debt service component is generally much higher than the operation and maintenance component. Therefore, financing conditions have a very great impact on a hydro project's feasibility. Love interest loans and/or grant funding are frequently available to promote the development of hydro facilities in rural Alaska communities, and should be pursued. Figure 2 and the following table illustrate the impact of these two factors on the cost of power from the Gartina Falls site. Table 5 COST OF POWER FOR VARIOUS FINANCING CONDITIONS (¢/KWH) GARTINA FALLS SITE Loan Interest Percent Funding by Grants Rate 0% ! 25% 50% 75% 100% 0% 9.3 7.6 i 6.0 4.3 , 2 ,7 4% .. _ ..__ 14.2 11.3 8.4 w 5.5 _ 2.7 8% 20.4 # 16.0 11.5 7.1 2.7 The cost of power values shown above are based on annual operating costs of $50,000 and a loan terra of 30 years. The operating costs are incremental costs, and assume that the same operators run, the hydro plant and the existing diesel plant_ The operating costs also include a royalty payment to Seaiaska Corporation for use of their lands. Note that the cost of power values shown above are the productions costs, and must be compared to the production costs for the existing T-HREA diesel generators to determine if the hydro project is feasible. These production cost values should not be compared to the retail power rates from T-HREA (currently about 37 0/kWh), because that amount is a system -wide rate and includes T-HREA overhead costs. The production cost for the existing diesel generators varies HydroWest Group LLC 6 Jane, 2002 Reconnaissance of Three Potential Hydroelectric Sites near Hoonah, Alaska primarily with the cost of diesel fuel. At $1.25 per gallon and a typical efficiency of about 13 kWh/gal, the fuel cost for the existing diesel generators is about 9.6 ¢/kWh. Variable operation and maintenance costs are typically about 2.0 0/kWh, for an avoided cost of 11.6 0/kWh. This value is also shown in Figure 2 as a solid horizontal line - - financing grant/interest rate combinations that result in a cost of power below the diesel line indicate a feasible project. The hydro generation could also reduce the cost of periodic overhauls of the diesel units, however, no amount for overhaul deferral has been included in the avoided cost rate because it is not certain that the hydro generation would decrease the number of hours of operation of the diesels. Note that the costs for diesel generation provided above are estimated for a typical existing diesel plant. Hoonah-specific values were requested from T-HREA, but were not obtained in time for this report. It should be recognized that costs estimated above are for the initial year of the hydro project operation. The production cost for the hydro project would be relatively stable, whereas the production cost for the diesels will likely rise over time as the cost of diesel fuel escalates. G. Permitting Issues Development of the Gartina Falls site would require permits from various Federal and state agencies. In 2001, AP&T obtained on behalf of Sealaska Corporation a determination by the Federal Energy Regulatory Commission (FERC) that it did not have jurisdiction. FERC jurisdiction arises if a project is on Federal land, uses water from a government darn, is on a navigable waterway, or affects interstate commerce. Federal and state fisheries agencies argued that the project's potential impact to anadromous fisheries would constitute an effect on interstate commerce, but FERC determined that any impact would be so small that interstate commerce would not be affected. The issue of FERC jurisdiction is important because the FERC licensing process is time- consuming, expensive, and affords certain federal agencies the power to prescribe mandatory environmental protection and mitigation measures. Note that recent federal legislation provided for exemption from FERC jurisdiction for small hydroelectric projects in Alaska once the State of Alaska institutes a permitting process that affords the same degree of environmental protection. As of yet, the state has not instituted such a process. Absent FERC jurisdiction, the most common permitting process is through the Coastal Zone Management program administered by the Division of Governmental Coordination. However, we understand that only part of the transmission line would be in the coastal zone for Hoonah, and therefore that process should not be too restrictive. Hoonah would nevertheless need to obtain a Title 16 permit from the Alaska Department of Fish and Game and a Water Right from the Alaska Department of Natural Resources. ADF&G in particular can be expected to require environmental studies to support the permit application and protection and mitigation measures to address the major environmental issues as discussed below. Other necessary permits would include a water quality certification from the Alaska Department of Environmental Conservation and either a Nationwide Permit or an Individual Permit from the Corps of Engineers; however, these are not expected to be problematic. H. Environmental Issues Environmental issues that would need to be addressed during permitting include. • Potential impacts to anadromous and resident fish HydroWest Group LLC 7 June, 2002 Reconnaissance of Three Potential Hydroelectric Sites near Hoonah, Alaska • Potential impacts to brown bears • Potential impacts to birds • Potential impacts to other mammals • Potential aesthetics impacts • Fish passage enhancement Potential impacts to anadromous and resident fish arise primarily from the reduction in flow between the diversion structure and the powerhouse. Although the length of this bypassed reach of stream is quite short (150-200 feet), it includes deep pools at the base of the falls that are important habitat, as shown in Photo 4 and 5. The project design includes a low rock weir downstream of the powerhouse to maintain water in these pools, however, without a constant flow over the falls the pools could become stagnant and any redds in the bypassed reach might not be productive_ If this becomes a major issue, some or all of the flow could be returned to the base of the falls (at a significant increase in construction cost). Improved access to the falls could also increase fishing pressure on both anadromous and resident fish. Another potential impact to fish that would need to be addressed is movement of gravel and woody debris through the diversion pool. The preliminary design includes measures to maintain gravel movement, although there would be a reduction for a couple of years until the diversion pool fills with gravel. Gravel and woody debris movement is necessary to prevent degradation of the downstream habitat. As noted earlier, the preliminary design includes a diffuser -type tailrace to minimize the potential for adult fish entering the powerhouse discharge. Another design feature commonly requested by ADF&G is a method for continuing discharge through the powerhouse to prevent dewatering of the bypassed reach during emergency shutdowns. However, at the Gartina Falls site the duration of dewatering would be very short, and therefore flow continuation measures have not been included. During the permitting process, it is likely that ADF&G would request a fish presence/absence survey to determine exactly what species use the creek, how many use the creek, and where specifically they spawn. After construction, a survey of the fish populations would likely be required over a period of 3-5 years to determine if impacts are occurring. Potential impacts to brown bears could occur from impacts to anadromous fish, the bear's prey, and from alteration of the streamside habitat. The powerhouse and access road would modify about 100 feet of streambank, which could disrupt normal bear feeding patterns. Also, the powerhouse would create some noise that could be disruptive, and the improved access could result in an increase in visitors or hunters. During the permitting process, it is likely that ADF&G would request monitoring of bear activity in the project area to determine the amount of use and when this use occurs. They may also request construction of a bear viewing station and/or other means to control be interactions after construction of the project, including ways to screen the project and dampen any noise from the powerhouse. Potential impacts to birds relate primarily to the loss of either nesting habitat and/or foraging habitat. Types of avian species that would likely require study are the eagle, goshawk, olive - sided flycatcher, marbled murrelet, and any species considered endangered, threatened, or a species of concern. Because the access road would pass primarily through open muskeg areas, HydroWest Group LLC 8 June, 2002 Reconnaissance of Three Potential Hydroelectric Sites near Hoonah, Alaska as shown in Photo 1& 6, little habitat is likely to be disturbed. However, if eagle nests are located within 600 feet of the project features, this could present an obstacle_ Improved access to the falls could also increase pressure on avian species that inhabit the creek margin by causing temporary disturbance from construction and on going disturbance from operation and maintenance visits. Potential impacts to other mammals would also likely require an analysis for impacts to determine if any endangered, threatened, or a species of concern exist in the area. The focus will primarily be on the riparian zone along the creek where species will normally congregate because of the food source that exists there. Improved access to the falls could also increase hunting pressure on wildlife. Potential aesthetics impacts relate primarily to the loss of the scenic value of the falls. If no instream flows are provided, then flow over the falls would occur only about 10% of the time. If instream flows are provided, they would need to be small for the project to be economical, and thus the scenic quality would be significantly reduced. It is unknown at this time whether the loss of the falls would be significant to the community. Initial conversations indicate the falls are not of cultural significance. Fish passage enhancement is based on a comment by ADF&G as part of the FERC jurisdictional determination that they would request evaluation of a fish passage structure to allow anadromous fish to move above and below the falls, because there is high quality habitat above the falls that could increase the fishery contribution of Gartina Creek. If such a structure were to be required, it could easily make the Gartina Falls site uneconomic because of the high initial cost, high operating cost, and loss of generation. A survey of the fish habitat above the falls would likely be requested as part of the permitting process. III. WATER SUPPLY CREEK A. Site Description Water Supply Creek is the name used herein to refer to a tributary of Gartina Creek that flows generally parallel and to the west of the main branch of Gartina Creek, and flows into Gartina Creek a few hundred feet upstream of Gartina Falls, (see Figure 3 and Photos 1 and 7). in the late 1980s, the City constructed a diversion dam on Water Supply Creek and a pipeline to provide the City's primary water supply. This diversion is located at about El 350 near the lower end of the basin, as shown in Photo 8. Although most of the basin is old growth forest, there has been some logging and there is one logging road, as shown in Photo 9, on the east side of the valley that ends at about El 750. The land is owned by Sealaska Corporation. The grade of the stream is about 7-8%, which is very steep. Small falls and rapids are numerous, and it isn't clear if the stream provides suitable habitat for resident fish. B. General Arrangement The project arrangement selected for the Water Supply Creek site is to divert at about El 800 into. a pipeline located adjacent to the existing logging road, and return the flow through a powerhouse near the water supply diversion dam. The principal project features are depicted in Figure 3, and would include: • A concrete and rockfiil diversion dam at about El 800, as shown in Photo 10, that raises the water surface about 8 feet; a good location was found during the site visit. The HydroWest Group LLC 9 rune 2002 Reconnaissance of Three Potential Hydroelectric Sites near Hoonah, Alaska diversion dam would have a reinforced concrete core wall keyed into bedrock, and grouted rockfill on both sides of the core wall to provide stability. On the left (west) abutment, the core wall and rockfill would be about 4 feet higher to create a central overflow spillway. The grouted rockfill would effectively dissipate much of the excess energy of the spill flows, so no stilling basin would be required. • A concrete intake structure and sluiceway on the right (east) abutment of the diversion dam. The sluicegate in the sluiceway would be opened during high flows to pass accumulated sediment downstream. The flow diverted to the power plant would first enter the sluiceway, then be drawn through a trashrack into the bellmouth intake. With this arrangement, when the sluicegate is open, the sluicing flows would flush material from the face of the trashrack. • A pipeline about 5,500 feet Iong from the intake structure to the powerhouse. The initial 4,000 feet of the pipeline would be 24-inch diameter high -density polyethylene (HDPE), either buried or laid directly on the ground if acceptable to the landowner.. The remaining 1,500 feet of the pipeline would be 20-inch diameter steel pipe, either buried or supported on concrete saddles. • A single -level powerhouse approximately 20 feet by 40 feet in plan dimension and 15 feet high, located immediately downstream of the water supply diversion darn, as shown in Photo I L The powerhouse foundation would be reinforced concrete and the superstructure would be a pre-engineered metal building. The powerhouse would contain either a twin -jet Turgo impulse turbine or a double -cell Ossberger turbine direct connected to a synchronous generator. The turbine would be rated for a flow of 20 cfs at a head of 400 feet. The generator would be rated at 600 kW. Rotational speed would be 720 rpm. The powerhouse would contain all necessary auxiliary equipment and systems for remote control and unattended operation. A single six -jet Pelton turbine would also be suitable for the site, and would be somewhat more efficient, but at a somewhat higher cost. A more detailed evaluation of the costs and benefits will be required to make a final selection. • A short tailrace pipeline to return flows from the powerhouse to the water supply diversion pond. With this powerhouse location and tailrace arrangement, potential disruptions to the water supply and quality during construction and operation are nearly eliminated. • A small switchyard would be Iocated adjacent to the powerhouse, consisting of a pad mounted disconnect switch and transformer. • A 12.5 kV transmission line about 4.1 miles long to transmit the power from the switchyard to an interconnection near the Hoonah airport. The transmission line would have single wood poles spaced approximately every 300 feet, and would generally follow the alignment of the City's water line. • An access road about 1300 feet long connecting the intake structure to the existing Forest Service road 85033. Also, the existing road to the water supply dam would need to be extended a short distance to provide construction and maintenance access to the powerhouse. An alternative to locating the powerhouse near the diversion dam would be to put it near Road 8503 as shown in Figure 3, and then purnp from the tailrace directly into the water supply HydroWest Group LLC 10 June, 2002 Reconnaissance of Three Potential Hydroelectric Sites near Hoonah, Alaska pipeline. This would allow slightly more generation, make the powerhouse more accessible and easier to construct, and reduce the length and cost of access roads and transmission line. C. Hydrology As with the Gartina Falls site, the flow available for diversion and generation at the Water Supply Creek site has been estimated by factoring the Kadashan River flows by the respective drainage areas (1.39 mil for Water Supply Creek, 10.2 rni2 for the Kadashan River. However, an additional adjustment has been made because of the somewhat higher elevation of the Water Supply Creek drainage basin (1700 feet for Water Supply Creek, 1020 feet for Kadashan River). USGS Report 93-4179 indicates the average precipitation at sea Ievel near Hoonah is about 80 inches, but at the crest of the mountains (about El 3000) the average precipitation is about 100 inches. Using these values as guides, the flow available at the Water Supply Creek was increased by 3.4%. D. Power Output The power output potential of the Water Supply Creek site has been determined by same method as described for Gartina Falls. At the hydraulic capacity of 20 cfs, the net head would be about 400 feet and the maximum output of the generator would be 600 kW. The average annual generation would be about 1,820,000 kWh. Because the flow would be returned above the anadromous barrier on Gartina Creek, anadromous fish would not be affected and therefore it is unlikely that instreann flows would be required. Note that instream flows are not being required at AP&T's South Fork Project, which is very similar to the Water Supply Creek site. E. Construction Cost The construction cost for the Water Supply Creek site is summarized in Table 6, and is estimated to be $3,100,000 for an on-line date of January 2006. Quicker development of the Water Supply Creek site is considered possible (relative to the Gartina Falls site) because there are expected to be fewer environmental issues to be resolved in the permitting process. Table 6 ESTIMATED CONSTRUCTION COST WATER SUPPLY CREEK SITE ITEM AMOUNT 1 ACCESS ROADS $61,000 2. DIVERSION STRUCTURE 130,000 3. POWER CONDUIT 504,000 4. POWERHOUSE 4.1 Structures and Improvements 122,000 4.2 Generating Equipment 250,000 4.3 Control System 375,000 5. TRANSMISSION 287,000 SUBTOTAL $1,729,000 HydroWest Group LLC 11 June, 2002 Reconnaissance of Three Potential Hydroelectric Sites neat- Hoonah, Alaska Table 6 (Continued) Contingency (25%) 432,000 Permitting & Design 625,000 CONSTRUCTION COST (2002 bid level) $2,786,000 Escalation (at 3 %) 1701000 CONSTRUCTION COST (2004 bid level) $2,956,000 Financing Cost (5%) 144,000 TOTAL CAPITAL COST $3,100,000 F. Cost of Power The effects of the financing interest rate and grant funding on the cost of power from the Water Supply Creek site are shown in the following Table 7 and Figure 4. As with the Gartina Falls site, the incremental operation and maintenance costs are estimated to be $50,000 per year. Table 7 COST OF POWER FOR VARIOUS FINANCING CONDITIONS (¢/KWH) WATER SUPPLY CREEK SITE Loan Interest ' Percent Funding by Grams Rate 0% 25% 5a% 7S% 100%a F 0% 8.4 7.0 5.6 4.2 2.7 4% 1 12.6 10.I 7.7 5.2 '; 2.7 8% 17.9 14.1 10.3 j 6.5 2.7 G. Permitting Issues Jurisdiction by the FERC is very unlikely for the Water Supply Creek site, since they have already ruled that they do not have jurisdiction over the Gartina Falls site, and the Water Supply Creek site presents even Iess basis for jurisdiction. Nevertheless, obtaining that jurisdictional determination is likely to be a required step. This jurisdictional determination could take up to a year to obtain. As with the Gartina Falls site, coastal zone certification would only be required for a section of the transmission line, but Hoonah would nevertheless need to obtain a Title 16 permit from the Alaska Department of Fish and Game and a Water Right from the Alaska Department of Natural Resources. ADF&G in particular can be expected to require environmental studies to support the permit application and protection and mitigation measures to address the major environmental issues as discussed below. Other necessary permits would include a water quality certification from the Alaska Department of Environmental Conservation and a Nationwide or Individual permit from the Corps of Engineers;. however, these are not expected to be problematic. HydroWest Group LLC 12 June, 2002 Reconnaissance of Three Potential Hydroelectric Sites near Hoonah, Alaska H. Environmental Issues Environmental issues that would need to be addressed during permitting include: • Potential impacts to resident fish • Potential impacts to the Hoonah water supply • Potential impacts to birds • Potential impacts to mammals Potential impacts to residential fish in Water Supply Creek would only occur if resident fish are found. Probably the more important early activity for development of this site will be a thorough survey of the bypassed reach to determine if resident fish are present. If fish are found, it can be expected that the agencies will require bypass flows between the impoundment and the powerhouse, which will have a negative impact on the economics of this project. Potential impacts to the Hoonah water supply could occur from construction activities disturbing the water quality and operational events disrupting the flow. Project design will require methods to ensure the continuation of flows to the Hoonah water supply reservoir during project shutdowns and maintenance. Erosion and sedimentation control methods will have to be developed that protect the water quality during construction. All of these measures are standard practices and should not be of great concern. Potential impacts to birds relate primarily to the loss of either nesting habitat and/or foraging habitat. Types of avian species that would likely require study are eagles, goshawk, olive -sided flycatcher, marbled murrelet, and any species considered endangered, threatened, or a species of concern. Because only about 0.25 miles of additional access road will be required to reach the impoundment site, only a small amount of habitat is likely to be lost. Of particular concern will be nesting habitat. This project is in a good stand of old growth forest that may contain good habitat for some species. Improving access into this basin could also increase pressure on avian species that may inhabit this forest by causing disturbance from operation and maintenance. Potential impacts to mammals would also likely require an analysis for impacts to determine if any endangered, threatened, or a species of concern exist in the area. Impacts should be minimal to most mammal species because of the small imprint this project should have. However, as the surrounding area is further logged, this basin may become more valuable to wildlife because of the old growth forest that exists within it. IV. ELEPHANT FALLS A. Site Description The location and general features of the Elephant Falls site are shown in Figure 5, Elephant Mountain rises to the southeast of Gartina Falls, and includes two steep bluffs, with relatively flat plateaus at the top of each bluff, as shown in Photo 12. A stream drains off of these plateaus in highly visible waterfalls, as shown in Photos 12 and 13, and then eventually into Gartina Creek upstream of Gartina Falls. The drainage basin appears to be undeveloped, but logging activity to the south has brought a road to within about 1/2 mile of the Iower plateau. Only a brief helicopter reconnaissance of the area was conducted due to inaccessibility. The drainage area is almost entirely within the Tongass National Forest. Although the stream is relatively small, the site offers. substantial head, and initially it appeared to offer the potential for developing some water storage. If storage could be developed HydroWest Group LLC 13 June, 20Q2 Reconnaissance of Three Potential Hydroelectric Sites near Hoonah, Alaska economically, the generation would be more reliable and valuable. Unfortunately, a good location for a reservoir was not found during the helicopter reconnaissance. A more thorough reconnaissance and/or topographic mapping might reveal a site, however, B. General Arrangement The project arrangement selected for the Elephant Falls site is to divert near the edge of the lower plateau at about El 1100 into a pipeline that would proceed down the lower bluff, across a sloping alluvial plain, eventually returning flow through a powerhouse on the cast bank of Gartina Creek. The principal project features are briefly described below. Because only a brief aerial reconnaissance was conducted, the locations and dimensions for the various structures can only be approximated. A concrete and rockfill diversion dam at about El 1100 that raises the water surface about 8 feet. The diversion dam would have a reinforced concrete core wall keyed into bedrock, and grouted rockfill on both sides of the core wall to provide stability. On the right (north) abutment, the core wall and rockfill would be about 4 feet higher to create a central overflow spillway. The grouted rockfill would effectively dissipate much of the excess energy of the spill flows, so no stilling basin would be required. A concrete intake structure and sluiceway on the left (south) abutment of the diversion dam. The sluicegate in the sluiceway would be opened during high flows to pass accumulated sediment downstream. The flow diverted to the power plant would first enter the sluiceway, then be drawn through a trashrack into the bellmouth intake. With this arrangement, when the sluicegate is open, the sluicing flows would flush material from the face of the trashrack. A pipeline about 3,900 feet long from the intake structure to the powerhouse. The initial 1000 feet of the pipeline would be 18-inch diameter high -density polyethylene (HDPE), either buried or laid directly on the ground if acceptable to the Iandowner. The remaining 2,900 feet of the pipeline would be 15-inch diameter steel pipe, either buried or supported on concrete saddles or steel frames. A single-Ievel powerhouse approximately 20 feet by 40 feet in plan dimension and 15 feet high, located near the bank of Gartina Creek about 1,500 feet upstream of Gartina Falls. The powerhouse foundation would be reinforced concrete and the superstructure would be a pre-engineered metal building. The powerhouse would contain a single twin - jet Pelton turbine direct connected to a synchronous generator. The turbine would be rated for a flow of 9.3 cfs at a head of 800 feet. The generator would be rated at 600 kW. Rotational speed would be 1200 rpm. The powerhouse would contain all necessary auxiliary equipment and systems for remote control and unattended operation. A short unlined tailrace channel to return flows from the powerhouse to Gartina Creek. A small switchyard would be located adjacent to the powerhouse, consisting of a pad - mounted disconnect switch and transformer. A 12.5 kV transmission line about 4.1 miles long to transmit the power from the switchyard to an interconnection gear the Hoonah airport. The transmission line would have single wood poles spaced approximately every 300 feet, and would generally follow the alignment of the City's water line. HydroWest Group LLC 14 June, 2002 Reconnaissance of Three Potential Hydroelectric Sites near Hoonah, Alaska An access road about 4000 feet -long connecting the intake structure to an existing logging road that currently terminates on the hillside below and south of the lower plateau. The route for this road would include one difficult section several hundred feet long up the very steep hillside to the lower plateau. A second access road estimated to be about 7500 feet long would also need to be constructed from the existing logging road system to the powerhouse. C. Hydrology The hydrology of the Elephant Falls site has been estimated in the same manner as that described earlier for the Water Supply Creek site, with appropriate adjustment for the smaller drainage area (0.66 miz) and higher mean basic elevation (1850 feet) D. Power Output The power output potential of the Elephant Falls site has been determined by same method as described for earlier for the Gartina Falls and Water Supply Creek sites. At the hydraulic capacity of 9.3 cfs, the net head would be about 800 feet, and the maximum output of the generator would be about 600 kW. The average annual generation would be about 1,780,000 kWh. Because the flow would be returned above the anadromous barrier on Gartina Creek, anadromous fish would not be affected and therefore it is unlikely that instream flows would be required (unless resident fish are found). E. Construction Cost The construction cost for the Elephant Falls site is summarized in Table 8, and is estimated to be $3,760,000 for an on-line date of January 2008. Note that a contingency factor of 33% has been used because of the lesser amount of information available with this site. Development of the Elephant Falls site would be slower (relative to the Gartina Falls and Water Supply Creek sites) because it would be on Forest Service land and thus a FERC license would be required. Table 8 ESTIMATED CONSTRUCTION COST ELEPHANT FALLS SITE ITEM AMOUNT 1 ACCESS ROADS $313,000 2. DIVERSION STRUCTURE 132,000 3. POWER CONDUIT 350,000 4. POWERHOUSE 4.1 Structures and Improvements 102,000 4.2 Generating Equipment 250,000 4.3 Control System 375,000 5. TRANSMISSION 287,000 SUBTOTAL $1, 809,000 HydroWest Group LLC 15 June, 2002 Reconnaissance of Three Potential Hydroelectric Sites near Hoonah, Alaska Table 8 (Continued) Contingency (33 %) 603,000 Permitting & Design 925,000 CONSTRUCTION COST (2002 bid level) $3,337,000 Escalation (at 3%) 419,000 CONSTRUCTION COST (2006 bid level) $3,756,000 Financing Cost (5%) 184,000 TOTAL CAPITAL COST $3,940,000 F. Cost of Power The effects of the financing interest rate and grant funding on the cost of power from the Elephant Falls site are shown in the following Table 9 and Figure 6. As with the Gartina Falls and Water Supply Creek sites, the incremental operation and maintenance costs are estimated to be $50,000 per year. Table 9 COST OF POWER FOR VARIOUS FINANCING CONDITIONS (¢/kWh ELEPHANT FALLS SITE Percent Funding by Grants Interest Rate 0% 25% i SOn/o 7S% 100% 0% 10.2 11 8.3 6.5 1 4.6 ; 2.8 407o 15.6 ? 12.4 9.2 6.0 2 g 8% 22.4 17.5 12.6 « 7.7 2.8 G. Permitting Issues Because this project site is within the Tongass National Forest, a FERC license would be required. The FERC licensing process can take approximately five years, or more if there are intractable environmental issues. If the City of Sealaska Corporation could obtain the lands through an exchange with the Forest Service, then the need for a FERC licensed would be removed. H. Environmental Issues Envirc-i ental issues that would need to be addressed during permitting include; • Potential impacts to resident fish • Potential impacts to the aesthetics of the falls • Potential impacts to avian species • Potential impacts to mammals HydroWest Group LLC 16 June, 2002 Reconnaissance of Three Potential Hydroelectric Sites near Hoonah, Alaska Potential impacts to residential fish in the Elephant Mt. tributary of Gartina Creek would occur only if resident fish are found. Because cutthroat and Dolly Varden are thought to reside in Gartina Creek, this tributary will also require a survey to determine if it is used and if the location of the powerhouse would be below some of their habitat. If this creek is used by fish, some head may be lost if the powerhouse has to discharge above the furthest extent of the fish habitat. This would have some impact on the projects generation. Bypass flows would otherwise be required if the powerhouse remains at the confluence with Gartina Creek. If this option is pursued, determining if there are fish in the tributary and how far up they go should be conducted as early as possible in the process, because of the importance finding fish could have. Potential impacts to the aesthetics of the falls would need to be evaluated. A survey of the community of Hoonah regarding any cultural significance and recreational- importance (even viewing fiom a distance can be considered recreation) would have to be conducted. Because the land is a part of the Tongass National Forest, the Forest Service may, or may not, have objections to reducing the falls flows. Potential impacts to birds relate primarily to the loss of either nesting habitat and/or foraging habitat. Types of avian species that would likely require study are eagles, goshawk, olive -sided flycatcher, marbled murrelet, and any species considered endangered, threatened, or a species of concern. This site has the potential to have significantly more environmental impacts because of the amount of road that would need to be constructed to access both the impoundment site and powerhouse site, unless this area continues to be logged. Of particular concern will be nesting habitat. There is old growth forest between Gartina Creek and the base of Elephant Mt., although a portion has been recently logged. This could be good habitat for some species. Improving access into this basin could also increase pressure on avian species that may inhabit this forest by causing disturbance from operation and maintenance. Logging pressure in the area could make this forest more valuable as habitat. Potential impacts to mammals would also Iikely require an analysis for impacts to determine if any endangered, threatened, or a species of concern exist in the area. Impacts to habitat will be more significant for this project site because of the longer roads required for access to the impoundment and powerhouse. As the surrounding area is further logged, this area may become more valuable to wildlife because of the old growth forest that exists there. V. SITE COMPARISON A. Economic Feasibility Based on the preliminary analysis conducted for this study, all of the sites are considered to be feasible when compared to the production cost of the existing diesel generators if suitable financing can be obtained. If the sites could be developed entirely with grant funds, then the cost of power from each site would be about 2.7 ¢/kWh, about 9 0/kWh less than the existing diesel units. If grant funding cannot be obtained, then low -interest loans are necessary. Several energy projects in Alaska have recently been funded with approximately 50% grant funds and 50% zero - interest loan. If only conventional financing is possible, then the production cost would be closer to that of the existing diesel units, and possibly' more. The situation described above is for the first year of operation. The cost of hydroelectric generation can be expected to remain relatively stable over time, whereas the cost of diesel generation can be expected to rise over time as the cost of diesel fuel escalates. Diesel fuel prices have been very volatile in the last several years, but the general trend has been increasing. HydroWest Group LLC 17 June, 2002 Reconnaissance of Three Potential Hydroelectric Sites near Hoonah, Alaska Since a hydroelectric project can have a life of 50 years or more, it is important to recognize that the benefits to a hydroelectric project may be small at first but become greater as time goes on. All three sites would have the same capacity (600 kW) and generate approximately the same amount of energy (1.8 to 1.9 GWh), assuming instream flows are not required for the bypassed reach at any site. However, there are clear advantages to the. Water Supply Creek site because it will cost less to construct, there appear to be fewer environmental issues, and it can be developed more quickly. None of the sites by itself would provide all of Hoonah's generation requirements except during high -flow periods (2,000,000 kWh is approximately 1/3 of the current annual generation). If only one site is developed, then all or nearly all of its potential generation would be usable. However, if two sites were developed, during high flow periods not all of the potential generation would be usable absent interconnection to other loads - The following table summarizes the key technical, economic, environmental, and permitting characteristics of each site. Installed capacity Annual generation On-line date Construction cost Cost of power (1} Known or likely environmental issues Potential environmental issues Table 10 HYDROELECTRIC SITE COMPARISON Cartina Falls 600 kW 1,88.0,000 kWh ,` January, 2007 $3,750,000 6.0 0/kWh Fish habitat at base of falls bypassed. Disturbance to brown bears from noise and loss of habitat Tailrace screening Fish passage over falls Aesthetics Instream flows Flow continuation Permit concerns Numerous environmental issues Water Supply Creek 600 kW 1,820,000 kWh January, 2006 1 $3,100,000 5.6 0/kWh Protection of water supply quality and function (flow continuation) instream flows (if resident fish exist) Flow continuation (if resident fish exist) FERC jurisdiction determination may be required Elephant Falls 600 kW 1,780,000 kWh January, 2008 $3,940,000 6.5 0/kWh Aesthetics Instrearn flows (if resident fish exist) Flow continuation (if resident fish exist) FERC license required. (without land exchange) (1) Based on financing with 50% grant and 50% zero -interest, 30-year loan. HydroWest Group LLC 18 June, 2002 Reconnaissance of Three Potential Hydroelectric Sites near Hoonah, Alaska VI. CONCLUSIONS AND RECOMMENDATIONS A. Conclusions We conclude the following from our review of the three identified potential hydroelectric sites near Hoonah: • All three sites offer approximately the same potential capacity and generation (about 600 .kW and 1,850,000 kWh, respectively), assuming instream flows would not be required. • The Gartina Falls and Water Supply Creek sites are purely run -of -river sites (i.e., a storage reservoir would not be economically feasible). The Elephant Falls site has been evaluated as a run -of -river project, as no obvious storage site was viewed during the helicopter reconnaissance. However, a more detailed evaluation of the Elephant Falls site could determine a suitable storage site. • If one site were developed, all or nearly all of its potential generation would be usable. If two sites were developed, not all of the potential generation would be usable (assuming both sites are run -of -river sites). • All three sites could produce power at a cost comparable to or less than the cost from the existing diesel generators, depending on the financing arrangements. Grant funding and/or low -interest financing would be instrumental in reducing the cost of power so that a substantial reduction in rates could be achieved. • The Water Supply Creek site is the superior site of the three due to a lower construction cost and fewer environmental issues. However, this is predicated on the assumption that resident fish are not found above the City's water supply diversion. The primary issue with the Water Supply Creek site is protection of the City's water supply, but that can be readily achieved. • The Gartina Falls site has a higher construction cost and would probably be somewhat more difficult and time-consuming to permit because of some significant environmental issues (principally regarding anadromous fish and brown bears). • The Elephant Falls site also has a somewhat higher construction cost than the Water Supply Creek site, and perhaps more environmental issues. It does have one serious permitting issue in that it affects Federal lands, thus requiring a FERC or equivalent state license. • Permitting of either the Gartina Falls or Water Supply Creek sites would be less complex and less costly if started prior to the State of Alaska completing their program for reviewing and permitting small hydro projects in place of the FERC, (which is estimated to be in 2003 or 2004). The South Fork Hydro project on Prince of Wales Island is an example of how permitting can be accomplished absent FERC's involvement and under the existing procedures. HydroWest Groin LLC 19 June, 2002 Reconnaissance of Three Potential Hydroelectric Sites near Hoonah, Alaska B. Recommendations I. Evaluate the City's potential for obtaining suitable grant and/or low -interest financing, and if favorable, proceed with development of the Water Supply Creek site as a hydroelectric generating resource for the City. Steps that should be taken in the near future are as follows: • Consult with FERC to determine if another jurisdictional determination is required. • Consult with Scalaska, ADF&G, ADNR, ADEC, and other parties as appropriate to determine issues and concerns, if any, regarding development of the stream. • Conduct a fish presence/absence survey of the stream between the proposed diversion site and the City's water supply diversion. • Install a stream gage on Water Supply Creek near the proposed diversion site to begin collecting stream flow data, which will be invaluable in confirming the capacity and generation potential of the site. Strearnflow data will also be critical to evaluating potential impacts on resident fish if found. • Obtain detailed topographic mapping in the areas of the diversion structure and powerhouse and along the pipe alignment. 2. Conduct an on -the -ground reconnaissance of the lower plateau of the Elephant Falls site to determine if the topography is suitable for the economical construction of a storage reservoir of approximately 2500 acre-feet capacity. If such a site is found, then the Elephant Falls site may be feasible as a second hydro development, and the City should evaluate the possibility of a land exchange land with the Federal government to acquire the lands associated with the Elephant Falls site (principally the southern half of Sec 12 and the western half of Sec 13 of T44S, R62E). 3. Development of the Gartina Falls site should be pursued only if issues arise regarding the Water Supply Creek site that make it infeasible, or if the Gartina Falls site's construction can be funded entirely through grants. Steps that would be taken in the near future are as follows. • Consult with Scalaska, ADF&G, ADNR, ADEC, and other parties as appropriate to determine issues and concerns regarding development of the site. This consultation will determine the environmental studies that would need to be conducted to support the permit applications. • Install a stream gage on Gartina Creek near the falls to begin collecting stream flow data, which will be invaluable in confirming the capacity and generation potential of the site and for evaluating environmental impacts. • Obtain detailed topographic mapping in the areas of the diversion structure and powerhouse and along the pipe alignment. 4. If Hoonah elects to proceed with development of either of the Water Supply Creek or Gartina Falls sites, then the agency consultation, field studies, and permit application preparation should be pursued as expeditiously as possible so that the permitting can proceed under the existing process. 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'.'- rra :.,'�"��. -��- � - '.tom• � - � 1 � ��� • i --Piun a voµoi -at Base of Pally ..ainn 'P W�l `"� .9, W4 .0 Gartina Creek FS Road 8 . 503,/ Hoonah Water Spy f Intake Structure .„.. y,. �F� .. pI ;r.�J'r �`�!K✓Tr�, ,�.� �r� _i_�..� 56��'� 'Y• J, IJ }} 7 . '17, , r—i r—� z �--- r..r ramm Ir `m M—M � s.... Elephant Mt. Falls ------P,-