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Connelly Lake Feasibility Report final Aug 2014
FEASIBILITY REPORT CONNELLY LAKE HYDROELECTRIC PROJECT By ALASKA POWER & TELEPHONE COMPANY AUGUST, 2014 RENEWABLE ENERGY FUND GRANT #7040066 FEASIBILITY REPORT CONNELLY LAKE HYDROELECTRIC PROJECT Contents SECTION 1 INTRODUCTION ............................................................................................................. 1 1.1 GENERAL ....................................................................................................................... 1 1.2 GRANT BACKGROUND .................................................................................................. 1 SECTION 2 DESCRIPTION OF PROJECT AREA ................................................................................... 3 2.1 GENERAL ....................................................................................................................... 3 2.2 GEOLOGY ....................................................................................................................... 3 2.3 CLIMATE ........................................................................................................................ 3 2.4 LAND OWNERSHIP AND PREVIOUS DEVELOPMENT ..................................................... 5 SECTION 3 ENVIRONMENTAL STUDIES ........................................................................................... 6 3.1 AQUATIC STUDIES ......................................................................................................... 6 3.1.1 Fisheries Resources ........................................................................................... 6 3.1.2 Aquatic Studies Results Summary .................................................................... 7 3.2 WILDLIFE AND BOTANTICAL STUDIES ........................................................................... 8 3.2.1 Bald Eagle Survey .............................................................................................. 8 3.2.2 Wildlife Habitat Survey ..................................................................................... 8 3.2.3 Threatened and endangered plant species survey ........................................... 9 3.2.4 Botanical Survey ................................................................................................ 9 SECTION 4 HYDROLOGY ................................................................................................................ 10 4.1 EXISTING STREAMFLOW RECORDS ............................................................................. 10 4.2 AP&T GAGING PROGRAM ........................................................................................... 10 4.3 CORRELATION STUDIES ............................................................................................... 11 4.4 FLOOD HYDROLOGY .................................................................................................... 13 SECTION 5 DESCRIPTION OF SELECTED PROJECT ARRANGEMENT ............................................... 15 5.1 SELECTION CRITERIA AND CONSTRAINTS ................................................................... 15 5.2 DAM ............................................................................................................................ 16 5.2.1 Dam Height and Storage Capacity .................................................................. 16 5.2.2 Dam Type ........................................................................................................ 17 5.2.3 Dam Features .................................................................................................. 18 5.3 POWERHOUSE ............................................................................................................. 20 5.3.1 Location ........................................................................................................... 20 5.3.2 Powerhouse Features ..................................................................................... 22 5.4 ACCESS ROAD .............................................................................................................. 22 5.4.1 Existing Road Reconstruction ......................................................................... 22 5.4.2 New Road ........................................................................................................ 24 5.5 POWER CONDUIT ........................................................................................................ 25 5.6 TRANSMISSION LINE ................................................................................................... 25 SECTION 6 POTENTIAL GENERATION ............................................................................................ 27 6.1 OPERATIONS MODEL .................................................................................................. 27 6.2 GENERATION WITH SELECTED PROJECT ARRANGEMENT .......................................... 27 i SECTION 7 CONSTRUCTION COST ESTIMATE and CONSTRUCTION SCHEDULE ........................... 28 7.1 CONSTRUCTION COST ESTIMATE................................................................................ 28 7.2 ASSUMED DEVELOPMENT SCHEDULE ........................................................................ 28 SECTION 8 ECONOMIC ANALYSIS .................................................................................................. 30 8.1 PROJECT ANNUAL COST AND COST OF POWER ......................................................... 30 8.2 ECONOMIC ANALYSIS METHODS AND ASSUMPTIONS ............................................... 30 8.2.1 Load Forecasts ................................................................................................ 31 8.2.2 Diesel Fuel Prices ............................................................................................ 32 8.3 ECONOMIC ANALYSIS MODELS ................................................................................... 33 8.4 ECONOMIC ANALYSIS RESULTS ................................................................................... 35 8.5 CONNELLY LAKE vs. SCHUBEE LAKE ............................................................................ 35 SECTION 9 PERMITTING ................................................................................................................ 37 9.1 FERC JURISDICTION ..................................................................................................... 37 9.2 OTHER FEDERAL PERMIT REQUIREMENTS ................................................................. 37 9.3 STATE AND LOCAL PERMIT REQUIREMENT ................................................................ 37 SECTION 10 CONCLUSIONS AND RECOMMENDATIONS ............................................................... 39 10.1 CONCLUSIONS ............................................................................................................. 39 10.2 RECOMMENDATIONS ................................................................................................. 39 List of Figures Figure 1 Project Location ...................................................................................................... 4 Figure 2 Connelly Lake Gage Rating Curve ......................................................................... 10 Figure 3 AP&T Gage Hydrograph ........................................................................................ 11 Figure 4 Correlation Results (Time Series) .......................................................................... 12 Figure 5 Correlation Results (Duration Series) ................................................................... 12 Figure 6 Flood Frequency Curves ........................................................................................ 14 Figure 7 Reservoir Storage Capacity Curve ......................................................................... 16 Figure 8 Storage vs Annual Energy ..................................................................................... 17 Figure 9 Selected Project Arrangement, Storage Dam ....................................................... 19 Figure 10 Selected Project Arrangement, Storage Components .......................................... 21 Figure 11 Selected Project Arrangement, Chilkoot Valley Access Road ............................... 23 Figure 12 Selected Project Arrangement, Penstock Profile .................................................. 26 Figure 13 SEIRP Load Projections for Haines ........................................................................ 32 Figure 14 SEIRP Fuel Price Projections for Haines ................................................................ 33 Figure 15 ULC Average Annual Generation by Unit, 2009-2013 .......................................... 36 List of Tables Table 1 Average Monthly Streamflows at Connelly Lake Outlet ....................................... 13 Table 2 Construction Cost Estimate .................................................................................. 29 Table 3 SEIRP Forecast and Actual ULC Loads ................................................................... 31 Table 4 Economic Analysis Assumptions and Input Values ............................................... 34 Table 5 Economic Analysis Results .................................................................................... 35 ii CONNELLY LAKE HYDROELECTRIC PROJECT FEASIBILITY REPORT SECTION 1 INTRODUCTION 1.1 GENERAL The purpose of this Feasibility Report is to document the studies undertaken by Alaska Power & Telephone Company (AP&T) to determine the economic viability of a hydroelectric development of Connelly Lake to supplement the existing generating resources of AP&T’s Upper Lynn Canal (ULC) system. The ULC system includes the following: • 4.0 MW Goat Lake storage hydro project near Skagway • 0.94 MW Dewey Lakes storage hydro project near Skagway (limited storage) • 3.0 MW Kasidaya Creek run-of-river hydro project near Skagway • 0.4 MW Lutak run-of-river hydro project near Haines • 2.4 MW diesel generation plant in Skagway (3 units) • 6.2 MW diesel generation plant in Haines (5 units) • 16-mile-long 34.5 kV submarine cable link between Skagway and Haines • Interconnection between the Haines system and IPEC’s Chilkat Valley system Nearly all of the hydro generation is near Skagway. AP&T has been pursuing the Connelly Lake project primarily to provide a storage hydro project near Haines to be able to provide renewable power in Haines in the event the submarine cable were to fail. The submarine cable was installed in 1998, and crosses deltaic deposits near Skagway that are potentially unstable. The Connelly Lake project would also eliminate the need for diesel generation in the winter when the storage in Goat Lake is depleted. 1.2 GRANT BACKGROUND In October 2011, AP&T entered into Grant Agreement #7040066 with AEA for evaluation of the hydroelectric potential of Connelly Lake near Haines, Alaska. The scope of work for the grant agreement includes four tasks: • Conceptual design, including stream gaging, geotechnical reconnaissance, and concept optimization • FERC scoping • Environmental field studies • Final feasibility report AP&T diligently pursued the grant scope of work, but found that the environmental studies would need to be more extensive than originally planned. Because of the critical nature of the environmental studies, AP&T elected to use grant funds originally intended for the engineering studies and feasibility report to pay for the environmental studies. On April 1, 2013, AEA made AP&T aware that the reallocation of funds was not acceptable. 1 During the same period, AP&T was conducting a reconnaissance-level feasibility study of a hydroelectric development of Schubee Lake, which had been suggested as an alternative to Connelly Lake. That study culminated in a report dated June 2013. The economic analysis conducted for that study determined Schubee Lake would only be feasible if there was very high load growth or a new industrial load such as a mine. Based on that analysis, AP&T recognized that the same result would be likely for Connelly Lake, and suggested to AEA that any further analysis was pointless. AEA nevertheless indicated that a feasibility report was still required. AP&T agreed to provide the feasibility report based on the following conditions: • No additional field work will be conducted, in particular, no additional geotechnical investigations or assessment of the existing road in the Chilkoot Valley. • Costs for environmental mitigation will be based on AP&T’s judgment, considering only the studies conducted to date. • No detailed analysis of alternative project arrangements will be conducted; AP&T will select one alternative for the analysis that it judges to be the most feasible. By email dated August 13, 2013, AEA agreed with these conditions. AP&T has completed its analysis, which is documented in this report. 2 SECTION 2 DESCRIPTION OF PROJECT AREA 2.1 GENERAL Connelly Lake is an alpine lake located in the Chilkoot River valley, and is about 15 miles north- northwest of Haines (see Figure 1). The drainage basin has an area of 4.59 sq. miles, most of which is above treeline. The lake is at El 2275, and the average elevation of the drainage basin is about El 4000. Approximately 40% is covered by glacier or permanent snowfield. The stream draining from Connelly Lake is referred to herein as Connelly Creek. It is primarily a continuous cascade from the lake outlet to its junction with the Chilkoot River at El 145. The average gradient is about 40%; the only sections with a mild gradient are short sections located in the Chilkoot River floodplain and at a shelf at about El 1450. Connelly Lake has a surface area of approximately 70 acres. A bathymetric survey from earlier studies of the site indicate that the lake has a maximum depth of about 60 feet and a volume of about 2,000 acre-feet. The main inlet stream enters the lake at the northeast corner after crossing a nearly-flat extensive delta. 2.2 GEOLOGY AP&T contracted with GeoEngineers, Inc. for a geological reconnaissance, which was conducted in September, 2011. A letter report from that reconnaissance is included as Appendix A. Note that the project arrangement evaluated for this report is significantly different than described in Appendix A; however, the discussions of the regional geology, seismicity, previous studies, and the dam and lake area are still valid. In summary, the project area is underlain by granitic rock, with varying amounts of colluvium on the slopes. The project area is considered to be seismically active, with faults defining many of the river and inlet valleys. Some researchers have identified a linear feature in the Chilkoot River valley that may be a fault. The area of the lake outlet is inferred to be granitic bedrock overlain by thin deposits of boulders, gravel, and soil; bedrock is exposed along the outlet stream and in isolated steep cliffs. The Chilkoot River valley is a glacial-carved U-shaped valley filled with alluvium that may be very deep. There are several large alluvial fan deposits on the west side of the Chilkoot River valley where larger tributary streams reach the valley bottom. The Chilkoot River appears to be quite dynamic; although there is generally a single river channel, there is considerable evidence that the channel migrates extensively. 2.3 CLIMATE The climate of the area is fairly typical of Southeast Alaska, with relatively heavy precipitation and mild temperatures due to the proximity of the Gulf of Alaska. Average precipitation is Haines is about 50 inches per year, but is significantly greater at higher elevations. Summer temperatures range from 50 to 70 °F; winter temperatures range from 10 to 35 °F. Snow accumulation can be dramatic, even at lower elevations. At Connelly Lake, snow cover persists well into the summer months. 3 FIGURE 1 PROJECT LOCATION HAINES BOUNDARY OF CHILKAT BALD EAGLE PRESERVE (CHILKOOT UNIT) CONNELLY LAKE IMAGE SOURCE: GOOGLE EARTH, 2013REBUILD EX IST ING ROAD W /ADJACENT BUR IED T -L INE6.75 M I BURIED T-LINE ADJACENT TO EXISTING HIGHWAY. 3.9 MI NEW ROAD AND PENSTOCK POWERHOUSE CHILKOOT RIVER 2.4 LAND OWNERSHIP AND PREVIOUS DEVELOPMENT Nearly all land in the Chilkoot valley is owned by the State of Alaska, and is either in the Haines State Forest or the Chilkat Bald Eagle Preserve (CBEP). There are also several private in- holdings in the valley. Figure 1 shows the boundaries of the CBEP and the private in-holdings. There is also a federal overlay of the project boundary under Section 24 of the Federal Power Act which occurs from filing for a Federal Energy Regulatory Commission preliminary permit. In the 1960s, a road was constructed along the west side of Lower Chilkoot Lake and into the Chilkoot Valley to provide access into the private in-holdings, which were then logged. The lower portion of the road was maintained for a few years, primarily for tourism trips to a salmon spawning area above Lower Chilkoot Lake known as the “Glory Hole”. None of the road is currently maintained, and it is generally impassable. In 2008-11 the Takshanuk Watershed Council, a local watershed preservation organization, surveyed the condition of the road; its maps indicate the following: • Good condition ............................................................................... 46% (2.8 mi) • Fair condition .................................................................................. 19% (1.1 mi) • Poor condition ................................................................................... 5% (0.3 mi) • Severely damaged ........................................................................... 30% (1.8 mi) As stated by the Haines State Forest Management Plan, "The primary purposes for the establishment of the Haines State Forest Resource Management Area are the utilization, perpetuation, conservation, and protection of the land and water, including, but not limited to, the use of renewable and nonrenewable resources through multiple-use management, and the continuation of other beneficial uses, including traditional uses and other recreational activities." 1 The Chilkat Bald Eagle Preserve, in contrast to the Haines State Forest Management Plan, “…has an ‘exclusive use’ management intent, rather than multiple use. Its management focuses on the protection of bald eagles and their associated habitat, as well as the spawning and rearing areas of the anadromous streams that provide food for the bald eagle population.” 2 Based on conversations with the Haines State Forest personnel, AP&T believes that development of the Connelly Lake project would be possible due to the multiple-use management prescription of the Haines State Forest Management Plan. However, the permitting process has not proceeded far enough to obtain a final determination. AP&T was also not able to get a final determination as to the compatibility of the Connelly Lake project with the CBEP, however, it is likely to be problematic. As discussed later in this report, AP&T modified the project arrangement to avoid the CBEP as much as possible. 1 Haines State Forest Management Plan, August 2002. p. 1-1 to 1-2. 2 Ibid. 5 SECTION 3 ENVIRONMENTAL STUDIES 3.1 AQUATIC STUDIES 3.1.1 Fisheries Resources Chilkoot Lake is a major nursery area for Sockeye Salmon in upper Lynn Canal. ADF&G estimates that 41% of the Sockeye salmon in upper Lynn Canal District 15 come from the Chilkoot River system, with 25% of those fish spawning in the Chilkoot River drainage above Chilkoot Lake. The value of this fishery is estimated at more than $1,000,000 annually to the upper Lynn Canal salmon fishery. For this reason AP&T conducted extensive aquatic surveys of west shoreline of Chilkoot Lake and the Chilkoot River above the lake, including significant wetlands on its west side. The Chilkoot River above Chilkoot Lake has Coho, Sockeye, and Dolly Varden. Connelly Lake and its outlet stream are above Chilkoot Lake and drain into the Chilkoot River. ADF&G conducted fish surveys in 1995 in Connelly Lake, the outlet stream from Connelly Lake, a stream above the creek/river confluence, and seven other streams along the access road north of Chilkoot Lake. The 1995 report states no fish were found in Connelly Lake. The goals of the aquatic field studies were: • Update the fisheries study results originally conducted by ADF&G in 1995 (the complete report can be found in the 2010 Round IV grant application); • Extend that fisheries database to cover both spring and fall timeframes; • Collect data on rearing habitat not surveyed in 1995, and new rearing habitat that may have developed in the drainage since the 1995 survey; • Assess the potential of adult salmon spawning within the lower 4 miles of the Chilkoot River; and • Establish an energy profile for potential spawning and overwintering habitat in the Chilkoot River. The fish surveys were conducted during the following periods: • September 20 to October 1, 2011 • May 16 to May 20, 2012 • October 24 to October 29, 2012 No studies were conducted in Connelly Lake because it was documented to be fishless. To update the rest of the ADF&G survey, fish studies were conducted in the following areas: • Connelly Creek – survey its confluence into the Chilkoot River • Chilkoot River – above the rivers confluence with Connelly Creek to its drainage into Chilkoot Lake, including its tributaries • Wetlands – evaluated the wetlands on the west side of the river along the access route for aquatic habitat and presence of fish • Chilkoot Lake – surveyed along the west shoreline the drainages below the access road 6 The local communities and resource agencies are concerned about impacts to the Sockeye salmon fishery that exists in the spawning and rearing habitat available in the Chilkoot River drainage and as such, one of the potential impacts to this fishery could be directly related to plankton availability in Chilkoot Lake where rearing takes place. AP&T added a new component in 2012 to assess food resources in Chilkoot Lake. Beginning in June, monthly surveys were initiated to measure plankton volumes in the top 200 feet of the water column and temperature in the top 50 feet of the water column. In addition, surface water turbidity to a depth of 10 feet was measured. This data is to provide a baseline of lake conditions and level of food resources available to juvenile Sockeye Salmon rearing in the lake, which can be used post construction to monitor if the project is impacting the lake habitat. Aquatic studies conducted with the grant funds were: • Water Quality Analysis; begun in 2011 through 2012 • Fisheries survey; begun in 2011 through 2012 • Plankton surveying; began June 2012 on a quarterly basis in Chilkoot Lake • Turbidity surveying; began June 2012 on a quarterly basis in Chilkoot Lake • Wetland survey (included with Botanical Survey); conducted August 2012 The results of these surveys can be found in the “122612 Final Aquatic Studies Report for Connelly Lake Hydro” (except for the wetland survey) submitted in the January 11, 2013, progress report. 3.1.2 Aquatic Studies Results Summary Water quality was similar in Chilkoot Lake, Chilkoot River, and Connelly Lake; all are high quality soft waters Channel characteristics of the river most closely fit the FP4/FP5 channel types with a substrate of sand, gravel, and cobble. Mature Sockeye salmon were observed in the Chilkoot River from one mile above the lake to mile 6 of the river with large numbers of mature fish from 1.5 miles to 3.5 miles upriver. Evidence of redd building and spawning were commonly observed within the mainstem of the river. Sockeye Salmon fry were captured at the mouth of the Chilkoot River at Chilkoot Lake and at the upper powerhouse site indicating that fish spawn above mile 4 of the river. Analysis of species composition of catches from important habitat areas showed that the mainstem of the Chilkoot River was more important for rearing of Dolly Varden, and conversely, tributaries were more important rearing areas for Coho Salmon. Particularly important rearing areas for Coho Salmon were the Glory Hole and marsh complex and the beaver ponds complex. The Plankton data collected for Chilkoot Lake was only collected from June through November 2012. The samples were taken from the top 50 foot water column and from the 200 foot depth. The 200 foot data showed higher volumes of plankton than the 50 foot data except for the month of July. The highest volumes in the 50 foot data were in June and November. High water flow in the summer months from the Chilkoot River may influence the lower plankton 7 densities near the lake surface; the river flow provides more than 70 times the total lake volume May through October. The turbidity data for Chilkoot Lake was measured at one and ten foot depths at five points across two transects from east to west. July turbidity was notably higher on the western side of the lake near the river inlet, which may indicate more river water is entering the lake on the west side in the spring and summer. The turbidity data from September through November showed little difference across each transect, with decreasing values each month, indicating a decreasing influence of river inflows on the lake water quality. Near surface lake water temperatures fluctuated between 41° and 59°F. A weak thermocline was present in July and August at a depth of 6-8 feet with the surface water having a 3.2°F and 9.5°F temperature difference respectively. Below water depths of 12 ft. the lake temperature only fluctuated from 41° to 48°F. Water temperature data in Chilkoot Lake showed that inlet water from the river was 1.9°F warmer than the lake outlet during the month of June (2012). Wetlands were found throughout the study area, with herbaceous and shrub wetlands present on the valley floor, on benches on the mountainside along the penstock and access road routes, Connelly Lake fringe, and on the slopes surrounding Connelly Lake. Beaver dams have had a significant influence in the river valley by backing up streams and creating additional wetlands, flooding areas that were once uplands. Some of these new wetlands have become salmon rearing habitat. The final “Botanical, Wetland, and Wildlife Habitat Studies” report was submitted to AEA in the January 11, 2013, progress report. 3.2 WILDLIFE AND BOTANTICAL STUDIES 3.2.1 Bald Eagle Survey The purpose of the bald eagle survey was to document bald eagle nest locations that would be within or near the buffer zones of project components and activity. The “Bald Eagle Nest Survey Report – Final” was issued in September 2012 by HDR and submitted to AEA in the September 2012 Progress Report. Methods used were to contact the USF&WS to get their most recent data and to conduct an aerial survey by helicopter before tree leaf-out occurred so that nests would be more visible. The USF&WS participated in the aerial survey. Four bald eagle nests were documented during the May 9, 2012, aerial survey (two active and two inactive). Of the two active nest sites, only one is located within the regulated buffer zone around project components. This nest is adjacent to an existing road that would be rehabilitated as part of the project. 3.2.2 Wildlife Habitat Survey The Wildlife Habitat Survey can be found in Appendix B of the March 2013 “Botanical, Wetland, and Wildlife Habitat Studies” report (enclosed). The Kittlitz’s Murrelet was eliminated from study at the recommendation of the USF&WS (see the enclosed July 16, 2012, e-mail from the USF&WS). Wildlife habitat mapping occurred concurrent with the vegetation and wetland surveys. The survey was general in nature and besides recording habitat type found on site observed wildlife 8 was also recorded. Vegetation data was used to help correlate wildlife habitat type. Examples of these types of features include abundance of tall snags (potential hunting raptor perches), recent animal sign such as beaver activity, scat and tracks, and open water that could provide habitat for waterfowl. Many birds were noted along with bear, moose, and beaver sign. No TES species were observed. 3.2.3 Threatened and endangered plant species survey No rare plant species were found during this study. All the identified vascular plants are can be found in Appendix B of the March 2013 “Botanical, Wetland, and Wildlife Habitat Studies” report. While not all collected plants were identified to species, each was examined to genus and sufficiently to determine it is highly unlikely to be a rare species. 3.2.4 Botanical Survey The dynamic ecosystem of the Chilkoot valley floor is subject to multiple types of disturbance, both natural and anthropogenic, which are reflected in the study area vegetation and wetland complexes. Anthropogenic influence includes past logging, the results of which are apparent by large swaths of early succession species such as alder and the remaining logging road (now more closely resembling a trail), and alteration of vegetation around the homestead site. Significant sources of natural disturbance to project-area vegetation include beaver activity, shifting valley bottom and mountainside stream courses, avalanches, and landslides. The complete Botanical Survey can be found in the enclosed March 2013 “Botanical, Wetland, and Wildlife Habitat Studies” report. 9 SECTION 4 HYDROLOGY 4.1 EXISTING STREAMFLOW RECORDS The outlet of Connelly Lake was gaged by the U.S. Geological Survey from August 1993 through September 1997 (Gage No. 15056280). The average annual flow for the four complete water years (1994-97) was 38.6 cfs, which is equivalent to 114 inches of annual runoff for the 4.59 mi2 drainage area. Because of the high elevation, the inflow to Connelly Lake is heavily influenced by snowmelt, which generally begins in May and is sustained throughout the summer months. Flows taper off during late September through early November, and are very low during the winter months. 4.2 AP&T GAGING PROGRAM Because of the short period of record for the USGS gage, AP&T installed a stream gage on September 27, 2011 at the Connelly Lake outlet. The gage consists of: • An Onset Hobo water level datalogger at the lake outlet, at approximately the same location as the previous USGS gage; • A staff gage attached to a 1” x 6’ steel rod driven into the rock substrate; and • An Onset Hobo barologger near the datalogger and staff gage. The water level was measured in the middle portion of the outlet channel, in about the same area as the prior USGS gage. Unfortunately, the outlet channel is choked with boulders that disturb the flow, particular at low flows. It is also subject to icing in the winter. The location chosen for the flow measurements was considered to be the best available, but it was nevertheless not ideal. Flow measurements were made with a GlobalWater depth averaging velocity meter on six dates, and measured flows ranging from 2 cfs to 82 cfs. The estimated gage rating curve is shown in Figure 2. Water depths were measured at 60 minute intervals, and converted with the rating curve to flow rates, which were then averaged to get daily values. The flow hydrograph is shown in Figure 3. Figure 2 Connelly Lake Gage Rating Curve The flow measurement site at the lake was difficult to measure and often inaccessible. Therefore, on May 16, 2012, AP&T installed a second similar gage on Connelly Creek near its discharge into the Chilkoot River, which provided a better channel for measurement and better accessibility. Three flow measurements were made at the site, but only captured a flow range from 5.6 to 10.0 cfs, which is not a wide enough range for establishing a rating curve. Both gages were removed on August 15, 2013 after it became apparent that development of the Connelly Lake project would not proceed as planned. y = 329x2 -843x + 534 R² = 1 0 10 20 30 40 50 60 70 80 90 1.4 1.5 1.6 1.7 1.8 1.9Flow, cfsWater Depth, feet 10 Figure 3 AP&T Gage Hydrograph 4.3 CORRELATION STUDIES The USGS gage record is not considered sufficiently long for establishing the site hydrology, therefore, AP&T has conducted correlation studies to extend that record based on longer-term records of other nearby gages. Unfortunately, there are no good candidate gage records - - the nearby gages were on much larger streams near sea-level and thus were hydrologically dissimilar, or were not concurrent with the Connelly record. The best gage record for correlation was found to be that for USGS Gage 15039900 (Dorothy Lake), which has a drainage area of 11.0 mi2 and records the outflows of an alpine lake at El 2420. However, it is approximately 100 miles from Connelly Lake in an area with significantly higher precipitation (the calculated annual runoff is about 147 inches, vs 114 inches for Connelly Lake). Nevertheless, the correlation studies have determined that the Lake Dorothy record provides a reasonable basis for extending the Connelly Lake record, as shown by Figures 4 and 5 (time series and duration graphs, respectively). Each figure shows the flows recorded by the Connelly Lake gage and the flows estimated by correlation with Lake Dorothy by two methods: 1) a power equation developed from the entire flow record, and 2) monthly linear equations. The second method was found to provide a somewhat better result, and was used for extending the USGS gage record. Figure 5 also includes a flow duration curve for the 2011-13 data collected by AP&T. The data is generally consistent with the correlated record, although there are significant deviations in the low flow range. That may be the result of difficulties measuring flows at the site during the winter low flow period. 0 50 100 150 200 250 9/1/2011 12/1/2011 3/1/2012 6/1/2012 9/1/2012 12/1/2012 3/1/2013 6/1/2013 9/1/201Flow, cfsDate 11 Figure 4 Correlation Results (Time Series) Figure 5 Correlation Results (Duration Series) 0.1 1 10 100 1000 FLOW, CFSConnolly Gage Record Connelly by Correlation -Annual Power Connelly by Correlation -Monthly Linear 0.1 1 10 100 1000 0%10%20%30%40%50%60%70%80%90%100%FLOW, CFSPERCENT TIME EXCEEDED USGS Gage Annual Power Correlation Monthly Linear Correlation AP&T 2011-13 12 Table 1 below provides average monthly flows for each year of the correlated streamflow record. As can be seen from the table, flows in the winter months are very low (2-4 cfs on average) and during the summer months are comparatively high (about 100 cfs on average). Table 1 Average Monthly Streamflows at Connelly Lake Outlet Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Avg. 1986 51.6 12.7 7.4 1987 5.6 3.1 1.3 2.1 18.2 81.8 106 85.7 77.6 53.6 12.7 7.1 38.2 1988 3.1 3.9 4.0 2.8 25.1 77.8 92.8 125 75.0 43.4 4.5 12.3 39.4 1989 4.4 2.0 0.7 1.4 32.2 100 106 97.2 76.9 36.6 12.6 13.9 40.6 1990 6.3 2.7 3.4 3.4 24.5 106 101 145 98.8 27.1 4.1 5.4 44.3 1991 3.2 5.5 2.7 2.8 26.2 97.9 105 141 114 45.1 5.6 6.2 46.5 1992 4.4 5.6 9.5 3.6 27.6 113 123 111 52.3 20.1 8.2 4.9 40.5 1993 3.2 6.6 2.7 2.2 40.8 91.3 79.9 84.5 67.9 40.7 14.1 6.6 36.9 1994 4.2 2.2 3.7 4.9 30.7 86.2 106 108 89.4 30.2 4.3 3.5 39.7 1995 1.8 2.2 1.5 2.6 37.0 83.3 83.9 82.5 83.6 27.0 3.4 3.7 34.5 1996 3.1 2.8 2.8 1.8 16.0 76.4 83.0 107 69.4 26.6 9.4 5.1 33.8 1997 1.7 3.5 2.9 3.0 34.9 93.2 112 104 69.0 21.7 7.7 11.0 39.0 1998 2.4 1.8 1.3 2.5 30.4 92.5 82.9 96.6 65.9 46.9 4.6 3.7 36.2 1999 3.6 2.7 1.6 2.4 16.1 90.2 108 114 79.9 31.2 5.8 17.0 39.6 2000 6.9 2.4 2.2 2.3 12.9 85.5 138 118 75.3 39.1 8.9 6.3 41.8 2001 5.2 2.8 2.2 1.6 10.4 77.3 112 95.4 74.1 21.0 3.7 3.6 34.3 2002 3.5 3.6 1.6 0.6 19.6 116 107 177 61.5 Avg. 3.9 3.3 2.8 2.5 25.2 92 103 112 77 35 7.6 7.3 39.5 4.4 FLOOD HYDROLOGY The peak flow record for USGS gage at Connelly Lake has only four data points, which is insufficient for developing a flood frequency curve; the four flows ranged from a low of 138 cfs to a high of 966 cfs. Therefore, two alternate methods were used. The first was to develop a flood frequency curve based on the Dorothy Lake record and then apply an appropriate adjustment factor. The second was to use the technique in a 2003 USGS study titled “Estimating the Magnitude and Frequency of Peak Streamflows for Ungaged Sites on Streams in Alaska and Conterminous Basins of Canada” (Curran, Meyer, and Tasker, USGS Water Resources Investigations Report 03-4188, 2003). That technique estimates flows for various return periods based on a site’s drainage area, % of the area in lakes and ponds, the mean annual precipitation, and the mean minimum January temperature. The results of the analyses are presented in Figure 6. 13 Figure 6 Flood Frequency Curves It is important to note that the highest peak flow recorded by the gage at Connelly Lake, 966 cfs, is very high in relation to the curves shown in Figure 6. However, the USGS gage on the Goat Lake outlet near Skagway also recorded an annual high flow on the same day (October 4, 1994). Also, the average flow for the Connelly Lake outlet that day was the highest of the entire record (611 cfs), which indicates that the high flows were sustained, and not just a brief wave, as from an avalanche. While it may be that whatever flood event happened on that day was an extremely rare circumstance, it also suggests caution when selecting the flood frequency curve. Accordingly, AP&T has used the curve in Figure 6 that is based on the Dorothy Lake curve factored by the square root of the drainage area ratio, which results in the following estimated flows: • 100-year return period (calculated) ........................................................ 834 cfs • 1000-year return period (extrapolated) ................................................ 1100 cfs • 10,000-year return period (extrapolated) ............................................. 1300 cfs These flood magnitudes have been used to size features of the dam, as described later. Proper sizing would require a Probable Maximum Flood (PMF) study, which is a design-level effort that is beyond the scope of this feasibility study. The estimated 10,000-year flood has been used as a proxy for the PMF. 10 100 1,000 10,000 PEAK FLOW, CFSRETURN PERIOD, YEARS 2 5 10 25 10050 200 1000 10000 CONNELLY LAKE OUTLET ESTIMATED FROM DOROTHY LAKE OUTLET, USING REGIONAL SKEW COEFFICIENT AND DRAINAGE AREA RATIO CONNELLY LAKE OUTLET ESTIMATED BY REGIONAL CORRELATION PER CURRAN, MEYER, AND TASKER, 2003 DOROTHY LAKE OUTLET (LOG PEARSON ANALYSIS WITH LINES FOR ZERO, REGIONAL (0.33), AND STATION SKEW (-0.30) COEFFICIENTS CONNELLY LAKE OUTLET ESTIMATED FROM DOROTHY LAKE OUTLET, USING REGIONAL SKEW COEFFICIENT AND SQUARE ROOT OF DRAINAGE AREA RATIO 14 SECTION 5 DESCRIPTION OF SELECTED PROJECT ARRANGEMENT 5.1 SELECTION CRITERIA AND CONSTRAINTS As discussed in Section 1, AP&T was responsible for selecting a project arrangement for this analysis based solely on its own judgment as to which alternative would be most feasible. In reality, AP&T has conceptually considered numerous alternatives prior to selecting the arrangement described below, including: • Dam height/storage capacity • Dam type • Installed capacity • Powerhouse location • Access to powerhouse (rebuild existing road or construct new road) • Access to lake (highline or road) Many of this alternatives are discussed in more detail in the remainder of this section. AP&T’s ultimate selection of the project arrangement was based on the following criteria and constraints: • The project must be able to store a significant portion of the annual inflow for it to have value in the Upper Lynn Canal (ULC) system. The ULC system currently includes two storage hydro projects (Goat Lake and Dewey Lakes) and three run-of-river hydro projects (Kasidaya, Lutak, and 10-Mile), and there is already a surplus of power in the summer months from the run-of-river generation. A project with little or no active storage (i.e., run-of-river) was considered, but was not selected for analysis because it would not provide generation when needed in the ULC system. In addition, one of AP&T’s incentives for developing Connelly would be to have a project available to supply Haines and Chilkat Valley load if the submarine cable linking Haines and Skagway failed, which would require a storage project. • There is considerable opposition to the Connelly Lake project from some Haines residents due to perceived impacts from the project, particularly from reconstruction of the existing abandoned road in the Chilkoot valley. There are fears that the project could damage the important fisheries of the Chilkoot River system. • The Chilkoot River is quite dynamic, particularly in the area near the confluence of Connelly Creek. Since the existing road is on the west side of the Chilkoot River and Connelly Lake is on the east side, some type of crossing of the river would be necessary, and thus at risk from a natural migration of the Chilkoot River stream channel. • The Chilkat Bald Eagle Preserve (CBEP) occupies much of the Chilkoot River valley bottom, including the area where the powerhouse was planned in previous studies (near the confluences of Connelly Creek and Power Creek with the Chilkoot River). AP&T has inquired with the State of Alaska as to whether the hydro project can be developed in the CBEP, but has not received a definite answer. Discussions with the State indicate that development in the CBEP could be problematic. 15 • Previous economic analyses for the Schubee Lake project indicate that a new expensive hydro project would only be feasible if there is a substantial increase in load, such as from development of a mine in the ULC area or interconnection of the ULC with the Yukon Energy Corporation (YEC) system (both of which are actively being pursued). 5.2 DAM 5.2.1 Dam Height and Storage Capacity The existing level of Connelly Lake is at El 2275, based on LiDAR mapping for the project. The existing Connelly Lake includes only a small amount of usable natural storage, estimated to be about 1,000 acre-feet, or approximately 3% of the annual inflow. That amount of storage is insignificant, and raising of the existing lake would be necessary to provide enough storage to make the project valuable. Figure 7 shows the storage capacity curve for the site; topography precludes a lake level any higher than about El 2360. Figure 7 Reservoir Storage Capacity Curve It is AP&T’s judgment that construction of a dam any higher than about 20 feet would require an access road to the dam site; helicopters could be used to support construction of a small dam (but at great cost). However, a small dam would still not provide the necessary storage for 2200 2250 2300 2350 2400 0 5,000 10,000 15,000 20,000Reservoir elevation, feetReservoir Capacity, acre -feet Existing lake level El 2275 Active storage -10,160 af Normal max. reservoir level El 2335 16 the project to be valuable for the ULC system. Therefore, a road to the dam site is considered to be necessary. As discussed in Section 4.3.2, a road to the dam would be a difficult and expensive task. In AP&T’s judgment, it makes the most sense for this analysis to assume development of as much storage as possible to fully utilize the value of the expensive access road, with the expectation that development could only proceed if a large load increase is assured (such as mine development or interconnection with Yukon Energy). However, operations modeling (as discussed in Section 5) indicates a distinct decrease in incremental annual generation with a normal maximum reservoir higher than El 2335 (see Figure 8). This occurs because with any higher reservoir, the reservoir would not always refill during low water years. Therefore, this analysis assumes that Connelly Lake would be raised from El 2275 to El 2335. Furthermore, the analysis assumes that a siphon system would allow drawing the reservoir down 15 feet to El 2260. Figure 8 Storage vs Annual Energy 5.2.2 Dam Type The existing outlet of Connelly Lake is through a small gorge in the bottom of a hanging valley. Connelly Creek flows through the gorge for only about 300 feet before cascading down the wall of the Chilkoot River valley; i.e. the area to locate the dam is very restricted. Previous geotechnical studies of the dam site indicate that the bedrock surface slopes up from Connelly Lake to the rim of the Chilkoot valley. Given the need for a dam approximately 80 feet high, the narrow area to put the dam, and the sloping bedrock surface, AP&T’s judgment is that a concrete gravity structure is the most appropriate type of dam for the site. Other possibilities include a concrete-faced rockfill or an asphalt-core rockfill, both of which would be able to utilize rockfill derived from quarries at the site for most of their volume; however, they would require a difficult cutoff to deep bedrock, and their side slopes could limit the height. 2290 2300 2310 2320 2330 2340 2350 2360 2370 20 25 30 35 40 45 50Reservoir Elevation, feetAverage Annual Energy, GWh Firm Energy, GWh Total Energy 17 A concrete gravity structure could be either conventional mass concrete or roller-compacted concrete (RCC). Almost all recently-constructed concrete gravity dams utilize RCC, due to its lower cost and more rapid construction. There have not been any RCC dams built in Alaska, although it has been used successfully for a road embankment in Ketchikan recently. AP&T has had discussions with RCC dam experts, and they believe it is an appropriate material even in a wet environment such as Southeast Alaska (although not all of the cost savings may accrue due to weather delays). The relatively long length of the Connelly Lake dam would allow for efficient RCC placement, and the inlet stream delta may provide a good source for RCC aggregate. Therefore, for this analysis AP&T has assumed that the dam would be an RCC concrete gravity structure. 5.2.3 Dam Features Figure 9 shows a preliminary arrangement of the Connelly Lake dam. It includes an ungated overflow spillway centered over the existing lake outlet with a crest length of 24 feet. A channel would cut through the left abutment of the dam and a siphon pipe installed to lower the lake and allow construction in the existing outlet channel; this siphon system would subsequently be utilized for the power and auxiliary outlet works. Conventional mass or reinforced concrete would be used in the following areas: • In the existing outlet channel up to El 2281 to provide a base for efficient RCC placement and to fill irregularities in the rock surface which often occur at lake outlets. • To encase the siphon pipe under the dam section • Near the left (east) abutment of the dam, where a section of dam would initially be unconstructed to provide access to the delta where the RCC would be mixed; the conventional concrete would be used fill in the dam section after the RCC production equipment has been removed. Note that this infill section is at a high point in the foundation and would be only 10-15 feet high. • For miscellaneous structures (dam parapet wall, spillway training walls, outlet works valve house, etc.). Based on previous explorations at the dam and a site reconnaissance in 2011, it appears that bedrock should be at shallow depth over most of the dam footprint. It has been assumed that approximately 5 feet of material would need to be excavated. Statistics for the dam and reservoir are provided below. Reservoir • Existing lake level ............................................................................ El 2275 feet • Normal maximum lake level ............................................................ El 2335 feet • Storage at normal maximum lake level .................................... 11,180 acre-feet • Normal minimum lake level ............................................................. El 2260 feet • Storage at normal minimum lake level ....................................... 1,020 acre-feet • Active storage capacity ....................... 10,160 acre-feet (34% of annual inflow) 18 FIGURE 9 SELECTED PROJECT ARRANGEMENT STORAGE DAM NORMAL MAX. RESERVOIR LEVEL EL 2335 FACE AND PARAPET (CONVENTIONAL CONCRETE) ROLLER COMPACTED CONCRETE OUTLET WORKS GUARD AND RELEASE VALVES PENSTOCK TO POWERHOUSE STAGE 2 CONCRETE EL 2345 MASS CONCRETE EL 2277 SPILLWAY CREST EL 2335 EL 2345 ROLLER COMPACTED CONCRETE FACE AND WALLS, CONVENTIONAL CONCRETE SIPHON PIPE TEMPORARY DIVERSION PIPE ORIGINAL GROUND SPILLWAY SECTION SCALE: 1" = 30' INTAKE AND OUTLET WORKS SECTION SCALE: 1" = 30' PLAN SCALE: 1" = 200' OUTLET WORKS INTAKE SCREEN STRUCTURE SPILLWAY COFFERDAM ȭDELTA ACCESS ROAD ȭPOWER CONDUIT (UPPER TUNNEL) ȭACCESS ROAD Dam • Top of dam parapet ......................................................................... El 2345 feet • Parapet height ............................................................................................ 4 feet • Maximum dam height (to top of parapet) .............................................. 85 feet • Dam crest length ................................................................................. 1,160 feet • RCC concrete volume ........................................................................... 30,500 cy • Conventional concrete volume .............................................................. 3,700 cy • Spillway crest length ............................................................................... 24 feet • Normal spillway capacity (water level at El 2341) ................................. 1400 cfs • Emergency spillway capacity (water level at top of dam parapet) ....... 2800 cfs 5.3 POWERHOUSE 5.3.1 Location Previous studies for the project placed the powerhouse adjacent to the Chilkoot River near Power Creek, about ¼ mile south of Connelly Creek, and 1 mile southwest of the outlet of Connelly Lake (horizontal distance). AP&T originally assumed the same location, as it would minimize the length of power conduit required. However, for the reasons described in Section 4.1 above, AP&T no longer believes that is the most appropriate location for this analysis. Two other locations have been considered: • In a relatively flat area adjacent to Connelly Creek and 1000 feet east of the Chilkoot River and approximately 270 feet higher in elevation; this location would also be immediately to the east of the CBEP boundary. An access road to the site could be developed outside of the CBEP boundary that would avoid the most problematic sections of the Chilkoot River, but it would cross the headwaters of Power Creek. • At a location approximately 1.7 miles south of the outlet of Connelly Lake. It would also be outside of the CBEP, and the powerhouse would discharge into a relatively large tributary of the Chilkoot River referred to herein as Bear Creek. This location has been considered as it would utilize the preferred route for the road to the dam, as discussed in Section 4.5 below. For this analysis, AP&T has chosen the second location, as it avoids the decrease is generating head associated with the first location, and is therefore consistent with the goal of maximizing the project generation. It also minimizes the length of road construction in the Chilkoot Valley and avoids construction in the area where the Chilkoot River is the most dynamic. It does however require a longer power conduit. Also, the lower portion of Bear Creek supports anadromous fish; it is mapped for Coho salmon rearing in the ADFG Catalog. The selected powerhouse location is shown in Figure 10, and is well above the anadromous barrier. However, it is likely that permitting for the project would result in instream flow release requirements to protect the anadromous fish population. 20 FIGURE 10 SELECTED PROJECT ARRANGEMENT GENERATION COMPONENTS CHILKAT BALD EAGLE PRESERVE BOUNDARY POWERHOUSE 8.5 MW RCC DAM NORMAL MAX. RESERVOIR LEVEL EL 2335 MIN. RESERVOIR LEVEL EL 2260 DELTA ACCESS ROAD (FOR CONSTRUCTION) DAM ACCESS ROADUPPER TUNNEL AND RAISE BORE BURIED DUCTILE IRON PENSTOCK LOWER TUNNEL AND RAISE BORE ABOVEGROUND STEEL PENSTOCK LOWER BORROW PIT ACCESS ROAD (FOR CONSTRUCTION) BORROW PIT FOR LOWER ROAD CONSTRUCTION NEW ACCESS ROAD EXISTING ROAD 5.3.2 Powerhouse Features For this analysis, AP&T has assumed the powerhouse would have a hydraulic capacity of 56.8 cfs, equal to twice the firm yield of the reservoir (see Section 5). The corresponding installed capacity would be 8.0 MW. For this analysis, it has been assumed that there would be two identical generating units in the powerhouse. This would allow the plant to provide all of the firm energy capability of the project even with one unit out of service. Note that the turbine and generator ratings are essentially equal to AP&T’s Goat Lake Project, which has one 4.0 MW unit rated at 2,000 feet of head and 30 cfs flow. The powerhouse and associated substation would have the following features: Powerhouse • Approximate dimensions ......................................................................... 50’x90’ • Type .......................... Pre-engineered metal building with concrete foundation • Number of generating units .............................................................................. 2 • Unit capacity ........................................................................................... 4.0 MW • Turbine type .................................................................... 2-jet horizontal Pelton • Turbine rated head ............................................................................. 1,965 feet • Turbine unit rated flow ........................................................................... 28.4 cfs • Rotational speed .................................................................................... 900 rpm • Generator voltage ................................................................................... 4.16 kV Substation • Approximate dimensions ......................................................................... 30’x50’ • Number of transformers .............................................................. Two (3-phase) • Transformer rating .................................................................................... 5 MVA 5.4 ACCESS ROAD 5.4.1 Existing Road Reconstruction Approximately 6.75 miles of the existing road into the Chilkoot River valley would be utilized for access to the project, as shown in Figure 11. As noted earlier, this road has not been maintained and is in various states of repair. Some sections would require only clearing and grading, and other section would require complete rebuilding, with substantial work required to improve drainage. Based on the road survey and mapping by the Takshanuk Watershed Council in 2008-2011, the following lengths of reconstruction are estimated: • Good condition ............................................................................... 46% (2.8 mi) • Fair condition .................................................................................. 19% (1.1 mi) • Poor condition ................................................................................... 5% (0.3 mi) • Severely damaged ........................................................................... 30% (1.8 mi) Reconstruction of the road would likely need to include some re-routing in the area of the Glory Hole to avoid impacts to that important fish spawning area. 22 FIGURE 11 SELECTED PROJECT ARRANGEMENT CHILKOOT VALLEY ACCESS ROAD CHILKOOT LAKECHILKAT BALD EAGLE PRESERVE BOUNDARY EXISTING ROAD ALIGNMENT; CONDITION VARIES POWERHOUSE 5.4.2 New Road Approximately 5.5 miles of new road would be constructed for access to the powerhouse and dam, as shown in Figure 10. The new road would include the following segments • Main access road in Chilkoot Valley ................................................... 0.85 miles • Borrow pit access road in Chilkoot Valley .......................................... 0.45 miles • Bridge over Chilkoot River ..................................................................... 160 feet • Main access road from bridge to dam site ......................................... 3.55 miles • Spur road to powerhouse ................................................................... 0.08 miles • Spur road to delta area at dam site .................................................... 0.57 miles The two road sections in the Chilkoot Valley have been aligned to avoid infringement on a large wetland area and to stay as far as possible from the Chilkoot River channel. These roads should be relatively easy to construct, although nearly all of it is in the CBEP. Note that the borrow pit has been located in a large alluvial fan deposit outside of the CBEP. The bridge across the Chilkoot River has been located at a bend in the river that appears to be relatively stable based on the size and type of trees. The east abutment appears to be bedrock. The west abutment is on alluvium; a deep foundation would be necessary to avoid undermining by flood scour. The bridge would be a single-lane modular bridge rated for construction loads. The main access road from the bridge to the dam site has been aligned with a maximum grade of 20% and a minimum curve radius of 75 feet. These values are consistent with AP&T’s access road for the Kasidaya Creek Project near Skagway, although the maximum grade is more than typical for logging roads. The average grade would be about 12.4%. This road would for the most part be quite difficult construction, requiring full bench cuts is some areas and deep fills in others. The most challenging sections appear to be 1) a 2,000-foot-long section from Sta 154+00 to Sta 174+00 where the road climbs a steep valley wall with primarily a full-bench section, and 2) a 1,000-foot-long section from Sta 198+00 to Sta 208+00 where the road is on a deep fill across a flat bench adjacent to a steep talus-covered slope. For the latter, the road has been aligned perpendicular to the talus slope to provide stability. For the former, there is heavy tree cover, and it is not known whether talus is present. The spur road to the powerhouse would be nearly level on a sidehill, and should be relatively easy construction. The spur road to the delta would also be relatively flat, however, it would require placing a fill about 300 feet long through a side bay of the lake. The lake bathymetry indicates the fill would be about 30 feet deep, but in an area of the lake with a flat bottom. 24 5.5 POWER CONDUIT The power conduit would have a horizontal length of 10,040 feet and a vertical drop of 2,080 feet. A profile is shown in Figure 12. It would comprise the following segments from top to bottom: • 48” HDPE (submerged intake to dam) ................................................... 500 feet • 48” steel (through dam) ......................................................................... 180 feet • 48” raise bore (drilled shaft) .................................................................. 220 feet • 36” saddle-supported steel (in 8’ tunnel) ............................................ 2230 feet • 36” ductile iron (buried adjacent to road) ........................................... 3340 feet • 48” raise bore (drilled shaft) ................................................................ 1090 feet • 36” saddle-supported steel (in 8’ tunnel) ............................................ 1490 feet • 36” saddle-supported steel (near lower access road) ......................... 2360 feet It may be possible to construct the two raise bore/tunnel sections by horizontal directional drilling (HDD) instead. AP&T has proposed use of HDD on other projects and believes it has considerable promise, however, it has not been used for penstock construction before to AP&T’s knowledge. Therefore, for this analysis AP&T has assumed the more conventional approach with horizontal tunnels and raise bores. Note that the upper ends of the raise bores would need to be lined with 36” steel pipe until there is sufficient rock strength to withstand the pressures. Pipe wall thickness would vary depending on the type of pipe and location. Near the powerhouse, the steel pipe would be about 1 inch thick. 5.6 TRANSMISSION LINE The 34.5 kV transmission line would be 11.8 miles long from the powerhouse to the interconnection with AP&T’s existing 34.5 kV system near the ferry terminal on Lutak Inlet. Of that length, 7.9 miles would be along the reconstructed and/or new road in the Chilkoot valley, and 3.9 miles would be along the Lutak highway. Because of environmental sensitivities with overhead lines in the area, it has been assumed for this analysis that the transmission line would all be buried. AP&T has a buried 7.2 kV line from the ferry terminal to the end of Lutak Inlet along the Lutak highway. When that line was installed, a spare 5” conduit was also installed in anticipation of the Connelly Lake development. 25 FIGURE 12SELECTED PROJECT ARRANGEMENTPENSTOCK PROFILERCC DAMSCREENSTRUCTUREUPPER RAISE BOREUPPER TUNNELMATCHLINE MATCHLINELOWER RAISE BORELOWER TUNNEL 67((/3,3(POWERHOUSE '8&7,/(,5213,3( '8&7,/(,5213,3(EXISTINGGROUNDEXISTINGGROUND SECTION 6 POTENTIAL GENERATION 6.1 OPERATIONS MODEL Annual generation has been calculated by a spreadsheet model that considers the estimated inflows to Connelly Lake (as discussed in Section 2), reservoir storage, head loss in the power conduit, estimated turbine/generator/transmission efficiencies, and power demands. Each of these factors are discussed in more detail below: Reservoir storage: A reservoir storage vs elevation curve is shown in Figure 7. This curve is based on LiDAR mapping of the topography above the existing lake level (El 2275) and a preliminary bathymetric survey of the lake made in previous studies for the project. Head losses: A head loss factor has been calculated based on the assumed power conduit materials and sizes described in Section 4. Pipe sizing was based on a 10% maximum head loss criterion when operating at maximum capacity. Efficiency: An overall efficiency of 85% was assumed for the operation, which includes the turbine (approx. 93%), generator (97%), transformer (99%), and transmission system (95%). Power demands: In keeping with the selection criteria and constraints described in Section 4.1, it has been assumed that the load to be served by the project would be a relatively constant industrial load such as a mine. Therefore, the generation has been calculated based on the constant water diversion rate that would deplete the reservoir only once during the 16 years of the correlated flow record. Because of the very high head for the project, there is little difference between assuming a constant power demand and a constant water diversion rate. 6.2 GENERATION WITH SELECTED PROJECT ARRANGEMENT For the selected reservoir capacity (10,160 acre-feet active storage), the constant water diversion rate (i.e. firm yield) was found to be 28.4 cfs. The selected arrangement is for two generating units, with the unit hydraulic capacity equal to the firm yield, for a total hydraulic capacity of 56.8 cfs. During high flow periods when the reservoir is full, the project would be capable of generating additional non-firm power. For the selected arrangement (56.8 cfs hydraulic capacity, 8.0 MW generating capacity), the generation amounts are: • Firm energy ......................................................................................... 36.9 GWh • Average annual energy ....................................................................... 43.2 GWh • Plant factor .................................................................................................... 62% 27 SECTION 7 CONSTRUCTION COST ESTIMATE and CONSTRUCTION SCHEDULE 7.1 CONSTRUCTION COST ESTIMATE The estimated construction cost for the Connelly Lake Project as described in Section 4 is $87,068,000. The cost estimate is based on AP&T’s experience with similar construction, limited quantity takeoffs from the preliminary site arrangement, and an estimated on-line date of January 2022. A summary of the construction cost estimate is shown in Table 6-1. The estimate includes a contingency allowance of 20%, 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 $2,073,000 for permitting costs and $5,874,000 for engineering costs, which are based on AP&T’s experience and current understanding of the probable permitting process. 7.2 ASSUMED DEVELOPMENT SCHEDULE AP&T is no longer actively planning to develop the Connelly Lake site, and will not do so until substantial new load develops and local opposition to the project diminishes. For the purposes of this analysis only, the construction schedule is based on a resumption of work in 2015 and the following general tasks and durations: Task Duration Schedule Completion of environmental studies and preparation of permit applications 2 years 2015-2016 Permit processing 2 years 2017-2018 Construction 3 years 2019-2021 28 330 LAND AND LAND RIGHTS 0.1 LEASES AND EASEMENTS 0 331 STRUCTURES AND IMPROVEMENTS 0.1 MOBILIZATION 2,300,000$ 0.2 POWERHOUSE 1,193,000$ 332 RESERVOIRS, DAMS, AND WATERWAYS 0.1 STORAGE DAM 13,028,000$ 0.2 UPPER TUNNEL AND RAISE BORE 5,239,000$ 0.3 UPPER PENSTOCK (DUCTILE IRON PIPE)1,663,000$ 0.4 LOWER TUNNEL AND RAISE BORE 5,020,000$ 0.5 LOWER PENSTOCK (STEEL PIPE)2,369,000$ 333 TURBINES AND GENERATORS 0.1 TURBINE SHUTOFF VALVES 760,000$ 0.2 HYDRAULIC TURBINES 4,480,000$ 0.3 SYNCHRONOUS GENERATORS 5,140,000$ 0.4 AUXILIARY DIESEL GENERATOR 56,000$ 334 ACCESSORY ELECTRICAL EQUIPMENT 0.1 SWITCHGEAR 104,000$ 0.2 CONTROL SYSTEM 325,000$ 0.3 DC POWER SYSTEM 45,000$ 335 MISCELLANEOUS MECHANICAL EQUIPMENT 0.1 POWERHOUSE CRANE 146,000$ 0.2 FIRE PROTECTION AND SECURITY 12,000$ 0.3 SHOP EQUIPMENT 14,000$ 336 ROADS AND BRIDGES 0.1 REBUILD EXISTING ROAD 1,802,000$ 0.2 NEW ROAD TO DAM 3,168,000$ 0.3 POWERHOUSE SPUR ROAD 30,000$ 0.4 DAM BORROW ROAD 233,000$ 0.5 LOWER BORROW ROAD 134,000$ 353 SUBSTATION EQUIPMENT AND STRUCTURES 0.1 POWERHOUSE SUBSTION 493,000$ 357 UNDERGROUND CONDUIT 0.1 TRANSMISSION LINE 844,000$ 358 UNDERGROUND CONDUCTORS AND DEVICES 0.1 TRANSMISSION LINE 3,573,000$ SUBTOTAL 52,171,000$ Contingency 20.0%10,434,000$ Escalation 10.4%6,499,000$ SUBTOTAL 69,104,000$ Permitting 3.0%2,073,000$ Design 4.0%2,764,000$ CM 4.5%3,110,000$ SUBTOTAL 77,051,000$ Financing 2.0%1,541,000$ IDC 11.0%8,476,000$ TOTAL CAPITAL COST 87,068,000$ Table 2 Construction Cost Estimate 29 SECTION 8 ECONOMIC ANALYSIS 8.1 PROJECT ANNUAL COST AND COST OF POWER 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. Low interest loans and/or grant funding are frequently available to promote the development of hydro facilities in rural Alaska communities. Much of AP&T’s work on the Connelly Lake project to date was funded through a Renewable Energy Fund grant. However, for purposes of this analysis, AP&T has assumed that no additional grant funding would be made available, but that low interest loans would be for 70% of the construction cost; loan terms have been assumed as 5% interest rate with a 30 year term. The remaining 30% of the construction cost has been assumed to be funded by AP&T equity with recovery at AP&T’s rates currently authorized by the Regulatory Commission of Alaska (RCA). Operation and maintenance costs have been estimated as $0.025 per kWh (2013 cost level). That rate includes costs for O&M labor, equipment, materials, insurance, taxes, and interim replacements. O&M costs are assumed to escalate at 2.5% annually. Based on the above assumptions, the first year (2022) annual cost is estimated to be $10,536,000, including $1,409,000 in O&M costs. For an annual generation of 43.2 GWh, that amounts to a unit energy cost of $243/MWh. The equivalent current year (2014) unit energy cost is $193/MWh. For comparison, AP&T’s current fuel cost for diesel generation is approximately $286/MWh. 8.2 ECONOMIC ANALYSIS METHODS AND ASSUMPTIONS The economic analysis described in this section is similar to that conducted for the Schubee Lake Project in 2013, as previously provided to AEA. However, to reduce the complexity, the analysis has not considered 1) variations in the Connelly construction cost 2) loss of the submarine cable linking Haines and Skagway, or 3) supplying power to cruise ships. Also, probabilities have not been assigned to the various cases and a weighted average B/C ratio has not been calculated. An economic analysis is fundamentally a comparison of the benefits and costs of a proposed undertaking. For a generation project, the benefits are determined as the costs associated with the most likely alternative for providing the same capacity and energy. For AP&T, the most likely alternative to development of Connelly Lake is generation with existing and/or new diesel generators. Economic analysis of a generation project with a long life, such as a hydroelectric project, can be problematic because of the need to forecast loads and alternative fuel prices well into the future. Fortunately, the recently-completed Southeast Integrated Resource Plan (SEIRP) 30 provides a reasonable basis for the projections. The SEIRP load and fuel price projections for the Upper Lynn Canal system are summarized in the following two subsections, as well as AP&T modifications to those projections. 8.2.1 Load Forecasts The SEIRP included a reference forecast for the Haines/Skagway system, as well as a low and high forecast. The reference forecast estimated the following compound growth rates in energy, based on historical patterns and near-term expectations for fuel prices: • Short Term (2011-2015)............................................................................... 2.7% • Intermediate term (2016-2035) ................................................................... 0.5% • Long Term (2036-2061)................................................................................ 0.3% The high forecast assumed loads would grow 1% faster than the reference case, and was meant to reflect additional economic development in the region and electric vehicle charging. The low forecast assumes adoption of the Demand Side Management (DSM) and Energy Efficiency (EE) measures proposed in the plan. For the Haines/Skagway system, this resulted in a forecast gradual reduction in generation until about 2020 (to about 93% of 2011 loads), and then growth at the same rates as the reference forecast. Table 3 below compares SEIRP-projected loads for the ULC system and the actual loads experienced in the last three years: Table 3 SEIRP Forecast and Actual ULC System Loads (All values in MWh) Year SEIRP Low SEIRP Reference SEIRP High Actual 2011 28,776 28,776 28,776 28,116 2012 29,285 29,343 29,633 27,516 2013 29,780 29,920 30,512 27,852 As can be seen from the table, actual loads have trended lower than even the SEIRP Low forecast. Construction will be completed soon on a new 11-unit apartment building in Haines, and a 50- unit hotel may start construction soon. AP&T expects a load increase of about 0.5 GWh from these facilities. Although it is a significant and welcome increase in load, it is not considered to be enough to affect the long-term planning for new generation. AP&T believes supplying power to a mine load is a distinct possibility. Explorations are currently underway for a mine in the Upper Chilkat Valley near the Canadian border (the Palmer mine), and reportedly could be on the scale of the Greens Creek mine south of Juneau. In addition, Yukon Power Corporation is actively looking at power supply options to meet expected mining loads in the Yukon Territory, including a transmission link to the ULC system. To estimate the economic impact of providing a mine load, AP&T’s mine scenario assumes an increase of 50 GWh above the SEIRP reference forecast, also to start in 2022. A 2013 capital 31 cost of $16,000,000 has been estimated as the incremental cost of the transmission line required to serve the mine load. The mine load is estimated to last for 20 years. The SEIRP load projections and AP&T’s mine load scenario are shown in Figure 13. Note that the SEIRP discussed the possibility of new mine loads, but specifically excluded them from their high load projection. Figure 13 SEIRP Load Projections for ULC System 8.2.2 Diesel Fuel Prices The SEIRP forecast diesel fuel prices for Haines and Skagway separately, although they are very similar. The SEIRP forecasts are based on work by Institute for Social and Economic Research (ISER) for the Power Cost Equalization (PCE) program. The low, medium, and high diesel price projections from the SEIRP are shown in Figure 14. 32 Figure 14 SEIRP Fuel Price Projections for Haines AP&T believes it is not realistic to assume the SEIRP/ISER diesel price projections as the basis for this economic analysis. Although diesel fuel prices are likely to increase, and quite possibly at the rates indicated, it is also likely that AP&T would move to an alternate fuel to minimize the cost of electricity to its customers. At the current time, the most likely alternative fuel to diesel is liquefied natural gas (LNG). Although LNG is not currently available in Alaska, there are efforts underway to create LNG from North Slope gas fields and bring it to parts of the State. There are also many proposals to ship LNG from terminals in the Prince Rupert area. Because the LNG business is still developing, prices are nearly impossible to forecast. For the purposes of this economic analysis, AP&T has developed low, medium, and high price projections for LNG (expressed as the diesel equivalent) that follow the SEIRP forecast for diesel closely until about 2030 when SEIRP prices begin to climb very rapidly; after 2030, the LNG prices are projected at the same rate at the previous years (3.0%, 5.0%, and 6.0% per year, respectively). 8.3 ECONOMIC ANALYSIS MODELS An economic analysis must consider both the capital costs of a project as well as operating costs (fuel, operation and maintenance (O&M)). The analysis model used by AEA to evaluate potential projects calculates the present worth of the capital and operating costs over the expected project life, with the capital costs lumped into the construction period early in the project life, followed by the series of annual fuel and O&M costs. This treatment of the capital 0 20 40 60 80 100 120 140 160 2010 2020 2030 2040 2050 2060 2070FUEL PRICES (EQUIVALENT DIESEL $/GAL)YEAR SEIRP Low diesel SEIRP Medium diesel SEIRP High diesel AP&T Low LNG AP&T Medium LNG AP&T High LNG 33 costs may be appropriate for a government agency such as AEA, but does not take into account the financial realities of a utility such as AP&T, which must fund projects through a combination of loans, equity investments, or grants if available. For the purposes of this economic analysis, AP&T has calculated benefits and costs with both the AEA model and with a second model that includes financing by varying amounts of loans and equity. The assumptions and input values used in the models are summarized below: Table 4 Economic Analysis Assumptions and Input Values AEA Model AP&T Model Analysis term 50 years 50 years General inflation rate 3.00% 3.00% Discount rate 8.00% 8.00% % of capital costs by loan N.A. 70% % of capital costs by equity N.A. 30% Loan interest rate 5.00% N.A. Loan term 30 years N.A. Regulated rate of return on equity N.A. 10.75% Depreciation method N.A. Straight line Depreciation term N.A. 30 years Existing diesel capacity 8.4 MW 8.4 MW Diesel reserve requirement 25% 25% Diesel capital cost (2013) $500/kW $500/kW New diesel unit capacity 2.0 MW 2.0 MW Diesel efficiency 14.4 kWh/gal 14.4 kWh/gal Diesel variable O&M cost (2013) 0.030 $/kWh 0.030 $/kWh Diesel fixed O&M cost (2013) $2/kW $2/kW Existing hydro energy production3 35,000 MWh 35,000 MWh Connelly capital Cost (2012)4 $74,772,000 $74,772,000 Connelly O&M Cost (2013) 0.025 $/kWh 0.025 $/kWh Connelly minimum O&M Cost (2013) $50,000 $50,000 Connelly annual generation 43,200 MWh 43,200 MWh Connelly development period 6 years 6 years Connelly construction period 3 years 3 years First year of Connelly operation 2022 2022 3 Goat Lake – 20,600 MWh, Dewey Lakes – 3,400 MWh, Kasidaya – 10,200 MWh, Lutak – 800 MWh 4 Capital cost estimate by HDR Alaska, Inc. 34 8.4 ECONOMIC ANALYSIS RESULTS The analysis includes 12 combinations of the primary variables (4 load growth cases, 3 fuel price cases). The analysis has assumed that the primary variables are independent, but in reality some of them are not. For example, high fuel prices would be expected to restrain load growth, and vice versa. Also, stable electric rates that would be expected if a new hydro project were built might stimulate load growth. The benefit-cost ratios for the 12 combinations are shown in Table 7-2 for both the AEA and AP&T models. Inspection of these results reveals that the Connelly Lake project would be economical to develop only under the following scenarios: • High loads and medium or high fuel prices • Mine loads and medium or high fuel prices These benefit cost ratios indicate that the Connelly Lake Project should be considered for development primarily if a large new industrial load (such as a mine) can be reasonably well assured and there are no better alternatives for meeting that load. Table 5 Economic Analysis Results AEA Analysis Method Load Case Low Fuel Case Medium Fuel Case High Fuel Case Discounted Benefits Discounted Costs B/C Ratio Discounted Benefits Discounted Costs B/C Ratio Discounted Benefits Discounted Costs B/C Ratio Low $316 $46,521 0.01 $316 $46,521 0.01 $316 $46,521 0.01 Reference $1,674 $46,890 0.04 $3,741 $46,890 0.08 $8,003 $46,890 0.17 High $28,518 $50,503 0.56 $70,974 $50,531 1.40 $154,762 $50,580 3.06 Mine $83,019 $74,523 1.11 $149,329 $81,737 1.83 $266,798 $94,455 2.82 AP&T Analysis Method Load Case Low Fuel Case Medium Fuel Case High Fuel Case Discounted Benefits Discounted Costs B/C Ratio Discounted Benefits Discounted Costs B/C Ratio Discounted Benefits Discounted Costs B/C Ratio Low $316 $57,187 0.01 $316 $57,187 0.01 $316 $57,187 0.01 Reference $1,674 $57,882 0.03 $3,741 $57,882 0.06 $8,003 $57,882 0.14 High $28,518 $62,475 0.46 $70,974 $62,502 1.14 $154,762 $62,552 2.47 Mine $83,019 $89,698 0.93 $149,329 $96,912 1.54 $266,798 $109,631 2.43 8.5 CONNELLY LAKE vs. SCHUBEE LAKE Based on the results of this analysis for the Connelly Lake Project and the 2013 analysis for the Schubee Lake Project, it would appear that there is no clear choice between the two, as there unit energy costs (construction cost divided by average annual energy) are nearly identical ($2,000/MWh). The capacity cost ($/kW) of Connelly Lake is lower than for Schubee Lake, but that is not considered to be a significant advantage. AP&T still considers Connelly Lake to be the superior site because it does not include a submarine cable and has better access. In addition, the hydrologic basis for the Connelly Lake analysis is far better than for Schubee Lake. 35 8.6 RUN-OF-RIVER DEVELOPMENT POTENTIAL The analysis described above is for a project with a substantial amount of storage. It would be possible to develop Connelly Lake as a run-of-river project, but because of the highly seasonal nature of the streamflows (as described in Section 4), generation would be concentrated in the summer months, with little generation in the winter. Figure 15 below shows the average monthly generation by the ULC hydroelectric projects and diesel units for the years 2009-2013; as can be seen, there is currently no need for additional hydro generation in the summer months. Diesel generation occurs primarily in the spring when reservoirs the ULC storage projects (Goat Lake and Dewey Lakes) are depleted. Since a run-of-river development of Connelly Lake would not provide generation when it is needed, it obviously would not be economically feasible. Figure 15 ULC Average Annual Generation by Unit, 2009-2013 36 SECTION 9 PERMITTING 9.1 FERC JURISDICTION The Federal Energy Regulatory Commission (FERC) has asserted jurisdiction over the Connelly Lake Project due to the existence of a Federal Power Act Section 24 withdrawal from many years ago when the project area was Federal land and someone proposed a hydropower development at Chilkoot Lake. Although the land has since been transferred to the State of Alaska, the Section 24 withdrawal still remains. Because FERC asserted jurisdiction, AP&T filed for and received a FERC preliminary permit during the course of its work on the project. It is possible that if any and all Section 24 land withdrawals are vacated, the Project could proceed without FERC jurisdiction. However, it is also possible that FERC could assert jurisdiction because of potential impacts to anadromous fish, which have been deemed to be interstate commerce. It can be argued that the Project would not have any significant impact on anadromous fish, but it is not clear how FERC would view the matter. As it currently stands, if a Connelly Lake project were to be proposed, a FERC license would be required, which is considered to be a major Federal action and thus require a NEPA analysis. Although it is not strictly required, a project proponent usually first obtains a FERC preliminary permit, which provides priority for a period of three years while the proponent collects the necessary information for the NEPA analysis and prepares the license application. AP&T’s environmental studies have provided much of the information needed for a license application, but they are not complete and will likely be considered outdated in a few years. Thus, it is likely that if the Project were to be advanced in the future, a full three years would be required to develop and submit a license application. 9.2 OTHER FEDERAL PERMIT REQUIREMENTS If FERC has jurisdiction, then the FERC license is the primary Federal permit required. The other major Federal permit that would need to be obtained is the Corps of Engineers Section 404 permit (for excavation or filling in streams and wetlands). The EPA also has permitting authority, but EPA usually waives its involvement when FERC has jurisdiction. These permits are generally applied for in conjunction with the license application. 9.3 STATE AND LOCAL PERMIT REQUIREMENT The primary state permits required for a development of Connelly Lake at this time would be: • Department of Fish and Game Habitat Permit • Department of Natural Resources water right permit • Department of Natural Resources – Parks and Outdoor Recreation permit (includes the Chilkat Bald Eagle Preserve under their jurisdiction) • Department of Natural Resources – Haines State Forest permit The State would not have jurisdiction over dam safety if an FERC license is required. If in the future it is determined that FERC does not have jurisdiction, then a permit for construction and monitoring of the dam would be required from the Alaska Department of Natural Resources. 37 Department of Environmental Conservation 401 Water Quality Certification is usually waived in Alaska on FERC-jurisdictional projects; the Corps of Engineers 404 permit then covers the 401 obligations. At this time, there would be no local permits required. The Haines Borough stated that since the State was involved, they did not need to be. 38 SECTION 10 CONCLUSIONS AND RECOMMENDATIONS 10.1 CONCLUSIONS AP&T concludes from this feasibility analysis of the Connelly Lake Hydroelectric Project that: 1. The Project is likely to be technologically feasible using well-known and reliable construction methods. However, the remote location of the lake and the need to develop storage makes the cost of the Project very expensive. 2. The selected arrangement for the Project avoids or reduces some of the potential environmental impact of the Project. Rebuilding of the existing road in the Chilkoot Valley would be necessary, and would be of great concern to some Haines residents. 3. The Project has the potential to generate 43.2 GWh per year on average, including 36.9 GWh of firm energy, based on an installed capacity of 8.0 MW and an active reservoir storage of 10,160 acre-feet. 4. The estimated cost of the selected arrangement is $87,068,000, including escalation to a projected earliest possible on-line date of 2022. 5. The benefit-cost ratio for the Project would be greater than one (indicating economic feasibility) only with medium or high fuel prices and high load growth (as forecast by the SEIRP) or a new large industrial load (such as the Palmer mine or interconnection between Yukon Energy Corporation and AP&T’s ULC system). 10.2 RECOMMENDATIONS Based on the results of this feasibility study, AP&T recommends that: 1. The Connelly Lake Hydroelectric Project should not be considered further for development as long as loads in the ULC system trend along the reference load case of the SEIRP. Should loads increase significantly more than the reference load forecast, or if the Palmer mine and/or Yukon Energy interconnection appear imminent, then development of Connelly Lake should be reconsidered. 39 APPENDIX A GEOTECHNICAL RECONNAISSANCE REPORT GEOENGINEERS, INC. April 18, 2012 8410 154th Avenue NE Redmond, Washington 98052 425.861-6000 April 18, 2012 Alaska Power & Telephone Company P.O. Box 3222 193 Otto Street Port Townsend, Washington 98368 Attention: Larry Coupe, Project Engineer Subject: Proposed Connolly Lake Hydroelectric Project Chilkoot River Basin Haines, Alaska File No. 18436-007-00 INTRODUCTION This report summarizes the results of our preliminary engineering geologic evaluation of the proposed Connolly Lake Hydroelectric project near Lutak, in the Haines Borough of Alaska. Our understanding of the project is based on conversations with, and material provided to us by Larry Coupe from mid-September 2011 through to early December 2011. We understand that Alaska Power and Telephone Company (AP&T) is evaluating the feasibility of the Connolly Lake Hydroelectric project in comparison with another possible hydroelectric project. The selected hydropower project will replace the power presently supplied to Haines by a transmission line from Skagway. The new power generating facility would also alleviate the need to use an existing diesel-powered generation plant located within the town limits of Haines during power outages. Craig Erdman of GeoEngineers visited the Connolly Lake site on September 27, 2011, along with Larry Coupe (AP&T) and other scientists. The purpose of the site visit was to observe the surface conditions of the project area and to assess the potential feasibility of constructing a new hydroelectric facility at the site. Connolly Lake site is located at approximate Elevation 2,280 feet at the crest of the east valley wall of the Chilkoot River. The project would include construction of a rock-fill dam with an upstream membrane along the west side of the lake, ultimately increasing the pool to maximum Elevation 2,340 feet (see Figures 1 and 2). As presently proposed, flow from the pool would be routed through an unlined rock penstock to a power plant located along a slightly elevated terrace adjacent to the Chilkoot River (see Figure 3). The project would have a hydraulic head of approximately 2,200 feet. Alaska Power & Telephone | April 18, 2012 Page 2 File No. 0000-001-00 File No. 18436-007-00 REGIONAL GEOLOGY A number of geologic maps, reports and documents were reviewed to understand the local geology. These documents are listed in the bibliography section. The bedrock geology of the region is mapped in greatest detail by Dusel-Bacon et al. (1996). March (1982) provides photointerpretive mapping of the surficial geology of the project area and vicinity. A summary of the engineering geology of the Haines, Alaska area is provided by Yehle and Lemke (1972). According to Dusel-Bacon et al. (1996), the Connolly Lake area is underlain by igneous intrusive bedrock consisting of late Cretaceous to early Tertiary granitic rocks. Gehrels and Berg (1992) describe the rocks as tonalite, though others have referred to similar rocks as quartz diorite or granodiorite (Barker, 1952; Beikman, 1975). Also mapped in the area by Dusel-Bacon and others are metamorphic rocks mapped as migmatites, a strongly foliated (a rock with minerals aligned in the same direction) metamorphic rock. Surficial geology of the area by March (1982) indicates that most of the area is mapped as bedrock, with colluvium (loose soil and rock transported down slope by gravity) mapped along the steep rock bluffs around Connolly Lake and along a portion of the west-facing slopes of the Chilkoot River, west of Connolly Lake. March also maps deltaic deposits on the east side of Connolly Lake at the mouth of the stream that flows into the lake. The west side of the Chilkoot River valley bottom and slope are mapped as covered by glacial till, inactive alluvial deposits and colluvial fan deposits. The engineering geologic study (Yehle and Lemke, 1972) does not appear to have extended to Connolly Lake, though a lineament (landscape scale linear feature on the ground surface) was mapped along the west side of the Chilkoot River valley. This lineament is discussed further below. SEISMICITY The site is located in an area that is considered seismically active. According to Plafker et al. (1993), the Denali fault is mapped to the west trending north along the Chilkat River valley. The Denali fault is mapped as connecting with the Chatham Strait fault in the Lynn Canal south -southeast of Haines, Alaska. At that time, the Denali and Chatham Strait faults were considered to be “suspicious” with the possibility of displacement in the Neogene (within approximately the last 24 million years). This appears to be supported by recent seismicity along the Denali fault trace from 1982 and 1987 reported by Rogers and Horner (1991) and 2002 earthquake activity along the Denali fault to the north. As referenced in the Regional Geology section, Yehle and Lemke (1972) identified a lineament that was inferred to be a potential fault that trends up the west side of the Chilkoot River valley. Neither Plafker et al. (1993), Rogers and Horner (1991) or Wesson et al. (2007) indicate a fault in the Chilkoot River valley, but the possibility remains that the Chilkoot lineament is seismically active. Wesson et al. (2007) consider the Chatham Strait – Denali fault system to be active. They provide an update to ground motions in Alaska and anticipate peak ground accelerations with a 2 percent probability of exceedance in 50 years of greater than about 0.4 to 0.6 g (estimated from a small scale map). Peak ground accelerations having a 10 percent chance of exceedance in 50 years are greater than about 0.14 to 0.17 g. Alaska Power & Telephone | April 18, 2012 Page 3 File No. 0000-001-00 File No. 18436-007-00 PREVIOUS STUDIES At least three separate geotechnical reports were completed in the early to mid-1990s for the Haines Light & Power Company in support of developing a hydroelectric power project using Connolly Lake. The dam axis for the project was being developed with a dam axis proposed in the early 1990s was located just west of the currently proposed dam. These reports include: R&M Engineering Inc., 1993, “Haines Hydro Project, Reconnaissance Level Geotechnical Report,” prepared for Haines Light & Power. R&M Project No. 931758. R&M Engineering Inc., 1994, “Upper Chilkoot Power Project, Preliminary Geotechnical Reconnaissance,” prepared for Haines Light & Power. R&M Project No. 941172. R&M Engineering Inc., 1995, “1995 Haines Light & Power Geotechnical Investigation, Connolly Lake Alternative Dam Site & Drawdown Trench,” prepared for Haines Light & Power. R&M Project No. 951124. The 1993 report summarizes the results of three site reconnaissance visits to observe surface and shallow subsurface (less than 3 feet below the ground surface) conditions along the (previously) proposed dam axis, the proposed overland penstock alignment, two options for siting the power plant, and to identify potential borrow areas. Hand tools were used to evaluate the near surface soil conditions. The report copy we were provided included only Sheet 1 of 5 that showed the topographic map for the lake area with a plan view of the proposed dam. The results of the first visit to look at the downslope portion of the approximate alignment for the southerly penstock option was summarized in a short letter, dated August 16, 1993, and attached to the report. A reconnaissance of the southerly alternative for the powerhouse was completed during the second visit. A reconnaissance of the dam, the delta at the inlet of Connolly Lake for a borrow source, and the northerly powerhouse alternative were also completed. The ground surface upslope from the Chilkoot River along the southerly penstock alignment was described as covered with boulders. Bedrock is described as diorite with a medium to coarse texture. Where observed, the soil horizon is described as being less than 6 inches thick and composed of organic rich sand and gravel. The boulders were “separate” (we infer they mean “isolated”) and up to 20 feet in diameter from approximate Elevation 250 feet to approximate Elevation 750 feet. From approximate Elevation 250 feet to approximate Elevation 1,000 feet, the boulders were described as being stacked 2 to 3 boulders high with boulders up to 10 feet in diameter. Between approximate Elevation 1,000 feet and approximate Elevation 1,600 feet, there were reported to be about four cliffs up to 150 feet high with boulder fields at the toe of the cliffs and a ground surface inclined at gradients of 30 to 40 percent. A muskeg was present at approximate Elevation 1,600 feet, with a steeply inclined rock slope upslope to the east. Jointing was reported in the rock with spacing of 10 to 20 feet. In the upper rock slope, the jointing is reported to strike N20°–30°W and dip 70° to 80°SW. Alaska Power & Telephone | April 18, 2012 Page 4 File No. 0000-001-00 File No. 18436-007-00 Geologic conditions along the previously proposed dam axis were described as consisting of diorite bedrock at each proposed abutment. Overburden was reported as consisting of boulders, peat and sand up to 36 inches deep between the abutments. High areas were inferred to be bedrock “knobs” with a thin (10 to 18 inches) soil layer consisting of peat and sand. The inlet delta was described as being composed of rounded to subrounded well graded gravel with fine to coarse sand. The material was reported as a good concrete aggregate source. Both powerhouse sites were described as being on an “inactive floodplain terrace” that abuts a steeply sloping surface composed of diorite bedrock. The terrace deposits observed in hand-dug holes were reported to consist of clean sand. Cobbles and gravelly layers were encountered below the upper sand horizons or observed in the river bank. In the 1994 and 1995 studies, a total of nine borings were completed in the vicinity of the dam and intake structure. Two hand-dug test pits were excavated in 1994 to a maximum depth of 7 feet. Eight shallow hand holes were completed in 1995 to maximum depths of 36 inches below the ground surface. The four borings completed in 1994 (CD-1, CD-2, CD-3A and CD-3B) were completed in material described as diorite bedrock to a maximum depth of 15 feet below the ground surface. Glacial deposits encountered in the explorations ranged from less than 1 to approximately 9 feet thick before terminating at the bedrock surface. Two excavated test pits were completed on the right bank abutment to a maximum depth of 3.5 feet. Glacial deposits consisting of silty sand, gravel, cobbles and boulders were encountered before reaching practical refusal and without encountering bedrock (A -Pit and B-Pit as shown on Figure 2). Bedrock was described as diorite. Five borings completed in 1995 by R&M Engineering were completed to a maximum of 16 feet below the ground surface or the bottom of the lake. Five feet of silty sand was encountered in boring DH-1, completed near a deep hole near the outlet of the lake. About 6.5 feet of silty sand, silt or cobbles were encountered in DH-2 before encountering bedrock. The boring was advanced a maximum of 4.5 feet into bedrock. About 15 feet of soil, including material described as “Glacial Till” or “Sand with Glacial Till,” was encountered in boring DH-3. The boring advanced about 1.5 feet into bedrock described as diorite. In boring DH-4, about 4.6 feet of sandy silt was encountered overlying about 1.6 feet of “Glacial Till” before terminating on bedrock. There was 1 foot of organic soil overlying bedrock encountered in DH -5. The boring was advanced 1.5 feet into bedrock. SITE RECONNAISSANCE General A site reconnaissance was completed by GeoEngineers on September 27, 2011. The weather was sunny with temperatures ranging from the low 40s to upper 50s (F). Travel to the site was accomplished by helicopter, which allowed us to complete an aerial reconnaissance of the lake perimeter, the slope between the powerhouse and the dam site and provided access to the dam and powerhouse sites. Alaska Power & Telephone | April 18, 2012 Page 5 File No. 0000-001-00 File No. 18436-007-00 Dam and Lake Area The proposed dam site is located on the west side of Connolly Lake. The ground surface is irregular and covered by moss, grasses, shrubs and generally widely spaced, low growing conifers. Boulders are present across most of the surface, although bedrock crops out along the banks of the outlet stream and along portions of the lake at the water level. The rock consists of a coarse -grained igneous rock composed of feldspar, quartz, hornblende and mica, consistent with mapped diorite or granodiorite. Steep rock bluffs adjacent to the lake typically have significant accumulations of talus consisting primarily of boulder-sized rock, consistent with mapping by March (1982). These are primarily located along the east and south sides of the lake. Powerhouse Site The proposed powerhouse site is located on an elevated terrace about 10 feet above the existing channel (see Figure 3). The terrace is tree covered with an understory of consisting of ferns, devils club and shrubs. The upstream edge of the terrace is presently on the inside bend of the Chilkoot River, but towards the downstream end, the main channel is directed into and along the terrace . A high flow channel, occupied by water at the time of our visit, was present along the toe of the terrace on the inside of the point bar. Based on available topographic mapping, aerial imagery and published geologic mapping, the terrace has been located along a relatively straight segment to a transition between the inside and the outside of a bend. The channel can be characterized as a braided, sediment rich system that is prone to avulsion and channel migration. The power house site could potentially be affected by either or both processes and mitigation alternatives to address those issues should be evaluated. The river has shifted since the late 1940s when the main channel of the river was flowing parallel to the left (east) bank where the terrace was located. Based on aerial photographs in the early 1970s (U.S. Air Force, 1972), the left bank was fairly linear, though it appears that a bend in the channel was developing such that flows would directly impinge on the terrace. In the photographs from the 1990s provided to us by AP&T, the edge of the terrace has a curvilinear shape in plan view. It appears that perhaps tens of feet of erosion has occurred along the bank, and the downstream edge of the terrace is located along the outside of a bend. Based on review of historical maps and aerial photographs, it appears that the river has migrated significantly and is likely to continue shifting due to the influx of sediment from valley walls and eroded by the river from older alluvial and colluvial deposits. The bedrock that crops out in the area will resist erosion, but the terrace deposits are susceptible to erosion. The western side of the valley appears to be underlain by older alluvium, colluvium and alluvial fan deposits, consistent with general mapping by March (1982) that can be eroded and contribute to the bedload. Granitic rock with veins or possible inclusions of metamorphic rock was observed east of the powerhouse site. The outcrops were observed in along bluffs at the slope break and at or upslope of the toe of the slope that descends to the terrace. The slope ascending to the east is inclined at 50 to 70 percent, with prominent rock outcrops projecting from the slope. It was not possible to identify bedrock outcrops in the aerial photographs taken of the site in the early 1990s. Alaska Power & Telephone | April 18, 2012 Page 6 File No. 0000-001-00 File No. 18436-007-00 Penstock The proposed penstock alignment underlies the steep valley wall that has at least two prominent benches as can be seen in the plan view in Figure 1 and the profile shown in Figure 4. Bedrock observed during the aerial reconnaissance appears to be granitic rock, similar to that seen at the dam site and in the vicinity of the powerhouse. Steep boulder covered slopes were also observed, consistent with reporting by R&M Engineering. CONCLUSIONS AND RECOMMENDATIONS GENERAL From a preliminary engineering geologic perspective, the proposed Connolly Lake project appears to be feasible for hydropower development. Geologic conditions we observed appear to be consistent with those reported by R&M Engineering. The possibility of a fault or shear zone that crosses the penstock alignment will need to be evaluated, as described below. Bedrock appears to be present at or near the ground surface along the proposed alignment of the dam. Bedrock is also present at or near the ground surface in the slope ascending from the river terrace to the east. The river system is actively migrating and has, in our opinion, a high potential during the anticipated life of the project to cause erosion of the terrace where the powerhouse and switchyard are planned, and could affect the fill for the planned bridge on the west (right) bank of the river. Preliminary Recommendations for the Dam Overburden consisting of soil and boulders will need to be removed to prepare the bedrock subgrade for the dam fill. Borings completed by others are located near the southern end of the currently planned dam location and encountered bedrock at relatively shallow depths. Overall, the overburden appears to be less than 10 feet thick, with an estimated average of about 5 feet in areas where glacial deposits are present. The boulders range from 1 to potentially 10 feet or more in diameter and may need to be broken into manageable sizes using mechanical means, non-explosive methods or by blasting. Once broken, it may be possible to re-use the material for fill. It is anticipated that a keyway will need to be excavated into the stripped bedrock surface to key in backfill. Excavation of the keyway will require controlled blasting to loosen the rock. Preliminary Recommendation for the Powerhouse Depending on anticipated bearing loads, the life cycle of the proposed plant and the subsurface conditions at the terrace, it may be possible to found the power plant on alluvial deposits where it is presently planned (see Figure 3). Siting of the powerhouse will also need to consider the potential for migration of the Chilkoot River. From that perspective, it may be desirable to found the powerhouse on bedrock. It may also be feasible to construct the power plant in the horizontal gallery planned for the penstock (as has been completed at a number of installations in Norway ). It is anticipated that armoring the bank adjacent to the powerhouse will be required to protect the powerhouse and switchyard as well access and other facilities. Alaska Power & Telephone | April 18, 2012 Page 7 File No. 18436-007-00 Preliminary Recommendation for the Penstock It is anticipated that the nearly horizontal portion of the penstock will be constructed using conventional drill and blast methods or perhaps by using a tunnel boring machine (see Figure 4). The alignment of the inclined portion of the penstock completed with unlined rock will need to consider the gradient of the Connolly Creek valley in combination with other factors using the guidance developed by Bergh-Christensen and Dannevig (1971): ܮൌሺߛݓ∙ܪ∙ܨሻ ሺߛ ∙ cosሺߚሻሻ Where: ■ ܮ = the shortest distance between the surface and the point studied, ■ ܪ = the static water head at the point studied, ■ ߛݓ = the density of water, ■ ܨ = the factor of safety, ■ ߛ = the density of rock, and ■ ߚ = the average slope of the valley wall. Profiles should be constructed perpendicular to the contour lines and protrusions in the valley slope should be ignored (Broch, 1982). We have completed a preliminary evaluation of the overburden requirements for the project based on the profile shown in Figure 4. We ignored protrusions and roughness in the valley wall and assumed an average slope of approximately 25 degrees for the valley wall, a unit weight of water of 62.4 pounds per cubic foot (pcf), a unit weight of rock of 170 pcf and a factor of safety of 1.5 for planning purposes. This results in a penstock inclined steeper than 45 degrees and a minimum distance of approximately 1,330 feet from the average slope for the valley wall at the tie-in between the raised bore and the tunnel (see Figure 4). We understand that the lower gallery will be tied to the outlet from Connolly Lake using raised bore method. Since the pilot hole will be drilled at an angle, the sag of the drill stem in the hole should be considered during design and construction of the penstock. Depending on the dimensions of the raised bore, an enclosed air surge chamber could be constructed to mitigate rapid changes in hydrostatic pressures in the penstock. This would likely be constructed using conventional drill and blast methods. The granitic rock excavated from the gallery using drill and blast methods should be suitable for use as riprap or processed and used for road surfacing or structural fill. Alaska Power & Telephone | April 18, 2012 Page 8 File No. 0000-001-00 File No. 18436-007-00 Future Work The following are geotechnical studies that should be completed to address feasibility issues with respect to the project: 1. Complete geophysical studies to evaluate the potential presence of a shear or fault zone near Station 48+00 along the penstock alignment. We suggest using seismic refraction along a line approximately 1,000 feet long. This line would also be used to evaluate the thickness of sediments overlying bedrock along the ridge top. 2. Complete geophysical studies to evaluate the depth to bedrock in the vicinity of the proposed powerhouse. We suggest using seismic refraction along a line approximately 500 feet long. 3. Complete a geophysical study along the axis and upstream (lake) side of the proposed dam to help identify potential undulations in the bedrock surface underlying the glacial deposits. Three to four lines would be completed totaling about 1,850 lineal feet. 4. Complete one boring approximately 400 feet deep angled down to the east at an inclination of about 45 degrees to evaluate the potential for a shear zone near Station 48+00 along the penstock alignment. This could be completed after the geophysical survey is performed and the data is reduced to optimize location and depth. 5. Complete one boring approximately 50 feet below the ground surface to evaluate subsurface conditions of the terrace deposits in the vicinity of the powerhouse. 6. Complete at least one boring up to 50 feet below the ground surface along the axis of the dam and one up to 50 feet below the ground surface near the toe of fill on the upstream (lake) side, 7. Complete one vertical boring to a depth of 200 feet circa Station 54+00 along the penstock alignment to evaluate thickness of any overburden and to help characterize the rock. 8. Complete packer tests to evaluate permeability of rock and for hydraulic jacking. 9. Revise the overburden requirements of the raised bore, taking into consideration irregularities in the valley wall slope along Connolly Creek. Additional efforts for final design should include: 1. Complete subsurface evaluations for thickness of soil deposits in low-lying areas (e.g. in muskegs) where fill for the dam is proposed. This may consist of peat probes or shallow hand auger explorations. 2. Complete additional borings in the vicinity of the proposed dam to facilitate design. 3. Complete an oriented camera survey of the pilot bore hole to confirm geologic conditions. 4. Complete hydraulic jacking testing to evaluate the in-situ stress and susceptibility for hydraulic fracturing. It may be possible to complete this in the pilot bore hole. This requires installing packers and pressurizing the sealed segment of pipe. Pressures are typically increased to greater than the anticipated in-situ stresses to evaluate how the rock responds to pressurization and depressurization and to gain a better understanding of the in-situ stresses to evaluate the bore path. 5. Develop geotechnical criteria for construction of the siphon. Alaska Power & Telephone | April 18, 2012 Page 9 File No. 0000-001-00 File No. 18436-007-00 6. Complete laboratory analyses of rock samples to evaluate strength, Cherchar hardness and petrographic analyses for use in selection of bits for boring equipment. 7. Evaluate the development of seiche from seismically induced failure of colluvial (boulder) slopes along the margin of Connolly Lake. 8. Evaluate the potential for channel migration in the vicinity of the powerhouse, switchyard, the bridge, other facilities and in areas where the access road may be impacted. 9. Complete hydraulic analyses for scour in the vicinity of the bridge in support of design. 10. Design bank stabilization for the powerhouse area, bridge and access road areas. 11. Evaluate bracing for the steel liner for the penstock tunnel. 12. Evaluate site-specific seismic design criteria. LIMITATIONS The opinions and preliminary recommendations presented in this report are based on review of limited information and on a relatively brief reconnaissance of portions of the project area. The information presented herein is intended for feasibility assessment only and is not adequate for design. Further geotechnical site studies and subsurface explorations will be needed before developing final design recommendations. REFERENCES Beikman, H.M., comp., 1975, Preliminary geologic map of southeastern Alaska: U.S. Geological Survey Miscellaneous Field Studies Map 673, 2 sheets, scale 1:1,000,000. Bergh-Christensen, I., and Dannevig, N.T., 1971, “Engineering Geological Consideration for an Unlined Pressure Shaft at Mauranger Hydro Power Station”, Unpublished report in Norwegian, Geoteam A/S, Oslo, Norway; 1971. Broch, Einar, 1982, “The Development of Unlined Pressure Shafts and Tunnels in Norway ”, Wittke, W. (ed): “Rock Mechanics: Caverns and Pressure Shafts”, A. A. Balkema, Rotterdam, Netherlands; 1982. Dusel-Bacon, Cynthia, Brew, D.A., and Douglass, S.L., 1996, Metamorphic facies map of Southeastern Alaska; distribution, facies, and ages of regionally metamorphosed rocks: U.S. Geological Survey Professional Paper 1497-D, p. 1-42, 2 sheets, scale 1:1,000,000. March, G.D., 1982. Photointerpretive map of the surficial geology of the Skagway B-2 quadrangle, Alaska. 1:63,360. Alaska Division of Geological and Geophysical Surveys, Open-File Report 161. Plafker, George, Gilpin, L.M., and Lahr, J.C., 1994. Neotectonic map of Alaska, (Plate 12) in Plafker, George, and Berg, H.C., eds., Geology of Alaska, Volume G-1 of the Geology of North America. Geological Society of America. Boulder, Colorado. Alaska Power & Telephone | April 18, 2012 Page 10 File No. 0000-001-00 File No. 18436-007-00 Rogers, Garry C., and Horner, Robert B., 1991. An overview of western Canadian seismicity, in Slemmons, D.B, Endahl, E.R., Zoback, M.D., and Blackwell, D.D., eds., Neotectonics of North America. Decade Map Volume 1. Geological Society of America. Boulder, Colorado. U.S. Air Force, 1972. Aerial photograph, Frame AF-71-40-1E R-2 194. 30,000 ft above sea level. July 3, 1972. Wesson, R.L., Boyd, O.S., Mueller, C.S., Bufe, C.G., Frankel, A.D., and Petersen, M.D., 2007. Revision of time-independent probabilistic seismic hazard maps for Alaska. U.S. Geological Survey Open-File Report 2007-1043, 33 p. Yehle, Lynn A., and Lemke, Richard W., 1972. Reconnaissance engineers geology of the Skagway area, Alaska, with emphasis on evaluation of earthquake and other geologic hazards. Open-File Report 72- 0454, 108 p. BIBLIOGRAPHY Brew, D.A., and Ford, A.B., 1998, The Coast Mountains structural zones in Southeastern Alaska; descriptions, relations, and lithotectonic terrane significance, in Gray, J.E., and Riehle, J.R., eds., Geologic studies in Alaska by the U.S. Geological Survey, 1996: U.S. Geological Survey Professional Paper 1595, p. 183-192. Brew, D.A., 1995, The Coast Mountains Complex of Southeastern Alaska and adjacent regions, in U.S. Geological Survey, Stratigraphic notes, 1994: U.S. Geological Survey Bulletin 2135, p. 21-28. Brew, D.A., 1988, Latest Mesozoic and Cenozoic igneous rocks of southeastern Alaska; a synopsis: U.S. Geological Survey Open-File Report 88-405, 29 p. Brew, D.A., and Ford, A.B., 1985, Preliminary reconnaissance geologic map of the Juneau, Taku River, Atlin, and part of the Skagway 1:250,000 quadrangles, southeastern Alaska: U.S. Geological Survey Open-File Report 85-395, 23 p., 1 sheet, scale 1:2,500,000. Brew, D.A., and Morrell, R.P., 1980, Intrusive rocks and plutonic belts of southeastern Alaska, U.S.A.: U.S. Geological Survey Open-File Report 80-78, 34 p Brew, D.A., and Morrell, R.P., 1980, Preliminary map of intrusive rocks in southeastern Alaska: U.S. Geological Survey Miscellaneous Field Studies Map 1048, 1 sheet, scale 1:1,000,000. Buddington, A.F., and Chapin, Theodore, 1929, Geology and mineral deposits of southeastern Alaska: U.S. Geological Survey Bulletin 800, 398 p., 2 sheets, scale 1:500,000. Combellick, R.A., and Long, W.E., 1983, Geologic hazards in southeastern Alaska: an overview: Alaska Division of Geological & Geophysical Surveys Report of Investigation 83-17, 17 p. Gehrels, G.E., and Berg, H.C., 1992, Geologic map of southeastern Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map I-1867, 24 p., 1 sheet, scale 1:600,000. Alaska Power & Telephone | April 18, 2012 Page 11 File No. 0000-001-00 File No. 18436-007-00 Gray, J.E., and Riehle, J.R., eds., 1998, Geologic studies in Alaska by the U.S. Geological Survey, 1996: U.S. Geological Survey Professional Paper 1595, 200 p. U.S. Geological Survey, 1995, Stratigraphic notes, 1994: U.S. Geological Survey Bulletin 2135, 28 p. We appreciate the opportunity to be of service to you on this project and look forward to working with you on this and future projects. Please contact Craig Erdman or Galan McInelly at 425.861.6000 if you have questions or comments regarding this report. Sincerely, GeoEngineers, Inc. Craig F. Erdman Galan W. McInelly Senior Engineering Geologist Principal, Engineering Geologist CFE:GWM:lc Copyright© 2012 by GeoEngineers, Inc. All rights reserved. List of Figures: Figures 1 through 3. Site Plan Figure 4. Penstock Profile Disclaimer: Any electronic form, facsimile or hard copy of the original document (email, text, table, and/or figure), if provided, and any attachments are only a copy of the original document. The original document is stored by GeoEngineers, Inc. and will serve as the official document of record. FEET 0120 120 W E N S Notes 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. can not guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Reference: CAD files "OG R&M.dwg, General arrangement.dwg and Topo Supplemental.dwg, ga3.dwg provided by Figure 3 Connolly Lake Hydro Project Connolly Lake, Alaska Site Plan Notes 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. can not guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Reference: CAD files "OG R&M.dwg, General arrangement.dwg and Topo Supplemental.dwg, ga3.dwg provided by Figure 4 Connolly Lake Hydro Project Connolly Lake, Alaska Penstock Profile FEET 0500 500 HORIZONTAL SCALE: 1"= VERTICAL SCALE: 1"= VERTICAL EXAGGERATION: 500' 500' 1X APPENDIX B AP&T STREAMFLOW DAYA CONNELLY CREEK AT CONNELLY LAKE OUTLET DAY OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP 1 30.8 22.5 12.0 10.3 7.9 4.7 0.6 7.4 58.2 101.6 110.4 66.7 2 26.4 16.1 8.1 12.1 17.3 6.4 0.6 7.8 67.6 85.6 99.8 73.2 3 23.5 11.9 7.1 9.9 17.1 7.0 0.5 7.8 68.2 75.5 107.7 70.6 4 22.2 8.5 7.6 10.1 13.2 6.3 0.4 7.2 60.6 73.3 99.9 96.4 5 20.5 6.8 13.7 9.4 10.7 5.4 0.2 7.3 56.7 77.5 94.6 91.7 6 21.5 7.7 11.6 8.3 9.6 5.2 0.2 8.2 71.7 77.6 117.0 87.3 7 26.3 8.8 8.2 10.7 7.7 4.5 0.2 8.8 83.8 100.7 171.1 83.6 8 25.2 8.7 9.0 17.1 6.6 5.1 0.2 11.4 107.4 120.6 164.1 98.8 9 22.3 10.6 11.2 14.5 5.6 7.0 0.3 10.9 95.5 113.1 148.1 110.4 10 21.6 10.4 7.1 11.4 4.9 7.1 0.3 9.9 79.8 144.1 118.3 90.1 11 18.7 15.3 5.8 13.4 4.4 6.3 0.3 12.2 74.9 120.3 96.5 64.0 12 19.4 16.0 7.5 14.9 5.6 5.1 0.6 13.5 78.3 94.3 86.8 60.7 13 19.6 14.9 5.5 13.5 5.7 4.1 0.9 12.1 69.6 95.3 87.4 72.9 14 18.8 13.2 4.4 10.2 5.2 3.3 1.4 10.0 60.7 109.6 99.3 100.6 15 21.5 9.4 4.6 8.4 4.9 2.7 2.1 9.1 57.3 119.6 105.6 81.0 16 23.0 10.3 5.2 7.7 5.7 2.3 2.8 8.4 57.5 117.0 104.3 71.7 17 19.3 11.4 4.5 7.8 5.4 1.9 3.7 7.7 71.0 104.6 98.2 71.9 18 28.0 10.3 5.5 8.3 4.5 1.9 4.6 9.1 80.6 111.6 114.4 69.8 19 26.7 12.2 9.6 8.8 4.2 1.8 5.4 10.0 88.4 127.2 106.3 59.1 20 20.8 19.8 7.5 9.4 4.4 1.9 5.8 11.7 93.1 146.1 93.2 53.7 21 16.0 4.6 8.3 9.9 7.7 1.7 6.9 14.5 121.8 147.9 87.1 65.1 22 17.5 5.1 13.7 12.1 7.1 1.5 6.1 22.2 129.0 133.6 84.0 77.6 23 18.8 5.4 16.4 11.0 5.8 1.3 5.5 26.1 168.1 127.4 88.8 93.0 24 16.9 5.5 15.8 9.8 4.9 1.3 5.2 28.0 194.0 118.4 86.5 97.5 25 22.2 4.5 14.3 10.9 3.8 1.4 4.8 35.3 190.8 111.7 85.5 75.4 26 24.2 4.7 12.9 10.4 3.6 1.4 4.7 35.9 164.9 128.2 88.3 77.6 27 20.6 3.8 13.5 8.9 6.1 1.4 5.3 48.2 139.2 153.4 85.0 109.4 28 17.6 5.9 11.2 7.8 6.6 1.2 5.8 48.5 110.2 146.1 106.2 105.0 29 18.4 6.1 10.5 6.5 5.5 1.0 6.9 42.0 102.4 121.8 101.2 80.7 30 18.7 7.3 10.1 6.5 0.7 7.3 43.6 111.8 110.1 80.1 68.6 31 47.0 9.3 7.5 0.7 52.9 117.7 71.3 AVG 22.4 9.9 9.4 10.2 7.0 3.3 3.0 19.0 97.1 113.9 102.8 80.8 CONNELLY CREEK AT CONNELLY LAKE OUTLET, WATER YEAR 2012 AVERAGE DAILY FLOW, CFS DAY OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP 1 50.8 19.8 8.4 11.1 6.5 9.4 4.8 8.0 115.7 140.4 149.3 2 43.3 18.7 8.3 12.6 7.2 8.1 4.6 11.1 97.0 145.2 143.1 3 39.4 18.6 8.5 10.7 9.6 6.6 4.0 15.2 79.1 130.4 139.5 4 36.4 20.4 8.3 9.6 9.0 5.6 3.4 28.0 84.7 115.9 124.2 5 34.5 24.5 8.3 8.6 7.7 4.8 3.1 45.0 87.1 100.1 115.2 6 35.4 20.5 8.4 9.1 6.6 4.2 2.5 38.7 77.6 87.7 114.4 7 38.5 17.0 7.8 9.5 7.3 3.9 2.3 33.3 75.6 82.4 117.2 8 38.4 15.5 7.8 9.3 9.8 3.4 3.0 31.0 79.3 110.4 123.9 9 37.4 13.7 9.5 8.3 10.2 4.6 8.5 30.1 87.3 128.4 124.1 10 37.2 14.1 10.4 7.5 18.3 5.5 8.3 30.3 109.7 106.3 105.2 11 35.4 14.6 10.3 6.9 15.8 5.7 7.5 34.1 126.4 95.6 109.4 12 32.1 14.9 10.7 6.5 11.0 5.0 6.1 39.4 143.1 92.5 121.3 13 34.3 14.3 12.7 6.9 9.0 4.4 4.8 48.0 133.4 101.3 130.7 14 41.6 15.7 13.1 9.1 10.3 4.0 3.9 64.0 108.5 101.3 130.5 15 38.4 17.3 14.8 13.7 12.4 3.9 3.4 67.8 124.7 98.7 134.6 16 36.8 15.2 13.3 12.0 11.0 3.5 3.6 53.7 162.4 112.2 17 32.3 13.7 10.7 16.9 10.0 3.3 4.6 43.6 190.3 128.8 18 30.2 11.8 9.1 15.0 9.8 2.9 4.4 50.5 177.0 133.9 19 31.0 11.1 8.4 11.5 10.0 2.8 3.9 50.0 180.3 119.6 20 24.1 10.2 8.2 10.0 10.7 2.5 3.0 38.0 190.5 110.0 21 21.8 9.9 7.7 10.0 10.1 2.4 2.5 31.7 174.8 126.4 22 21.1 10.2 7.7 9.1 8.9 2.4 2.4 29.9 168.1 125.0 23 20.4 10.1 8.2 9.3 8.2 2.5 2.5 31.5 148.7 121.9 24 19.3 9.6 8.8 10.0 8.3 2.9 3.3 37.8 153.0 120.3 25 18.6 9.5 8.2 9.3 7.1 4.3 7.2 47.3 224.7 114.8 26 17.7 9.2 7.5 10.3 6.0 5.4 6.9 57.6 211.5 102.8 27 17.4 8.8 7.7 9.7 5.8 4.8 5.9 73.1 189.4 99.6 28 16.0 8.6 8.5 8.6 7.3 4.2 5.3 92.9 154.4 117.1 29 15.6 7.9 8.7 8.3 3.7 4.3 115.6 132.4 136.0 30 16.6 8.8 10.2 7.5 5.3 4.7 129.8 123.6 150.9 31 21.2 11.1 7.0 4.9 123.5 155.8 AVG 30.1 13.8 9.4 9.8 9.4 4.4 4.5 49.4 137.0 116.5 125.5 CONNELLY CREEK AT CONNELLY LAKE OUTLET, WATER YEAR 2013 AVERAGE DAILY FLOW, CFS