Blue Lake Hydroelectric Project (FERC No. 2230) Expansion Environmental Analysis

Transcription

1 United States Departme nt of Agriculture Forest Service Alaska Region Tongass National Forest (907) Blue Lake Hydroelectric Project (FERC No. 2230) Expansion Environmental Analysis Dear Planning Participant: September 1, 2011 The Forest Service, Tongass National Forest,, is seeking your involvement regarding an application submitted by the City and Borough of Sitka to expand a hydroelectric facility for generating power at Blue Lake on Baranof Island, Alaska. The purpose of this letter is to inform you of the project and request your comments on the proposal as part of the National Environmental Policy Act (NEPA) scoping process. The environmental analysis will provide the responsible official, Forrest Cole, Forest Supervisor of the Tongass National Forest with enough information to make a decision. Scoping is the first step in public participation for the project planning efforts. The purpose of scoping is to identify potential issues, concerns, and opportunities associated with the proposed project. WE NEED YOUR HELP to make sure we consider all the issues and affects that are of concern to you or your communities. Please examine the enclosed information and map, and send us comments that will help us to develop a comprehensive and sound environmental evaluation. We have provided forms on which to write your comments, or you can use your own format to write, call, or fax us your comments. It is important that your comments identify specific issues to be considered, places within the project area that are important, or suggestions to improve or change the project, including your comments for alternatives. Remember, in order to be most useful to our analysis COMMENTS SHOULD BE RECEIVED BY September 30, We look forward to your comments and participation in the process. Your views are important to us. Public Scoping September 2011 The public is invited to provide comments and concerns on the proposed project. Public Comment Period Ends October 1, 2011 The public comment period lasts for 30 days from date of this scoping letter. All comments must be postmarked by October 1, 2011 Decision Notice and Finding of No Significant Impact Anticipated by November 15, 2011 Construction Begins CAROL A. GOULARTE District Ranger Anticipated by January 2012 USDA is an equal opportunity provider and employer. Caring for the Land and Serving People Printed on Recycled Paper

2 Purpose and Need The purpose of this project is for the to be responsive to an application for the use and occupancy of National Forest System lands. The City and Borough of Sitka (CBS) has petitioned to raise the dam at Blue Lake to generate additional electricity CBS s recent electrical load forecasts show a marked increase in electrical demand in the near future. Two primary factors have driven this increase: 1) fuel costs in Sitka over the past four years have nearly tripled, making electric heating economically preferable to oil heating and driving up electrical demand in locations with a choice between oil-based and electrical heat; and 2) constructed high energy-need industries in Sitka have added to overall electrical demand. These factors, weighed against CBS s existing electric generation capacity, predict an increase in expensive and polluting diesel generation within a few years unless hydroelectric generating capacity is increased. Key to CBS s planning is continued preference for hydroelectric generation to assure lower electrical rates and increased environmental acceptability when compared to use of diesel fuel, the only other current generation alternative.. Proposed Action The USDA, Forest Service, Tongass National Forest proposes to authorize the City and Borough of Sitka to construct, operate, maintain, and expand hydroelectric facilities at Blue Lake to provide power to the Municipality on Baranof Island. Authorization will occur through the issuance of a special use permit to CBS for a period concurrent with FERC License 2230 (~ 30 years). The project lies within the USGS Sitka A-4 and A-5 Quadrangle maps within the land descriptions below. Project Features Dam, Spillway and Intake Structure Power Conduit Fish Valve Unit Pulp Mill Feeder Unit Blue Lake Powerhouse Primary Transmission Line Map Locations Section 35 of T55S, R64E, Copper River Meridian. Sections 34 and 35 of T55S, R64E, Copper River Meridian. Section 34 of T55S, R64E, Copper River Meridian. Section 34 of T55S, R64E, Copper River Meridian. Section 34 of T55S, R64E, Copper River Meridian. Section 33 & 34 of T55S, R64E, Copper River Meridian; Section 4, 5 and 6 of T56S, R64E, Copper River Meridian; Section 1 of T56S, R63E, Copper River Meridian; Section 35 & 36 of T55S, R63E, Copper River Meridian. Blue Lake Hydroelectric Project (FERC No. 2230) Expansion, Environmental Analysis Scoping Information 2

3 Project description Proposed Dam Raising: It is the CBS s goal to raise the dam to the highest structurally feasible level because each foot of increased dam height would generate an additional 328 megawatt/hours per year (MWh/yr) of electricity. A dam height of El 425 would increase the Blue Lake Project average annual generation by 50 percent. Geologic and engineering evaluations have suggested that the existing dam could be raised to El 425, (a raise of 83 feet above the existing spillway elevation) and that the existing dam would be competent to serve as the base of any dam structure rising to that height. Intake Structure Modifications: If the existing intake location and structure were retained, water temperature at the intake, and hence in Sawmill Creek would be significantly colder than at present. In addition, CBS wishes to replace the current intake because of difficulty in maintaining it at a greater depth (possible only by divers) and to decrease the likelihood that construction-related contaminants and other inputs would compromise drinking water quality. The existing intake structure is located in an area that receives considerable overland runoff during rainstorms and snowpack melt. Because the intake is located at a juncture with the flat lake bottom, sediment and organic material tend to accumulate and impede the intake. Under the new design and location, the intake would be located on a steep slope, past which overland runoff material would continue without settling out. The existing intake gate would be replaced with a new fixed wheel intake gate located within a gate shaft and a bulkhead gate at the intake location. The new intake arrangement and gates would offer a more reliable seal than the existing gate. The existing intake gates will be decommissioned in the closed position and winch house would be removed from service. Dam Site Power Electrical Distribution Facilities: To operate the new gate winch, a 1400 ft-long dam site power distribution line would run from the FVU along the tunnel alignment to the Blue Lake Road, and would follow the Blue Lake road to the dam site. This line would be buried along its entire length eliminating the need for poles or other visible structures. Affected Reservoir Area and Energy Production: Inundated area of Blue Lake reservoir would increase by approximately 35 percent with a dam height of El 425. Energy would increase by 32,000 MWh per year or 50 percent. Federal lands would all be on USFS lands of the Tongass National Forest. Non-Federal lands are largely owned by CBS. New Powerhouse and Generators: The current proposal is to replace the existing powerhouse and two generators with a new powerhouse and three new generators. The new powerhouse, approximately 65 by 140 feet in area and 40 feet tall, would be located on Sawmill Creek s left bank about 20 yards downstream from the existing powerhouse. The new powerhouse would house three new Francis turbine-generators with installed capacities of approximately 5.3 MW each. The turbines would release water into an afterbay and then into Sawmill Creek via a tailrace similar to that at the existing powerhouse. Fish Valve Unit: The FVU turbine and generator will be replaced with a 1.0 MW turbine generator capable of supplying needed generation output and instream flow requirements at the higher water pressures resulting from increased head. Pulp Mill Feeder Unit: The PMFU and PMFU transmission line will be decommissioned because the turbine is not suited for the increased pressure. The new generators have been sized to utilize the water designated to the PMFU and replace the generation previously derived from the PMFU. The PMFU and PMFU transmission line have been removed from the proposed project boundary. Power Conduit: Due to the increased pressure associated with the dam raise, the steel liners at the portals of the power conduit must be lengthened. The existing lower penstock is 7 feet diameter. In order to decrease the pressure drop in this penstock a replacement 9-foot diameter penstock will be constructed between the lower portal and the new power house. Blue Lake Hydroelectric Project (FERC No. 2230) Expansion, Environmental Analysis Scoping Information

4 Surge Chamber: An underground 20 foot diameter surge chamber would be constructed near the lower portal. The surge chamber would be vented to the surface at about El 465. The surge chamber would be necessary to decrease water pressure in the power conduit resulting from load rejection and a consequent pressure spike which might damage the power conduit and generating equipment. The surge chamber would allow system operation at a higher average pressure and would improve the electrical frequency response of the Blue Lake Project. The surge chamber will be constructed from an adit located near the PMFU. Switchyard: New transformers will be installed in the location of the existing transformers next to the existing powerhouse. The switchyard would transform the generation voltage (12.47 kv) to transmission voltage (69kV) and would connect to the existing transmission line from the Green Lake powerhouse. Development of New Access and Dam Site Staging Facilities for Dam Raising: Dam raise construction would generally be done using cranes positioned on the right abutment and at the downstream base of the existing dam. Access would be primarily via existing roads with some upgraded road construction leading to the right abutment and staging areas. An approximately 1.5 acre construction staging area would be developed by leveling a hill just south and west of the current Blue Lake overlook to EL 462. This area would be leveled and supplied with an appropriately-sized gravel base to support dam raising equipment. Reusable spoils will be used on site. Organic material will be disposed of offsite. Relationship to the Forest Plan All management decisions on the Tongass National Forest must be consistent with the 2008 Tongass National Forest Land and Resource Management Plan (Forest Plan). The existing facility is located in a Municipal Watershed Land Use Designation (LUD), which provides protection of municipal water supplies in a manner that meets provisions of the Safe Drinking Water Act and State of Alaska Drinking Water Regulations and Water Quality Standards, in accordance with FSM 2542 and 36CFR Your Comments Please Participate! Scoping is a process by which the public and other agencies may take an active role in project development. To assist the Forest Service in identifying and considering issues and concerns on the Proposed Action, we invite you comments. Comments should be as specific as possible. YOUR COMMENTS SHOULD BE RECEIVED BY: September 30, 2011 Please send your comments to: Clay R. Davis,, FAX: Telephone: clayrdavis@fs.fed.us Blue Lake Hydroelectric Project (FERC No. 2230) Expansion, Environmental Analysis Scoping Information

5 Location of Proposed Action Blue Lake Hydroelectric Project (FERC No. 2230) Expansion, Environmental Analysis Scoping Information

6 Here are my scoping comments for the Blue Lake Hydroelectric Project (FERC No. 2230) Expansion Environmental Analysis: Due September 30, 2011 If you have no comments at this time, but wish to remain on the mailing list, please return this form with your name and address legibly filled out. IF WE DO NOT HEAR FROM YOU AT THIS TIME, YOUR NAME MAY BE REMOVED FROM THE PROJECT MAILING LIST. Your Signature: Print Your Name and Address: Blue Lake Hydroelectric Project (FERC No. 2230) Expansion, Environmental Analysis Scoping Information 6

7 Mail or hand-deliver comments to: Clay R. Davis Attn: Blue Lake Expansion Telephone: (907) FAX: (907) Fold along line, staple, stamp, and mail FROM: Place Stamp Here (return address required) TO: Clay R. Davis Attn: Blue Lake Expansion Blue Lake Hydroelectric Project (FERC No. 2230) Expansion, Environmental Analysis Scoping Information 7

8 Please Participate! To assist the Forest Service in identifying and considering issues and concerns on the Proposed Action, comments during scoping should be as specific as possible. STAY IN TOUCH STAY INVOLVED Blue Lake Hydroelectric Project (FERC No. 2230) Expansion, Environmental Analysis PROPOSED PROJECT: Expand a hydroelectric facility for generating power at Blue Lake, Baranof Island, Alaska. Details inside FOR FURTHER INFORMATION CONTACT: Clay R. Davis Telephone (907) clayrdavis@fs.fed.us COMMENTS DUE: September 30, 2011 District Ranger Blue Lake Hydroelectric Project (FERC No. 2230) Expansion, Environmental Analysis Scoping Information 8