OCR Text |
Show Dam outlet works from 820 to 1,105 c. f. s., constructing a 78- inch diameter pipeline 3,500 feet long from the end of the outlet works to the alternative tunnel portal, modifying Docs Diversion Structure and Feeder Pipeline as described in paragraph 2_ below, decreasing the length of the tunnel about 1,000 feet, flattening the grade of the tunnel to provide the additional head required- thus increasing the minimum tunnel diameter needed from 7 to 8.5 feet, and eliminating the headworks of the Strawberry Aqueduct at the Upper Stillwater Reservoir. It has been estimated that this alternative would cost approximately $ 1 million more than the proposed plan. The beneficial environmental effects of this alternative over the proposed plan are described in paragraph 2_ below. The adverse effects include the following: ( l) The pipeline to Stillwater Tunnel would be constructe< through dense timber and would require removal of a strip of trees and vegetation over 50 feet wide and 3,000 feet long and, although the strip would be reseeded after construction, many years would be required before the new vegetation would be indistinguishable from the adjacent area. ( 2) The pipeline would traverse a planned camping area and could adversely affect the design of the campgrounds. ( 3) The tunnel portal would be on a gentle forested slope, so that an open cut about 200 feet long and 100 feet wide would be required. The resulting construction scar would be highly visible from the surrounding area. Although smoothed and reseeded, it would take several years for the scars to be obliterated. { k) It would be more difficult and would cost more to transport the tunnel spoil to the reservoir basin for disposal than it would under the proposed plan. Because of the surrounding vegetation and proposed campgrounds, a suitable disposal area near the tunnel portal would be difficult to locate as an alternative. ( 5) The required construction access road would also cause the removal of additional trees and vegetation. Originally it was assumed that power requirements for construction and operation of the Stillwater Tunnel would be supplied by Moon Lake Electric Association, which has contracted to furnish power to the outlet portal of the tunnel. However, recent 578 |