Electrical Power for Valdez and the Copper River Basin-1981

2. Biologicala. Vegetation:,r-.Hydroelectric: No direct vegetative impacts would be associated withthe underground penstock, however, the tailings from the tunnel would berenwved from the portal and dumped into a canyon located to the east.The material would De dumped over a near vertical cliff and cover an areaof a dense alder stand with devils Club, red elderberry and salnlonberryunderstory at the bottom of the canyon. Revegetation of the impactedarea witn simi lar species proDably WOuld not occur for nlany years due tothe different nature of the tunnel material and the existing disposalsite material. Alternative methOdS and sites for tailings disposal havebeen eliminated mainly because of physical constraints. Roadconstruction to the tunnel portal would require consideraole excavationinto the mountain side which would cause esthetic degradation and greatlyincrease the possibilities of erosion. No alternative sites are near thetunnel portal with gradual slopes that could contain the tailings. Theproposed disposal site does not drain into either Allison Creek orSolomon Creek and any increased sedimentation would not affect anadromousfish.The above-ground penstock would require a 2,8S0-foot right-of-wayapproximately 10 feet wide. The lower portion of the proposed right-ofwayconsists of a dense alder thicket while the upper portion of theright-of-way is either unvegetated or consists of alpine tundra. Alllarge bushes and snrubs would be removed, with the low ground coverremalnlng. Sixteen concrete anchor blocks and 190 concrete support piersWould be utilized to support the penstock above ground. In these areasall vegetation would be cleared. In the exposed areas where thevegetative cover would be removed, revegetation with suitable specieswould occur upon project completion.The transmission line would impact tne Sitka spruce/mountain hemlockforest located along the 3.S-mile long, 50-foot wide corridor. Theentire line would require essentially continuous clearing regardless ofthe exact alignment. Small shrubs and bushes would remain and all othermaterials would be burned, chipped, or left in place as determined by theU.S. Forest Service which is the administrator of the land. The terrainexclUdes establiShing the transmission line next to tne Dayville Road(refer to Photo on page ii of the Feasibility Report and thetopographical map. Plate D-A-3 in Appendix D). Although the Trans-AlaskdPipeline Corridor has been clearcut, Alyeska Pipeline Service isreluctant to allow any construction tnat would hinder their access alongthe corridor. The tentative route would De as near the Dayville Road aspossible.The powerhouse would only occupy an area large enough to house the twoturbines. The proposed powerhouse site is in an area co~ered mainly withalder with a portion of the site having been previously cleared. Aproposed mitigative tailrace leading to Port Valdez would cross an areawhich has been cleared and covered with gravel and supports littlevegetation.E I S- 11