Vantage to Pomona FEIS Index 34 - Laserfiche WebLink

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Vantage to Pomona Heights Executive Summary 230 kV Transmission Line Project FEIS October 2016 PAGE ES-iii As proposed by Pacific Power, most of the proposed transmission line would be constructed on H-frame wood pole structures between 65 and 90 feet tall and spaced approximately 650 to 1,000 feet apart depending on terrain. The H-frame structures would typically be used in open flat to gently rolling terrain. In developed or agricultural areas, single wood or steel monopole structures would be used. The single pole structures would be between 70 and 110 feet tall and spaced approximately 400 to 700 feet apart. The ROW width required for the H-frame structure type would range between 125 to 150 feet. The ROW width for the single pole structure would range between 75 to 100 feet. Dead-end or angle structures would require additional ROW width to accommodate guy wires and anchors. For the Columbia River crossing below the Wanapum Dam or below the Priest Rapids Dam (depending on the Action Alternative), steel lattice structures approximately 200 feet tall would be used to safely span the approximate 2,800-foot crossing. The Project would also require upgrades to the Pomona Heights Substation located east of Selah and the Vantage Substation located east of the Wanapum Dam. Construction techniques considered in this FEIS are based on industry standards and methods used on other transmission line projects. ENVIRONMENTAL IMPACTS Potential environmental impacts of the Action Alternatives are related to: vegetation and special status plants; general wildlife and Greater Sage-Grouse (Centrocercus urophasianus; Sage-Grouse) and their habitat; agricultural, residential, and military land uses; recreational activities and the displacement of recreational land uses; the visibility of the transmission line and roads from sensitive viewers; scenic views and changes in natural scenery; potential incompatibility with the visual character of existing development; transportation and roadway systems; archaeological resources and properties listed on the National Register of Historic Places (National Register); sensitive Native American areas and uses; communities and landowner economic effects; public health and safety; air quality, climate and global warming; and Special Management Areas. Impacts are analyzed considering the implementation of Required Design Features (RDFs) and other mitigation measures where applicable as discussed in Chapter 2 and Chapter 4. Vegetation Long-term disturbance to vegetation would be similar for all the Action Alternatives ranging from Alternative G with the least amount of disturbance (139.7 acres) to Alternative A with the most amount of disturbance (210.1 acres). The Agency Preferred Alternative (NNR Alternative – Overhead Design Option) would result in 163.5 acres of long-term disturbance. The Agency Preferred Alternative would result in moderate impacts to 28.6 miles of vegetation, primarily associated with long-term disturbance to sagebrush/perennial grassland communities. The scope and intensity of vegetation impacts would fall near the middle range of all Action Alternatives considered. The Agency Preferred Alternative would cross 8.4 miles of Washington Natural Heritage Program (WNHP) special status plant species polygons, 2.7 miles of special status plant occurrences found during Project-specific surveys, and no WNHP priority ecosystems. Of the nine Project Action Alternatives, the Agency Preferred Alternative has among the lowest impacts to special status plant species and potential special status plants suitable habitat. Wildlife The Agency Preferred Alternative would result in the least amount of direct disturbance to wildlife habitat (204 acres, exclusive of Sage-Grouse habitat) and Sage-Grouse habitat (192 acres). This alternative would also require the second fewest number of transmission structures (328). By comparison, the NNR Alternative - Underground Design Option would require the fewest number of new structures (251),