Vantage to Pomona FEIS Index 34 - Laserfiche WebLink

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Vantage to Pomona Heights Chapter 4 230 kV Transmission Line Project FEIS Environmental Consequences PAGE 4-120 roughly correlate with amount of ground disturbance. The least ground disturbance would occur with the Agency Preferred Alternative (204 acres). The NNR Alternative - Underground Design Option would require greater ground disturbance (254 acres) in underground construction locations through trenching and new, permanent access road construction. The NNR Alternative - MR Subroute would require construction in areas that are not located adjacent to an existing line and in areas with few or no access roads, resulting in 260 acres of ground disturbance. Alternatives A-H would require much more ground disturbance (316 to 350 acres) due to their longer length. The Agency Preferred Alternative and the NNR Alternative - Underground Design Option closely parallel Pacific Power’s existing 230 kV transmission line that primarily uses transmission structures similar to those proposed for this Project, with most new structures located within approximately 200 feet of existing structures. Given the territorial nature of raptor and corvid species and density limitations imposed by food availability, it is unlikely that the addition of a structure 200 feet from a similar existing structure would have much, if any, effect on the density of corvids or raptors. In those areas, the new perching opportunities could increase the amount of habitat that is within view of a perch and effectively widen the corridor of increased predation risk, by approximately 200 feet from the existing condition. Construction of the Agency Preferred Alternative or the NNR Alternative - Underground Design Option would require the fewest structures greater than 0.25 mile from an existing transmission line (50 structures). All other Action Alternatives and the NNR Alternative - MR Subroute are longer and follow existing transmission lines for lesser proportions of their lengths, necessitating more structures greater than 0.25 mile from an existing transmission line—135 structures for NNR Alternative – MR Subroute, and 338 to 432 for each of the Alternatives A-H. Because the NNR Alternative - Underground Design Option would be underground for 10.9 miles of its 40.3 mile length it would require the fewest number of total structures (251), but the NNR Alternative - Underground Design Option would not reduce the number of structures greater than 0.25 mile from an existing structure (50) because all 10.9 miles planned for undergrounding closely parallel Pacific Power’s existing 230 kV transmission line. The close proximity of the underground sections to existing overhead lines would negate most of the benefit to wildlife that undergrounding might otherwise have. Wildlife habitat that is sensitive to disturbance includes sagebrush-steppe, riparian areas, intermittent streams/dry gullies, wetlands, and trees. The proposed Project traverses through sensitive habitats ranges from as low as 21.8 miles for Alternative G to as high as 35.1 miles for Alternative A. The Agency Preferred Alternative would cross 31.1 miles of sensitive habitat—primarily sagebrush-steppe. The NNR Alternative – MR Subroute would have the least amount of centerline within one mile of documented special status species raptor nests (9.1 miles), followed by Alternative A (10 miles), and then the Agency Preferred Alternative, and NNR Alternative – Overhead Design Option (10.5 miles). Alternative C would have the greatest length within one mile of special status raptor nests—19.6 miles. Spatial and temporal buffers would minimize disturbance of nesting raptors during construction and maintenance activities. Special status species occurrence points within 0.5 mile of the Action Alternatives include striped whipsnake, night snake, loggerhead shrike, American white pelican, pallid bat, black-tailed jackrabbit, and white-tailed jackrabbit. The Agency Preferred Alternative, NNR Alternative - Underground Design Option, and NNR Alternative - MR Subroute had the shortest length of centerline within 0.5 mile of special status species occurrences (8.6 miles), with the next smallest amount associated with Alternative H (10.4 miles) and the greatest amount associated with Alternative B (19.4 mile). Priority Species Regional Areas crossed by the Action Alternatives include concentration areas for waterfowl, common loon, long-billed curlew, chukar, bighorn sheep, elk, and mule deer, and cliff areas that provide nesting substrates for raptors. The Agency Preferred Alternative and NNR Alternative -