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Vantage to Pomona Heights Chapter 3 230 kV Transmission Line Project FEIS Affected Environment PAGE 3-298 Route Segment 3a corresponds to 0.0 acres of soils with high water erosion potential, 13.2 acres of soils with high wind erosion potential, and 13.2 acres of soils with low soil restoration potential. 3.15.4.9 Route Segment 3b Route Segment 3b proceeds west along the edge of the Columbia River and crosses the river below Wanapum Dam. While there are no landslide features along the route segment, rockfall and ephemeral washes do pose a hazard. In addition, there are some localized zones of moderate to high liquefaction susceptibility along the southern portion. The northern portion of the route segment crosses larger moderate to high areas of liquefaction susceptibility, including the crossing location. There are some active (Class B) faults in the southern portion and the northern portion of the route segment crosses the Late Quaternary Period (<130,000 years) Saddle Mountain thrust fault. Route Segment 3b corresponds to 364.2 acres of soils with high water erosion potential, 111.6 acres of soils with high wind erosion potential, and 779.4 acres of soils with low soil restoration potential. 3.15.4.10 Route Segment 3c Route Segment 3c proceeds east along the Columbia River, then crosses the river and continues north across a bench to the Saddle Mountains as shown on the Geohazards Map in Appendix A. The Columbia River crossing location is in an area of low liquefaction susceptibility. At the southern foot of the Saddle Mountains, the liquefaction susceptibility increases to moderate. During the traverse of the Saddle Mountains, ephemeral creek washes become more numerous. Some active (Class B) faults are located near Route Segment 3c at the top of the Saddle Mountains and the Late Quaternary Period (<130,000 years) Saddle Mountain thrust fault is located at the northern foot of the mountains. This inferred fault trace parallels the mountains and Lower Crab Creek. The northern slopes of the Saddle Mountains along Route Segment 3c is subject to rockfall and sluffing due to the steep slopes. While large mass-wasting events are improbable in their current undisturbed condition, large-scale modification of the existing slope conditions (e.g., access roads) should be avoided. As Route Segment 3c crosses the confluence of the Columbia and Lower Crab Creek, there are significant areas mapped as exhibiting moderate to high liquefaction potential. Route Segment 3c corresponds to 106.7 acres of soils with high water erosion potential, 1,149.5 acres of soils with high wind erosion potential, and 942.3 acres of soils with low soil restoration potential. 3.15.4.11 Route Segment NNR-2 Route Segment NNR-2 runs through developed areas, approximately 0.5 mile east of the Yakima River. One thin strip of moderate to high liquefaction susceptibility lies along a creek that passes through the route segment. Class B Structure Faults associated with the Umtanum Ridge-Gable Mountain Fault pass through the six-mile wide study area—the nearest is approximately 1.5 miles from the route segment. A few historic and/or quaternary landslide deposits lie within the six-mile wide study area, but not within the route segment. The route segment crosses two intermittent/ephemeral creek washes. Route Segment NNR-2 corresponds to 184.3 acres of soils with high water erosion potential, 0.0 acres of soils with high wind erosion potential, and 34.7 acres of soils with low soil restoration potential. 3.15.4.12 Route Segment NNR-3 Route Segment NNR-3 crosses Umtanum Ridge, an east-west trending anticline, west of Interstate (I) 82. The route segment crosses several Class B structure faults associated with the Umtanum Ridge-Gable Mountain Fault System. The six-mile study area contains a few strips of moderate to high liquefaction susceptibility along rivers and creeks, but none pass through the route segment. Several historic and/or quaternary landslide deposits lie within the six-mile study area, but not within the route segment. The route segment crosses three intermittent/ephemeral creek washes.