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Vantage to Pomona Heights Chapter 2 230 kV Transmission Line Project FEIS Proposed Action and Alternatives PAGE 2-76 between Wanapum/Vantage and Midway (an alternative to building a new Midway-Vantage Transmission Line) The study concluded that even with a new Midway-Vantage 230 kV Transmission Line, the existing Wanapum-Pomona 230 kV Transmission Line would still overload for N-1 Union Gap-Midway and N-2 Midway Bus 3 contingencies in the 2012 case. In the 2017 case, the Wanapum Bus contingency would produce a reactive shortage and voltage collapse without a new Vantage-Pomona 230 kV Transmission Line. The study determined that building a new Vantage-Pomona 230 kV Transmission Line provided the most benefit to the system and outperformed building a new Midway-Vantage 230 kV Transmission Line (Option 2) or tying the Wanapum-Walla Walla, Midway-Potholes-Coulee, and Midway-Rocky Ford- Coulee 230 kV transmission lines together at their crossing about 12.6 miles east of Wanapum Substation along the Walla Walla Transmission Line to create a new 230 kV path between Wanapum/Vantage and Midway (Option 3). Additionally, the study concluded that a new Vantage-Pomona 230 kV Transmission Line would still be required even if a new Midway-Vantage 230 kV Transmission Line was constructed. Based on the findings of the NTAC, Mid-Columbia Transmission Study Group, the alternative of building a new Midway-Vantage 230 kV Transmission Line was eliminated from further study because the system studies did not show that it would provide the required system loading relief and, therefore, would be ineffective. 2.5.1.3 Underground Transmission Line Construction through JBLM YTC Underground construction in limited areas (route segments) of the proposed Project were considered in response to agency comments on the DEIS regarding impacts to Sage-Grouse received by the WDFW and USFWS. During the consideration of potential route segments to underground to address Sage-Grouse concerns, the Army proposed undergrounding a section of the NNR Alternative through the Cantonment Area in the location shown below in Figure 2-15. Undergrounding specific segments of the NNR Alternative as a Design Option is discussed above in Section 2.2.5. Undergrounding through JBLM YTC along route segment NNR-2 as a Design Option was considered on JBLM YTC between in the Cantonment Area near the Vagabond Army Heliport and Ammunition Supply Point in a north-south direction for a distance of up to 0.5 mile. Undergrounding was considered primarily to mitigate the visual and land use impacts of overhead structures on features such as the JBLM YTC headquarters, the heliport, the parade field, and Wilson Field. Undergrounding the transmission line on the base in this area would require the construction of two transition stations (1 to 2 acres each) in the area: 1) North: Located northeast of the heliport, south of Firing Center Road and east of E Street 2); South: Located in the vicinity east/northeast of the water tower and about 1,000 feet southwest of the Ammunition Supply Point. This Underground Design Option applied to Route Segment NNR-2 was considered and eliminated because it would: • Require the construction of two transition stations that would permanently preclude future development of up to four acres of the Cantonment Area that serves as the administrative center for most training activities at JBLM YTC; • Preclude the development of 1.5 acres within the Cantonment Area due to the duct bank ROW restrictions and necessary access road;