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Vantage to Pomona Heights Chapter 2 230 kV Transmission Line Project FEIS Proposed Action and Alternatives PAGE 2-16 Drilled Concrete Piers-Steel Lattice Structures The Columbia River crossing single-circuit steel lattice structures would require four foundations with one on each of the four corners of the steel lattice towers. The foundation diameter and depth would be determined during final design and are dependent on the type of soil or rock present at each specific site. Typically, the foundations for the single-circuit tangent steel lattice towers would be composed of steel- reinforced concrete drilled piers with a typical diameter of four feet and a depth of approximately 15 feet. 2.2.2.3 Conductors The conductor (the wire cable strung between transmission line structures through which the electric current flows) would be aluminum stranded with a steel stranded reinforced core. The aluminum carries the majority of the electrical current and the steel provides the tensile strength to support the aluminum strands. The conductor size would be 1,272 kilo-circular mils (kcmil; 1.354 inch diameter). The proposed transmission line would be designed for one 230 kV three phase (three conductors) circuit and one shield wire. Conductor phase to phase and phase to ground clearance parameters are determined in accordance with the National Electrical Safety Code (NESC) and Pacific Power design standards. This code provides for minimum distances between the conductors and the ground, crossing points of other lines and the transmission support structures, other conductors and a minimum working clearances for personnel during energized operation and maintenance activities (Institute of Electrical and Electronics Engineers [IEEE] 2007). Minimum conductor height above the ground or vegetation would be 28 to 35 feet, typically. The conductor height for Action Alternatives involving crossing of Interstate (I) 82, however, would be a minimum of 34 feet, according to Washington State Department of Transportation (WSDOT). Minimum conductor clearances would dictate the exact height of each structure based on topography and safety clearance requirements. During detailed design, clearances may be increased to account for special situations that may arise in site-specific locations. 2.2.2.4 Insulators and Associated Hardware Insulators, which are made of an extremely low conducting material such as porcelain, glass, or polymer, are used to suspend conductors from each structure. Insulators inhibit the flow of electrical current from the conductor to the ground or another conductor. The proposed 230 kV transmission line would utilize polymer type insulators. The assemblies of insulators are designed to maintain electrical clearances between the conductors, structure and ground. To protect conductors from lightning strikes, each structure would have one lightening protection shield wire installed near the top of each pole. Current from lightning strikes would be transferred through ground wire attached to structures into the ground. The shield wire would be grounded at regular intervals to meet NESC code and Pacific Power standards. The shield wire would be composed of extra high strength steel wire with a diameter of 0.360 inch and a weight of 0.273 pound per foot. 2.2.2.5 Right-of-Way Acquisition Acquisition of Right-of-Way Across Federal Lands New permanent and temporary land use rights are required for the construction, operation, and maintenance of transmission line facilities such as the transmission line, access roads, and temporary work sites (e.g., ROW grant, easement, license agreement, franchise agreement, and fee simple). Pacific Power has filed ROW applications with the BLM, JBLM YTC, and Reclamation for transmission facilities located on federal land. The grant of ROW required would be: • A width of between 125 feet and 150 feet for H-frame structures and 75 feet to 100 feet for single pole structures and for a specific number of miles across federal land.