The primary advantage of an underground transmission line is the reduced visibility of the line, but an underground line would also prevent potential collisions and electrocution of birds associated with overhead transmission lines. Disadvantages of an underground transmission line are similar to those described for the underground pipelines (see Section 2.7.5). In areas where bedrock is near the surface construction would include blasting. Construction of trenches would cause significant surface disturbance and soil erosion potential along the entire transmission line route, and until vegetation is reestablished, disturbed areas along the line would remain visible. New access roads would be needed for construction and maintenance of the buried line. Installation, repair and maintenance of the buried lines requires more time and cost compared to overhead lines and could extend the down-time that the power plant is off-line and not generating electricity.

Buried transmission lines are also susceptible to geological hazards not typically associated with overhead transmission lines, including: (a) possible exposure to damage in rough terrain from soil erosion; (b) damage from landslides on steep slopes; (c) seismic or tectonic activity could result in damage or rupture; and (d) thermal instability could result from landslide overburden on top of the backfill that could hamper dissipation of heat through the backfill to the atmosphere and could result in line damage, burnout or reduced capacity (Dames & Moore 1981).

Other problems unique to a buried transmission line would include: (a) access to the line in areas where deep snow can accumulate such as the Medicine Lake Highlands; (b) trenching and burying the transmission line through stream or ephemeral channels could adversely affect creek bottom, increase sedimentation and potentially affect water quality down gradient.

Based on the technical and economic constraints and the increased environmental effects associated with underground transmission lines in a rough terrain area such as Medicine Lake Highlands, this alternative was eliminated from detailed study in the EIS/EIR.

2.8 Preferred Alternative

2.8.1 Environmentally Superior Alternative and Environmentally Preferable Alternative

CEQA regulations state that if the No Project alternative (i.e., the No Action Alternative) is the Environmentally Superior Alternative, then the EIR must also identify an Environmentally Superior Alternative from among the other alternatives (CEQA Guidelines Section 15126(d)(4)). Similarly, NEPA implementing regulations state that NEPA lead agencies must identify the alternative or alternatives considered to be environmentally preferable in the Record of Decision (ROD) in cases where an EIS is required (40 CFR 1505.2(b)).

Based on the analysis provided in this EIS/EIR, the Project Alternative that would result in the fewest significant environmental impacts would be the No Action Alternative and would, therefore, be considered the Environmentally Superior Alternative; however, CEQA requires that an Environmentally Superior Alternative also be selected from among the other action alternatives. The Environmentally Superior Alternative that would cause the least damage to the biological and physical environment, and that would best protect, preserve, and enhance historic resources, cultural resources, and other natural resources, while meeting both the objectives of, and the purpose and need for, the Project, would be the Proposed Action (see Executive Summary Section “Environmentally Preferred Alternative”).

Assuming the Environmentally Superior Alternative identified in the Fourmile Hill Project EIS/EIR (BLM et al. 1998) is approved and the transmission line is timely constructed, then a Northern Utility Corridor would exist, and the Environmentally Superior Alternative route for interconnecting the Telephone Flat Project transmission line to the Northern Utility Corridor would be Alternative Transmission Line Route 1 (see Executive Summary Section “Environmentally Preferred Alternative”).

2.8.2 Agency Preferred Alternative

A Draft EIS may identify a NEPA lead agency’s Preferred Alternative or alternatives, if one or more exists; and the Final EIS must identify the Preferred Alternative unless another law prohibits the expression of such a preference (40 CFR 1502.14(e)). There is no requirement for a CEQA lead agency to identify a Preferred Alternative under CEQA regulations.

Based on the findings in this EIS/EIR and agency and public comments received on the Draft EIS/EIR, the federal lead agencies have identified the Proposed Action as the Agency Preferred Alternative and Alternative Transmission Line Route 1 as the Agency Preferred Alternative route for interconnecting the Telephone Flat Project power plant site to the proposed Northern Utility Corridor (see Executive Summary Section “Environmentally Preferred Alternative”).