3. Proposed Changes to Project Design

As described in the Final EIR/Recirculated Final EIR, the 115 kV subtransmission line upgrade, subsequently approved by D.08-12-031, includes installation of approximately 225 new steel poles, ranging from 65 to 85 feet tall. The project description, based on the conceptual design, anticipates use of both bolted-base tubular steel poles (TSP) and direct-buried lightweight steel (LWS) poles, in the ratio of approximately 25 percent TSP and 75 percent LWS. Except for poles installed at the substation site, the project description also contemplates placement of all poles within existing 115 kV rights-of-way (ROW) or along public street ROW. Steel poles that replace existing wooden poles in existing ROW generally are to be sited at the same location (defined as within 10 feet of the poles they replace).

In the course of performing the final engineering for the project, SCE determined that nearly double the number of poles would be required to upgrade Segments 2 and 4 of the 115 kV subtransmission line and these poles would need to be spaced much more closely than previously contemplated. Specifically, Segment 2 would require 61 poles (instead of 33) and Segment 4 would require 57 poles (instead of 30). In addition, the pole heights in Segments 2 and 4 would increase, with a new range of 75 to 120 feet, rather than 65 to 85 feet.

SCE's petition explains that the increased pole count, tighter spacing and greater pole heights in Segments 2 and 4 result from SCE's efforts to arrive at an optimal solution for adjusting the subtransmission line's conceptual design to meet all engineering requirements. SCE's process for final engineering considered a number of factors, including terrain requirements along the length of the subtransmission line, the results of a detailed property rights check, strength ratings for individual structures, wind loading, the costs of the two types of poles (LWS poles are less costly to purchase and construct), likely environmental consequences of specific design change options, and permitting requirements.

The petition states:

[C]hanges to the conceptual design were both necessary and unavoidable. And, modifications to the design of particular segments had ramifications for the remainder of the line...a change in one segment would affect the design of other segments. The design evolved in this manner until SCE arrived at the now proposed final design, which is optimal, feasible, and cost-effective. (Petition at 8-9.)

The greater number of poles now proposed for Segments 2 and 4 is necessary for the project as a whole to remain as close as possible to the 25 percent/75 percent ratio between the more costly TSP and less costly LWS poles in order to meet engineering demands while minimizing visual impact. In fact the ratio shifts somewhat, to 39% TSP/61% LWS for the project as a whole. For Segment 2, the new ratio is 20% TSP/80%LWS; for Segment 4, the new ratio is 16% TSP/84% LWS. The petition states: "SCE cannot feasibly develop a final design for this subtransmission line with 225 poles in the ratio of TSPs and LWS poles initially described (25 percent and 75 percent, respectively)." (Petition at 8.)

As discussed further below, the Commission determined that SCE's final engineering resulted in design changes in Segments 2 and 4 substantially different from the project D.08-12-031 approved and accordingly, has undertaken additional environmental review pursuant to CEQA.