Docket No. 37232
On August 7, 2009, Oncor Electric Delivery Company filed an application for approval of a new 138 kV double-circuit transmission line to be built in Collin County, Texas. The proposed transmission line would connect the new Oncor Parker Maxwell Creek substation located east of the City of Parker to the existing Allen Sw Sta – Ben Davis (TMPA) 138 kV transmission line. The estimated cost of the proposed project is $12,468,000. Oncor proposes to complete the project and energize the facilities by May 2011.
Oncor’s Preferred Route (Alternative 1) would be located on existing transmission line right-of-way previously acquired by Oncor. Oncor evaluated 67 alternative routes, which varied in length and number of habitable structures affected by the proposed transmission line. Portions of some of the alternate routes also would be located within the existing right-of-way. Oncor proposes to use double-circuit steel or concrete poles that will vary in height from 80 to 120 feet tall. For some portions of routes paralleling the existing Royse – NW Carrolton 345 kV transmission line, the 138 kV structures will be placed adjacent to the existing structures. As a result, the span lengths will exceed the normal length for a typical 138 kV line, so Oncor will use steel poles to support the additional conductor weight.
In its application, Oncor states that the northeast Plano, east Allen, Parker, Lucas, Murphy, Saint Paul, and Wylie area of Collin County (“Parker Area”) has been experiencing a steady growth in electric load. Much of that growth is due to construction of new homes and light industrial facilties. The load is expected to continue to grow due to new residential, light industrial, retail, and municipal construction and added load at existing facilities. Also, the expansion of Highway 190 will stimulate load growth in the project area as it has for Plano.
The current system uses long distribution feeders to delivery electricity from the substations to customers in the Parker Area. Oncor states that an analysis of the projected 2011 summer conditions indicates a number of substation, substation transformer, and distribution feeder overloads can be expected. The proposed Parker Maxwell Creek substation will be located near the center of the Parker Area and the load transfer will prevent the projected overloading. The average distribution feeder length would be reduced from 32,500 feet to 16,900 feet, which Oncor claims will improve service reliability and voltage management. Reliability also will be improved because transmission service to the proposed substation will be provided by a different 138 kV line.
Oncor retained an engineering firm to prepare its Environmental Assessment and Alternative Route Analysis. After public meetings were held, modifications were made to some lines and new links created to minimize potential impacts based on the public meeting comments. In total, 67 alternative routes were evaluated. Oncor’s application provides detailed information about the evaluation of the routes. The summary information includes such items as: length of route, length of route parallel to existing transmission lines, highways, pipelines, railroads, and property boundaries; length of route through commercial areas, pastures, cropland, forest and wetlands; number of habitable structures within 500 feet of a route; and cost of constructing the route.
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