LCRA Transmission Services Corporation (LCRA TSC) on May 31 filed with the Public Utility Commission of Texas an application to amend its certificate of convenience and necessity for the proposed Mountain Home 138-kV Transmission Line Project in southwestern Gillespie County, northeastern Kerr County, and a portion of southeastern Kimble County in Texas.
The proposed project consists of building the new Mountain Home substation –near the community of Mountain Home – as well as the new line, which would connect the Mountain Home substation to the electric grid at either the existing Hunt substation or Ingram substation and at the existing Harper substation. LCRA TSC added that the new line would be about 21.5 miles to 29.8 miles long, depending on the route selected.
CTEC owns the existing Harper substation. LCRA TSC added that it would expand and convert the Harper substation for 138-kV operation as part of the project. At the new Mountain Home substation, CTEC would install a 138-kV power transformer to connect to the proposed project, LCRA TSC said, noting that CTEC would be served by, and connected to, the proposed Mountain Home substation. LCRA TSC noted that electric service requirements for a large number of current and future end-use customers within the project area would be met by CTEC with the installation of the new electric load-serving substation – Mountain home. The new substation would provide the electrical source to supply existing and future electrical loads in the project area, LCRA TSC said, adding that the new substation would also increase service reliability to the broader area.
LCRA TSC noted that it and CTEC have filed an application at the commission to transfer the existing 69-kV Harper to Live Oak transmission line (T288) from CTEC to LCRA TSC (Docket No. 49357). Following approval of the transfer by the commission and completion of the proposed project, the existing T288 line would be upgraded to 138 kV.
Further discussing the need for the proposed project, LCRA TSC said that load growth at a compound annual growth rate of about 2% in western Gillespie and western Kerr counties has resulted in a combined winter loading level in excess of 20 MW – about 10% of CTEC’s consumer load – served by a single radial 69-kV transmission line extending from Fredericksburg to the communities of Harper and Doss. The absence of existing substations near the areas of higher consumer density along IH 10 has resulted in long and heavily loaded distribution feeders serving that area, LCRA TSC said.
The load growth requires construction of a new load-serving substation in the Mountain Home area, LCRA TSC said, noting that Mountain Home is located along IH 10 west of Kerrville in the area of the intersection of State Highway 41 and State Highway 27 between Harper to the northeast and Garven Store to the southwest. A new 138-kV transmission line is needed in order to serve the new Mountain Home substation since there are no existing 138-kV transmission lines within seven miles of the proposed substation location, LCRA TSC said.
LCRA TSC noted that it identified Route 13 as the primary alternative route that it believes best addresses certain requirements, adding that that route has:
- The third shortest length of the 40 primary alternative routes included in the application – about 22.34 miles
- A relatively low number of habitable structures located within 300 feet of the route centerline – 32 – and 16 of the 32 habitable structures within 300 feet of Route 13 are currently located within 300 feet of the centerline of an existing 138-kV transmission line
- The fourth lowest estimated cost – about $65.8m – of the 40 primary alternative routes
- The third shortest length of right of way (ROW) across areas of high archaeological/historic site potential – about 10.7 miles
LCRA TSC noted that land uses within the project area include scattered residential areas and agricultural areas represented by pastureland, rangeland, and cropland. The project area is situated within the Edwards Plateau physiographic region of Texas, LCRA TSC said, noting that the region’s topography is characterized by flat upper surfaces, interspersed by drainages that open up into larger draws or box canyons.
LCRA TSC said that along most alternate segments, the proposed project would be built on single-circuit pole structures. LCRA TSC added that if Segments X3, B, F, or E4 are part of the commission-approved route, then those segments would be built on double-circuit, 138-kV poles containing the new 138-kV circuit from Hunt or Ingram to Mountain Home and the existing LCRA TSC 138-kV circuit connecting Hunt to Ingram (T487). LCRA TSC noted that it is seeking commission approval for the new 138-kV circuit from Hunt or Ingram to Mountain Home to Harper in the application.
According to the estimated schedule, ROW and land acquisition would begin in July 2020 and be completed in January 2022; engineering and design would begin in July 2020 and be completed in June 2021; material and equipment procurement would begin in May 2021 and be completed in July 2021; and construction of facilities would begin in August 2021 and be completed in December 2022, which is also when the facilities would be energized.