Sweetwater 4 Transmission Line / Sweetwater, TX
How do you build a transmission line parallel to two existing lines?
The Sweetwater 4 345kV transmission line was completed in December 2006 after a 16-week construction duration. Mortenson was contracted to perform all work on the 19.4-mile steel monopole line with a 795 ACSR bundled conductor configuration and 40 strand OPGW. There were two self-supported heavy angle structures that had concrete foundations which were 28' deep x 9.5' wide and the other 30' deep x 10' wide. Both were drilled into solid limestone/caliche rock while the rest of the structures were direct embed and backfilled with concrete. Guy wires were supported by 8'10" helix screw anchors, which were either screwed into native soil or into wet 3000 psi strength concrete in rocky conditions. The line was constructed under the same contract as the substation to tie-in two wind farms of the same name. The project was constructed in parallel to two existing 138 kV transmission lines, built on very rough terrain through the mesas of west Texas with (1) railroad crossing and (3) crossings of 138kV power lines. There were 132 structures total, including (22) turning structures.
Facts And Figures
Engineer, Procure and Construct