I-10 138kV Underground Transmission

Project Scope

Scope included 5.5 miles of dual duct bank each containing nine 8 Inch Schedule 40 conduits (total conduit footage over 500,000 feet). The 11 miles of underground duct bank encloses a 138 kV transmission line with a large portion under the Interstate 10 West bound frontage road. The project presented many challenges due to the proximity to existing utilities, businesses, streets and the always-congested Interstate 10 corridor. Project requirements included placement of 25,000 yards of special thermally conductive red concrete encasement and 20,000 yards of flowable thermal back-fill under paved areas. There were 46 manholes sized 24 foot by 11 foot by 8 foot tall varying in burial depth from 16 to 30 feet. Several creek and road crossings required tunneling and directional drilling the longest was 1200 feet long.