CALHOUN COUNTY, TX
ECI/EPCS provided detailed design, procurement, and construction services to support the interconnection of the new Tres Bahias Solar project in Calhoun County, Texas.
The EPC project included the 138 kV – 34.5 kV Tres Bahias Collection Substation, which included a 138kV/34.kV Main Power Transformer, a 138 kV, 2000A 40kA Power Circuit Breaker, six 34.5 kV 1200A, 40 kA Circuit Breakers associated with 10 collection circuits, a 10 MVAR Capacitor Bank with Cap Switcher, all instrument transformers, disconnect switches, and arrestors. Also included a full self-contained Control House with station auxiliaries, relay and metering panels, and SCADA / Telecommunications. Substation site was graded to match the overall grade design of the broader solar facility.
The design, procurement and construction also included a new 5.9-mile 138 kV gen-tie line between the Tres Bahias project substation on the solar site and a new POCO (point of change of ownership) pole outside of the existing Joslin Substation. Routing and preliminary modeling of the gen-tie line was previously accomplished under a separate project for the owner. The transmission alignment runs through heavily industrial facilities adjacent to Cox Bay, and includes significant conflicts that presented design concerns, including many pipeline crossings, overhead transmission and distribution crossings, a reservoir crossing, a covered landfill crossing, and both river flooding and storm surge concerns from adjacent waterways.
In order to minimize final costs to the client for the lengthy reservoir and landfill crossing spans, ACSS HS285 477 kcmil 26/7 “Hawk” high-temperature low-sag (HTLS) conductor was used. Two communication paths were required by the project interconnection agreement. These, as well as all shielding requirements, were accomplished via the use of two AFL DNO-11877 OPGW wires, installed on pole-top arms. All structures were galvanized steel. Tangent structures were supported on direct-embedded foundations, and all other structure types supported on concrete foundations.
- 138 kV-34.5kV Substation EPC
- 5.9-mile, 138 kV gen-tie line to Joslin Substation through heavily industrialized facilities
