The Mountain Creek Wastewater Relief Interceptor (Segment 7 and 8) project includes approximately 20,000 LF of new interceptor up to 84-inches in diameter, designed along Fish Creek in Grand Prairie. This project was implemented to replace an existing undersized and failing sewer interceptor and included an initial route study to determine alignment alternatives through the heavily developed corridor. The project included more than 3,000-LF of tunneled crossings of major roadways and developments. Extensive coordination with TxDOT due to IH-20 improvements drove much of Phase 1 design and negotiating construction access points with the City of Grand Prairie was a driver for Phase 2.

This project presented several unique challenges that the LAN team was able to successfully navigate. The project was bid in phases, with the first phase expedited to coordinate with TxDOT improvements along IH-20. If the new interceptor was not constructed prior to TxDOT improvements, the project would be delayed until the improvements were completed, with increased costs likely due to restricted access and surface improvements. Also, much of the alignment paralleled Fish creek, which required coordination with and a permit from the USACE, extensive City of Grand Prairie floodplain manager coordination, and permitting with the Texas Parks and Wildlife Department for habitat relocation at the crossing of a small pond.

The alignment required three crossings of the existing interceptor, which could not be taken out of service until the new line was in place. Our team developed junction box and bypass designs to avoid extended bypass pumping during construction, resulting in significant construction cost savings.