This $12.4 million project for the North Texas Municipal Water District involves 2,534 linear feet of 118-inch excavated diameter tunneling. The tunnel will consist of 4-flange liner plate and will house 84-inch steel carrier pipe. It will be driven through Austin chalk with a double-shielded, open-faced, gripper-type machine with articulated steering.

Tunneling was completed on Jan. 6, 2021. Stiver Engineering provided tunnel design services for the project.

The City of Houston’s Northeast Water Purification Plant (NEWPP) Expansion Project is a design-build project that will add 320 million gallons per day (mgd) by 2024 to the existing water plant’s capacity. The expansion project will allow the City and the regional water authorities to meet projected demands, while fulfilling requirements set by the Harris-Galveston and Fort Bend Subsidence Districts resulting in a shift from historical groundwater usage to a predominant reliance on surface water.

​Construction on the $1.7 billion project started in early 2018 and has been called the largest expansion project in the world. The NEWPP expansion is required to comply with subsidence district rules for conversion from groundwater to surface water supply, resulting in a reduction of the subsidence rate.  Features of the project include the design, construction and commissioning of:

  • Intake pump station
  • Twin 108-inch transmission mains
  • Pre- and post-treatment chemical addition
  • Flocculation/sedimentation basins
  • Ozone treatment
  • Filtration
  • Finished water storage tanks
  • High service pumping station

Stiver Engineering provided construction consulting through the following designs for contractors working on the NEWPP Project:

  • Shoring design for 10,200 LF of twin 108-in.-dia. raw water transmission mains in common trench at a depth of 18 ft. to 40 ft.
  • Pipe buoyancy calculations for the 38,000 CY of controlled low strength material (CLSM) backfill.
  • Entry shaft, exit shaft and tunnel design for the 360-LF, 132-in.-dia. tunnel using liner plate.
  • Shoring design for the filter/transfer pump station.

This project specified the installation of 510 feet of electrical duct bank in the Houston Medical Center in Houston, Texas. To complete the project, we provided the client with construction consulting through a 42-inch by 48-inch wood box tunnel design. Stiver Engineering provides wood box tunnel designs to clients across the country that vary in size and cover.

Stiver Engineering provides clients with construction consulting through trench safety & bore pit/access shaft plans throughout the country. These plans are designed per OSHA Regulations: 29 CFR 1926, Subpart P – Excavation, Trenching, and Shoring [1926.652(c)(4)]. We incorporate trench boxes, steel plates, and timber lagging into our trench safety & bore pit/access designs, which are sized and designed per the required depth of the excavation and the project’s soil conditions.

A client requested construction consulting assistance in the installation of supply and return piping beneath Memorial Circle on Texas Tech University’s campus in Lubbock, Texas. Stiver Engineering designed a shoring system using soldier piles, steel plates, timber lagging, a wale set, and cross struts. We also designed three concrete vaults and the steel pipe support structures to support piping and provide access along the length of the tunnel.