The Integrated Pipeline is a joint water supply project between Dallas Water Utilities and Tarrant Regional Water District. It involves building 150 miles of pipeline to transport up to 350 million gallons water daily from three East Texas Reservoirs into the Metroplex to increase reliable water access. The project recently reached a new milestone when the new tunnel under Trinity River was completed. Workers are now beginning to add 50‐foot sections of 108‐inch diameter steel pipe.

Stiver Engineering performed full design work for the IPL tunnel. The design/build project scope included construction of approximately 3,802 linear feet of 108‐inch water line including 2,614 linear feet of tunnel under the Trinity River and the remainder in deep open cut segments along the proposed alignment of Section 17.

Other aspects include tunnel launch and retrieval portals/shafts, deep open cut approach ramps with temporary shoring at approximately 12:1 slope, pipe laying within approach ramps and tunnel initial support, pipe encasement with flowable fill and reinforced concrete, tunnel grouting, a 15.6‐foot diameter custom designed tunnel boring machine, and precast segmental tunnel lining.

The new TxDOT bridge will replace the existing truss bridge over the Colorado River in Columbus, Texas.  Stiver Engineering provided construction consulting to the bridge contractor with cofferdam designs for crane access on both banks of the Colorado River.  The cofferdams allowed the crane to get closer to the center of the proposed bridge so that the bridge beams could be lifted and installed.  The cofferdam was constructed using driven sheet piles, wales and cross ties.

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 construction of two reinforced concrete boxes from Buffalo Bayou to San Felipe Road in Houston, Texas. The excavation was located a short distance from high-voltage power line towers and two main railroad lines. Stiver Engineering was hired to provide construction consulting through a braced shoring system that included sheet piles, wales, and a cross strut design that could be adjusted to accommodate construction.

One of our clients had to install a force main on a piles at a depth of 12-feet below Charleston Bay. The project is located on the South side of Plum Island in the Ashley River Basin in Charleston, South Carolina. Stiver Engineering was retained for construction consulting to design a shoring system for the installation of the force main to provide the contractor access to the site during low tide conditions. The shoring was designed with sheet piles, wales, and cross struts, enabling the contractor to drive an excavator and front-end loader on the wale set for access to the excavation and installation of the force main. The force main now connects the new lift station to the existing Plum Island wastewater treatment facility.