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 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.

The largest of the Lower Colorado River Authority’s (LCRA) new water supply projects is an off-channel reservoir that is being constructed near the Texas Gulf Coast. The project will be the first significant new water supply reservoir developed in the lower Colorado River basin in decades. The Lane City Reservoir will be constructed off the main channel of the Colorado River, near Lane City in Wharton County.  The reservoir will add up to 90,000 acre-feet of firm water to the region’s supply.  Firm water is water that can be counted on without shortage even during a repeat of the worst drought conditions in the region’s history.  The Highland Lakes were created to manage floods on the Colorado River and to provide a sustainable source of water for the basin as a whole. The Lane City Reservoir is the first project that will allow LCRA to capture and store significant amounts of water downstream of the Highland Lakes.  The new reservoir will benefit the entire basin by helping reduce the amount of water otherwise required to be released from the Highland Lakes.

Stiver Engineering was retained by the contractor to provide construction consulting through excavation plans for the reservoir inlet/outlet structure, a permanent sheet pile shoring system in the Colorado River around the vertical intake pumps, miscellaneous structural design, excavation consulting  and dewatering consulting.

Stiver Engineering was retained by a local contractor to provide structural design through an alternative cantilevered wall design for the Hardy Yards project in Houston, Texas. The alternative design consisted of soldier piles and timber lagging and ranged in height from 4 feet to 10 feet.

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.