The sewer system in the city of Las Vegas was disjointed and inefficient. Connections to the main sewer line were sporadic, and relief sewers could not adequately intercept flow. To support the City’s waste management, Stiver Engineering provided key design services for the Paradise Whitney Interceptor in Las Vegas.

The project consisted of a 32,000-foot gravity sewer that conveys flow from the Enterprise Water Resource Center and existing interceptors. Over 26,000 lf of trenchless construction were installed, making it one of the most significant trenchless new installation programs in terms of footage undertaken in the United States. The project received an honorable mention for trenches project of the year by Trench Technology.

Stiver Engineering provided a trench excavation safety plan for the open cut sections including fall restraint systems in addition to the trench shoring, bore pits for the tunnel operations, tunnel design, steel casing design, tunnel grouting design and tunnel settlement analysis.

The Integrated Pipeline is a $48.5 million 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. Crews are installing 4,400 linear feet of pipe using an open face tunnel boring machine with hydraulic jacks and concrete segmental lining. 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. Our work included several trench safety plan designs, pipe buoyancy and support calculations, shoring design, a design for a CMU bulkhead, and an alternative design using steel plates and members for grouting abandoned tunnel. We also created a plan and profile drawing set for a new tunnel profile including new geotechnical data, as well as analysis and design for increasing the depth of an existing liner plate and ring beam shaft, among other services.

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.

To help secure the Baltimore, Maryland City’s water supply, the Baltimore City Department of Public Works is covering a considerable portion of Druid Lake and installing two large underground water tanks.  Druid Lake holds filtered and treated water that is ready to be sent to consumers. To protect this drinking water supply, two covered storage tanks, holding more than 50 million gallons of drinking water, will be constructed underground on the western end of the lake.  The estimated project cost is $140 million and is expected to be completed in March of 2022.  Stiver Engineering provided the excavation plans and shoring plans for the installation of the two underground water storage tanks.  The tanks are approximately 400 ft. and 500 ft. diameter and will be installed 40 ft. below natural grade.  Stiver Engineering provided construction consulting through a sloped earth design along with a soil nail and shotcrete wall design where sloping was not feasible.

The purpose of the Luce Bayou Interbasin Transfer Project is to provide additional surface water supplies to end users that utilize water from Lake Houston.  Additional surface water supplies will be transferred from the Trinity River to Lake Houston via the Luce Bayou Interbasin Transfer Project to meet the increased demand for surface water.  There are currently no conveyance facilities to provide raw Trinity River water to the Northeast Water Purification Plant, which treats water from Lake Houston. The Northeast Water Purification Plant is vital in providing treated surface water to City of Houston customers  and previous studies have shown that Lake Houston and Northeast Water Purification Plant cannot meet future demands at their current capacity.  Transfer of additional raw water supplies to Lake Houston and future expansion of treatment capacity at the Northeast Water Purification Plant is required to allow for the mandatory conversion from groundwater to surface water. The Luce Bayou Interbasin Transfer Project will provide the additional raw water resources necessary to satisfy these demands. The City of Houston, Texas holds permits to divert raw water at a maximum rate of 775 cubic feet per second (approximately 500 million gallons per day) from the Capers Ridge site to Lake Houston.

The Luce Bayou Interbasin Transfer Project includes the Capers Ridge Pump Station located on the Trinity River in Liberty County, 3 miles of dual 96 inch diameter pipelines, and 23.5 miles of earthen canal system.  The pump station will be located on the Trinity River. The pipeline will extend west southwest approximately 3 miles along a geological ridge (Capers Ridge). The pipeline will then outfall into the sedimentation basin at the start of the canal. The canal will outfall into the lower reaches of Luce Bayou, which flows into the northeastern corner of Lake Houston.

Stiver Engineering was retained by the contractor to provide construction consulting through a cofferdam design for the construction of the Capers Ridge Pump Station.  Stiver Engineering also provided excavation plans for the installation of the proposed dual 96 inch diameter outlet piping.