Stiver Engineering provided launch shaft, excavator digger shield and thrust block design services for a 108-inch-diameter water line project along city easements from Milner Road to Aldine Westfield Road in Houston, Texas, near the Intercontinental Park area. Two shoring pits, each more than 30 feet deep, were designed with soldier piles, steel plates and timber lagging. Waler beams were used to support the soldier piles. At the launch pit, a jacking frame was designed at the bottom of the pit to resist the thrust from the excavator boring shield system. The jacking frame consisted of three extra waler sets and diagonal bracings connected to a portal support frame using king beams, a header beam and a footer beam.
Stiver Engineering provided liner plate tunnel and bore pit design (launch and receiving) for 10 tunnel crossings as part of this integrated pipeline project. We also provided a trench safety design for pipeline installation, calculations for required jacking loads for carrier pipe in tunnels, and a grouting plan that accounted for pipe buoyancy calculations. This $21 million project for the Tarrant Regional Water District included 2,000 linear feet of 9-foot, 5-inch excavated diameter tunnel in 10 different tunnels crossing Texas Department of Transportation roads, each with launch and receiving shafts (20 shafts).
The Eastern New Mexico Rural Water System project will provide potable water to eight city and county member agencies and Cannon Air Force Base in east-central New Mexico. It will replace current groundwater supplies from the Ogallala (or High Plains) Aquifer with a renewable surface water supply, the Ute Reservoir. Stiver Engineering performed excavation plans, dewatering design, CLSM backfill calculations and pipe buoyancy calculations for this 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
- 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.