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.

Stiver Engineering provided key design services for the Northeast Transmission Line (NETL) project in Houston. The NETL will transmit 365 million gallons of water a day from the Northeast Water Purification Plant through a 108-inch steel waterline to approximately 900,000 homes in Harris County. Stiver provided a shoring design using soldier piles, wale sets, and steel plate and timber lagging. We also developed a design for a temporary bulkhead to grout fill the annulus of the waterline pipe inside the casing pipe and a cradle design to support the existing 84-inch diameter waterline.

Photo Credit: LAN

Stiver Engineering provided numerous services for capital improvements to a 108- inch-diameter water line running from Aldine Westfield Road to Willis Street in Houston, Texas. We created shoring and portal designs for launch and receiving shafts — some as deep as 31 feet — using sheet pile and soldier piles, wale sets, steel plates, timber lagging, and other methods. Stiver also created trench safety designs for installation, special shoring requirements with trench boxes, steel plates and soldier piles, and steel casing designs.

The Joes Creek Interceptor project in Dallas involves 8,370 linear feet of 60-inch excavated diameter tunnel that will house 36-inch HOBAS carrier pipe. There are 20 shafts (ranging from 21 to 48 vertical feet in depth), and ground conditions include sand, sand with gravel, sandstone, sandy clay, shaley clay, and shale (Eagle Ford). Stiver Engineering provided steel casing pipe calculations for 8 runs. We also created designs for various sizes of shoring pits using sheet piling and wale sets, as well as designs for a 32-foot-diameter liner plate and ring beam shaft at various locations and TBM face pressure calculations.

As part of a major infrastructure project at the Schoharie Reservoir in Gilboa, New York, Stiver Engineering provided a variety of services for a low-level outlet designed to release water downstream into Schoharie Creek to facilitate dam maintenance and emergency response, mitigate flood risk, and enhance downstream habitat for fish and wildlife. The work includes construction of a 9.5-foot diameter micro-tunnel at a depth of 160 feet. Stiver provided designs for the gate shaft as well as analysis of the steel jacking frame for the tunnel machine and steel pipe. We also provided trench safety designs, thrust block designs, steel pipe casing designs, anchor bolt attachment designs, and a structural review of the Herrenknecht tunnel launch seal and pipe break frames, among other services.