Stiver Engineering provided the horizontal directional drilling alignment and pulling calculations for a 42’’ inch diameter force main crossing beneath the Houston Ship Channel adjacent to the 69th street wastewater treatment plant. The purpose of the HDD installation was to replace the existing Hedrick Force Main Aerial Crossing. The HDD was approximately 1,000 ft. and was installed to a depth of 100 ft.

Stiver Engineering provided the contractor with an alternate tunneling method for a 6-inch diameter force main.  The alternate design consisted of a horizontal directional drill (HDD) that was 21 ft. beneath an existing railroad.  The pull forces and pipe stresses were analyzed and a profile was delivered to the contractor for construction.

Stiver is proudly supporting the Ashbridge’s Bay Treatment Plant Outfall. This $300 million project for the City of Toronto will replace the current outfall tunnel, which is at the end of its service life. It is set to be the largest wastewater outfall in Canada. The project includes a 16-meter diameter shaft by 85-meter deep, a 3.5-kilometer TBM excavated tunnel that has a 7-meter ID and precast concrete segmental lining. We are providing riprap placement plans for the riser sections on the lakebed. These cages will be placed at the bottom of Lake Ontario and will be guided in place by divers. The riprap baskets will be installed around each of the fifty – 1-meter diameter risers that extend from the tunnel to the lakebed. Learn more about this project in Tunnel Business Magazine: http://bit.ly/tbm-stiver-1-2022

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 City of Houston has spearheaded the Northgate Regional Lift Station project as part of its plan to reduce operational and maintenance costs by consolidating 39 wastewater treatment plants and more than 380 lift station facilities. As a result, the project will decommission the Imperial Valley Wastewater Treatment Plan, which handles 4 million gallons of water per day.

As part of the Northgate project, Stiver Engineering successfully delivered to the contractor an expedited alternate design for a 70-foot-deep caisson. Stiver performed a detailed finite element analysis, and the structure was checked against various load cases. We designed the outer shell along with the interior partition wall, bottom slab and the top slab.

The design was performed and checked for each phase of construction, including casting, sinking, and installing the bottom slab, the partition wall and the top slab. Each condition was analyzed and optimized to provide the field crews with a more normalized rebar pattern and installation procedure.