Terraphase led the design of drainage improvements and stormwater sedimentation basins for a Northern California utility district. The location of the work was a receiving yard for soil generated during construction and maintenance projects and is permitted under the State Water Resources Control Board (SWRCB) Construction General Permit (CGP).
Scope of Services
Terraphase led the engineering design of drainage improvements across the entire stockpile site to accommodate planned upgrades and long-term expansion.
Terraphase completed hydrological analyses of the stockpile site to develop drainage areas and estimate run-off quantities. These analyses supported the design of two new sedimentation basins (totaling over 100,000 cubic feet of capacity) and their tributary drainage channels for detention and sediment reduction of all run-off prior to discharge to the surrounding open space areas. The design was delivered in a design-build approach working collaboratively with the utility district and the earthwork contractor.
Notable Accomplishments
- Collaborated with the utility district and its earthwork contractor to design and construct the drainage improvements before the rainy season
- Met the utility’s operational and compliance requirements
- Incorporated access improvements requested by stakeholders, including utility district operations and maintenance staff, contractors, and rangers for the adjacent park area
