Stormwater Management & Water Quality

State Route 92/Interstate 880 Interchange Reconstruction/Wetland Mitigation Project | City of Hayward, California

Project Rendering /
Project Rendering /
Caltrans District 4
Project Description:
The State Route 92/Interstate 880 Interchange Project is currently under construction modifying State Route 92/Interstate 880 separation by reconstructing the existing four-quadrant cloverleaf interchange and replacing it with a new interchange with direct connectors. The total disturbed area is 59 acres (ac) within the project limits; the added and reworked impervious area is 34 ac.

During the initial design phase, an off-site treatment project was proposed with the City of Hayward to mitigate the project's anticipated stormwater runoff. However, the off-site treatment plan was not adopted, resulting in the need for additional treatment within the project's limits.

WRECO assessed the feasibility of approved Best Management Practices (BMP) at multiple locations within the project limits and determined the best course of action to optimize treatment. Due to the limited right-of-way and depressed area at the project location, innovative solutions were necessary to provide adequate treatment. A double biofiltration swale was proposed downstream of the pump station to maximize treatment for the project and would treat 16.60 ac of stormwater runoff. The double swale would share a watershed with the pump station and with two BMPs that were proposed during the design phase.
Key Tasks:
Water Quality Support Services, Stormwater Treatment BMP Design of Double Biofiltration Swale, Contract Change Orders and Construction Support
Constructed Double Bioswale
Constructed Double Bioswale
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