Schaaf & Wheeler prepared a city-wide multi-year stormwater trash reduction plan for Livermore. This trash capture and feasibility plan meets the National Pollutant Discharge Elimination System (NPDES) permit requirements of 100% reduction goals by 2022. Schaaf & Wheeler mapped optimal locations and types of trash capture devices to be installed across the City to reach those goals.

During the feasibility effort, Schaaf & Wheeler identified an industrial region in the southern portion of the City that contributes to a large percentage of the city’s stormwater trash pollution. The region covers about 300 acres and was a prime candidate for a large-scale trash capture device.

The device is modeled and designed to the NPDES standard of treating a "1-year 1-hour" storm event. Trash nets, installed with a bypass weir and covering two 66-inch pipes feature a discharge mechanism that auto-release and cinch the net closed when it becomes full. Hydraulic calculations completed using MIKE-URBAN confirm the preference of this device as it minimizes upstream flooding impacts. The recommended design and placement of the device allows for easy access, reducing the cost of maintenance.

Two 30” diameter, 8-foot long nets filter up to 48 cfs, thereby meeting the NPDES Section C.10 permit requirements. Work continues towards 100% trash reduction goal to meet NPDES regulations continues with seven more large-scale capture devices planned across the City.