Stormwater capture facility helps improve water quality along California shoreline
At a glance
The Los Angeles Water Board regulates discharges from municipal separate storm sewer systems (MS4s) through the Los Angeles County, Long Beach, and Ventura County MS4 Permits, issued under the National Pollutant Discharge Elimination System Program.
The challenge
The partnership between the City of Signal Hill, City of Long Beach, Los Angeles County Department of Public Works, and the California Department of Transportation located on Los Angeles County Flood Control District and Long Beach Airport properties needed a stormwater capture facility.
Our response
Our team conducted the design-build phase of the stormwater diversion and aquifer infiltration facility to meet near and long-term total maximum daily load requirements of the Los Cerritos Channel Sub-Basin 4 Watershed, described in the Los Cerritos Channel Watershed Management Plan.
The new diversion structure in the Los Cerritos Channel diverts and captures up to 166-cubic-feet-per second of stormwater into a series of underground concrete storage chambers. The chambers contain open bottoms with a series of rock-filled wicks that penetrate an underlying clay lens to facilitate infiltration with a minimum capacity of 25-acre-feet of storage. The underground chambers were located under the apron at the Long Beach Airport and designed to withstand commercial aircraft loads.
- Modified the County’s existing forty-foot-wide by twenty-foot-deep channel including a low-flow diversion structure and maintenance access ramp.
- Built twelve-foot wide by three-foot high diversion inlet structure in the channel, and sixty-inch reinforced concrete pipe, with a transition structure.
- Completion of the project enabled compliance with Municipal Stormwater Permit, Los Angeles Regional Water Quality Control Board Order R4-2012-0175.