2023 Top Projects: Dry-weather diversion captures low-flow runoff

Nov. 21, 2023
Stormwater Solutions recognizes this year’s top stormwater & erosion control projects.

To help Ballona Creek with it s Total Maximum Daily Load (TMDL), the city of Culver embarked on this project. While the primary goal is to improve water quality in Ballona Creek, the project includes a dry-weather diversion that will capture low flow runoff from Centinela Creek Channel, a tributary to Ballona Creek and Santa Monica Bay, that will be discharged into the City of Los Angeles’ sewer system. An inlet with a steel grate will be placed in the channel to allow for the runoff to flow.

The runoff will then be conveyed to a pump station within the channel and pumped to the Mesmer Pump Station with a 6-inch force main. When wet weather occurs, the diversion pump station will shut off, leaving sufficient capacity for sewer flows.

Securing the proper environmental permits proved challenging. Because the project includes improvements within an open channel subject to environmental permit regulation, the team had to secure permits for Sections 401, 404, 408, and 1602 before construction.

Permit restrictions also crunched the channel construc- tion timeline. Work was not allowed in the open channel between April and October without extensive and expensive bypass controls. Nevertheless, the team secured the correct permitting with proper, and early, planning and the project began. The contractor implemented two mobilizations to avoid work in the channel during the storm season. This project is the first of three identified for Ballona Creek.

"This project is important because it improves water quality and increases local water supply reliability, both of which enhance the environment now and in the future,” said Katie Harrel, special projects manager for CWE.

About the Author

Katie Johns

Katie Johns, editor-in-chief of Stormwater Solutions, graduated from the University of Missouri in 2016 with a Bachelor of Journalism and a Bachelor of Arts in Spanish. Johns joined the Stormwater Solutions team in September 2019. Johns also helps plan the annual StormCon conference and co-hosts the Talking Under Water podcast. Prior to entering the B2B industry, she worked as a newspaper reporter and editor in Sarasota, Florida, and a magazine assistant editor in the Chicago suburbs. She can be reached at [email protected].