Orange Memorial Park Water Capture

SOUTH SAN FRANCISCO, CA

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Colma Creek runs through the heart of Orange Memorial Park in the City of South San Francisco (City), draining over 6,500 acres from 6 different municipalities. This regional stormwater capture project is on track to be the first of its kind in Northern California, diverting flows from the Colma Creek Flood Control Channel into the park for pretreatment to remove trash, debris, and sediment. Water then flows to an underground cistern for storage and advanced treatment for non-potable reuse. When the cistern is full, treated water overflows to an infiltration gallery or, during larger storms, is returned to the channel. While the primary objective is to reduce trash, PCBs, and mercury loadings to the San Francisco Bay for compliance with Total Maximum Daily Load (TMDL) requirements, the project also achieves additional City goals to:

  • Reduce peak wet-weather flows to alleviate downstream flooding issues in the lower reaches of Colma Creek

  • Infiltrate treated water to recharge the Westside Ground Water Basin

  • Offset potable consumption by using treated water to meet irrigation demands in the park

  • Realize park improvements consistent with its ultimate vision expressed in the 2008 Master Plan.

The project has two phases. For the initial phase of work, Lotus developed three preliminary concepts that were vetted through an extensive public and interagency outreach process to build consensus behind a preferred alternative. The second phase of work entailed completion of 100% construction documents and supporting the bidding and construction phases. During project design, Lotus realized an opportunity to upsize this project to double its diversion and treatment capacity, helping to secure an additional $6M in funding from Caltrans in a three-way grant negotiation between the City/Lotus, Caltrans, and the Regional Water Quality Control Board (RWQCB). Lotus provided construction oversight and technical support services throughout construction, which began in Spring 2021 with completion in Spring 2022.

Lotus continues to provide a variety of post-construction services, including:

  • Analyzing and reporting on the three-month water reuse system commissioning period;

  • Directing the first year of O&M and monitoring;

  • Analyzing monitoring data to discern project performance and submit annual reports to the RWQCB; and

  • Supporting negotiations with co-permittees and regulatory agencies to develop a cost-credit framework wherein all municipalities receiving credit towards NPDES compliance will contribute towards ongoing O&M costs.

Awards

  • 2022 Project of the Year, American Public Works Association (APWA) of Silicon Valley

  • 2022 Environment + Parks Award, American Public Works Association (APWA) of Silicon Valley

  • 2022 Outstanding Stormwater Capture & Use Project, California Stormwater Quality Association (CASQA)

  • 2022 Outstanding Environmental Engineering Project, American Society of Civil Engineers (ASCE) San Francisco