Protecting the Beach and Beneficial Use of Stormwater: Santa Monica CBI Project

The city of Santa Monica (city), along with the city of Los Angeles, and the county of Los Angeles developed the Enhanced Watershed Management Plan (EWMP) for the Santa Monica Bay Jurisdictional Group 2 and 3 in response to the 2012 Municipal Separate Storm Sewer System (MS4) Permit. The development and implementation of regional best management practices (BMPs) are a critical component for addressing the water quality goals and objectives of the EWMP. The city is implementing the Santa Monica Clean Beaches Initiative (CBI) Project as a regional BMP that will result in the improvement of the beach water quality and improve the city’s drought resiliency. The objective of the project is to develop a diversion and holding system for up to 85th percentile 24-hour storm event at the Santa Monica Pier outfall and pipeline delivery system to the Santa Monica Urban Runoff Recycling Facility (SMURRF). The project consists of building a diversion structure to direct dry- and wet-weather runoff into a subsurface modular storage facility to store approximately 1.6 million gallons (6.1 million liters) per storm event. In addition, the storage facility is equipped with underdrains to collect and pump brackish groundwater into the storage facility when stormwater is scarce. The stored urban runoff, stormwater runoff, and brackish water within the facility is pumped to and treated at the SMURRF for non-potable use. This project included the incorporation of real-time supervisory control and data acquisition (SCADA) controls to further increase system performance. The presentation will highlight the innovative approach to designing a regional BMP concept that enhances the existing low flow diversion and provides benefits for protecting beach water quality.