Broadway Neighborhood Stormwater Greenway Project in Los Angeles, California

摘要

Stormwater runoff poses potential flooding and pollution concerns in urban areas such as Los Angeles. The potential impacts of urban stormwater have given rise to solutions such as Low Impact Developments (LID) to remove pollutants from entering river/ocean and provide groundwater replenishment/water supply benefits. The Broadway Neighborhood Stormwater Greenway (Project) is a joint partnership between City of Los Angeles, California State Water Resources Control Board, Water Replenishment District of Southern California, Santa Monica Bay Restoration Commission, and Geosyntec Consultants, to develop a neighborhood system of LID stormwater capture/infiltration in South Los Angeles. The Project is located in public right-of-way and retrofits segments of the Broadway neighborhood with stormwater LID designed to capture, infiltrate and treat stormwater runoff, recharge groundwater, and help address Los Angeles River -Total Maximum Daily Load (TMDL) water quality requirements. Total Project cost was $4.9 million and has four levels of LID: parcel based (19 residential rain gardens/infiltration trenches); street-ends (eight dry wells); commercial green streets (four parkway infiltration swales); and sub-regional infiltration gallery (417,000-gallon underneath parking). Water quality monitoring with continuous flow meters are installed to quantify water quality/groundwater recharge. Design drainage area is approximately 45 acres and benefits from a total of tributary area of 220 acres. With its particular location above the "Los Angeles Forebay", the project is expected to recharge on average 41 acre-feet/year into the underlying Central Groundwater Basin. The Project meets TMDL requirements for the design drainage area through the removal of pollutants such as trash, bacteria, and metals. The Project provides educational, ecological, community benefits leading to a healthier, vibrant neighborhood.