Green Stormwater Infrastructure (GSI) for Stormwater Management in the City of Los Angeles: Avalon Green Alleys Network

Stormwater runoff creates flooding/pollution hazards in urban areas and Green Stormwater Infrastructure (GSI) provides modern technologies for prevention and mitigation. The Avalon Green Alley Network North and South GSI Demonstration Project (The GSIs) described in this article is a joint partnership between Los Angeles Sanitation (LASAN) and The Trust for Public Land (TPL). The GSIs is located in public alley right-of-way in a high-density neighborhood (residential, schools, parks, commercial building). The GSIs slows and infiltrates stormwater on site, capturing runoff from intersecting street catch basins, employing dry-well chambers, replacing impervious/conventional asphalt with permeable surfaces, percolating stormwater, and providing underground storage. The GSIs north section is closed to vehicular traffic after construction of a grassy swale to capture stormwater. Stormwater drains toward interlocking pavers and into underground infiltration trenches, with extra flows conveyed to a dry-well system. Monitoring includes groundwater monitoring wells, flow meters, and water-level loggers (measure water quality/quantity). Further benefits for the community includes of growing of vines/espalier trees, artistic paving, and mural artwork evoking artistic expression. The GSIs approach is setting a new trend for stormwater management in the City of Los Angeles in the untapped 1440 km of alleys, and serves as a model of community development through stormwater management to other cities.