Greening the Los Angeles Public Right-of-Way: Prioritizing Green Stormwater Infrastructure for Multiple Benefits
The City of Los Angeles (City) faces substantial challenges associated with flood control, water quality, water supply, and aging infrastructure within the public right of way. It is estimated that 2,400 centerline miles of roadway are near or at failing, and the city sidewalks will require $1.3 billion in repairs. Budget constraints aside, the region is looking at roughly $20 billion in stormwater compliance costs. In an effort to employ a more targeted and comprehensive approach to infrastructure expenditures that go above and beyond minimum MS4 permit regulations, the City of Los Angeles - LA Sanitation (LASAN) is developing an inter-departmental strategy for Green Stormwater Infrastructure (GSI) Low Impact Development (LID) within the public right-of-way (PROW).
The vision of this project is to develop a sustainable framework for all City construction projects that will utilize the untapped potential of the PROW for green streets implementation, while also providing water quality, water supply, and other benefits such as heat island reduction, flood control risk minimization, and other social, economic, and environmental benefits. Additional goals are to cost-effectively implement green infrastructure, while enhancing the local sense of community, aesthetics, safety, options and incentives for alternative modes of transportation, and overall mobility of City streets.
The current vision of the program would require that City construction projects (not just private developers) implement Best Management Practices (BMPs), as tailored to local environmental needs, as well as project location, size, and scope of work. The current planning approach uses a spatial overlay of combined water quality and water supply needs to assign an “environmental significance category” to their project. The location screening for water quality priorities considers land use‐specific pollutant loads, and the impairments of the receiving waters, using methodologies developed in part by the City of Los Angeles, and endorsed by the Regional Water Quality Control Board, and utilized in the Greater Los Angeles County Integrated Regional Water Management Plans (a partnering effort of multiple agencies, including the City of Los Angeles). The potential benefits of recharge of stormwater to groundwater basins were analyzed as part of the City’s Stormwater Capture Master Plan and other regional studies. This analysis examined aquifer type, soils types, geologic units (groundwater aquifers), groundwater depth, and surface slopes, and consolidated the results as a prioritized, geospatial data layer in support of the program.
The presentation will further present a key decision matrix developed to categorize projects by size and scope of work, and assign tailored BMP requirement thresholds and design criteria. Discussion will also cover what projects would be categorically exempt due to such factors as emergency repairs, lack of environmental significance, or routine maintenance activities. LASAN is currently in the process of developing an accompanying Stormwater Management Handbook, which will guide the user to site- and scope-specific GSI types, required levels of implementation, and cut sheets for each specific GSI type. This presentation will walk through the process, including the identification and development of the “GSI unit” approach, opening a door for a potential stormwater credit trading system to provide additional planning flexibility.
This presentation will also highlight potential costs savings, as it is recognized that by integrating GSI elements into already planned projects, significant cost savings may be realized (when compared to “business‐as‐usual” approaches of independent project development).
Ken Susilo is a Senior Principal and Vice President with Geosyntec Consultants, managing the firm’s Los Angeles operations. He has been a practicing water resources engineer and PE in California for 25 years, and is focused on multi-benefit water resources project planning, funding, development, and delivery. He is a D.WRE, and CPSWQ, and graduate of UC Berkeley.