California Department of Transportation BMP Retrofit Pilot Program

The California Department of Transportation (Caltrans) has initiated a multi-year study in Los Angeles and San Diego to examine the technical feasibility, costs and operation and maintenance requirements of retrofitting structural Best Management Practices (BMPs) into existing highway and related infrastructure. Thirty-three locations are being retrofitted with thirty-nine BMPs using twelve different types of BMP technology. Automated monitoring stations have been installed upstream and downstream of each BMP. Constituents monitored in the runoff include: suspended solids (e.g., sediment), metals, nutrients, and organics (e.g., gasoline). Data currently being collected will show how much each constituent is reduced across each BMP. To date the projects have been sited, designed, constructed and monitored (for the first year). The purpose of the program is to identify the problems, and the solutions to those problems, that occur with structural BMP retrofit. Results to date indicate that there are substantial construction, maintenance, and cost challenges in retrofitting conventional structural BMP technology to existing infrastructure.