Clean Watersheds for a Clean Bay
Clean Watersheds for a Clean Bay (CW4CB), EPA Water Quality Improvement Grant is evaluating a variety of potential control options to reduce mass loadings of PCBs, mercury and other pollutants in urban stormwater runoff to the San Francisco Bay. The project lays the groundwork for meeting TMDL waste load allocations and restoring water quality in the future. Task 3 of this project has selected five high priority project watersheds that discharge urban runoff with PCBs and other pollutants to the Bay and is identifying PCB and mercury source properties within the project watersheds for referral to regulatory agencies for cleanup and abatement. Task 4 is evaluating methods to optimize removal of sediment with PCBs and other particle-bound pollutants during routine municipal street sweeping and street flushing operations. Task 5 is retrofitting 10 urban runoff treatment BMPs into existing infrastructure throughout the Bay Area and evaluating effectiveness to address best retrofit options.
ADH, as a subcontractor to Applied Marine Sciences, has performed the following:
Task 3: Sediment Sampling within PCB Hotspot Watersheds
With strict adherence to clean sampling techniques, ADH collected targeted sediment samples on public right of ways adjacent to known or suspected PCB source properties.
Task 4: Street Sweeper Study - Vacuum Sampling of Roadway Sediments
Adopting proven sampling techniques from the University of Wisconsin, ADH field crews have performed dozens of vacuum sediment sampling events on four roadways in known Bay Area PCB hotspots. Composite sampling was performed across multiple random transects of roadways immediately before and after street sweeping operations.
Task 5: Stormwater Monitoring of BMP Treatment-Control Devices
DH designed the sampling and flow monitoring methods that are used to assess the effectiveness of a variety of BMP types located in PCB hotspots throughout the Bay Area including: bioretention swales and cells, tree wells, hydrodynamic separators, media bed filters, etc. ADH staff have sampled several storms at five BMP paired locations (influent and effluent monitoring) during water year 2014. In addition to managing and performing event monitoring, ADH is collecting and processing hydrologic data to aid in BMP effectiveness evaluation. A particle size fractionation component is currently being added to the program such that suspended sand and silt are separated in the field from suspended fine particulate matter to better assess BMP performance of large vs. small particles and associated PCBs.