Bioretention reduction of PCBs study

In cooperation with the U.S. Fish and Wildlife project on bioretention amendments with fungi and plants, King County is evaluating capture of polychlorinated biphenyls (PCBs) in the same bioretention cells.

The merging of these two projects creates efficiencies in storm sample collection. The project will use stormwater gathered from Interstate 5 near the Ship Canal in Seattle.

Study questions

The study’s sampling quality assurance project plan provides information on the sites and study design.

  • Does the default bioretention soil mix to reduce PCB concentrations in highway runoff?
  • Is the capture of PCB by the soil mix seasonal, or longer?
  • Are the amended mixes still capable of preventing toxicity to aquatic organisms?

Study findings

Monitoring is underway through 2018.

Project tasks and deliverables

Scope of Work, Amendment 1

  1. Equipment invoices and Quality Assurance Project Plan (QAPP)  
  2. Stormwater and soil sampling – semiannual progress reports
  3. Data year one and year two validation memorandum
    • Deliverable 7+8
  4. Draft and final report, and final project database
    • Deliverable 9
    • Deliverable 10
  5. Project presentation
    • Deliverable 11