Oyster shell retrofits in catch basins

King County evaluates the effectiveness of stormwater treatment by oyster shell. This study compares water quality in two groups of catch basins in the City of Mercer Island — one with crushed oyster shell retrofit and the other without them. King County also provides detailed project information.

Study questions

  • Does oyster shell provide treatment for dissolved metals?
  • Can catch basins with oyster shell retrofits reduce stormwater pollutants significantly more than catch basins without oyster shell?

Study findings

The study will continue until April 2022.

Project tasks and key deliverables

  1. Project management 
  2. Planning and Quality Assurance Project Plan 
  3. Field sampling and analysis
    • Flow and chemical analysis results 
  4. Final report 
  5. Communication of findings 
    • Presentation 
    • Fact sheet