Measuring Street Sweeping 6PPDQ Whole Environment Load Reductions

Seattle Public Utilities is monitoring the potential for street sweeping to reduce the amount of tire wear pollutants, including 6PPD-quinone (6PPDQ), on the roadway. This new information will help permittees and Ecology adaptively manage street sweeping programs to better address stormwater impacts and specifically target 6PPDQ reductions.


Study Questions

  • Does street sweeping reduce 6PPDQ pollutant loads from Seattle’s arterial streets?
  • Are the concentrations and pickup rates of 6PPDQ and other parameters influenced by particle size, season, or land use?
  • Can we detect a correlation between the concentrations of 6PPDQ and zinc, another tire contaminant? If so, could zinc be used as a 6PPDQ indicator to reduce analytical costs?
  • To what extent does street sweeping reduce the pollutant loads of other contaminants on the street?

Study Findings

This project will continue through December 2028.

Project Tasks & Key Deliverables

Contract & Scope of Work

  1. Project Management
    • List of TAC members 
    • 2024 annual status report
    • 2025 annual status report
    • 2026 annual status report
    • 2027 annual status report
  2. Study Design
    • Revised Quality Assurance Project Plan
  3. Field Sampling, Data Collection, Analysis, and Validation
    • 2024 data package
    • 2025 data package
    • 2026 data package
    • 2027 data package
  4. Communication of Findings
    • Final Report
    • SAM Fact Sheet
    • Stormwater Work Group Presentation
    • Local or regional Presenation