Ecology's stormwater management manuals describe a default 60/40 bioretention soil mix (BSM) and list soil specifications for designers to create a custom filtration mix. In this project, collaborators from municipalities, academia, and the private sector will continue work to develop alternative BSM blends that do not leach phosphorus.
- Are there alternative mixtures for the bioretention soil mix (BSM) that will meet basic, enhanced, and phosphorus treatment objectives?
- Do these alternative mixes prevent toxicity to aquatic organisms?
- Are these mixes affordable and available to permittees in Washington state?
This study continues work done under an Ecology grant to develop and test eight media blends to find a high performing alternative soil mix to provide stormwater treatment, particularly to areas draining to phosphorus sensitive water bodies.
Project tasks and deliverables
1. Project management
2. Project advisory team
- Deliverable 2.1 April 2018 kickoff meeting agenda and notes
- Deliverable 2.2 Meeting agenda and notes on media components and blend
- Deliverable 2.3 Meeting agenda and notes on results and selecting the highest performing blends
- Deliverable 2.4 Meeting agenda and notes on blends physical and chemical characteristics
3. Quality Assurance Project Plan (QAPP)
4. Testing of alternative bioretention media blends
- Deliverable 4.1 Results from four clean water flushing events for water quality and saturated hydraulic conductivity. Water quality results from eight stormwater dosing events.
- Deliverable 4.2 Physical and chemical characteristics: nine metrics for developing specifications of six components of the media blend.
- Deliverable 4.3 Physical and chemical characteristics: nine metrics for developing specifications for the final three highest performing media blends.
5. Evaluate ability of media blends to protect aquatic organisms
- Deliverable 5.1 Acute toxicity results for daphnia and zebra fish
6. Distribution of findings
- Deliverable 6.1 Draft Report
- Deliverable 6.2 Presentation to SWG
- Deliverable 6.3 SAM Fact Sheet
- Deliverable 6.4 Final Report