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Agenda
- Regulatory application of Low Impact
Development (LID)
- LID and Underground Injection Control
- Research
- Lessons Learned
GSI in Washington State Status and Trends Urban GI Summit February - - PowerPoint PPT Presentation
GSI in Washington State Status and Trends Urban GI Summit February - - PowerPoint PPT Presentation
GSI in Washington State Status and Trends Urban GI Summit February 21, 2018 1 Agenda Regulatory application of Low Impact Development (LID) LID and Underground Injection Control Research Lessons Learned Minimum Requirement #5
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In MSW Permit, LID addressed on 3 levels:
- Site & subdivision
- Development Codes
- Watershed Scale
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Minimum Requirement #5 On-site Stormwater Management
Employ On-site Stormwater Management BMPs to infiltrate, disperse, and retain stormwater runoff on-site to the extent feasible
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LID Performance Standard
Match post-development discharge durations to pre- developed durations from 8% of the 2-year flow to 50% of the 2-year flow
- Pre-development generally a
forested land cover
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Flow Control Standard
MR #7 MR #5
LID Standard 5
LID Std: Control durations from 8% of 2-yr through 50% of 2-year
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List #2
- Soil Quality and Depth
Lawn and landscaped areas:
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Glacial till: high in runoff and poor turf quality Same soil with 30% compost added. Up to 50% less runoff. Turf still healthy 4 years later
Photos: UW Test Plots
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List #2
- Full Dispersion or
Downspout Full Infiltration
- Bioretention
- > 5% of drainage area
- Downspout Dispersion
Systems
- Perforated Stub-out
Connections
Roofs: Consider in order listed; use first feasible
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Full Dispersion Permeable pavement Bioretention > 5% of drainage area Sheet Flow Dispersion, or Concentrated Flow Dispersion
Other Hard Surfaces (driveways, roads, patios, walks, parking lot) consider in order listed; use first feasible
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List #2
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What happens if all items on list are infeasible?
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Applicant must show this is true No need for anything from list(s) Must still meet Runoff Treatment and Flow Control
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MR #5 and Flow Control Exempt Water Bodies
Post-Construction Soil Quality and Depth Downspout Full Infiltration, Downspout Dispersion Systems, or Perforated Stub-out Connections Concentrated Flow Dispersion or Sheet Flow Dispersion
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Underground Injection Control
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Research
- Washington
Stormwater Center
- Full Scale Porous
Asphalt and Permeable Concrete
- Mesocosm BSM
- Full Scale
Bioretention
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GROSS Grants
- Redmond
- Kitsap County
- Tacoma
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SAM/Permittee
- Bioretention Soil Media
- Bellingham Phosphorus free BSM
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Lessons Learned
- Infiltration isn’t the end of stormwater
- May need to temper use (there are places
where you can’t do LID)
- Local Jurisdictions need freedom to limit
where LID is implemented
- Need training on non-BMP aspects of LID (Site
Planning, trees, etc.)
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Questions?
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SLIDE 17
Contact Information
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Douglas C. Howie, P.E.
- Dept. of Ecology