Advocating Water Quality Improvement in Detroit
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The document outlines the challenges and recommendations for urban stormwater management, emphasizing the need for specific, objective, and enforceable permit terms to effectively manage runoff. It discusses performance standards for stormwater management and provides examples of permit criteria from California and Boise, Idaho, promoting the use of green infrastructure practices. The goal is to enhance municipal stormwater permits to better capture and treat stormwater, ultimately protecting water quality.
Advocating Water Quality Improvement in Detroit
- 1. Permitting Green Infrastructure Katie Rousseau Associate Director, Clean Water Supply Program 2013 Healing Our Waters Great Lakes Restoration Conference S
- 2. Background National Research Council (NRC) 2009 report Urban Stormwater Management in the United States S The stormwater permit program s over-reliance on general permits, most of which contain vague, subjective, and unenforceable permit terms S The relative lack of permits that require stormwater management practices that will actually reduce runoff volume rather than simply convey or detain it
- 3. EPA s Response S Objective performance standard that control volume and mimic pre- development hydrology S Explicit requirements for green infrastructure measures S Establishing limits or ceilings on the amount of impervious area 2010 MS4 Permit Improvement Guide
- 4. Permits need specific, objective language
- 5. Objective Performance Standards • 1 of rainfall • Runoff from a 2 year-24 hour storm event • 85th percentile storm
- 6. California Phase II Permit E.12.e(ii)(c) Numeric Sizing Criteria for Storm Water Retention and Treatment The Permittees shall require facilities designed to evapotranspire, infiltrate, harvest/ use, and biotreat storm water to meet at least one of the following hydraulic sizing design criteria: (a) Volumetric Criteria (1) The maximized capture storm water volume for the tributary area, on the basis of historical rainfall records, determined using the formula and volume capture coefficients in Urban Runoff Quality Management, (that is, approximately the 85th percentile 24-hour storm runoff event); or (2) The volume of annual runoff required to achieve 80% or more capture using local rainfall data.
- 7. California Phase II Permit (b) Flow-based Criteria (1) The flow of runoff produced from a rain event equal to at least 0.2 inches per hour intensity; or (2) The flow of runoff from a rain event equal to at least 2 times the 85th percentile hourly rainfall intensity as determined from local rainfall records.
- 8. Boise, Idaho Draft Phase I Permit B.2.a(i) The ordinance/regulatory mechanism must include site design standards for all new and redevelopment that require, in combination or alone, storm water management measures that keep and manage onsite the runoff generated from the first 0.6 inches of rainfall from a 24-hour event preceded by 48 hours of no measurable precipitation. Runoff volume reduction can be achieved by canopy interception, soil amendments, evapotranspiration, rainfall harvesting, engineered infiltration, extended filtration, and/or any combination of such practices that will capture the first 0.6 inches of rainfall.
- 9. Thank You Katie Rousseau American Rivers krousseau@americanrivers.org 419-936-3759 Permitting Green Infrastructure: A Guide to Improving Municipal Stormwater Permits and Protecting Water Quality by Jeff Odefey (http://www.americanrivers.org/newsroom/resources/permitting-greeninfrastructure-a-guide-to-improving-municipal-stormwater-permits-andprotecting-water-quality/) *News and Media ‒ Reports & Publications