new bioretention standards
Post on 29-Jul-2015
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Construction Site Permitting and
New Bioretention Standards
Chris Cotton
Stormwater Program Coordinator
Ohio EPA – Southwest District Office
Christopher.cotton @ epa.ohio.gov
937.285.6442
OEPA’s Construction General PermitOEPA’s Construction General Permit
Revised every 5 yearsRevised every 5 years ESC at active construction sites, andESC at active construction sites, and Proper mgmt of materials, wasteProper mgmt of materials, waste “ “Post-construction” runoff mgmt toPost-construction” runoff mgmt to
Improve water quality Improve water quality Protect stream stability/functionProtect stream stability/function
Post-ConstructionPost-Construction & the & the “Water Quality Volume”“Water Quality Volume” (p 18 of CGP) (p 18 of CGP)
WQv = C x P x A/12 WQv = C x P x A/12 C = runoff coefficientC = runoff coefficient P = 0.75 inches of rain P = 0.75 inches of rain
A = area draining to BMPA = area draining to BMP
-- BMPs listed in permit (p 21) -- BMPs listed in permit (p 21)
-- Alternative BMPs => OEPA approval-- Alternative BMPs => OEPA approval
Bioretention as Post-con BMPBioretention as Post-con BMP
• Size to handle all (or part) of a siteSize to handle all (or part) of a site• • 24 hour draindown 24 hour draindown •• Rain gardens not considered bioretentionRain gardens not considered bioretention
• Lack specific design standardsLack specific design standards• Rain gardens typically smallRain gardens typically small• Better suited for retrofitsBetter suited for retrofits
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