HomeMy WebLinkAbout_Workshop/Stormwater Management Code 5/17/2012
Storm Water Management Code
Common Council Workshop
May 22, 2012
Jim Bachhuber, P.H. James Rabe, P.E., CPESC
AECOM City of Oshkosh
North American Stormwater Civil Engineering Supervisor
Practice Leader
Overview
Current Code
Requirements
Construction Erosion Control
Post Construction Storm Water Management
Illicit Discharge Detection and Elimination
Summary
Questions
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5/17/2012
Current Code
Peak Flow Control (Flood Control) Only
• All Sites greater than 3 acres.
• Sites 1 —3 acres AND greater than 50% impervious
cover.
• Sites within"Areas of Known Flooding".
• Expansions exceeding 50% of the impervious area in
place when ordinance was originally implemented.
(1990)
• Post-Construction 100-year, 24-hour design storm peak
flow shall not exceed Pre-Construction 10-year, 24-
hour design storm.
Requirements
Construction Site Erosion Control Ordinance
• Comply with NR 151 and NR 216
• Implement by January 2, 2009
Post Construction Storm Water Management
• Comply with NR 151 and NR 216
• Implement by January 2, 2009
Illicit Discharge Detection and Elimination
• Comply with Clean Water Act
• Implement by July 2, 2009
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5/17/2012
Construction Erosion Control
Applies to:
• Site with 4,000 square feet or greater of disturbance.
• Site that has 100 cubic yards or greater of excavation.
• Sites involving street, highway, road or bridge
enlargement, relocation or reconstruction.
• Sites within Waters of the State, Wetlands, and
Protective Areas.
Post Construction Storm Water
Management
Applies to:
• All Post-Construction sites except:
➢ 1 and 2 family dwellings that are not part of a
"larger common plan of development".
➢ Non-point discharges from agricultural activity
areas.
➢ Non-point discharges from silvicultural activity
areas.
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5/17/2012
Post Construction Storm Water
Management
Performance Standards:
• Total Suspended Solids (TSS) Reduction
➢ New Development: 80%
➢ In-fill Development: 80%
➢ Redevelopment: 40% from roads and parking areas
Post Construction Storm Water
Management
Performance Standards continued:
• Peak Flow Rate Reduction
➢ New Development: 100-year post-development not to
exceed 10-year pre-development, 1-year, 2-year, and
10-year post-development not to exceed respective pre-
development.
➢ In-fill Development:
• Greater than 5 acres, same as New Development.
• Less than 5 acres, no 1-year and 2-year design
storm requirement.
➢ Redevelopment:No requirement.
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5/17/2012
Post Construction Storm Water
Management
Performance Standards continued:
• Infiltration:
➢ Low imperviousness: 90% of Pre-development
volume.
➢ Moderate imperviousness: 75% of Pre-development
volume.
➢ High imperviousness: 60% of Pre-development
volume.
Exemptions for soils that are not conducive to infiltration per NR 151.
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Illicit Discharge Detection and
Elimination
Prohibit discharge, spilling, or dumping of all non-storm
water substances into system.
Some Examples:
• Cross connections from sanitary sewer.
• Dumping waste oil.
• Floor drains from buildings.
• Blowing grass clippings into street.
• Improper disposal of pet waste.
• Fertilizers spilled onto impervious surfaces.
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5
5/17/2012
Summary
Overview
Current Code
Requirements
Construction Erosion Control
Post Construction Storm Water Management
Illicit Discharge Detection and Elimination
Questions
Questions
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