conn bar assoc. - stormwater
DESCRIPTION
04-27-09 Talk on Stormwater to the Land Use Section of the Connecticut Bar AssociationTRANSCRIPT
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Changing Requirements for Stormwater in Changing Requirements for Stormwater in ConnecticutConnecticut
Connecticut Bar Association, Planning & Zoning SectionConnecticut Bar Association, Planning & Zoning SectionNew Haven, CTNew Haven, CTApril 27, 2009April 27, 2009
Presented by: Terrance Gallagher, P.E.
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Current Efforts to Regulate Stormwater that Impact Current Efforts to Regulate Stormwater that Impact Development in ConnecticutDevelopment in Connecticut
Municipal Regulations – an increasing use of LID-Style BMP’s
State Regulations and
DEP Initiatives Regional &
Environmental Groups (HVA, CFPA)
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Municipal MS-4 Program Components Municipal MS-4 Program Components
Public Education
Public Participation
Illicit Discharge Detection Construction Storm Runoff
Control
Post-Construction Stormwater Management
Pollution Prevention\Good Housekeeping
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Types of Pollution Found in Stormwater Types of Pollution Found in Stormwater
Total Suspended Solids (TSS) is a main design pollutant – carries oils, metals, and nutrients
Phosphorous causes algae blooms in lakes
Nitrogen impacts coastal waters and can cause hypoxia in Long Island Sound.
Road Salt can impact wells and drinking water supplies
Trash and Fecal Coliform Bacteria can be issues near Swimming Beaches and Lakes
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Conventional Catch Basin with Sump – limited Conventional Catch Basin with Sump – limited sediment removal capacity, but no nutrient removal sediment removal capacity, but no nutrient removal capabilitycapability
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Stormwater requirements may occur in a variety of Stormwater requirements may occur in a variety of places in Municipal Regulations places in Municipal Regulations
Zoning Regulations
Subdivision Regulations
Inland Wetland Regulations
Drainage Manuals (Greenwich, Norwalk, East Harford)
MS-4 Stormwater Plans
Other Documents (GNHWPCA Design Manual)
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Vortechnics Oil-Grit Separator – removes TSS, oil, Vortechnics Oil-Grit Separator – removes TSS, oil, grease & floatable debris – good “End of Pipe” grease & floatable debris – good “End of Pipe” treatment, but does nothing for controlling runoff treatment, but does nothing for controlling runoff volume or soluble nutrientsvolume or soluble nutrients
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Perforated HDPE Pipe Bed – provides groundwater Perforated HDPE Pipe Bed – provides groundwater recharge under commercial parking lotrecharge under commercial parking lot
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““Wet” Detention Basin with multiple cells for Wet” Detention Basin with multiple cells for increased filtering increased filtering
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What is LID?What is LID?
Low Impact Development (LID) is a variety of methods to reduce pollutant loading
Less impervious cover =
less runoff volume
Less runoff volume = lower pollutant loads to watercourses & wetlands
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Typical LID BMP – no curb & grass swales provide Typical LID BMP – no curb & grass swales provide filtering parking lot runoff instead of catch basins filtering parking lot runoff instead of catch basins and pipes and pipes
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How LID Impacts Site DevelopmentHow LID Impacts Site Development
LID consumes Real Estate
LID can provide groundwater recharge, nutrient filtering, and control of runoff volumes
Urban sites have different constraints from Suburban & Rural Sites
Preserving Existing Trees & Streambank Buffers
Minimizing Pavement - Parking Standards, Roadway Width, Parking Waivers, Overflow Parking
Opportunities for Improvements
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Minimizing Pavement – narrow roads in cluster Minimizing Pavement – narrow roads in cluster subdivisions create less pollution subdivisions create less pollution
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Biofilter Basin catches Road Sand before entering Biofilter Basin catches Road Sand before entering wetlands – allows for Town maintenance with wetlands – allows for Town maintenance with backhoebackhoe
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View Upstream at Biofilter Outlet – low tech solution View Upstream at Biofilter Outlet – low tech solution that fits into New England landscapethat fits into New England landscape
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Close-up of Tree Protection Measures during Close-up of Tree Protection Measures during construction construction
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Bioretention Basins incorporated into parking Bioretention Basins incorporated into parking garage landscaping garage landscaping
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Detail of Bioretention Basins – normally dryDetail of Bioretention Basins – normally dry
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Retrofitting bioretention into Existing Commercial Retrofitting bioretention into Existing Commercial SitesSites
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Rain garden in an Endcap IslandRain garden in an Endcap Island
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Reducing Impervious SurfacesReducing Impervious Surfaces
Gravel or Crushed Stone
Pervious Paver Blocks
Grid Paver Systems
Visit UConn’s NEMO Website for examples: http://www.nemo.uconn.edu/reducing_runoff/index.htm
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Conventional Bituminous Asphalt and Porous Paver Conventional Bituminous Asphalt and Porous Paver Blocks – Jordan Cove Subdivision –Waterford, CTBlocks – Jordan Cove Subdivision –Waterford, CT
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Detail of Eco-Stone Paver Blocks – set on crushed Detail of Eco-Stone Paver Blocks – set on crushed stone base to recharge runoff directlystone base to recharge runoff directly
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Turfstone Pavers – control run-on from paved Turfstone Pavers – control run-on from paved parking lot & provide parking for peak use parking lot & provide parking for peak use
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Infiltration Trench recharges sheet flow from parking Infiltration Trench recharges sheet flow from parking lot prior to discharge to biofilter basin lot prior to discharge to biofilter basin
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Bioretention Basin provides filtering and volume Bioretention Basin provides filtering and volume control prior to discharging to wetlands control prior to discharging to wetlands
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Bioretention Basins built successfully very close to Bioretention Basins built successfully very close to inland wetlands without impacting wetlands.inland wetlands without impacting wetlands.
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““Wet” Bioretention Basin with wetland seed mix treat Wet” Bioretention Basin with wetland seed mix treat runoff at the edge of the parking lotrunoff at the edge of the parking lot
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Operations & Maintenance SchedulesOperations & Maintenance Schedules
Construction – daily road sweeping, weekly site clean up, before storms, after every large storm
Daily – general clean-ups, sweeping parking lots and walks, trash pick up
Monthly – inspections, clearing debris, watering vegetated areas
Seasonal – Spring and Fall road sweeping, sand removal, snow storage
Annual – tank pump outs, replacing oil absorbent pillows,
Semi-Annual – checking detention berms, outfall protection
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Recent Connecticut Funding for Towns in the Recent Connecticut Funding for Towns in the Farmington River Watershed to incorporate LID into Farmington River Watershed to incorporate LID into Town RegulationsTown Regulations Avon Barkhamsted Colebrook East Granby Harwinton New Hartford Plainville Simsbury Torrington Winchester
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For Further Information Contact:For Further Information Contact:
Terrance Gallagher, P.E.
Tighe & Bond
1000 Bridgeport Avenue
Shelton, Connecticut 06484
(203) 712-1100