Conn Bar Assoc. - Stormwater

Tighe&Bond

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.

Tighe&BondTighe&Bond

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)


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


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


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


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)


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


Perforated HDPE Pipe Bed – provides groundwater Perforated HDPE Pipe Bed – provides groundwater recharge under commercial parking lotrecharge under commercial parking lot


““Wet” Detention Basin with multiple cells for Wet” Detention Basin with multiple cells for increased filtering increased filtering


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


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


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


Minimizing Pavement – narrow roads in cluster Minimizing Pavement – narrow roads in cluster subdivisions create less pollution subdivisions create less pollution


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


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


Close-up of Tree Protection Measures during Close-up of Tree Protection Measures during construction construction


Bioretention Basins incorporated into parking Bioretention Basins incorporated into parking garage landscaping garage landscaping


Detail of Bioretention Basins – normally dryDetail of Bioretention Basins – normally dry


Retrofitting bioretention into Existing Commercial Retrofitting bioretention into Existing Commercial SitesSites


Rain garden in an Endcap IslandRain garden in an Endcap Island


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


Conventional Bituminous Asphalt and Porous Paver Conventional Bituminous Asphalt and Porous Paver Blocks – Jordan Cove Subdivision –Waterford, CTBlocks – Jordan Cove Subdivision –Waterford, CT


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


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


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


Bioretention Basin provides filtering and volume Bioretention Basin provides filtering and volume control prior to discharging to wetlands control prior to discharging to wetlands


Bioretention Basins built successfully very close to Bioretention Basins built successfully very close to inland wetlands without impacting wetlands.inland wetlands without impacting wetlands.


““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


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


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


For Further Information Contact:For Further Information Contact:

Terrance Gallagher, P.E.

Tighe & Bond

1000 Bridgeport Avenue

Shelton, Connecticut 06484

(203) 712-1100

[email protected]