Stormwater Management

For DevelopingMunicipalitiesWhat Residents

Can Do

What Towns Can Do

ACKNOWLEDGEMENTS

• CENTER FOR WATERSHED PROTECTION, www.cwp.org

• www.stormwatercenter.net

• Tom Schueler, Director of Watershed Research and Practice at CWP

• NEMO PROGRAM - University of Connecticut, http://nemo.uconn.edu/

Development Impactson the Water CycleDevelopment ImpactsDevelopment Impactson the Water Cycleon the Water Cycle

50%50%50%10%10%10%

15%15%15%55%55%55%

Development Means Less Infiltration

Nutrients Pathogens Sediment Toxic Contaminants Debris Thermal Stress

NutrientsNutrients

PathogensPathogens

SedimentSediment

Toxic ContaminantsToxic Contaminants

DebrisDebris

Thermal StressThermal StressIncreased quantityIncreased quantity

Decreased qualityDecreased quality

Development Impacts on Water QualityDevelopment Impacts on Development Impacts on Water QualityWater Quality

NutrientsPathogensSedimentToxic ContaminantsDebrisThermal Stress

Waterway Health & Waterway Health & ImperviousnessImperviousness

Waterway Health & Waterway Health & ImperviousnessImperviousness

ADAPTED FROM SCHUELER, ET. AL., 1992ADAPTED FROM SCHUELER, ET. AL., 1992

8080

7070

6060

5050

4040

3030

2020

1010

00

STREAM DEGRADATIONSTREAM DEGRADATION

WA

TE

RS

HE

D I

MP

ER

VIO

US

NE

SS

WA

TE

RS

HE

D I

MP

ER

VIO

US

NE

SS

(%)

(%)

DEGRADED

PROTECTED

IMPACTED

Waterway Health Declines

Imperviousness Increases

MUNICIPAL ACTION

• Public Works – Streets– Playing Fields and parks– Stormwater sewer

system

• New Development– Planning– Zoning– Maintenance

Culvert and Outfall

Opportunity for Retrofit

Scenario for erosion

STORMWATER MANAGEMENT ORDINANCE

For New Development

Groundwater Recharge Requirement

• Maintain Existing (100%) Average Annual Groundwater Recharge post development

OR

• Infiltrate the Post Development Increase in the 2-year Storm •

Nonstructural SWM Strategies

• Protect areas that provide water quality benefits

• Minimize & Separate Impervious Cover

• Maximize protection of natural drainage features and vegetation

• Minimize Disturbance

• Minimize Reduction in Time of Concentration

• Minimize soil compaction

(should be in municipal ordinance)

• Provide Low-maintenance Landscaping and use of native vegetation

• Provide Opportunities for Reduction of Pollutants at the Source – Trash Racks and Receptacles

– Minimize Vegetation That Needs Fertilizers

– Use Native Plants

• Manage stormwater runoff at source

LAND USE ORDINANCESESTABLISH DESIGN

STANDARDS