Stormwater Management University of North Carolina at Chapel Hill

Stormwater Management Stormwater Management University of North Carolina University of North Carolina at Chapel Hillat Chapel Hill

Sharon Myers, L.G.Environment, Health, and Safetysamyers@email.unc.edu(919) 962-9752

What is Stormwater What is Stormwater Runoff?Runoff? NC DENR definition:

Stormwater runoff is water from rain or melting snow that “runs off” across the land instead of seeping into the ground. This runoff usually flows into the nearest stream, creek, river, lake or ocean. The runoff is not treated in any way.

UNC Stormwater UNC Stormwater Management GoalsManagement Goals“Balance growth with the

preservation of the natural drainage system.”

Meet Town of Chapel Hill Development Plan requirements

Meet NPDES Phase II requirements

Meet TMDL Requirements for Jordan Lake

A Little BackgroundA Little Background

In 1999 we realized we would be subject to Phase II permitting requirement

Did some research - Duke was paying stormwater fee to Durham of about $230,000 per year

We already were on our way to a good program via master planning process

UNC’s Phase II ApplicationUNC’s Phase II Application

Submitted application to DENR on March 10, 2003

Have been through two revision cycles

NC DENR is drafting the permit

6 Minimum Measures of 6 Minimum Measures of Phase IIPhase II Public Education and Outreach Public Involvement/Participation Illicit Discharge Detection and

Elimination Construction Site Stormwater Runoff

Control Post-construction Stormwater

Management Pollution Prevention/Good

Housekeeping

Public Outreach and Public Outreach and EducationEducation Colleges have a unique population

to educate about stormwater issues

Students, employees, and visitors can be reached though university publications, websites, and events

Many UNC employees live outside of Chapel Hill, so town’s outreach program may not be effective

Public ParticipationPublic Participation

Colleges have many willing volunteers who care about environmental issues

UNC sponsors several stream cleanups every year

Various campus groups participate in drain marking activities

Stream Clean UpsStream Clean Ups

Illicit Discharge Detection Illicit Discharge Detection and Eliminationand Elimination Old buildings have old sanitary sewer

pipes

Old buildings have floor drains that connect to the stormwater system

Liquids other than stormwater are disposed to floor drains

Sometimes people dispose of paint, wash water, etc. to the stormwater system

System needs to be completely mapped

Chemetrics KitsChemetrics Kits

Immediate Results

Ammonia, Detergent, Phenol, Chlorine, Phosphate

Relatively Inexpensive

Construction Site Runoff Construction Site Runoff ControlControl UNC has erosion and sedimentation

control requirements Emphasis is on covering exposed

soils and maintaining ESC measures Tree protection helps Construction managers are key Neighbors help NC Land Quality Section is our

regulatory agency

Post Construction Post Construction Stormwater ManagementStormwater Management

Phase II program – mostly addresses water quality

Town of Chapel Hill – addresses rate and volume of runoff in addition to quality

NPDES Phase II Post-NPDES Phase II Post-Construction Construction RequirementsRequirements Control and treat difference between pre

and post-development runoff volume for the 1 yr. 24 hr. storm

Volume drawdown in 24 to 120 hrs. 85% removal for total suspended solids 30 foot stream buffers Deed restrictions to protect BMPs Maintenance program for BMPs

Chapel Hill Development Chapel Hill Development Plan Stormwater Plan Stormwater RequirementsRequirementsNo increase in the volume of

run-off– 2 Year, 24 hour, 3.6” storm event

No increase in peak runoff ratesRemove 85% of suspended solids

for the first inch of precipitationPromise to improve our

stormwater practices.

The Problem with The Problem with PavementPavementIncrease in pavement or

buildings (impervious surface) causes– More water to run off– Water to run off faster– Degraded water quality

Analysis of Best Analysis of Best Management Practices Management Practices (BMPs)(BMPs)UNC BMP requirements

– allow stormwater to infiltrate – allow stormwater reuse– reduce runoff– fit existing landscaping (National

Landmark for Outstanding Landscape Architecture by the American Society of Landscape Architects)

– allow continued University growth

Infiltration Bed with ReuseInfiltration Bed with Reuse

Carmichael Intramural field with storage/infiltration in underlying gravel with water reuse from cistern

Storage:73,500 CF or 550,000 gallons

Pervious PavementPervious Pavement

+ PerviousAsphalt

Stone Bed with 40%Void Space forStorage/Recharge

Riverjacks OpenInto Recharge Bed

Green RoofsGreen Roofs

Carrington Hall Nursing School Addition - offices with a view

Rams Head Center- parking, gym, good food, stormwater

Other BMPs Under Other BMPs Under Consideration Consideration Rain gardensTree trenchesLandscape conversions (lawn

to fields, planting areas, reforestation)

CisternsWater quality inlets

0

50

100

150

200

250C

ost

Ben

efi

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the 2

-Yr

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rmBMP Cost Benefit Comparison

Pollution Prevention and Pollution Prevention and Good HousekeepingGood Housekeeping Secondary containment and

covered chemical storage Thoughtful usage of fertilizers and

pesticides Education for proper disposal of

maintenance chemicals and wash waters

Proper disposal or composting of grounds maintenance waste

Street and parking lot sweeping