Stormwater Management University of North Carolina at Chapel Hill Sharon Myers, L.G. Environment,...
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Transcript of Stormwater Management University of North Carolina at Chapel Hill Sharon Myers, L.G. Environment,...
Stormwater Management Stormwater Management University of North Carolina University of North Carolina at Chapel Hillat Chapel Hill
Sharon Myers, L.G.Environment, Health, and [email protected](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
t ($
/CF
)
for
the 2
-Yr
Sto
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