WQv = (c)(P)(A)/12
| ||||
---|---|---|---|---|
Where
| ||||
WQv
|
=
|
Water quality volume in acre-feet
| ||
c
|
=
|
Rational Method post-development runoff coefficient for the
two-year storm
| ||
P
|
=
|
1.25 inches
| ||
A
|
=
|
Area in acres of proposed regulated activity
|
Best Management Practice
|
Design Reference
| |
---|---|---|
Bioretention
|
Low Impact Development Design Strategies, Prince George's County,
Md., June 19992
| |
Capture reuse
|
Texas Guide to Rainwater Harvesting, 2nd Edition. Texas Water
Development Board, Center for Maximum Potential Building Systems,
19973
| |
Constructed wetlands
|
2000 Maryland Stormwater Design Manual, Maryland Department
of the Environment4
| |
Minimum disturbance/minimum maintenance practices
|
Conservation Design for Stormwater Management Delaware Dept.
of Natural Resources and Brandywine Conservancy, September 19975
| |
Oil/water separators
|
Georgia Stormwater Management Manual Volume 2 Technical Handbook,
August 20016
| |
Sediment traps/catch basin sumps
|
U.S. Environmental Protection Agency's Post-Construction Stormwater
Management in New Development & Redevelopment BMP Fact Sheet for
"Catch Basins/Catch Basin Insert"7
| |
Significant reduction of existing impervious cover
|
N/A
| |
Stormwater filters (sand, peat, compost, etc.)
|
Design of Stormwater Filtering Systems. Claytor, R. and Schueler,
T., Center for Watershed Protection, December 19968
| |
Trash/debris collectors in catch basins
|
Pennsylvania Handbook of BMPs for Developing Areas9 or latest PA Department of Environmental Protection
Manual
| |
Vegetated buffers/filter strips
|
Pennsylvania Handbook of BMPs for Developing Areas9 or latest PA Department of Environmental Protection
Manual
| |
Vegetated roofs
|
Roof Gardens: History, Design, and Construction. Osmundson,
T., W. W. Norton & Co., 199810
| |
Vegetated swales/filter strips
|
2000 Maryland Stormwater Design Manual, Maryland Department
of the Environment4
| |
Water quality inserts for inlets
|
Pennsylvania Handbook of BMPs for Developing Areas9 or latest PA Department of Environmental Protection
Manual
| |
Wet detention ponds
|
Pennsylvania Handbook of BMPs for Developing Areas9 or latest PA Department of Environmental Protection
Manual
|
NOTES:
| ||
---|---|---|
1
|
If this BMP is used to treat the entire WQv, then only one BMP is required because of this BMP's superior water
quality performance.
| |
2
|
Available at www.co.pg.md.us/Government/AgencyIndex/DER/PPD/LID/LiDNatl.pdf
as of January 2004
| |
3
|
Available at www.twdb.state.tx.us/publications/reports/RainHarv.pdf
as of January 2004
| |
4
|
Available at www.mde.state.md.us as of January 2004
| |
5
|
Available at www.dnrec.state.de.us/dnrec2000/Divisions/Soil/Stormwater/Apps/
DesignManualRequest.htm as of January 2004
| |
6
|
Available at www.georgiastormwater.com as of January 2004
| |
7
|
Available at http://cfpub.epa.gov/npdes/stormwater/menuofbmps/post_7.cfm
as of January 2004
| |
8
|
Available from the Center for Watershed Protection (www.cwp.org)
as of January 2004
| |
9
|
Available at www.dep.state.pa.us (keyword "stormwater") as of
January 2004
| |
10
|
Available at www.wwnorton.com as of January 2004
|
Hot Spot Land Use
|
Pretreatment Method(s)
| ||
---|---|---|---|
Vehicle maintenance and repair facilities including auto parts
stores
|
•
•
•
•
|
Oil/water separators
Use of drip pans and/or dry sweep material under vehicles/equipment
Use of absorbent devices to reduce liquid releases
Spill prevention and response program
| |
Vehicle fueling stations
|
•
•
•
|
Oil/water separators
Water quality inserts for inlets
Spill prevention and response program
| |
Storage areas for public works
|
•
•
•
•
•
•
•
|
Oil/water separators
Sediment traps/catch basin sumps
Water quality inserts for inlets
Use of drip pans and/or dry sweep material under vehicles/equipment
Use of absorbent devices to reduce liquid releases
Spill prevention and response program
Diversion of stormwater away from potential contamination areas
| |
Outdoor storage of liquids
|
•
|
Spill prevention and response program
| |
Commercial nursery operations
|
•
•
•
|
Vegetated swales/filter strips
Constructed wetlands
Stormwater collection and reuse
| |
Salvage yards and recycling facilities*
|
•
|
BMPs that are a part of a stormwater pollution prevention plan
under an NPDES Permit
| |
Fleet storage yards and vehicle cleaning facilities*
|
•
|
BMPs that are a part of a stormwater pollution prevention plan
under an NPDES Permit
| |
Facilities that store or generate regulated substances*
|
•
|
BMPs that are a part of a stormwater pollution prevention plan
under an NPDES Permit
| |
Marinas*
|
•
|
BMPs that are a part of a stormwater pollution prevention plan
under an NPDES Permit
| |
Certain industrial uses (listed under NPDES)*
|
•
|
BMPs that are a part of a stormwater pollution prevention plan
under an NPDES Permit
|
NOTES:
| ||
---|---|---|
*
|
Regulated under the NPDES Stormwater Program
|
Pretreatment Method
|
Design Reference
| |
---|---|---|
Constructed wetlands
|
2000 Maryland Stormwater Design Manual, Maryland Department
of the Environment1
| |
Diversion of stormwater away from potential contamination areas
|
Pennsylvania Handbook of BMPs for Developing Areas2 or latest PA Department of Environmental Protection
Manual
| |
Oil/water separators
|
Georgia Stormwater Management Manual Volume 2 Technical Handbook,
August 20013
| |
Sediment traps/catch basin sumps
|
U.S. Environmental Protection Agency's Post-Construction Stormwater
Management in New Development and Redevelopment BMP Fact Sheet for
"Catch Basins/Catch Basin Insert"4
| |
Stormwater collection and reuse (especially for irrigation)
|
Texas Guide to Rainwater Harvesting, 2nd Edition, Texas Water
Development Board, Center for Maximum Potential Building Systems,
19975
| |
Stormwater filters (sand, peat, compost, etc.)
|
Design of Stormwater Filtering Systems. Claytor, R. and Schueler,
T., Center for Watershed Protection, December 19966
| |
Trash/debris collectors in catch basins
|
Pennsylvania Handbook of BMPs for Developing Areas2 or latest PA Department of Environmental Protection
Manual
| |
Vegetated swales/filter strips
|
2000 Maryland Stormwater Design Manual, Maryland Department
of the Environment1
| |
Water quality inserts for inlets
|
Pennsylvania Handbook of BMPs for Developing Areas2 or latest PA Department of Environmental Protection
Manual
|
NOTES:
| ||
---|---|---|
1
|
Available at www.mde.state.md.us as of January 2004
| |
2
|
Available at www.dep.state.pa.us (keyword Stormwater) as of
January 2004
| |
3
|
Available at www.georgiastormwater.com as of January 2004
| |
4
|
Available at http://cfpub.epa.gov/npdes/stormwater/menuofbmps/post_7.cfm
as of January 2004
| |
5
|
Available at www.twdb.state.tx.us/publications/reports/RainHarv.pdf
as of January 2004
| |
6
|
Available from the Center for Watershed Protection (www.cwp.org)
as of January 2004
|
(Area tributary to infiltration BMP/base area of infiltration
BMP) *100%
|
The area tributary to the infiltration BMP shall be weighted
as follows:
| ||
All disturbed areas to be made impervious:
|
Weight at 100%
| |
All disturbed areas to be made pervious:
|
Weight at 50%
| |
All undisturbed pervious areas:
|
Weight at 0%
| |
All existing impervious areas:
|
Weight at 100%
|
Permeability Range*
(inches/hour)
|
Thickness Factor
| |
---|---|---|
6.0 to 12.0
|
0.8
| |
2.0 to 6.0
|
1.0
| |
1.0 to 2.0
|
1.4
| |
0.75 to 1.0
|
1.2
| |
0.5 to 0.75
|
1.0
|
NOTES:
| ||
---|---|---|
*
|
If the permeability rate falls on a break between two thickness
factors, the smaller thickness factor shall be used.
| |
Sites with soil permeability greater than 12.0 inches/hour or
less than 0.5 inch/hour are not recommended for infiltration.
|
Return Period
|
24-Hour Rainfall Depth
(inches)
| |
---|---|---|
1-year
|
2.40
| |
2-year
|
3.00
| |
5-year
|
3.60
| |
10-year
|
4.56
| |
25-year
|
5.52
| |
50-year
|
6.48
| |
100-year
|
7.44
|