REv = (0.25) * (I)/12
| ||||
Where
|
REv
|
=
|
Recharge volume in acre-feet
| |
I
|
=
|
Impervious area in acres
|
Best Management Practice
|
Design Reference NumberC
| |
---|---|---|
BioretentionA
|
4, 5, 11, 16
| |
Capture reuseB
|
4, 14
| |
Constructed wetlands
|
4, 5, 8, 10, 16
| |
Dry extended detention ponds
|
4, 5, 8, 12, 18
| |
Minimum disturbance/minimum maintenance practices
|
1, 9
| |
Significant reduction of existing impervious
cover
|
N/A
| |
Stormwater filtersA (sand, peat, compost, etc.)
|
4, 5, 10, 16
| |
Vegetated buffers/filter strips
|
2, 3, 5, 11, 16, 17
| |
Vegetated roofs
|
4, 13
| |
Vegetated swalesA
|
2, 3, 5, 11, 16, 17
| |
Water quality inletsD
|
4, 7, 15, 16, 19
| |
Wet detention ponds
|
4, 5, 6, 8
|
NOTES:
| ||
A
|
This BMP could be designed with or without an
infiltration component. If infiltration is proposed, the site and
BMP will be subject to the testing and other infiltration requirements
in this Part 2.
| |
B
|
If this BMP is used to treat the entire WQv
then it is the only BMP required because of this BMPs superior water
quality performance.
| |
C
|
See table below.
| |
D
|
Water quality inlets include such BMPs as oil/water
separators, sediment traps/catch basin sumps, and trash/debris collectors
in catch basins.
|
Number
|
Design Reference Title
| |
---|---|---|
1
|
"Conservation Design For Stormwater Management
— A Design Approach to Reduce Stormwater Impacts From Land Development
and Achieve Multiple Objectives Related to Land Use," Delaware Department
of Natural Resources and Environmental Control, The Environmental
Management Center of the Brandywine Conservancy, September 1997
| |
2
|
"A Current Assessment of Urban Best Management
Practices: Techniques for Reducing Nonpoint Source Pollution in the
Coastal Zone," Schueler, T. R., Kumble, P. and Heraty, M., Metropolitan
Washington Council of Governments, 1992
| |
3
|
"Design of Roadside Channels with Flexible Linings,"
Federal Highway Administration, Chen, Y. H. and Cotton, G. K., Hydraulic
Engineering Circular 15, FHWA-IP-87-7, McLean Virginia, 1988
| |
4
|
"Draft Stormwater Best Management Practices
Manual," Pennsylvania Department of Environmental Protection, January
2005
| |
5
|
"Evaluation and Management of Highway Runoff
Water Quality," Federal Highway Administration, FHWA-PD-96-032, Washington,
D.C., 1996
| |
6
|
"Evaporation Maps of the United States," U.S.
Weather Bureau (now NOAA/National Weather Service) Technical Paper
37, Published by Department of Commerce, Washington D.C., 1959
| |
7
|
"Georgia Stormwater Manual," AMEC Earth and
Environmental, Center for Watershed Protection, Debo and Associates,
Jordan Jones and Goulding, Atlanta Regional Commission, Atlanta, Georgia,
2001
| |
8
|
"Hydraulic Design of Highway Culverts," Federal
Highway Administration, FHWA HDS 5, Washington, D.C., 1985 (revised
May 2005)
| |
9
|
"Low Impact Development Design Strategies —
An Integrated Design Approach, Prince Georges County, Maryland Department
of Environmental Resources, June 1999
| |
10
|
"Maryland Stormwater Design Manual," Maryland
Department of the Environment, Baltimore, Maryland, 2000
| |
11
|
"Pennsylvania Handbook of Best Management Practices
for Developing Areas," Pennsylvania Department of Environmental Protection,
1998
| |
12
|
"Recommended Procedures for Act 167 Drainage
Plan Design," LVPC, Revised 1997
| |
13
|
"Roof Gardens History, Design, and Construction,"
Osmundson, Theodore. New York: W.W. Norton & Company, 1999
| |
14
|
"The Texas Manual on Rainwater Harvesting,"
Texas Water Development Board, Austin, Texas, Third Edition, 2005
| |
15
|
"VDOT Manual of Practice for Stormwater Management,"
Virginia Transportation Research Council, Charlottesville, Virginia,
2004
| |
16
|
"Virginia Stormwater Management Handbook," Virginia
Department of Conservation and Recreation, Richmond, Virginia, 1999
| |
17
|
"Water Resources Engineering," Mays, L. W.,
John Wiley & Sons, Inc., 2005
| |
18
|
"Urban Hydrology for Small Watersheds," Technical
Report 55, U.S. Department of Agriculture, Natural Resources Conservation
Service, 1986
| |
19
|
U.S. EPA, Region 1 New England Web site (as
of August 2005) http://www.epa.gov/NE/assistance/ceitts/stormwater/techs/html
|
Hot Spot Land Use
|
Pretreatment Method(s)
| |
---|---|---|
Vehicle maintenance and repair facilities including
auto parts stores
|
- Water quality 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
| ||
Vehicle fueling stations
|
- Water quality inlets
| |
- Spill prevention and response program
| ||
Storage areas for public works
|
- Water quality 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 ReferenceA
| |
---|---|---|
Constructed wetlands
|
4, 5, 8, 10, 16
| |
Diversion of stormwater away from potential
contamination areas
|
4, 11
| |
Stormwater collection and reuse (especially
for irrigation)
|
4, 14
| |
Stormwater filters (sand, peal, compost, etc.)
|
4, 5, 10, 16
| |
Vegetated swales
|
2, 3, 5, 11, 16, 17
| |
Water quality inlets
|
4, 7, 15, 16, 19
|
NOTES:
| ||
A
|
These numbers refer to the Design Reference Title Chart in Subsection O above.
|
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 per 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 (as measured by the
adapted 25 PA Code § 73.15. percolation test in Appendix
G) falls on a break between two thickness factors, the smaller thickness
factor shall be used.
| |
Sites with soil permeability greater than 12.0
inches per hour or less than 0.5 inches per hour, as measured by the
adapted 25 PA Code § 73.15 percolation test in Appendix
G, 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
| |
A graphical and tabular presentation of the
Type II, 24-hour distribution is included in Appendix C.[3]
|