1. Legal Framework
      1. Applying the Manual
        1. Stormwater Management Standard:
        2. Post construction stormwater runoff volume, rate and quality should mimic pre-construction stormwater runoff volume, rate and quality to the maximum extent possible.
          1. _

Legal Framework
Land development activities that change the surface features of land alter stormwater runoff
characteristics. Unmanaged changes in stormwater runoff volume, rate and water quality that
alter the chemical, physical or biological properties of receiving waters can constitute pollution
that is regulated under the federal Clean Water Act, as well as the Pennsylvania Storm Water
Management Act and Clean Streams Law.
As specifically outlined in the Department’s 2002 Comprehensive Stormwater Management
Policy, DEP Policy No. 392-0300-002, post construction stormwater management must be
addressed under several regulatory programs administered by the Department of Environmental
Protection including: the NPDES Permit for Discharges Associated with Construction Activities
and the NPDES Permit for Municipal Small and Large Separate Storm Sewer System programs,
as well as under the Pennsylvania Storm Water Management Act requirements.
These regulatory programs utilize narrative based effluent limitations in the form of “best
management practices” (“BMPs”) to achieve the regulatory standard of preventing pollution.
BMPs used to manage post construction stormwater runoff must ultimately protect the water
quality of special protection waters (EV and HQ) and protect, maintain, and restore water uses
for all surface waters.
The Manual is intended to be a tool to achieve the regulatory standard to protect, maintain, and
improve the Commonwealth’s water resources through comprehensive site planning and BMP
design guidance, while allowing for the continued growth and development of Pennsylvania.
This guidance manual identifies information on resource planning, techniques for land
development, and concepts and procedures for designing and implementing performance-based
BMPs for managing stormwater for quantity and quality. The comprehensive planning approach
to stormwater management emphasizes reducing the impacts of development activities through
the mitigation process by employing practices that avoid and minimize potential impacts to
watershed resources. The BMPs are designed to minimize or mitigate for the unavoidable
impacts that development has on watershed resources.
This manual lists various BMPs and design standards, which are acceptable in Pennsylvania to
manage stormwater and prevent pollution of waters of the Commonwealth. Stormwater
management plans and the BMPs designed according to these standards when properly applied,
implemented and maintained, will achieve the Department’s water quality mandates established
in 25 Pa. Code Chapter 93 and required by the federal Clean Water Act, federal NPDES
regulations, the Pennsylvania Storm Water Management Act and the Pennsylvania Clean
Streams Law. The proper utilization and implementation of these BMPs will protect and
maintain existing uses and the level of water quality necessary to protect the existing uses, and
will protect and maintain the water quality of high quality and exceptional value waters of the
363-0300-002 / December 30, 2006

Applying the Manual
Stormwater Management Standard:
In Special Protection Waters – There should be no measurable change in post
construction stormwater runoff volume, rate and quality.
In Waters other than Special Protection – There should not be a loss of the existing
use from any change in post construction stormwater runoff volume, rate and quality.
Recommended Approach to Achieve the Standard:
Post construction stormwater runoff volume, rate and quality should mimic pre-
construction stormwater runoff volume, rate and quality to the maximum extent
This Manual Provides:
A standardized process for evaluating site design and BMP selection to minimize or
eliminate the net change in post construction volume, rate and quality.
A standardized approach to measuring pre-construction volume, rate and quality and
post construction site runoff volume, rate and quality.
Standardized specifications for BMPs to manage stormwater to minimize the net
change in post construction runoff volume, rate and quality.
Alternate BMPs, not listed in this manual, that provide the same or greater level of protection,
may also be used to attain the regulatory standard. It is incumbent on the person proposing the
use of alternative BMPs to demonstrate their effectiveness with appropriate supporting analysis,
calculations, test results or other documentation.
BMPs that fail after installation must be repaired to function properly or replaced by comparable
BMPs that will serve the intended purpose. Likewise, if unforeseen conditions occur at a site,
and the installed BMPs are obviously not effective, then alternate BMPs must be designed and
installed. The need for redesign will be determined on a case-by-case basis.
363-0300-002 / December 30, 2006

The following individuals and organizations participated in developing this manual.
Participation does not infer concurrence or endorsement of the manual or it’s contents.
Stormwater Manual Oversight Committee
Special thanks are expressed to the members of the Stormwater Manual Oversight Committee
who assisted in providing direction, guidance and expertise in the preparation of this manual
Committee members include:
Kevin Abbey, Center for Dirt and Gravel Road Studies, Pennsylvania State University
John Amend, Malcolm Pirnie, Inc.
Mark A. Bahnick, P.E., Van Cleef Engineering Associates
Theresa M. Bentley, Bucks County Planning Commission
Joan Blaustein, Three Rivers Wet Weather, Inc.
Scott A. Brown, P.E., The Pennsylvania Housing Research Center
Frank X. Browne, PhD, P.E., F.X. Browne, Inc.
Albert T. Brulo, P.E., Herbert Rowland & Grubic, Inc.
Rebecca Burns, Pennsylvania Department of Transportation
Paul A. DeBarry, P.E., P.H., Borton-Lawson Engineering, Inc.
Warren Neal Cohn, ACF Environmental
Timothy J. Edinger, P.E., Base Engineering, Inc.
Lawrence A. Fennessey, PhD, P.E., Sweetland Engineering & Assoc., Inc.
Dan Greig, District Manager, Chester County Conservation District
David Klepadlo, P.E., Malcolm Pirnie, Inc.
Anthony Miller, P.E., Pennsylvania Department of Transportation
Timothy J. Murphy, P.E., Natural Resources Conservation Service
Scott Pidcock, P.E., R.A., The Pidcock Company
James W. Pillsbury, P.E., Westmoreland County Conservation District
Bruce R. Snyder, Atlas America, Inc.
Mike M. Stadulis, Realen Homes
Thaddeus K. Stevens, President, Sylvan Glen, Inc.
Albert H. Todd, U.S. Forest Service
Robert G. Traver, PhD, P.E., Civil and Environmental Engineering Department, Villanova
Maya K. van Rossum, the Delaware Riverkeeper, Delaware Riverkeeper Network
Paul White, P.G., Walter B. Satterthwaite Assoc., Inc.
Kerry Wilson, Pennsylvania Department of Community and Economic Development
Paul Zeigler, P.E., Governors Green Government Council
Pennsylvania Department of Environmental Protection Committee Members:
Steven Burgo, Stuart Demanski, Durla Lathia, Margaret Murphy, Kenneth Murin, Kenneth
Reisinger, Edward Ritzer, Dennis Stum, and Raymond Zomok
363-0300-002 / December 30, 2006

363-0300-002 / December 30, 2006
Special technical assistance and editing provided by Karen Beyerle, Patrick Bowling, Stuart
Demanski, Stuart Gansell, Dave Goerman, Joseph Hebelka, Cedric Karper, William Kochnov,
Sharon Hill, William Manner, Jeffrey Means, Claudia Merwin, Barry Newman, Tahmina Parvin,
Frank Payer, Shelby Reisinger, Domenic Rocco, and Diane Wilson.
Contractor and Supporting Project Teams
Contractor Team
Michele Adams, P.E., Thomas Cahill, P.E., Wesley Hoerner, and Courtney Marm of Cahill
Associates Inc., West Chester, PA
Supporting Project Team
Amy Green, Amy Green Associates, Flemington, NJ
Charles Miller, P.E., Roofscapes, Philadelphia, PA
Ann Smith, Pennsylvania Environmental Council, Philadelphia, PA
Eric Strecker, P.E., and Steven Roy, P.S., GeoSyntec Consultants, Boxborough, MA
Neil Weinstein, P.E., Low Impact Development Center, Inc., Rockville, MD

Back to top