In Pennsylvania, responsibility for administering the federal Clean Water Act and state stormwater regulations resides with the Department of Environmental Protection.
From The Foreword
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 Commonwealth.
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.
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 possible.