In Pennsylvania, responsibility for administering the federal Clean Water Act and state stormwater regulations resides with the Department of Environmental Protection.
DEP manages stormwater through various regulatory programs, including: NPDES Permit for Municipal Small and Large Separate Storm Sewer System (MS4 Program); NPDES Permits for Discharges Associated with Construction Activities; and the Pennsylvania Storm Water Management Act. Details can be found here.
Pennsylvania’s MS4 Program reflects the six Minimum Control Measures (MCMs) of the federal program, as discussed here, and calls for the application of Best Management Practices (BMPs) to each MCM.
In order to assist municipalities, designers, developers, and engineers in understanding, developing, and implementing stormwater management programs, PA DEP published the PA Stormwater BMP Manual in 2006. As noted in the Foreword:
"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."
As such, the Manual’s main focus is on BMPs that help meet the requirements of MCMs 4 through 6. These BMPs are generally classified as “non-structural” (design and planning techniques that preserve natural systems and hydrologic functions on a site) and “structural” (more conventional “brick and mortar” techniques, which may include vegetation and soil-based mechanisms.) The key distinction between Non-Structural and Structural BMPs is that the former are intended to prevent stormwater generation, while the focus of the latter is on mitigating unavoidable stormwater-related impacts.
When it comes to development, the Stormwater Management Program described in the Manual emphasizes a comprehensive total site design approach. Whether referred to as “Low Impact Development”, “Conservation Design”, or “Green Design”, this environmentally sensitive approach to site development and stormwater management aims to minimize the effect of development on water, land, and air resources.
The use of best management practices, or BMPs, is the primary method of controlling stormwater discharges and preventing runoff from adversely affecting water quality. BMPs are a suite of planning processes, development methodologies, and specific techniques designed to be used in combination to:
- Prevent disturbances to natural systems and hydrologic functions; and
- Minimize the impacts of disturbances where they do occur.
The Comprehensive Stormwater Management Site Planning and Design Procedure described in Chapter 4 of the PA BMP Manual provides guidance on how to determine the most appropriate solution for managing stormwater on a specific site. It is important to use this Procedure or a similar process to develop a stormwater management plan that meets local regulations and aligns with the Commonwealth’s water quality and quantity goals.
Together with the Brandywine Conservancy, StormwaterPA has created a multi-media tour through the land development process—from initial planning to final design.