Stormwater General Permits and Incorporation of Low Impact Development Evaluation
The Connecticut Department of Energy and Environmental Protection (DEEP) is in the process of evaluating the incorporation of Low Impact Development principles into our Stormwater General Permits. This process incorporates:
- Discussion of project including general purpose, goals and objectives
- Project partner work plan
- Partner workshop schedule, agendas, workshop summaries, and workshop materials
- Partner technical documents such as technical memoranda
- Project-related links
- Contact information
DEEP is responsible for protecting water quality under several regulatory programs including the US EPA's National Pollutant Discharge Elimination System or NPDES. The NPDES Storm Water Program, in place since 1990, regulates discharges from municipal separate storm sewer systems (MS4s), construction activities, industrial activities, and those designated by EPA due to water quality impacts. To further the goals and objectives of the NPDES legislation, the DEEP intends to incorporate low impact development (LID) best management practices (BMPs) and pollution prevention practices in its regulatory policy. This means potentially building LID into current Stormwater Permits and Design Guidance Manuals including:
- General Permit for the Discharge of Stormwater from Small Municipal Separate Storm Sewer Systems
- General Permit for the Discharge of Stormwater and Dewater Wastewaters from Construction Activities
- General Permit for the Discharge of Stormwater Associated with Industrial Activity
- General Permit for the Discharge of Stormwater Associated with Commercial Activity
Four Tenets of LID
LID-style best management practices (BMPs), such as vegetative filter strips, pocket sand filters, and infiltration systems for example, have been available for the control of stormwater for several decades, however the LID approach to site design is a relatively recent development and represents a significant change in site planning and stormwater management philosophy. LID emphasizes working within the constraints of landscapes to prevent stormwater generation, while traditional stormwater management emphasizes shunting away stormwater and treating it to the extent practicable (e.g., 80% total suspended solids removal from the first inch runoff from impervious surfaces) at or near its point of discharge.
The ideal way to manage stormwater is by preventing runoff generation. LID is a group of stormwater management techniques that do just that by controlling stormwater at its source. This occurs through the application of four key principles:
- Minimizing site disturbance
- Working with site hydrology
- Minimizing and disconnecting impervious surface
- Applying small-scale controls at the source
Specific Goals and Objectives of this Process
Pursuant to this process DEEP intends to:
- Establish LID and pollution prevention, performance goals, and criteria for management practices common to Stormwater General Permit implementation.
- Identify how the performance goals and criteria can be most effectively incorporated into the Stormwater General Permit(s) to meet permit limits and conditions; and
- Identify mechanisms for incorporating LID BMPs and pollution prevention practices into the Stormwater General Permit(s) for priority attention.
DEEP also intends this process to explore several critical aspects of current and developing stormwater management practices to protect receiving waters and to provide clear regulatory guidance for the regulated community to effectively comply with permit requirements. This means providing the technical, planning and design tools necessary for effective site design, as well as a framework for broader compliance of the municipal regulatory community. These critical aspects include:
- Use of runoff volume as an indicator of environmental effect
- Relationship between volume control and pollutant control
- Appropriate permit limits for runoff volume relative to storm size
- Necessary guidance including performance criteria for LID and pollution prevention and end-of-pipe BMPs
- Role and benefit of stormwater utilities
- Building LID, stormwater utilities, and other management tools into permits and guidance
- Expanding the approach to other general permits such as the MS4 and Industrial Stormwater General Permits.
DEEP also intends to explore approaches for incorporating LID into stormwater policies that are being used by other states.
Stakeholder Meetings: A series of five Stakeholder meetings were held at CT DEEP, 79 Elm Street, Hartford, CT.
#1 May 26, 2010:
#2 July 1, 2010
#3 August 31, 2010
#4 October 20, 2010
#5 December 15, 2010
August 2011 (revised to incorporate public comment)