ESD Background Stormwater Management Act of 2007
Local ordinance revisions
Revise Chapter 5 of the MD SWM Design Manual
Phased SWM design & review process
Implement ESD planning techniques
ESD to the Maximum Extent Practicable (MEP)
Structural practices as last priority
ESD Background Stormwater Management Act of 2007 October 1, 2007 Act Effective May 5, 2009 COMAR revisions effective April 15, 2009 Design Manual Chapter 5 Revised November 11, 2009 Local ordinances due to MDE May 4, 2010 Local ordinances must be adopted
The design process will require the developer to adhere to the following procedures to achieve ESD to the MEP:
Following the Design Process for New Development as outlined in the step wise procedures in Figure 5.1
Developing a map that identifies natural resource areas and drainage patterns and devising strategies for protection and enhancement.
Minimizing total site imperviousness by implementing clustered development and other better site design techniques.
Demonstrating that all reasonable opportunities for meeting stormwater requirements using ESD have been exhausted by using natural areas and landscape features to manage runoff from impervious surfaces and that structural BMFs have been used only where absolutely necessary.
Participate in the comprehensive review process for interim plans review and approval at the conceptual, site development, and final phases ofproject design.
Integrating strategies for erosion and sediment control and stormwater management into a comprehensive development plan.
ESD Design Philosophy Eliminate stormwater impacts with materials selection Treat stormwater as close to the source as possible – convey AFTER treatment Use small-scale vegetated practices integrated throughout the site Site layout guidelines Locate green spaces down-slope of impervious for treatment Grade site to maintain sheet flow Avoid concentrated flows
Option 1 Maintain Existing 1- and 2-Year Rate AND Volume
NOT within ESD Practices Design Framework
Option 2 Stream Channel Protection
Fits within ESD Practices Design Framework
Non-ESD Calculations Required
Case 2 - Existing Impervious Greater Than 50%
Reduce Existing 2-Year Rate AND Volume by 25%
NOT within framework of ESD
LEED 6.1 ESD Peak Discharge Rate Control Y Y Volume Control Y N
LEED Sustainable sites 6.1 Quantity Control ESD PRACTICE PEAK VOLUME A-1 Green Roofs Y N A-2 Permeable Pavements Maybe/Enhanced Maybe/Enhanced A-3 Reinforced Turf Maybe/Enhanced Maybe N-1 Disconnection of Rooftop Runoff N N N-2 Disconnection of Non-Rooftop Runoff N N N-3 Sheetflow to Conservation Areas N N M-1 Rainwater Harvesting Maybe/Enhanced Maybe/Enhanced M-2 Submerged Gravel Wetland N N M-3 Landscape Infiltration Maybe/Enhanced Maybe/Enhanced M-4 Infiltration Berms N N M-5 Dry Wells Maybe/Enhanced Maybe/Enhanced M-6 Micro-Bioretention Maybe/Enhanced Maybe/Enhanced M-7 Rain Gardens Maybe/Enhanced Maybe/Enhanced M-8 Swales N N M-9 Enhanced Filters Maybe/Enhanced Maybe/Enhanced