Low Impact Development Applicationsmedia.clemson.edu/public/restoration/carolina clear... ·...
Transcript of Low Impact Development Applicationsmedia.clemson.edu/public/restoration/carolina clear... ·...
Low Impact Development
ApplicationsStormwater Compliance Support Workshop
Geoff Smith, P.E.
BP Barber
June 3, 2010
Outline
Background
LID Goals
Design Strategies
Practice Examples
LID Background
What is LID?
Technology based
Hydrologic evaluation
LID Background
LID Mechanisms
Impervious cover reduction
Increased green space
Open space preservation
LID Goals
Discharge reduction
Peak and volume
Water quality treatment
Infiltration
Aquifer Recharge
Less reliance on traditional facilities
Peak and volume
Increased green space
Design Strategies
Non-structural
Regulatory mechanisms
Site Planning
Buffer setbacks
Structural
Water quality improvements
Aquifer recharge
Water reuse
Non-structural LID Practices
Regulatory ordinances
Design requirements
Utility “credits”
Development Design
Cluster development
“Micro” treatment
Source Control
Buffer Setbacks
Green Space
Structural Practices - Overview
Small Scale water reuse
Cisterns
Rain Barrels
Development
Infiltration
Treatment trains
Storage
Structural Practices
Discharge Reductions
Bioretention
Versatile application
Aesthetically pleasing in urban environments
Relatively low maintenance costs compared to
traditional BMPs
Design considerations:
Water quality treatment of first flush
Small water quantity control
Bioretention
Bioretention
BMP Type Pollutant Treated Removal Efficiency
Bioretention Total Suspended Solids 50-85%
Copper 35-70%
Zinc 35-90%
Total Nitrogen 35-55%
Lead 50-90%
Total Phosphorous 55-70%
Pathogens (fecal) 10-60%
Bioretention Areas:
Applications
Parking lots
Individual home sites
Small commercial sites
Advantages
Low maintenance
Size vs. treatment
“Green” applications
Drawbacks
Potential Cost
Size restrictions
Limited quantity control
Pervious Pavement
Infiltration recharge
Reduced runoff
Varied Applications
Design considerations:
Low traffic areas
Pedestrian walkways
Significant reduction in impervious cover
Routine maintenance required
Pervious Pavement
Pervious Pavement
Center for Watershed Protection
Grassed Swales
Reduced Discharge velocities while
maintaining “design” volume capacity
Dry swales vs. wet swales
Design based on soil and landscape conditions
Lining materials can vary
Low maintenance
Grassed Swales
Typical dry swale profile
Typical wet swale profile
Grassed Swales
Infiltration Trenches
On-site storage
Low water table preferred
Used as part of a treatment train
Routine maintenance necessary
Infiltration Trenches
Infiltration Trenches
Conclusion
Design considerations
Regulatory mechanisms
Cost considerations
Water quality treatment
Aesthetic benefits
Discussion