Balancing Wetland and Balancing Wetland and Stream Preservation with Stream Preservation with Stormwater Management: A Stormwater Management: A Case Study Case Study Presentation for National Association of Environmental Professionals 39 th Annual Conference St. Petersburg, Florida April 8, 2014 Andrew T. Der & Associates, LLC Environmental Consulting 1000 Fell Street | Baltimore, MD 21231 1.410.491.2808 | [email protected]
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Balancing Wetland and Balancing Wetland and Stream Preservation with Stream Preservation with
Stormwater Management: A Stormwater Management: A Case StudyCase Study
Presentation forNational Association of Environmental Professionals 39th Annual Conference
St. Petersburg, Florida
April 8, 2014
Andrew T. Der & Associates, LLCEnvironmental Consulting
•...Protection of Aquatic Life ...Fishable ...Swimmable...Includes EPA Anti-Degradation Policy (ADP):
“...To accomplish the objective of maintaining existing water quality...Nonpoint sources shall achieve all cost effective and reasonable best management practices
for nonpoint source control...”
What is a Best Management What is a Best Management Practice (BMP)?Practice (BMP)?
BMPs are policies, practices, procedures, or structures (engineered practices) implemented to mitigate the adverse environmental effects on surface water quality resulting from rain water runoff. BMPs are categorized as structural or non-structural.
• Early Planning/ Avoidance
• “Low Impact Development”, or “Better Site Design”, or “Environmental Site Design”
• Local stream buffers and setbacks
• Minimize or disconnect impervious surfaces sheet flow, open section pavement
• Devices or engineered practices (ponds, bioretention, etc.)Most significant factor affecting performance is construction and
maintenance
Hierarchy of Engineered Hierarchy of Engineered PracticesPractices
Smaller Volumes“First Flush”Preferred and most compatiblewith ESD at-source and/orpretreatment quality control
• Infiltration– trench/basin
• Filtering– sand filter/bioretention
• Hydrodynamic Devices above or underground– Curb & gutter
vortex/filter basin
• “Newer” Technology– pervious surfaces/green
roofs
Larger VolumesWhen preferred is
Insufficient for quantity and quality
• Stormwater Ponds– wet pond– wet ED pond– dry ED pond (for cold
water w/ pre-treatment)– multiple pond system
• Stormwater Wetlands– shallow marsh– ED shallow wetland– pond/wetland systems
Location of Example Project Location of Example Project AreaArea
Location of Project AreaLocation of Project Area
Watershed and Initial Watershed and Initial Development at Low PointDevelopment at Low Point
Historic Bioassessment DataHistoric Bioassessment Data
Rapid Bioassessment Metric Comparisons to Pre-Construction ScoresYear ST2 ST6 ST101993 Non Impaired ** Non Impaired **1994 Non to Mod. Impaired Non Impaired Non Impaired **1995 Non to Mod. Impaired Non to Mod. Impaired Non Impaired1996 Non to Mod. Impaired Moderately Impaired Non to Mod. Impaired1997 Non to Mod. Impaired Non to Mod. Impaired Moderately Impaired1998 Moderately Impaired Non to Mod. Impaired1999 Moderately Impaired Moderately Impaired Moderately Impaired2000 Moderately Impaired Non to Mod. Impaired2001 Non to Severely Impaired Moderately Impaired Non Impaired2002 Non to Mod. Impaired Mod. to Severely Impaired
** Non Impaired value is given to the first (reference) date for comparison purposes;
the streams on those dates are not necessarily truly non-impaired.