This document summarizes a case study presentation on balancing wetland and stream preservation with stormwater management. It discusses how initial plans avoided disturbing surface water resources but still did not meet state criteria. The proposed solution included limiting habitat impacts, establishing stream buffers, wetland mitigation, and implementing a hierarchy of stormwater BMPs including infiltration, filtration, and retention ponds. Water quality monitoring of macroinvertebrates and chemistry was also proposed before, during, and after construction to evaluate project impacts.

1. Presentation for International W
ater W
eek 2013
Symposium
in Amsterdam
Balancing Wetland and Stream
Preservation with Stormwater
Management: A Case Study
November 5, 2013
Andrew T. Der & Associates, LLC
Environmental Consulting
1000 Fell Street | Baltimore, MD 21231
1.410.491.2808 | AndrewTDer@comcast.net

2. Habitat Avoidance Insufficient

3. W Happens
hat

4. Habitat Avoidance Insufficient =
New Construction SW criteria
M
Disturbance to Surface water resources
• State nontidal waters and wetlands including 100 year floodplain and water
quality criteria
• State tidal waters and wetlands
• Federally regulated waters of the United States
Disturbance to Land (nonpoint source pollution)
• State stormwater management regulations – includes delegated point and
nonpoint source federal criteria
• State and local erosion and sediment control criteria
• Special state tidal water criteria

5. Classification of State W
aters
• Use I & I-P: Water Contact Recreation and Protection of
Aquatic Life
• Use II: Shellfish Harvesting Waters
• Use III & III-P: Natural Trout Waters
• Use IV & IV-P: Recreational Trout Waters

6. State W
ater Quality Standards
Numerical
• Dissolved Oxygen, Temperature, pH, Turbidity, Fecal Coliform, Toxics
Narrative
•...Protection of Aquatic Life ...Fishable ...Swimmable...Includes EPA AntiDegradation 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...”

7. W is a Best Management
hat
Practice (BMP)?
BMPs are policies, practices, procedures, or structures implemented to
mitigate the adverse environmental effects on surface water quality
resulting from activities. BMPs are categorized as structural or nonstructural.
• Early Planning/ Avoidance
• Low Impact Development (LID), or Better Site Design, or Environmental Site Design
• Local stream buffers and setbacks
• Minimize or disconnect impervious surfaces sheet flow, open section pavement
• Devices
Most significant factor affecting performance is construction and
maintenance

8. Hierarchy of Engineered Practices
Smaller Volumes
Most compatible with ESD atsource and/or pretreatment
quality control
Larger Volumes
When preferred is Insufficient
for quantity and quality
• Infiltration
– trench/basin
• Stormwater Ponds
– wet pond
– wet ED pond
– dry ED pond (for cold
water w/
pre-treatment)
– multiple pond system
• Filtering
– sand filter/bioretention
• Hydrodynamic Devices
– Curb & gutter
vortex/filter basin
• “Newer” Technology
– pervious surfaces/green
roofs
• Stormwater Wetlands
– shallow marsh
– ED shallow wetland
– pond/wetland systems

9. Location of Project Area

10. Location of Project Area

11. W
atershed and Initial
Development at Low Point

12. Initial Permit Review Steps
• Higher Quality Use I-P Water
• Purpose and Need
• Avoidance and Minimization of Waters of the U. S. from Roads,
Utilities, and Other Disturbances
• Nonpoint Source Pollution Management: Quality
• Stormwater Management (SWM): Quantity
• Coordination with Local Authorities, NGOs, and Stakeholders
• How to Address ADP and SWM

13. Apply Hierarchy of SW
M
Preferences to Site Character
• Vegetative buffers, disconnects, open
section pavement
• Infiltration Practices if Soils Allow
• Bioretention, Swales, Wetland Filtering
• Retention or Extended Detention Pond with
Wetlands (to include quantity management)

14. Proposed Site-specific Mitigation
and BMP’s
• Stream/wetland impacts limited to necessary roads/utilities
• In-stream SWM in marginal/poor areas only
• Minimum stream buffer of 100‘ (30.5 meters)
• Wetland mitigation and replanting in cropped riparian buffer areas
• “First flush” stormwater quality management in uplands
• Infiltration/filtration where feasible (permeable soils and depth)
• Primary quantity stormwater management in “horseshoe” pond
• Water pooling areas planted with wetland vegetation

15. BMPs and Mitigation – Forest and
W
etlands

16. BMPs and Mitigation - Maximize
W
etland Treatment with Site

17. BMPs and Mitigation - Pond and
W
etlands

18. BMPs and Mitigation – Impact
Avoidance and W
etland Filtration

19. BMPs and Mitigation - Sensitive
Resources

20. BMPs and Mitigation - Transition
Habitat

21. BMPs and Mitigation - SW &
M
Landscaping

22. BMPs and Mitigation – SW and
M
Landscaping

23. BMPs and Mitigation – Urban
Areas

24. BMPs and Mitigation – Urban
Areas

25. BMPs and Mitigation – Urban
Areas

26. BMPs and Mitigation - Stream
Stabilization and Restoration
• Can be effective
watershed sediment
control practice
• Can be local approval
requirement
• Can be a traded credit
• Can be out-of-kind
wetland mitigation

27. Public & NGO Involvement
• Public Notice
• Waters may have Use III or IV (higher quality trout
water) potential
• Temperature and ponds potential concern
• EPA Antidegradation Policy may apply
• Implemented stream Rapid Bioassessment
• Findings - no Use III or IV standards but higher
quality Use I

28. Additional Mitigation and W
ater
Quality Management Practices
• Water Quality Monitoring Plan
• Stream Reach Temperature Model and Percent
Contribution of “QED” 2, 10 year event to Stream Flow
• Maximum 20% Diversion Base Flow
• Shade Planting of SW Conveyance and Management
Areas
•Toe Drain Pipes Under Embankment Fill

29. Stream and W
ater Quality
Monitoring
Can be used for state Watershed
Compliance
Can be used for state natural resource
studies
Preconstruction, construction and postconstruction
Macroinvertebrate studies
(more common examples are WWTP &
mining requirements)
Chemistry
Geomorphology
Groundwater

30. Primary Monitoring Component

31. Historic Bioassessment Data
Rapid Bioassessment Metric Comparisons to Pre-Construction Scores
ST6
ST10
Year ST2
1993 Non Impaired **
Non Impaired **
1994 Non to Mod. Impaired
Non Impaired
Non Impaired **
1995 Non to Mod. Impaired
Non to Mod. Impaired
Non Impaired
1996 Non to Mod. Impaired
Moderately Impaired
Non to Mod. Impaired
1997 Non to Mod. Impaired
Non to Mod. Impaired
Moderately Impaired
1998
Moderately Impaired
Non to Mod. Impaired
1999 Moderately Impaired
Moderately Impaired
Moderately Impaired
2000 Moderately Impaired
Non to Mod. Impaired
2001 Non to Severely Impaired Moderately Impaired
Non Impaired
2002 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.

32. Historic Dissolved Oxygen Data
Piney Branch Mean Dissolved Oxygen Levels for Stations 2, 6 and 10
ST. 2 Mean D.O.
ST. 6
Mean D.O.
ST. 10
Mean D.O.
1998
1999
Use I Min. D.O.
14
12
10
mg/l
8
6
4
2
0
1992
1993
1994
1995
1996
1997
Year
2000
2001
2002

33. Historic Temperature Data
Piney Branch Instream Peak Tem peratures
Stations 2, 6 and 10
ST. 2
ST. 6
ST. 10
1997
1998
35
Temperature (oC)
30
25
20
15
10
5
0
1992
1993
1994
1995
1996
Year
1999
2000
2001
2002

34. Lessons Learned
• Basis for “how we do it now”
• Basis for groundbreaking county Special Protection
Area legislation
• Basis for local, state, federal coordinating committees
and public processes
• Basis for initial findings for Municipal US Environmental
Protection Agency Compliance