Restore ~4,000 feet by returning the form and function of the channel to dynamic equilibrium and improve the ecological processes of the riparian corridor.

1. A Fairfax County, VA, publication
Department of Public Works and Environmental Services
Working for You!
Accotink Tributary @ Danbury Forest
Stream Restoration Project
July 15, 2021

2. Stormwater Planning Division
Stream Restoration
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3. 3
Stormwater Planning Division
Stream Restoration

4. Stormwater Planning Division
Hydrology and Channel Evolution
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5. Stormwater Planning Division
Hydraulics and Channel Evolution
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6. Stormwater Planning Division
Project Goals
Restore ~4,000 feet by returning the form and function of the
channel to dynamic equilibrium and improve the ecological
processes of the riparian corridor.
Water quality improvement
Sustainability
Infrastructure protection
Habitat Improvement
Stakeholder coordination
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7. Crook Branch Stream Restoration
DPWES Stormwater Planning Division
Restoration Strategies
• Floodplain Reconnection
• Grade control
• Enhance hyporheic zone
• Stable vegetated banks
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Before restoration After restoration

8. Water Quality Benefits
– Annual Pollutant Load Reductions
• Ex. Project: Flatlick Branch Phase II stream restoration. Restored
approximately 4,600 linear feet of Flatlick Branch and its tributaries using
natural channel design techniques to improve water quality, channel stability,
ecological function, floodplain connectivity and safety. The project included
outfall step pools, rock steps, boulder riffles, rock cross vanes and J-hooks, a
reinforced channel bed, large woody debris habitat features, wetland habitat
creation and reforestation with native vegetation.
– Annual Pollutant Load Reductions via erosion prevention, hyporheic zone
bio-chemical processes and floodplain connectivity/storage:
• Phosphorous: 350 lbs./yr.
• Nitrogen: 3,247 lbs./yr.
• Total Suspended Solids: 61 tons/yr.
– In-Stream and Riparian Habitat
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Stormwater Planning Division

9. Stormwater Planning Division
Social Goals
1. Maintain open communication and share information.
2. Coordinate design and construction with property owner,
community and stakeholders.
3. Build partnerships with local organizations such as HOAs and
Friends Of groups.
4. Design Team:
 Stormwater Planning Division
 Danbury Forest Community Association
 AMT Engineering
 Urban Forest Management Division
 Park Authority
 Wastewater Collection Division
 Utilities Design and Construction Division
 Maintenance and Stormwater Management Division
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10. Project Area
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Stormwater Planning Division

11. Stormwater Planning Division
Existing Conditions
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12. Stormwater Planning Division
Existing Conditions
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13. 13
Existing Conditions
Stormwater Planning Division

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Existing Conditions
Stormwater Planning Division

15. Existing Conditions
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16. Final Design
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17. Final Design
Conceptual Design
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18. Final Design
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19. Final Design
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20. Final Design
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21. Final Design
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22. Tree Impacts
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23. Tree Impacts
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24. Tree Impacts
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25. Tree Impacts
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26. Tree Impacts
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27. Stormwater Planning Division
Natural Channel Design Features
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Reinforced Bed and Riffle Grade Control
Step Pools
Native Vegetation
Cross Vanes
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28. Stormwater Planning Division
Video of Typical Structures Used
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29. Stormwater Planning Division
Construction Example
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30. Construction Example
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31. Stormwater Planning Division
Construction Example
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32. Stormwater Planning Division
Growing Season Following Construction Completion
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33. Stormwater Planning Division
Design Development
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34. Example Rendering - before
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35. Example Rendering - after
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36. Government Center Stream Restoration
Before & After
Drainage Area
(acres)
Phosphorous Removal
(lbs/yr)
Nitrogen Removal
(lbs/yr)
Sediment Removal
(tons/yr)
150 10.7 202 1.6
Restoration of 1,000 LF of an unnamed tributary of Difficult Run for improvements
to water quality and ecological function of the stream corridor.

37. Channel Evolution

38. • Local, state and federal requirements
– Fairfax County PFM
– Virginia Erosion and Sediment Control
Program
– Chesapeake Bay Preservation Act
– Endangered Species Act
– Fish and Wildlife Coordination Act
– Clean Water Act – National Pollutant
Discharge Elimination System (NPDES)
• Permits and Certifications
– No-rise certification (for mapped
floodplains)
– Joint permit
• US Army Corps of Engineers –
Section 404 Certification, Nationwide
permits
• VA Department of Environmental
Quality – Section 401 Certification,
Virginia Water Protection permit
• VA Marine Resources Commission
(VMRC) – Subaqueous Permit
• Fairfax County Wetlands Board
– VDOT Land Use permit
Regulatory Requirements
http://www.fairfaxcounty.gov/dpz/environment/wetlandspermit.pdf
VMRC, DEQ, US
ACE
US ACE, DEQ,
Wetlands Board
Bay Act Programs
Uplands
Streams &
Wetlands
Subaqueous
Lands

39. Stormwater Planning Division
Stormwater Program Drivers
• Clean Water Act, 1972
– Municipal Separate Storm Sewer Permit (MS-4)
– Chesapeake Bay Total Maximum Daily Loads (TMDL)
• Regulates amount of pollutants in waterways (Nitrogen, Phosphorus, and Total Suspended
Solids )
– Local TMDLs (sediment, bacteria, and PCBs)
– Erosion and Sediment Control
• Inspection and maintenance of conveyance systems (pipes and
appurtenances)
• Inspection, maintenance, and rehabilitation of stormwater management
facilities
• Dam Safety
• FEMA/NFIP/CRS programs
• Emergency and Flood Response
• Watershed planning and monitoring
• Design and implementation of capital improvement projects , including
stream restoration and other water quality improvement projects
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40. Stormwater Planning Division
One Year After Construction Completion
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41. Stormwater Planning Division
Three Years After Construction Completion
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Before and After Examples
Big Rocky Run II
Before After
Stormwater Planning Division

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Before and After Examples
Rabbit Branch
Before
After
Stormwater Planning Division

44. Stormwater Planning Division
What’s Next?
• Construction is tentatively scheduled to begin in Summer or Fall 2022
• Pre-Construction Community meeting
• Construction duration = approximately 14 months
• Post-Construction Community meeting
• Warranty Inspections
• Monitoring
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45. Stormwater Planning Division
Contact Information
Justin Pistore – Project Manager
703-324-5685
justin.pistore@fairfaxcounty.gov
Fairfax County Stormwater Planning Division
703-324-5500 TTY 711
12000 Government Center Parkway
Suite 449
Fairfax, Virginia 22035
www.fairfaxcounty.gov/dpwes/stormwater
To request this information in an alternate format call 703-324-5500, TTY 711
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46. Online Resources
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Stormwater Planning Division Website
http://www.fairfaxcounty.gov/dpwes/stormwater/
Fairfax County Watershed Planning
http://www.fairfaxcounty.gov/nvswcd/newsletter/planning.htm
Accotink Creek Watershed Plan
http://www.fairfaxcounty.gov/dpwes/watersheds/accotinkcreek.htm
EPA Water Quality Laws & Regulations
http://www.epa.gov/water/laws.html
Stormwater Planning Division