Dead Run Stream Restoration Public Meeting May 19, 2015

1. A Fairfax County, VA, publication
Department of Public Works and Environmental Services
Working for You!
Dead Run Segment 2/3 Stream Restoration Project
Public Meeting
McLean Community Center
May 19, 2015

2. Dead Run Segment 2/3 Stream Restoration Project
Stormwater Planning Division
Meeting Outline
2
• Project Scope and Status
• Plan Summary and response to citizen comments
• Concept Plan Overview
– Basis for design
– Tree save options
– Floodplain analysis and review of more frequent storm impacts
– Buffer restoration measures
– Examples
• Next Steps
• Q and A
• Walk to site

3. Stormwater Planning Division
Dead Run Segment 2/3 Stream Restoration Project
Project Limits
3
Segment 2 – McLean
Central Park
• 800 Linear Feet
• Completely in Park
• Starts below previously
restored section near
library
Segment 3 – Dead Run
Stream Valley Park
• 1,500 Linear Feet
• Extends to Churchill Road
• Residential lots along
Elizabeth Drive and Carol
Rayes Street

4. Stormwater Planning Division
Dead Run Segment 2/3 Stream Restoration Project
Project timeline
4
• Project initiated: Fall, 2013
• Surveys and assessment completed: Winter, 2013
• Pre-concepts submitted: April, 2014
• First public meeting – April 23, 2014
• Field walk with FCPA, MTA, Urban Forestry – August 15, 2014
• Pre-concept revisions to minimize tree loss completed: February, 2015
• Second public meeting – February 18, 2015
• Revised concept plan with alternative access options for Segment 3:
completed May 12, 2015
• First field walk with community – May 19, 2015
• Second field walk with community – June 9, 2015

5. Stormwater Planning Division
Dead Run Segment 2/3 Stream Restoration Project
Overview of Plans
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• _PG1-27.pdf: Existing and proposed conditions (plan, profile, and cross-
sections)
- Plan: Bird’s eye view
- Profile: Change in elevations along the proposed stream channel centerline
- Cross-sections: View of a section taken perpendicular to the channel
centerline at a particular location.
• _PG28-31a.pdf: Plan view of access with and without aerial photography
background – two options for Segment 3
• _PG32-43.pdf: Hydrology (flows) summary, and hydraulics (water surface
elevations) of existing and proposed conditions
• Excel files: Tree inventory – diameter, condition, removal status

6. Stormwater Planning Division
Dead Run Segment 2/3 Stream Restoration Project
Summary of comments received
6
• Need to understand full scope of project:
• Access points, how they will be secured, personal liability if county
seeks to access our property (_PG28-31a)
• Type/Size of equipment that will be used (Do not dictate means and
methods, equipment proposed by contractor can be shared by
contractor at Pardon Our Dust meeting)
• Consideration of alternative modes of accessing creek that could
reduce impact on foliage (_PG28-31a – also discussed in detail
later)
• Duration of project, hours of construction, how long neighborhood
will be denied access to pathways (Estimated 6-9 months, Standard
work hours are 7am – 5 pm. Loss of access to trails will be
minimized to the extent possible)

7. Stormwater Planning Division
Dead Run Segment 2/3 Stream Restoration Project
Summary of comments received
7
• Need to understand full scope of project:
• Any revision to path of creek (_PG1-27.pdf)
• Impact on topography and what type of approach will be used in
what parts of creeks (terracing, widening) (_PG1-27.pdf)
• Commitment of funding for replacement of lost trees and
maintenance by county to ensure trees survive (_PG28-31a)
• Aesthetic impact of sediment erosion techniques. (Erosion and
Sediment controls are detailed as part of the final plans, all
structures proposed to be installed are shown in the plan and
profile).

8. Stormwater Planning Division
Dead Run Segment 2/3 Stream Restoration Project
Summary of comments received
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• How flooding concerns will be addressed:
• Creek jumps the bank a few times a year and threatens to flood homes
• Danger of flash floods in the park, property of nearby residences, and
Churchill Road bridge
(_PG32-43.pdf, also discussed in detail later)
Recurrence
Interval Probability
100-year 1%
10-year 10%
2-year 50%
1-year approaches 100%

9. Stormwater Planning Division
Dead Run Segment 2/3 Stream Restoration Project
Summary of comments received
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• How flooding concerns will be addressed (continued):

10. Stormwater Planning Division
Dead Run Segment 2/3 Stream Restoration Project
Churchill Road Bridge Flooding
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• VDOT inspection reports indicate no deficiencies with the bridge.
• No current or future project planned for the bridge.
• Not subject to frequent closures because of overtopping.

11. Stormwater Planning Division
Dead Run Segment 2/3 Stream Restoration Project
Summary of comments received
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• Loss of tree canopy:
• Desire strong measures to maintain and preserve the existing canopy
• Anticipated tree impacts shown on plan sheets – 6-12” tree impacts for
Segment 3 access options being updated
• Tree save efforts discussed in detail later
• Proposed buffer restoration measures discussed in detail later

12. 1 Basis for Design
• Stable Channel
• Understanding of
Floodplain
• Address Erosion

13. 1 Basis for Design
• Natural Channel Design (NCD) Approach – reference reach, analytical,
regional relationships and hydraulic analysis
• Stream pattern, profile and section
• Range of values for stable stream pattern
• Tree loss is unavoidable but provides opportunity to improve riparian
diversity

14. 1 Basis for Design
• Establish Goals:
• 1. Improve Flow Conditions in the Channel through Adjustments to
Plan/Profile/Section
• 2. Create a Stable Channel by Reducing Bed/Bank Erosion that has Benefit
of Reducing Contributions of Nitrogen and Phosphorus (i.e. Water Quality
Improvement)
• 3. Improve Channel Geomorphology and Opportunities for Species
Diversity (i.e. Use Structures to Stabilize Channel and Create Pool Habitats)
• 4. No-Rise / No-Impact of the Floodplain

15. 2 Tree Save Efforts
12” and Larger Trees:
• ~557 trees 12” and larger assessed
• ~43 trees 12” and larger are “at risk”
• Species: ~32% tulip tree, ~27% red maple, ~7% green ash
6-12” Trees:
• ~214 trees 6-12” assessed
• ~28 trees 6-12” are “at risk”
• Species: ~23% red maple, ~21% boxelder, ~18% slippery elm, ~11%
green ash

16. 2 Tree Save Efforts
• Pre-Concept Plan (Feb. 2014) = ~137 trees 12” and larger removed. This
was same plan walked in August 2014.
• Concept Plan (Feb. 2015) = ~110 trees 12” and larger removed. Initial
alternative access options developed.
• Since Feb. 2015 meeting, we’ve modified the channel layout and access
options, and located 6 to 12” size trees.

17. 2 Tree Save Efforts
Some of the saved trees

18. 2 Tree Save Efforts
Some of the saved trees

19. 2 Tree Save Efforts
Some of the saved trees

20. 2 Tree Save Efforts
Some of the saved trees

21. 3 Access Options
• Current Plan (May 2015) = ~88 trees 12” and larger proposed
for removal, of which ~23 are “at risk”. Up to 10 additional
trees could be removed due to access. ~133 trees 6-12”
proposed for removal, of which ~28 are “at risk”. Up to 20
additional trees could be removed due to access.
• 12” and Larger Trees species most affected:
• ~24% tulip tree, ~20% red maple, ~17% green ash
• 6-12” Trees most affected:
• ~20% red maple, ~27% boxelder, ~20% slippery elm, ~13% green ash
• Woody vegetation should not be in the sanitary easement
and is subject to removal by Wastewater at any time.

22. 3 Access Options
Segment 2
Tree DEC474 has been
removed

23. 3 Access Options
Segment 3 Alternative 1
Removals due to access are
primarily on the left bank. ~9
trees (~2 >12” and ~7 6-12” size)
Trees DEC91 & DEC301
have been removed

24. 3 Access Options
Segment 3 Alternative 2
Removals due to access are primarily on
the right bank. ~21 trees (~7 are >12” and
~14 are 6-12” size) – most are within the
sanitary easement

25. 4 Floodplain Analysis
• Studied more frequent storm events 1-, 2-, 10- year flows
• Studied less frequent storm events 50-, 100- year flows
• No-Rise / No-impact to the floodplain
• See pages 32-43 of plan

26. 4 Floodplain Analysis
Pre/Post Comparison – Existing Section 1355
2 year flow out of banks
• Existing Conditions Analysis

27. 4 Floodplain Analysis
Pre/Post Comparison – Existing Section 1355
Proposed Channel and Nested Channel

28. 4 Floodplain Analysis
Pre/Post Comparison 100 and 10 year
Typical Channel Section

29. Stormwater Planning Division
Dead Run Segment 2/3 Stream Restoration Project
Stream Restoration Pictures
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Government Center Stream Restoration - Before and After

30. Stormwater Planning Division
Dead Run Segment 2/3 Stream Restoration Project
Stream Restoration Pictures
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Poplar Springs, Burke - Before and After

31. Stream Restoration
Stormwater Management
Dead Run at Dolley Madison Library
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32. Stream Restoration
Stormwater Planning Division
Dead Run at Dolley Madison Library
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August 2014 Right
January 2010 Below

33. Dead Run Segment 2/3 Stream Restoration Project
Stormwater Planning Division
Stream Buffer Restoration Potential
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34. Dead Run Segment 2/3 Stream Restoration Project
Stormwater Planning Division
Chesapeake Bay Preservation Ordinance
Resource Protection Area (RPA)
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http://www.fairfaxcounty.gov/dpwes/environmental/cbay/

35. Dead Run Segment 2/3 Stream Restoration Project
Stormwater Planning Division
Stream Buffer Existing Conditions
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36. Dead Run Segment 2/3 Stream Restoration Project
Stormwater Planning Division
Stream Buffer Restoration Potential
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Segment 3 Stream Buffer Concept

37. Dead Run Segment 2/3 Stream Restoration Project
Stormwater Planning Division
Stream Buffer Restoration - Example
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Typical Planting Area
County Staff will
coordinate with
individual
homeowners on
plant selection and
placement on their
properties
Buffer Parameters
35’ Minimum from
edge of stream
bank
50’ Offset optional
Plant density
determined by
Chesapeake Bay
Preservation
Ordinance
Dense planting will
provide privacy
screening and help
mitigate tree loss

38. Dead Run Segment 2/3 Stream Restoration Project
Stormwater Planning Division
Stream Buffer Restoration - Example
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Shrub Layer
Typical Shrub
Species
Spicebush
American
Elderberry
Witch Hazel
Winterberry Holly
Silky Dogwood
Button Bush

39. Dead Run Segment 2/3 Stream Restoration Project
Stormwater Planning Division
Stream Buffer Restoration - Example
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Understory Trees
Typical Understory
Species
Sweetbay Magnolia
Eastern Redbud
American
Hornbeam
Hazel Alder
Slippery Elm
Sassafras

40. Dead Run Segment 2/3 Stream Restoration Project
Stormwater Planning Division
Stream Buffer Restoration
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Canopy Layer
Canopy
Tree
Evergreen
Understory
Tree
Deciduous
Understory
Tree
Shrub
Typical Canopy
Tree Species
Sugar Maple
River Birch
American Basswood
Common Persimmon
Swamp White Oak
Pin Oak
Willow Oak
Black Gum

41. Stormwater Planning Division
Dead Run Segment 2/3 Stream Restoration Project
Next steps with target dates
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• Receive concept design comments by June 19th, 2015
• Compile comments, finalize concept plans and publish to
website by July 10th, 2015
• Develop 95% design plans, permitting by September, 2015
• Final design phase public meeting, October, 2015
• Final plan authorization and bidding phase – TBD based on
funding and approved budget
• Target is late spring/early summer, 2016
• Sequence with Dead Run Segment 1 (Dominican Retreat)
• Pardon Our Dust meeting with residents and contractor
before issuing construction notice to proceed.

42. Additional Information
For additional information, please contact
www.fairfaxcounty.gov/dpwes
Dead Run Segment 2/3 Stream Restoration Project
Stormwater Planning Division 42
Dipmani Kumar
703-324-5500
dkumar@fairfaxcounty.gov