Dead Run Stream Restoration Project Segments 2/3 – Final Concept Plan

A Fairfax County, VA, publication

Department of Public Works and Environmental Services

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Dead Run Stream Restoration ProjectSegments 2/3 – Final Concept PlanCommunity MeetingDolley Madison Library

May 4, 2016

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Dead Run Segment 2/3 Stream Restoration Project

Stormwater Planning Division

Meeting Outline

• Project Scope• Project Timeline• Background• Existing Conditions• Task Force and Community Involvement • Revised Final Concept Changes – Summary• Proposed Condition Renderings• Revised Final Concept Design Approach• Buffer and Riparian Corridor Restoration Plan• Next Steps• Q&A

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Dead Run Stream Restoration

Project Limits – Two Projects

Segment 2:McLean Central Park• 750 linear feet of main

channel and 560 feet of tributary channels

Segment 3:Dead Run Stream Valley Park• 1,460 linear feet of main


Segment 1:Dominican Retreat• 1,500 linear feet of main


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Dead Run Stream RestorationSegment 2 – McLean Central Park• 750 linear feet main


• Completely in Park

• Starts below previously restored section near library

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Dead Run Stream RestorationSegment 3 – Dead Run Stream Valley Park• 1,460 linear feet of main channel

and 350 feet of tributary channels

• Extends to Churchill Road

• Residential lots along Elizabeth Drive and Carol Raye Street

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Project timeline• Fall, 2013: Project initiated

• Winter, 2013: Surveys and assessment completed

• April, 2014: Pre-concepts submitted

• April 23, 2014: First public meeting

• August 15, 2014: Field walk with FCPA, MTF, Urban Forestry

• February, 2015: Pre-concept revisions to minimize tree loss completed

• February 18, 2015: Second public meeting

• May 12, 2015: Revised concept plan with alternative access options for Segment 3 completed

• May 19, 2015: Third public meeting and first field walk with community

• June 9, 2015: Fourth public meeting and second field walk with community

7Stormwater Planning Divison


Project timeline• Community Stream Team – Task Force

• Held 4 meetings between August and December 2015

• Visited completed stream restoration sites

• Met with residents adjacent to project in March, 2016

• Revised final concept design completed in April, 2016.

Next Steps:

• Site visit with Community (May 19, 2016)

• Final design phase

• Coordination with task force and community

• Final construction documents and bidding

• Pardon our dust community meeting and construction

• Post-construction monitoring and maintenance


Watershed Planning and Project Implementation

• Watershed Characterization– Water Quality Monitoring– Physical Stream Assessment– Land Use Change– Pollutant Loading

• Structural Project– 25 year plan

• Non-Structural Practices– Policy and Regulations

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http://www.fairfaxcounty.gov/dpwes/watersheds/

9Stormwater Planning Division

Watershed Planning and Project Implementation

• Dead Run has a drainage area just over 3 mi2

• 24 priority projects identified in the watershed management plan• Pond retrofits• LID Stormwater Enhancements• Stream Restoration• Neighborhood Stormwater

Improvements

http://www.fairfaxcounty.gov/dpwes/stormwater/projects/project_list.htm




Stormwater Program Regulatory Drivers

• National Pollutant Discharge Elimination System (NPDES)

• Virginia Stormwater Management Program (VSMP)– Municipal Separate Storm Sewer Permit (MS4)– Discharge from approximately 7,000 storm drain outfalls– Includes watershed planning and project implementation

• Total Maximum Daily Loads (TMDLs)– Chesapeake Bay– Local Streams– Establishes pollutant loading budget for a given impaired water

body to meet water quality standards


Dead Run– Stream Conditions

http://www.deq.virginia.gov/Programs/Water.aspx



Existing Conditions - Biological Monitoring Data

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Dead Run– Stream Conditions

Fairfax County Annual Water Quality Report• http://www.fairfaxcounty.gov/hd/streams/strannualrpt.htm

Virginia Department of Environmental Quality • Water Quality Report (305b report)• http://www.deq.virginia.gov/Programs/Water.aspx

U.S. Geological Survey• Dead Run stream gage at Whann Avenue• Fairfax County Water Resources Monitoring• http://va.water.usgs.gov/fairfax/

http://www.fairfaxcounty.gov/hd/streams/strannualrpt.htm



http://va.water.usgs.gov/fairfax/

http://va.water.usgs.gov/fairfax/



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Dead Run Stream Valley – A historical perspective

1937



Dead Run Stream Valley – A historical perspective

1954



Dead Run Stream Valley – Today

2015



Segment 2 Existing Conditions




Stream Bank Erosion and at Risk Trees




February 2012

July 2015

Trees along stream bank continue to fall and/or die




February 2012

July 2015




Bridge at Churchill Road



On-line: Story Map of Existing ConditionsExisting conditions: http://arcg.is/1Y55MNj

http://arcg.is/1Y55MNj

http://arcg.is/1Y55MNj

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Summary of Task Force Comments and Concerns• Project Benefits • Design Approach • Tree Loss• Frequent Yard Flooding• Flooding at Churchill Road• Construction Equipment and Footprint • Trail Closures• Invasive Plant Management• Others

– Site restoration and maintenance– Stream conditions and erosion below Churchill Road

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Project Benefits

• Estimated annual erosion rates for Segment 2/3 based on field data is between 783 to 1,500 tons/year

Stream Bank Erosion Field Data• Chesapeake Bay Expert Panel protocols used for estimating stream restoration nutrient and sediment credits.

• Estimated reduction in Total Phosphorus loading is between 190 and 788 lbs/year

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Churchill Road Flooding

• VDOT staff attended last Stream Team meeting (December, 2015)

• VDOT inspection reports indicate no deficiencies with the bridge

• No current or future project planned for the bridge at this time

• Proposed stream restoration project includes removing sediment and debris upstream of the bridge and aligning channel with bridge abutments.



Churchill Road Bridge Backwater area



Summary of Plan Revisions – Tree LossTree Loss Summary

Date 6” to 12” 12” and Larger Total Trees at Risk

February 2014Not Surveyed

137 137

February 2015 110 110

May 2015

Alt 1 133 88 221

Alt 2 153 98 251

December 2015

Alt 1 76 72 148 48

Alt 2 81 72 153 45

Alt 1 and Alt 2 refer to access alternatives 1 and 2:Alt 1: Access road is closer to the stream for Segment 3Alt 2: Access road follows trail and utilizes cut-throughs for access to stream for Segment 3.



Summary of Plan Revisions – Tree Loss

• Total number of trees to be removed for project (148-153)

• Total number of trees within the LOD that were either dead or at risk (45-48) – approximately 1/3rd

• Reduction in tree loss impact as a result of design modification between May 2015 and December 2015:

• Alt 1 – 73 trees saved (33% reduction)

• Alt 2 – 98 trees saved (39% reduction)

• Existing trees have very little diversity with only 2 species making up the majority of trees: red maples and tulip poplars.



Proposed Planting

• Proposed Planting Based on Alternative 1

• Approx. 250 trees 1 inch to 1.5 inch caliper size

• Approx. 500 trees that are 6 to 8 feet tall

• Approx. 2,600 shrubs

• All vegetation is native species and specifically selected for the stream corridor

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Dead Run Stream Restoration Project

Existing Park Conditions• Park Area = 33.25 acres• Tree Canopy = 27.45 acres



Summary of Plan Revisions – Area disturbed Total Acres* Woodland /

Open**May 2015

Alt 1 ~5.05 Acres 3.65Alt 2 ~5.15 Acres 3.75

December 2015 Alt 1 ~4.58 Acres 3.18Alt 2 ~4.72 Acres 3.32

*Excludes trail area, ** Excludes stream channel area and trail area

Conclusion Alt 2 access has slightly more disturbance and would close the trails for a longer period of time compared to Alt 1, and would likely necessitate the use of woodchip trails which would have additional impacts.

The overall area of disturbance has been reduced by 10% from May 2015. If the stream channel area (1.4 ac) is excluded (i.e only impacts to woodland/open areas considered), the actual AOD has been reduced by 11-13%



Summary of Plan Revisions – Channel Size

Segment 2 Upper Segment 3 Lower Segment 3

Existing channel size(SF) 59-82 57-113 62-70Proposed channel size (SF) 55-80 60-129 62-72

Proposed channel size is now comparable in size to the existing channel.

This channel was sized using natural channel design principles and represents a balance to minimize impacts but still provide long-term channel stability and water quality benefits.

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Summary of Plan Revisions – Floodplain and Drainage

• No change in 100-year or FEMA floodplain

• No rise certification• Improve drainage from

existing storm drains

Fairfax County 100-Year Floodplain

FEMA Special Flood Hazard Area



Proposed Conditions Renderings – Segment 2

Existing Conditions




Rendering of Proposed Conditions




Existing Conditions



Proposed Conditions On-line Map Tour

http://arcg.is/1N4KSgq





Riparian Corridor Restoration Plan

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Existing vegetation baseline characterization

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Existing Vegetation classified into 5 major areas:

MCPP1: Gazebo area, Area near Martha Jane Street

MCPP2: Areas adjacent to Segment 2 and upstream of Segment 2.

MCPP3: Adjacent to Segment 3

MCPP4: Area to the right of trail along middle and lower Segment 3 (looking towards Churchill Road

MCPP5: Area to the right when entering park from Oak Ridge Avenue (near tennis courts)

Story Map: http://arcg.is/1TKK67P

http://arcg.is/1TKK67P




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Dolley Madison Library Outfall before Restoration

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Stormwater Planning Divison


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Elements of Riparian Corridor Restoration Plan

• Invasive Plant Management• Planting plan

– Inside and outside project limits within park

• Residential lots adjacent to stream

• Warranty requirements (2-years)• Long-term monitoring and

maintenance



Chesapeake Bay Preservation Ordinance Resource Protection Area (RPA)

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http://www.fairfaxcounty.gov/dpwes/environmental/cbay/



Proposed Planting

• Proposed Planting Based on Alternative 1

• Approx. 250 trees 1 inch to 1.5 inch caliper size

• Approx. 500 trees that are 6 to 8 feet tall

• Approx. 2,600 shrubs

• All vegetation is native species and specifically selected for the stream corridor



Next Steps

• Continue to work with residents to develop buffer enhancements on private lots adjoining Segment 3.

• Site visit (May 19, 2016) – trees to be flagged

• Final design phase and prepare construction documents

• Coordination with Task Force and community

• Bidding and contract award

• Pardon Our Dust Meeting

• Construction

• Post-construction monitoring and maintenance

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Next Steps: Site VisitSite Visit

• Date: Thursday, May 19, 2016

• Time: 6:30 – 8:00 pm

• Meeting Location: McLean Central Park - Pedestrian bridge crossing Dead Run near tennis courts

Meeting Location

Additional Information

For additional information, please contact

www.fairfaxcounty.gov/dpwes

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Dipmani KumarProject Manager

[email protected]

Dead Run Stream Restoration Project Segments 2/3 – Final Concept Plan

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