Crook Branch at Mantua Elementary School Stream Restoration
1. A Fairfax County, VA, publication
Department of Public Works and Environmental Services
Working for You!
April 25, 2018
Community Meeting
Mantua Elementary School Cafeteria
Crook Branch at Mantua Elementary School Stream
Restoration Project
Accotink Creek Watershed Plan Implementation
2. Crook Branch Stream Restoration
DPWES Stormwater Planning Division
Meeting Outline
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• Status and General Schedule
• Site Location and Project Limits
• Discuss General Design Approach
• Review Historical Data
• Existing Conditions
• Design Goals
• Proposed Alignment and Access
• Projected Tree and Trail Impacts
• Native Vegetation
• Mantua Elementary School Chamber System
• Q&A
3. Crook Branch Stream Restoration
DPWES Stormwater Planning Division
Status and General Schedule
• Data Collection (Completed)
• Stream Restoration Design Process (In Progress)
– Pre-Concept Plan Development (Completed)
– Concept (35%) Design Plan Development (Completed)
– Field Walk – August 2017 (Completed)
– Preliminary (65%) Design Plan Development (In Progress)
– Final Design Plan Development – Fall 2018
– Construction Documents
• Construction (± 12 months)
– Bidding and Contract Award
– Pardon Our Dust Community Meeting
– Construction date dependent on future funding
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25. Crook Branch Stream Restoration
DPWES Stormwater Planning Division
Design - Tree Impacts
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Tree impact considerations
Ecological / Habitat Value
• Size / Diameter
• Higher - Climax species: Oaks, Hickory, Holly (mast
producers, long-lived).
• Lower – Early successional species: Maples, Poplar
(fast-growing, short-lived).
Existing Condition
• Undercut by stream, high proportion of exposed
roots, short life expectancy
• Dead, dying, diseased, or damaged trees that pose a human safety hazard
• Impacting or pending impact to infrastructure (utilities, roads, trails, etc.)
Proposed Condition
• Long-living, healthy, native species that help to stabilize the banks and floodplain
• Increased bio-diversity
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DPWES Stormwater Planning Division 29
Post Construction Example
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DPWES Stormwater Planning Division 30
Growing Season Following Construction Completion
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DPWES Stormwater Planning Division 31
One Year After Construction Completion
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DPWES Stormwater Planning Division 32
Three Years After Construction Completion
33. Pre-Construction Construction
Post Construction After plant establishmentPost-Construction
Crook Branch Stream Restoration
DPWES Stormwater Planning Division
Examples – Big Rocky Run Tributary
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34. Crook Branch Stream Restoration
DPWES Stormwater Planning Division
Examples – Rabbit Branch
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Pre-Construction Construction
Post-Construction 8 Months After Construction
35. Crook Branch Stream Restoration
DPWES Stormwater Planning Division
Strategies for Successful Revegetation
• Stream Restoration Design Goals
– Structural:
• Including grading and rock structures
– AND Biological:
• Soils and Plants support
• Insects, Reptiles, Birds, and Mammals
• Pre-Construction
– Non-Native Invasive Plant Management
• Establish clear zone so that natives can re-establish
– Native plant rescues
• Final Phase of Construction
– Stabilize with native seed
– Plant native shrubs and trees
– Minimum 1 year warranty
• Minimum 3 year monitoring
– For Native Vegetative Cover
– Less than 20% Invasive
– Zero % Highly Invasive
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36. Crook Branch Stream Restoration
DPWES Stormwater Planning Division
Reduce the Competition
• Non-Native Invasive Plant Management
• Pre-treatment of vines, shrubs, bamboo, trees
• Within Limit of Disturbance
• Physical removal and chemical control
• Buffer Zone At least 25’ from LOD
• Work with you to set boundaries
• Establish clear zone so natives plants can re-establish
• Minimize/eliminate non-natives in adjacent yards -
volunteer
• Maintain clear zones adjacent to stream on private
property - volunteer
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37. Crook Branch Stream Restoration
DPWES Stormwater Planning Division
Tips for Planting on Private Property
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• Plant for Native Wildlife not Urban Invaders
• Native Oak trees support over 500 native species of insects, birds, amphibians
• Bradford pear supports less than 10 species
• English Ivy harbors rats and Asian tiger mosquitos – replace with Sedges,
Golden groundsel, Christmas fern
• Common violet supports the early spring Fritillaria butterfly
• Increase plant layers in plant beds
• Maintain natural leaf litter
• Reduce lawn areas and use a mulching mower
• Reduce use of chemical pesticides - Tip and Toss to control mosquitos
38. Crook Branch Stream Restoration
DPWES Stormwater Planning Division
Managing Rainwater on Private Property
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• Reduce Stormwater Run-off at the Source
• Increase canopy from trees, shrubs and groundcover
• Forested areas intercept 90% more rainfall than lawns
• Plant trees and multiple layers of plants
• Reduce fertilization
• Detain rainfall on site
• Dis-connect downspouts
• Install rain barrels
• Rain gardens
• Pervious paving
39. Crook Branch Stream Restoration
DPWES Stormwater Planning Division
Resources for Gardening for Wildlife
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Guidance and Grants:
Northern Virginia Soil and Water Conservation District
• https://www.fairfaxcounty.gov/soil-water-conservation/
Native Plant Resources & What Not to Plant:
Plant NOVA Natives – plant descriptions and where to buy
• https://www.plantnovanatives.org/
Audubon at Home – site visits from Virginia Master Naturalists or Master Gardeners
• http://audubonva.org/audubon-at-home-1
Virginia Native Plant Society - Potowmack Chapter at Greenspring Gardens – displays, lectures
• http://vnps.org/potowmack/
DCR List of Non-Native Invasive Plants – over 90 species currently
• http://www.dcr.virginia.gov/natural-heritage/document/nh-invasive-plant-list-2014.pdf
Fairfax County Stewardship – Invasive Forest Plants
• https://www.fairfaxcounty.gov/parks/sites/parks/files/assets/documents/naturalcultural/invasive%20forest
%20plants%20brochure.pdf