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Crook Branch at Mantua Elementary School Stream Restoration Project

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Crook Branch at Mantua Elementary School Stream Restoration Project

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Crook Branch at Mantua Elementary School Stream Restoration Project

  1. 1. A Fairfax County, VA, publication Department of Public Works and Environmental Services Working for You! February 1, 2016 Community Meeting Mantua Elementary School Cafeteria Crook Branch at Mantua Elementary School Stream Restoration Project Accotink Creek Watershed Plan Implementation
  2. 2. Crook Branch Stream Restoration DPWES Stormwater Planning Division Meeting Outline 2 • Fairfax County Stormwater Management and Program Drivers • Accotink Creek Watershed Management Plan • Crook Branch Stream Restoration – Project Scope • Stream Restoration Approaches • Crook Branch – Historical and Existing Conditions • Design Approach • Illustrative/Example Projects • Next Steps • Q&A
  3. 3. Crook Branch Stream Restoration DPWES Stormwater Planning Division Fairfax County Department of Public Works and Environmental Services 3 Department of Public Works and Environmental Services Land Development Services Capital Facilities Solid Waste Stormwater Stormwater Planning Division Maintenance and Stormwater Management Division Wastewater
  4. 4. Crook Branch Stream Restoration DPWES Stormwater Planning Division Fairfax County Stormwater Management Major Program Areas 4 • Inspection and maintenance of conveyance systems (pipes and appertunces) • 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 water quality projects
  5. 5. Crook Branch Stream Restoration DPWES Stormwater Planning Division Stormwater Infrastructure 5 • Conveyance System – 1,600 miles pipe and constructed channel – 43,000 structures – 6,800 outfalls • Management Facilities – 1,540 County Maintained – 3,720 Privately Maintained • State Regulated Dams
  6. 6. Crook Branch Stream Restoration DPWES Stormwater Planning Division Program Drivers and Project Types 6 • Chesapeake Bay Total Maximum Daily Load (TMDL) • Other (local streams) TMDLs • MS4 permit • Major project types  Stream and outfall restorations  Stormwater Pond retrofits  Site retrofits using Green Infrastructure • List of projects is developed from watershed plans, and referral from a variety of sources including the maintenance division and citizen complaints
  7. 7. Crook Branch Stream Restoration DPWES Stormwater Planning Division Countywide Watershed Planning 7 “Healthy Watersheds, Healthy Communities” • 30 Designated Watersheds • All 15 watershed plans have been adopted by Fairfax County
  8. 8. Crook Branch Stream Restoration DPWES Stormwater Planning Division Accotink Creek Watershed Management Plan 8 http://www.fairfaxcounty.gov/dpwes/watersheds/accotinkcreek.htm
  9. 9. Crook Branch Stream Restoration DPWES Stormwater Planning Division Accotink Creek Watershed Management Plan 9 http://www.fairfaxcounty.gov/dpwes/stormwater/projects/project_list.htm
  10. 10. Crook Branch Stream Restoration DPWES Stormwater Planning Division Accotink Creek Watershed Management Plan Wakefield Run Stream Restoration 10
  11. 11. Crook Branch Stream Restoration DPWES Stormwater Planning Division Accotink Creek Watershed Management Plan Brookfield Pond Repair and Retrofit 11
  12. 12. Crook Branch Stream Restoration DPWES Stormwater Planning Division Accotink Creek Watershed Management Plan Brookfield Pond Repair and Retrofit 12
  13. 13. Crook Branch Stream Restoration DPWES Stormwater Planning Division Accotink Creek Watershed Management Plan Mantua Elementary School Stormwater Retrofit (proposed) 13
  14. 14. Crook Branch Stream Restoration DPWES Stormwater Planning Division 14 http://www.fairfaxcounty.gov/dpwes/watersheds/accotinkcreek.htm Stormwater Citizen Complaints
  15. 15. Crook Branch Stream Restoration DPWES Stormwater Planning Division 15 Stormwater Citizen Complaints
  16. 16. Crook Branch Stream Restoration DPWES Stormwater Planning Division Project Limits 16 Reach 2
  17. 17. Crook Branch Stream Restoration DPWES Stormwater Planning Division Supervisory Districts and Existing Easements 17
  18. 18. Crook Branch Stream Restoration DPWES Stormwater Planning Division Supervisory Districts and Existing Easements 18
  19. 19. Crook Branch Stream Restoration DPWES Stormwater Planning Division Wetland Studies and Solutions, Inc. Natural & Cultural Resources consulting firm • Founded in 1991 • Consulted on 5,000+ project sites encompassing 200,000+ acres • 100+ staff Expertise • Geographic Information Systems • Environmental Science • Archeology • Surveying • Regulatory and Permit Compliance • Environmental Engineering • Landscape Design • Ecosystem Restoration Acquisition by The Davey Tree Expert Company: • Expertise in tree protection, assessment, and analysis • Largest employee-owned service company in U.S. • Founded in 1880 Locations: • Gainesville, VA • Roanoke, VA • Odenton, MD 19 Virginia’s First LEED® Gold-Certified Office Crook Branch Restoration Project Team – Brian Chromey, P.E. – Mike Marsala, P.E., C.F.M. – Aaron Estep, E.I.T. – Matt MacFarland, E.I.T.
  20. 20. Crook Branch Stream Restoration DPWES Stormwater Planning Division Why Restore Streams? • Eroding bed and banks are threatening private property and creating sediment pollution 20
  21. 21. Crook Branch Stream Restoration DPWES Stormwater Planning Division Why Restore Streams? • Erosion results in poor water quality; high levels of: – Total Suspended Solids (TSS) – Total Nitrogen (TN) – Total Phosphorous (TP) 21 • The Environmental Protection Agency Chesapeake Bay TMDL Plan Requires Fairfax County pollutant reductions Poor water quality Good water quality
  22. 22. Crook Branch Stream Restoration DPWES Stormwater Planning Division General Approach • What caused the current erosion problems? • What can be done to fix the erosion and prevent future issues? 22
  23. 23. DPWES Stormwater Planning Division Crook Branch Stream Restoration The Urban Watershed Problem 23 Source: The Federal Interagency Stream Restoration Working Group
  24. 24. Crook Branch Stream Restoration DPWES Stormwater Planning Division Overall Goals • Reconnect to the existing floodplain to: – Slow velocities – Increase evapotranspiration – Remove pollutants (TP, TN, and TSS) – Improve riparian habitat – Restore groundwater levels 24 Before restoration After restoration
  25. 25. DPWES Stormwater Planning Division Crook Branch Stream Restoration Channel Evolution Model 25
  26. 26. Crook Branch Stream Restoration DPWES Stormwater Planning Division Design Methodology for Urban Streams • Natural Channel Evolution – Evolutionary process considers the channel’s incision, bank stability, and sedimentation load (aggrading or degrading) 26 Severe Poor Marginal Suboptimal Optimal Severe Channel Condition South Lakes High School Optimal Channel Condition Ellanor Lawrence Park
  27. 27. Crook Branch Stream Restoration DPWES Stormwater Planning Division Urban Stream – Design Realities 1. Significantly more flow than rural streams. 2. Significantly more “bankfull” events than in rural watersheds. 3. Given site constraints, reinforcement is necessary. – Rock structures – using native diabase rock – Reinforced bed – Heavy planting densities – native vegetation only 27 Wolftrap Creek (after 2 years)Rabbit Branch (after 7 months)
  28. 28. DPWES Stormwater Planning Division Crook Branch Stream Restoration Stream Reinforcement 28 Reinforced Bed Step Pools Cross Vanes
  29. 29. DPWES Stormwater Planning Division Crook Branch Stream Restoration Stream Reinforcement 29 Toe Wood Log J-Hook Native Vegetation In-Stream Habitat Log Sill
  30. 30. Crook Branch Stream Restoration DPWES Stormwater Planning Division Restoration Approaches Priority 1 Restoration – Raise stream to reconnect with floodplain. 30 Fewer trees removed Width of disturbance Balanced cut and fill volumes result in less waste Before After
  31. 31. Crook Branch Stream Restoration DPWES Stormwater Planning Division Restoration Approaches Priority 2 Restoration – Excavate floodplain at lower elevation. 31 Width of disturbance Large cut volumes result in waste material Many trees removed Priority 3 Restoration – Confined stream valleys.
  32. 32. Crook Branch Stream Restoration DPWES Stormwater Planning Division Restoration Approaches Priority 4 Restoration – Stabilize in-place. 32
  33. 33. DPWES Stormwater Planning Division Crook Branch Stream Restoration Crook Branch: Historic Conditions 33 1937 1954
  34. 34. DPWES Stormwater Planning Division Crook Branch Stream Restoration Crook Branch: Historic Conditions 34 1994 2004
  35. 35. DPWES Stormwater Planning Division Crook Branch Stream Restoration Crook Branch: Historic Conditions 35 2013
  36. 36. Crook Branch Stream Restoration DPWES Stormwater Planning Division Crook Branch: Existing Conditions • Drainage Area: – 827.8 acres • Imperviousness: – 35% • Average Channel Slope: – 0.0081 36
  37. 37. Crook Branch Stream Restoration DPWES Stormwater Planning Division Crook Branch: Existing Conditions 37
  38. 38. Crook Branch Stream Restoration DPWES Stormwater Planning Division Crook Branch: Existing Conditions 38
  39. 39. Crook Branch Stream Restoration DPWES Stormwater Planning Division Crook Branch: Existing Conditions 39
  40. 40. Crook Branch Stream Restoration DPWES Stormwater Planning Division Crook Branch: Existing Conditions 40
  41. 41. Crook Branch Stream Restoration DPWES Stormwater Planning Division Crook Branch: Existing Conditions 41
  42. 42. Crook Branch Stream Restoration DPWES Stormwater Planning Division Crook Branch: Existing Conditions 42
  43. 43. Crook Branch Stream Restoration DPWES Stormwater Planning Division Crook Branch: Existing Conditions 43
  44. 44. Crook Branch Stream Restoration DPWES Stormwater Planning Division Crook Branch: Existing Conditions 44
  45. 45. Crook Branch Stream Restoration DPWES Stormwater Planning Division Crook Branch: Existing Conditions 45
  46. 46. Crook Branch Stream Restoration DPWES Stormwater Planning Division Plan Development Process • Project Introduction Meeting (Today) • Data Collection (Partially Completed) • Stream Restoration Design Process* – Pre-Concept Plan Development (± 3 months) – 35% Design Plan Development (± 5 months) – 65% Design Plan Development (± 3 months) – Final Design Plan Development (± 8 months) – Pre-Construction Review (± 2 months) • Construction (± 9 months) *Community meeting to follow County review of pre-concept design. Additional meetings scheduled as we progress toward final design. 46
  47. 47. Crook Branch Stream Restoration DPWES Stormwater Planning Division Data Collection • Obtain topography • Survey, locate, and tag trees (>12” dbh) • Survey channel profile and cross- sections • Existing streambed sediment sampling • Obtain County GIS utility information • Obtain County floodplain information • Perform wetland delineations and obtain Jurisdictional Determinations (JD’s) from U.S. Army Corps of Engineers • Obtain geotechnical soil borings 47
  48. 48. Crook Branch Stream Restoration DPWES Stormwater Planning Division Community Involvement In Plan Development Objective – Partnership between Fairfax County staff and the residents of Mantua and Ridgelea Hills • Establish community representative(s) to coordinate with County staff as the project progresses • Community involvement at all levels of the plan development process (Concept, Preliminary, Final Design, and Construction) – Plan review, discussion, and feedback 48
  49. 49. Crook Branch Stream Restoration DPWES Stormwater Planning Division Stream Restoration Design Process 49 THEDESIGNPROCESS Determine Bankfull Width and Bankfull Area to convey current flows. Apply Bankfull Width to reference ranges of sinuosity and meander radii. Layout initial design alignment (minimize impact to infrastructure and trees) Revise restoration design and access (based on citizen input) Final Design Citizen Meeting Citizen Meeting
  50. 50. Crook Branch Stream Restoration DPWES Stormwater Planning Division Stream Restoration Design Process 50 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 • Drip line heavily impacted during restoration, minimal chance of survival, AND • Human safety hazard to trails, houses, bridges, etc.
  51. 51. Crook Branch Stream Restoration DPWES Stormwater Planning Division Stream Restoration Design Process 51 Short term impact for long term benefit • Cleared trees “recycled” as in-stream habitat, grade control, wood-chip trails, habitat “brush” piles, firewood • Restoration raises the water table, (raises stream bed) which increases stream access to floodplain and nutrient delivery to roots. • Healthier ecosystem will develop with the density and species variety of replacement plantings – Mosquito population control via predator habitat – Dense streambank planting will provide shade, reduce water temperatures, increase oxygenation, increase fish survivability – Dragonfly larva molting access via heavily planted streambank with shallower slope • Canopy loss will close as remaining trees adjust and react to increased sunlight, growing to fill in openings Fewer trees cut = lower restoration cost • Tree-climbing removal method vs. traditional forestry timbering (minimize impacts to neighboring trees) is expensive. Lower water table Higher water table Incised stream Restored (raised) stream
  52. 52. Crook Branch Stream Restoration DPWES Stormwater Planning Division Examples – Snakeden Reach 2 52 Pre-Construction Construction Post-Construction 5 Months After Construction
  53. 53. Crook Branch Stream Restoration DPWES Stormwater Planning Division Examples – Rabbit Branch 53 Pre-Construction Construction Post-Construction 8 Months After Construction
  54. 54. Pre-Construction Construction Post Construction After plant establishmentPost-Construction Crook Branch Stream Restoration DPWES Stormwater Planning Division Examples – Big Rocky Run Tributary 54
  55. 55. Crook Branch Stream Restoration DPWES Stormwater Planning Division Planting – Trees & Shrubs 55 Split into 2 planting zones: - Riparian - 1 gallon containers (planted at 640 plants/acre) - both trees & shrubs - Streamside - live stakes/tubelings (planted 1ft o.c.) - shrubs (planted 3 ft o.c.) Tree Species: Pin Oak, Willow Oak, White Oak, Swamp White Oak, Northern Red Oak, Sweet Gum, Black Gum, River Birch, Sycamore, Red Maple, Box Elder, and Black Willow. Shrub Species: Silky Dogwood, Southern Arrowwood, American Holly, Service-Berry, Black-Haw, Eastern Redbud, Elderberry, Flowering Dogwood, and Brookside Alder, Hazelnut, Northern Spicebush, Black-Haw, Winterberry. Eastern Redbud
  56. 56. Crook Branch Stream Restoration DPWES Stormwater Planning Division Planting – Riparian Seed Mix 56 • Typical Tree Species • Musclewood • Black Gum • American Sycamore • Red Maple • Eastern Redbud • Flowering Dogwood • Typical Forbs • Oxeye Sunflower • Joe-Pye Weed • Grass Leaved Goldenrod • PLUS 24 additional species! • Typical Shrub Species • Witch Hazel • Winterberry • Southern Arrow Wood • Northern Spicebush • Canadian Serviceberry • Black Chokeberry • Black-Haw • Typical Grass Species • Squarrose Sedge • Riverbank Wild Rye • Foxtail Millet • PLUS 8 additional species! • Applied at a rate of 125 lbs/acre • Custom mix • Consists of native species found in a healthy, diverse NOVA ecosystem:
  57. 57. Crook Branch Stream Restoration DPWES Stormwater Planning Division Greater Biodiversity 57 • Mature forest continues to provide habitat for raptors, woodpeckers, bats and deer • Recently planted areas provide habitat for small mammals, song birds, fox and deer • All species benefit from the “edge effect” • Restored stream allows detrital input to be processed, thus increasing stream health and function Orchard Oriole Red-shouldered Hawk Cottontail Rabbit
  58. 58. Crook Branch Stream Restoration DPWES Stormwater Planning Division Conclusion 58 1. The “Crook Branch” tributary of the Accotink Creek Watershed is severely degraded due to urbanization – a situation made worse by inadequate stormwater management. 2. Fully restored streams will provide long- term stability, improved aesthetics, & greater open space usability. 3. Short-term construction disturbance will provide long-term societal and ecological benefits to a heavily used, urban stream valley network.
  59. 59. Crook Branch Stream Restoration DPWES Stormwater Planning Division Next Steps 59 • Complete pre-concept design • Continue to work to acquire easements on Reach 1 • Community Meeting to present pre-concept design • Solicit community representation • Authorize design contract with WSSI – Final Concept Plan – Final Design and Construction Documents • Hold additional community meetings/stream walks as design progresses • Complete design and preparation of construction documents • Project bidding and construction
  60. 60. Crook Branch Stream Restoration DPWES Stormwater Planning Division Questions? 60
  61. 61. Additional Information For additional information, please contact www.fairfaxcounty.gov/dpwes Crook Branch Stream Restoration DPWES Stormwater Planning Division 61 Dipmani Kumar, Project Manager Matt Meyers, Branch Chief Watershed Projects implementation Branch - North 703-324-5500 Dipmani.Kumar@fairfaxcounty.gov Matthew.Meyers@fairfaxcounty.gov

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