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A Fairfax County, VA, publication
Department of Public Works and Environmental Services
Working for You!
August 27, 2019
C...
DPWES Stormwater Planning Division
Introductions
Design Team includes:
– Members of the Hollin Hills Civic Association
– M...
DPWES Stormwater Planning Division
Meeting Outline
3
• Status and General Schedule
• Site Location and Project Limits
• Pr...
DPWES Stormwater Planning Division
Status and General Schedule
• Scoping (Completed)
• Data Collection (Completed)
• Strea...
DPWES Stormwater Planning Division
Project Limits
5
Hollin Hills Stream Restoration
Brickelmaier Park
Goodman Park
Voigt P...
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
Design – Proposed Alignment (Goodman Upper)
6
• Hand-wo...
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
Design – Proposed Alignment (Goodman Middle)
7
• Use ex...
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
Design – Proposed Alignment (Goodman Lower)
8
• Lower a...
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
Design – Proposed Alignment (Brickelmaier Upper)
9
• Al...
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
Design – Proposed Alignment (Brickelmaier Lower)
10
• C...
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
Design – Proposed Alignment (Brickelmaier Lower)
11
• T...
Hollin Hills
Questions and Comments
DPWES Stormwater Planning Division 12
• 46 + households presented comments/questions v...
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
Design – Tree Preservation
13
• Surveyed 293 trees (Goo...
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
Design – Tree Preservation
14
• Goodman has 46 trees to...
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
Design – Tree Preservation
15
• Brickelmaier has 49 tre...
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
How did we minimize tree loss?
16
• Does not address pa...
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
How did we minimize tree loss?
17
• Does not address fl...
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
How did we minimize tree loss?
18
• Construction stagin...
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
How did we minimize tree loss?
19
• Tree save areas add...
Hollin Hills Stream Restoration
Restoration Planting
DPWES Stormwater Planning Division 20
Replacement planting/landscapin...
Hollin Hills Stream Restoration
Restoration Planting
DPWES Stormwater Planning Division 21
Replacement planting/landscapin...
Pre-Construction Construction
Post Construction After plant establishmentPost-Construction
Hollin Hills Stream Restoration...
Hollin Hills Stream Restoration
Flooding – I haven’t seen any flooding
DPWES Stormwater Planning Division 23
August 2019Au...
Hollin Hills Stream Restoration
Flooding – I haven’t seen any flooding
DPWES Stormwater Planning Division 24
• The problem...
Hollin Hills Stream Restoration
Flooding – I haven’t seen any flooding
DPWES Stormwater Planning Division 25
• The problem...
DPWES Stormwater Planning Division
Construction Example
26
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
Construction Example
27
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
Construction Example
28
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
Construction Example
29
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
Construction Example
30
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
Construction Example
31
Hollin Hills Stream Restoration
Hollin Hills Stream Restoration
DPWES Stormwater Planning Division
Program Drivers
32
1. State and Federal Regulations
1. ...
Hollin Hills Stream Restoration
Questions and Comments
DPWES Stormwater Planning Division 33
• Cost to date of the two pro...
Hollin Hills Stream Restoration
Design Solution
DPWES Stormwater Planning Division 34
• Poured in place concrete as oppose...
Hollin Hills Stream Restoration
Design Solution
DPWES Stormwater Planning Division 35
• Extend the Marthas outfall to Paul...
Hollin Hills Stream Restoration
Design Solution
DPWES Stormwater Planning Division 36
• Minimize staging areas even if it ...
Hollin Hills Stream Restoration
Design Solution
DPWES Stormwater Planning Division 37
• Have smaller access roads
– The ac...
DPWES Stormwater Planning Division
Q&A
Things to remember when evaluating this design:
80% of a stream restoration is infl...
Additional Information
For additional information, please contact
www.fairfaxcounty.gov/publicworks
Hollin Hills Stream Re...
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Paul Spring at Hollin Hills Stream Restoration Community Meeting 8-27-2019

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Meeting Outline:
Status and General Schedule
Site Location and Project Limits
Proposed Alignment and Access
Comments/Questions
Alternate Proposed Design Solutions
Q&A
Subject Matter Tables

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Paul Spring at Hollin Hills Stream Restoration Community Meeting 8-27-2019

  1. 1. A Fairfax County, VA, publication Department of Public Works and Environmental Services Working for You! August 27, 2019 Community Meeting Mt. Vernon District Paul Spring Branch @ Hollin Hills Stream Restoration Project Goodman and Brickelmaier Park
  2. 2. DPWES Stormwater Planning Division Introductions Design Team includes: – Members of the Hollin Hills Civic Association – Members of the Hollin Hills community – Mt. Vernon District Supervisor Daniel G. Storck – County staff: Project Manager, Construction Manager, Wastewater, Urban Forester, Stormwater Ecologist – Design Engineers: Stantec – History Commission – Northern Virginia Soil and Water Conservation District 2 Hollin Hills Stream Restoration
  3. 3. DPWES Stormwater Planning Division Meeting Outline 3 • Status and General Schedule • Site Location and Project Limits • Proposed Alignment and Access • Comments/Questions • Alternate Proposed Design Solutions • Q&A • Subject Matter Tables Hollin Hills Stream Restoration
  4. 4. DPWES Stormwater Planning Division Status and General Schedule • Scoping (Completed) • Data Collection (Completed) • Stream Restoration Design Process (In progress) – Pre-Concept Plan Development (Completed) – Concept (35%) Design Plan Development (Completed) – Field Walk (Completed) – Easements (Completed) – Preliminary (65%) Design Plan Development (In Process) – Final Design Plan Development (late fall) – Construction Documents (mid-winter) • Construction – Construction date dependent on future funding – Bidding and Contract Award – Community Meeting/just at Notice to Proceed – Construction • Warranty and Maintenance 4 Hollin Hills Stream Restoration
  5. 5. DPWES Stormwater Planning Division Project Limits 5 Hollin Hills Stream Restoration Brickelmaier Park Goodman Park Voigt Park McCalley Park
  6. 6. Hollin Hills Stream Restoration DPWES Stormwater Planning Division Design – Proposed Alignment (Goodman Upper) 6 • Hand-work above the lateral • Stockpile for leftover materials • Minimize disturbance • Minimize tree removal
  7. 7. Hollin Hills Stream Restoration DPWES Stormwater Planning Division Design – Proposed Alignment (Goodman Middle) 7 • Use existing alignment, grading the banks to remove instability • Add stormwater pipe and drop structures to connect pipe to main channel (reducing LOD) • Add stabilization structures above and below confluence • Removed riprap reinforcement
  8. 8. Hollin Hills Stream Restoration DPWES Stormwater Planning Division Design – Proposed Alignment (Goodman Lower) 8 • Lower alignment includes work on private property • Protect the trail and eliminate runoff into adjacent property (less than 100-year flood) • Expanded tree save area - increased buffer with private property • Lower alignment was to avoid work in Reach 7, recently modified with the July 8 and 10 storms
  9. 9. Hollin Hills Stream Restoration DPWES Stormwater Planning Division Design – Proposed Alignment (Brickelmaier Upper) 9 • Alignment includes work to address headcuts, including small amount of grading on private property • Work stays out of stable wetland areas, but corrects deep incision • Civic Association will work to relocate trail off of private property
  10. 10. Hollin Hills Stream Restoration DPWES Stormwater Planning Division Design – Proposed Alignment (Brickelmaier Lower) 10 • Construction access is very tight, neighbors will hear noise • Staging area moved behind slight hill to minimize noise and disturbance • Includes habitat wood to improve stream health in perennial section of the stream
  11. 11. Hollin Hills Stream Restoration DPWES Stormwater Planning Division Design – Proposed Alignment (Brickelmaier Lower) 11 • This area (including private property) is a Resource Protection Area (RPA), a larger buffer of denser plants is recommended. – https://www.fairfaxcounty.gov/landde velopment/designation-resource- protection-area
  12. 12. Hollin Hills Questions and Comments DPWES Stormwater Planning Division 12 • 46 + households presented comments/questions via email • 9 households have easements or letters of permission • 8 community members attended design team meetings • Several main themes: Minimize tree removal Don’t exacerbate flooding (and/or flooding doesn’t exist) Construction Regulatory/Authority Design Suggestions
  13. 13. Hollin Hills Stream Restoration DPWES Stormwater Planning Division Design – Tree Preservation 13 • Surveyed 293 trees (Goodman) and 237 trees (Brickelmaier) • This plan would remove 89 trees 12” or greater, and an additional 3 trees greater than 8”; trees less than 8” were not surveyed • Up to 64 of these trees could be reused on site • A subsample of vegetation in Goodman Park – 35% of the native trees under 8” are Ash – 25% of all trees under 8” are non-native invasive Brush Habitat Large Log Habitat
  14. 14. Hollin Hills Stream Restoration DPWES Stormwater Planning Division Design – Tree Preservation 14 • Goodman has 46 trees to be removed – 7 trees are removed for permanent access, 2 are dead – 7 trees are removed for staging – 6 trees are removed for realignment of the stream – 19 trees are removed because grading will affect their critical root zones, 2 are dead – 7 trees are removed because they are dead or dying Tree snag
  15. 15. Hollin Hills Stream Restoration DPWES Stormwater Planning Division Design – Tree Preservation 15 • Brickelmaier has 49 trees to be removed – 12 trees are removed for permanent access, 3 are dead – 3 trees are removed for staging – 15 trees are removed for realignment of the stream – 11 trees are removed because grading will affect their critical root zones – 8 trees are removed because they are dead or dying Habitat Logs
  16. 16. Hollin Hills Stream Restoration DPWES Stormwater Planning Division How did we minimize tree loss? 16 • Does not address path flooding • Does not address bank erosion above restoration • Goodman project doesn’t go to top of stream Protect Native Vegetation
  17. 17. Hollin Hills Stream Restoration DPWES Stormwater Planning Division How did we minimize tree loss? 17 • Does not address flooding of Paul Spring • Voigt, McCalley and other areas were removed from work area
  18. 18. Hollin Hills Stream Restoration DPWES Stormwater Planning Division How did we minimize tree loss? 18 • Construction staging area/access minimized Added to tree save
  19. 19. Hollin Hills Stream Restoration DPWES Stormwater Planning Division How did we minimize tree loss? 19 • Tree save areas added/and or critical root zones honored Added to tree save
  20. 20. Hollin Hills Stream Restoration Restoration Planting DPWES Stormwater Planning Division 20 Replacement planting/landscaping honors the native community • A small workgroup of interested residents met and approved a concept, we will see this implemented at 95% • The CAHH has asked that 25% of the plantings be larger trees – 1.5”-2” caliper • The CAHH has asked that the plantings make sense in logical groupings that would occur as part of an ecological community • The planting will receive some sort of deer protection, due to the high deer browse • The treatment of wisteria and knotweed will continue through construction, and additional invasive species treatment will be organized through the warranty period as needed • The trail surface will be left as unimproved (current condition)
  21. 21. Hollin Hills Stream Restoration Restoration Planting DPWES Stormwater Planning Division 21 Replacement planting/landscaping requires maintenance • The Civic Association can and are encouraged to have workdays to maintain trees and deer protection • The county will continue to monitor tree and vegetation establishment • The site will have good vegetation cover to support nutrient removal, slope stability and wildlife support
  22. 22. Pre-Construction Construction Post Construction After plant establishmentPost-Construction Hollin Hills Stream Restoration DPWES Stormwater Planning Division Example – Big Rocky Run Tributary 22
  23. 23. Hollin Hills Stream Restoration Flooding – I haven’t seen any flooding DPWES Stormwater Planning Division 23 August 2019August 2016 10-12’ 16’+
  24. 24. Hollin Hills Stream Restoration Flooding – I haven’t seen any flooding DPWES Stormwater Planning Division 24 • The problem in these two streams isn’t the flooding – it’s the erosion • No additional flooding occurs because of a project –No rise/No impact • Another example of erosion – not from Marthas Circle 2016
  25. 25. Hollin Hills Stream Restoration Flooding – I haven’t seen any flooding DPWES Stormwater Planning Division 25 • The problem in these two streams isn’t the flooding – it’s the erosion • No additional flooding occurs because of a project –No rise/No impact • Another example of erosion – not from Marthas Circle 20162019
  26. 26. DPWES Stormwater Planning Division Construction Example 26 Hollin Hills Stream Restoration
  27. 27. DPWES Stormwater Planning Division Construction Example 27 Hollin Hills Stream Restoration
  28. 28. DPWES Stormwater Planning Division Construction Example 28 Hollin Hills Stream Restoration
  29. 29. DPWES Stormwater Planning Division Construction Example 29 Hollin Hills Stream Restoration
  30. 30. DPWES Stormwater Planning Division Construction Example 30 Hollin Hills Stream Restoration
  31. 31. DPWES Stormwater Planning Division Construction Example 31 Hollin Hills Stream Restoration
  32. 32. Hollin Hills Stream Restoration DPWES Stormwater Planning Division Program Drivers 32 1. State and Federal Regulations 1. Chesapeake Bay Agreement 1. Partnering states (VA, MD, DC, DE, PA, WV) signed the agreement to restore the bay health and ecosystem. 2. Municipal Separate Storm Sewer Permit (MS-4) 1. Easements rights and responsibility to maintain/upgrade 3. Local TMDLs (Total Maximum Daily Loads – sediment, bacteria, PCBs) 1. Regulates amounts of pollutants in waterways 2. Public Safety 1. Erosion control 2. Flooding 3. Maintenance of existing facilities
  33. 33. Hollin Hills Stream Restoration Questions and Comments DPWES Stormwater Planning Division 33 • Cost to date of the two projects, inclusive? $600,000 • Where will the equipment be during the project? How much equipment? • Equipment in will be stored within the LOD. 10-20 construction vehicles, but not all at one time. • How long will the project take? • Each individual stream is predicted to take about 1- year. We anticipate joining the two streams will shorten the total duration of the project, this estimate will get tighter closer to construction. • What is the pump-around? • The pump around moves any water in the stream around the active construction. It is only used as needed and it is specified to be low-decibel. • Can the CAHH address the problem without the county? • The CAHH is the landowner. They can propose solutions, and if they are permitted, and funded, they can be built. Maintenance of a private stormwater feature usually falls to the landowner. The CAHH is considering such a solution in the upper reaches of Goodman Park.
  34. 34. Hollin Hills Stream Restoration Design Solution DPWES Stormwater Planning Division 34 • Poured in place concrete as opposed to boulders – Poured in place concrete is not currently in the accepted practice design manual – We have inquired with the Corps about this option, but it has not yet been permitted – Concrete is more risky regarding structural integrity and spalling, especially if poured in place and not held for curing under stable conditions
  35. 35. Hollin Hills Stream Restoration Design Solution DPWES Stormwater Planning Division 35 • Extend the Marthas outfall to Paul Spring and abandon the other proposed work – Piping is not a natural channel design stream restoration, so this would not achieve credit for the Bay TMDL reduction program – The pipe would need to be more than 600 feet long, triggering several regulatory requirements regarding dimensions, access, maintenance – The pipe itself would have a construction footprint and staging areas, these would be straight and not work with the contour of the land – The entire easement would need to remain tree-free – Paul Spring is not an adequate outfall, that is, piping additional water, undetained into the channel may cause additional damage to the properties along Paul Spring
  36. 36. Hollin Hills Stream Restoration Design Solution DPWES Stormwater Planning Division 36 • Minimize staging areas even if it causes more trips by delivery vehicles – Staging areas are relatively small for the amount of cut/fill – Need to minimize truck trips for the neighborhood and neighbors adjacent to construction entrances – Would add cost – Primary staging area has trees at the end of their life span; and the unknown factor of the well
  37. 37. Hollin Hills Stream Restoration Design Solution DPWES Stormwater Planning Division 37 • Have smaller access roads – The access roads are responsible for a small percentage of the tree loss – Smaller access roads increases risk of damaging trees, causing long-term problems – The permanent access road has already shrunk from 24 feet to 16 feet – There is not an opportunity to further shrink it
  38. 38. DPWES Stormwater Planning Division Q&A Things to remember when evaluating this design: 80% of a stream restoration is inflexible: regulatory/driven by engineering/constraints on the site Our program is funded to do stream restoration, primarily with Natural Channel Design The county uses the best design engineering and contract oversight available – this is not low bid The landowner’s opinion overrides a neighbor’s opinion We listen to all opinions, but that does not mean every suggestion is taken/feasible/used The county uses the low bid construction contractor 38 Hollin Hills Stream Restoration
  39. 39. Additional Information For additional information, please contact www.fairfaxcounty.gov/publicworks Hollin Hills Stream Restoration Meghan Fellows 703 324 5807 meghan.fellows@fairfaxcounty.gov DPWES Stormwater Planning Division 39

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