Popes Head Creek at Brecon Ridge Resident Meeting
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The project seeks to stabilize excessive & ongoing stream erosion negatively impacting water quality, undermining trees, threatening the riparian corridor, and degrading habitat for aquatic life. Project components include: Install instream structures to direct flow, alleviate erosive forces on stream banks, and provide instream habitat Raise the stream channel bottom to allow water to spread out over the floodplain On a tributary to the main channel, stabilize a headcut & debris jam holding back sediment from channel erosion upstream Control non-native invasive plants Reforest the site with native trees, shrubs, and plants
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Popes Head Creek at Brecon Ridge Resident Meeting
- 1. A Fairfax County, VA, publication Department of Public Works and Environmental Services Working for You! Headwaters of Popes Head Creek @ Brecon Ridge (PH9271/PH9272) Project No. SD-000031-220 Springfield District Tax Map No. 067-2 & 068-4 March 2021
- 2. Stormwater Planning Division Agenda • Stormwater Program Drivers • Watershed • Project Goals • Existing Conditions • Typical Restoration Practices • Example Construction Efforts • Example Completed Projects • Next Steps 2 Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration
- 3. Stormwater Planning Division Stormwater Program Drivers – Water Quality area The Clean Water Act of 1972 Regulate pollutant discharge to the Waters of the U.S. Chesapeake Bay Preservation Act Program to improve the water quality in the Chesapeake Bay Other State & Federal Standards – Municipal Separate Storm Sewer System Permit (MS-4): – Total Maximum Daily Loads (TMDL) Popes Head Creek is an impaired water for bacteria (E. coli) and for benthics (sediment) 3 Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration
- 4. Stormwater Planning Division Fairfax County Watersheds 4 Project site in the Popes Head Creek watershed Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration
- 5. Stormwater Planning Division Project Goals 5 The project seeks to stabilize excessive & ongoing stream erosion negatively impacting water quality, undermining trees, threatening the riparian corridor, and degrading habitat for aquatic life. Project components include: • Install instream structures to direct flow, alleviate erosive forces on stream banks, and provide instream habitat • Raise the stream channel bottom to allow water to spread out over the floodplain • On a tributary to the main channel, stabilize a headcut & debris jam holding back sediment from channel erosion upstream • Control non-native invasive plants • Reforest the site with native trees, shrubs, and plants Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration
- 6. Stormwater Planning Division Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration General Project Extent 6
- 7. Stormwater Planning Division Existing Conditions 7 A short distance downstream from Braddock Road. Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration
- 8. Stormwater Planning Division Existing Conditions 8 Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration Slightly downstream from the first residential property along Popes Head Creek.
- 9. Stormwater Planning Division Existing Conditions 9 Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration Vertical bank with undercut and exposed tree roots.
- 10. Stormwater Planning Division Existing Conditions 10 Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration Dry, friable soil sloughed under its own weight.
- 11. Stormwater Planning Division Existing Conditions 11 Location is approximately 300 linear feet up the unnamed tributary to the Popes Head Creek mainstem. Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration May 2020 November 2020 Yellow arrows identify the same small beech tree adjacent to the debris jam/headcut. Comparison showing the loss of woody debris in ~6 months.
- 12. Stormwater Planning Division Existing Conditions 12 Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration Another large tree being undermined by stream flows.
- 13. Stormwater Planning Division Existing Conditions 13 Tree being undermined. Channel eroded down to bedrock. Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration
- 14. Stormwater Planning Division Existing Conditions 14 Another outside meander where trees on the outside bank are being undermined due to increased sheer stress. Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration
- 15. Stormwater Planning Division Existing Conditions 15 Fallen tree took a portion of the channel bank down to the existing water surface. Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration
- 16. Stormwater Planning Division Existing Conditions 16 Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration
- 17. Stormwater Planning Division Typical Restoration Practices – Brush Run 17 In stream woody structures catch debris/detritus providing habitat for fish and other aquatic life. Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration
- 18. Stormwater Planning Division Typical Restoration Practices – Root Wads 18 Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration For roughness & habitat.
- 19. Stormwater Planning Division Typical Restoration Practices – Toe Log Structure 19 Toe logs provide armoring & direct flows away from the bank. Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration
- 20. Stormwater Planning Division Example of Construction Access Road 20 Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration Access road - typically wood timber matting underlaid with mulch for construction equipment to travel.
- 21. Stormwater Planning Division Construction Example 21 Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration
- 22. Stormwater Planning Division Design consideration – Tree Removal 22 • 1,095 trees surveyed • 240 proposed for removal. Of these, 15 are dead & 67 are assessed as either dead or in poor health. • Please keep in mind that we have a general alignment that is still to be engineered. As we move through an iterative design process, decisions will be made to preserve as many tree as possible. • Removed trees can potentially be reused as natural structures within the stream (e.g., log sills, root wads, and habitat logs) Evaluated trees are marked with tree tags. This helps us identify trees when reviewing design plans and when in the field. Headwaters of Popes Head Creek @ Brecon Ridge Stream Restoration
- 23. Stormwater Planning Division * Following Planting Density Requirements, as part of project construction & for every disturbed acre we will plant: • 100 overstory trees • 200 understory trees • 1,089 shrubs * proposed quantities of plants will be provided at the 65% Design plan 23 Native Plants – woody & herbaceous material examples
- 24. Stormwater Planning Division Native Plants – woody material examples 24
- 25. Stormwater Planning Division 25 Lower Potomac Ballpark Outfall May 2020 (immediately following completion) July 2016 - pre-existing condition Completed Project Examples
- 26. Stormwater Planning Division 26 Pike Branch Tributary @ Ridgeview Park December 2018 March 2020 (immediately following completion) Completed Project Examples
- 27. Stormwater Planning Division 27 Turkey Run at Truro February 2018 (∼2 Year after construction completion) March 2016 Completed Project Examples
- 28. Stormwater Planning Division Completed Project Examples 28 Turkey Run at Truro May 2019 (∼2 Years after construction completion) March 2016
- 29. Stormwater Planning Division 29 Dead Run Segment 1 March 2016 May 2020 (∼2 Years after construction completion) Completed Project Examples
- 30. Stormwater Planning Division Next Steps 30 • Easement Acquisition • Complete Design • Permitting • United States Army Corps of Engineers • Virginia Department of Environmental Quality • Fairfax County • VDOT • Construction • Approximate duration: ~14 months • Post Construction • Completed project carries 1-year warranty • After warranty period, County assumes monitoring & maintenance responsibilities
- 31. Additional Information For additional information, please contact www.fairfaxcounty.gov/publicworks Stormwater Planning Division 31 Dave Anglin, Section Chief www.fairfaxcounty.gov/publicworks dave.anglin@fairfaxcounty.gov For additional information, please contact 571-722-8515
Editor's Notes
- This seems like a long agenda, I would suggest paring it down. Your audience is probably really focused on the project, this agenda, with the exception of project goals seems like a presentation on environmental programs and practices.
- MS4: Under this permit, we need to have programs to regulate pollutant discharge TMDLs: Under this permit, we need to have programs to regulate pollutant discharge. Local TMDLs include bacteria (12), sediment (3), & PCB’s along the tidal Potomac area.
- Emphasize that the soil being eroded is from the home lots & the HOA property.
- A triple box culvert outfall from under Braddock Road. The watershed extends north almost to Lee Hwy & south of the mobile home development. Other portions extend east to West Drive in Fairfax City & west along Shirley Gate Road. Incised channel bank height averaging 5.5 feet in this area.
- The channel is deeply incised on each bank side. Most vegetation close to the bank edge is seasonal, herbaceous cover and/or turf grass. A few small trees are visible on the left bank. However, note the incised left bank extends from the foreground through the downstream extent visible in the photograph.
- Beyond being at risk of loss due to erosion, the tree’s critical root zone has been severely compromised. This risks root decay that will hasten tree loss.
- Visible where the stream flow meets the raw bank is friable soil that sloughed off under its own weight. So, a variety of factors contribute to soil loss beyond just water flows.
- Unstable debris jam at a headcut that is holding back sediment accumulated from the upper reaches of this unnamed tributary to Popes Head Creek. When the debris jam fails, the accumulated sediment will be discharged downstream. It is also likely that the headcut here will begin to erode upstream again.
- As with other locations, this tree is at high risk of loss due to being undermined &/or root decay.
- Ensures that erosive force will be expressed on the channel banks leading to cutting & channel widening.
- This also blocked a portion of the channel area causing eddying & water flows against the raw soil increasing erosion on the down stream side.
- Root wads can be placed along meanders (bends) to armor/protect the bank. These wads also act as some roughness to help manage water velocity. Root wads also provide habitat & cover for fish & other aquatic life.
- Using logs in this manner also incorporates native woody material into the channel mimicking natural stream banks & re-uses material on site.
- This matting & mulch disperse equipment weight & decrease tree root impacts & soil compaction.
- Above - newly graded & stabilized stream channel through a series of step pools. Below – placing large stone creating a step pool to lower stream flows over steep grade in a controlled manner .
- We work closely with Urban Forest Management Division staff, arborists, and landscape architects to minimize impacts and preserve trees. All trees within a project area with a diameter equal to/greater than 12 inches were surveyed, tagged, and species, diameter size, and health are recorded.
- DO you have an after picture that is green and shows the extent of planting
- This is nice