Tucker Avenue Neighborhood Stormwater Project Community Meeting Sept 19, 2019
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Recent Storms and Flood Response Update Project Updates Design Status Existing Drainage Conditions Existing Utilities Preliminary Conceptual Design Easement Homeowner Drainage Improvements Proposed Schedule and Next Steps
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Tucker Avenue Neighborhood Stormwater Project Community Meeting Sept 19, 2019
- 1. A Fairfax County, VA, publication Department of Public Works and Environmental Services Working for You! TUCKER AVENUE and SURROUNDING NEIGHBORHOODS Community Meeting Storm Response and Project Update September, 2019 Neighborhood Stormwater Improvement Project Dranesville District
- 2. Tucker Avenue and Surrounding Neighborhoods Community Information Meeting Wednesday, September 18, 2018 Chesterbrook Elementary 1753 Kirby Rd, McLean @JohnFoustva @DranesvilleSupervisor Dranesville@FairfaxCounty.gov https://www.fairfaxcounty.gov/dranesville/ WELCOME AND THANK YOU!
- 3. Tucker Avenue and Surrounding Neighborhoods Stormwater Management Introductions • Department of Public Works and Environmental Services (DPWES) – Maintenance and Stormwater Management Division (MSMD) – Stormwater Planning Division (SWPD) – Wastewater Collection Division (WCD) • Land Development Services (LDS) • Northern Virginia Soil and Water Conservation District (NVSWCD) • Virginal Department of Transportation (VDOT) • Stantec – Design Consultants 3
- 4. Tucker Avenue and Surrounding Neighborhoods Stormwater Management Agenda • Recent Storms and Flood Response Update • Project Updates – Design Status – Existing Drainage Conditions – Existing Utilities – Preliminary Conceptual Design – Easement • Homeowner Drainage Improvements • Proposed Schedule and Next Steps 4
- 5. Tucker Avenue and Surrounding Neighborhoods Stormwater Management July 8th Storm Response • Intense storm with heaviest rainfall ranging from 3 to 5 inches in 90 minutes. 5 Gridded (2-square mile) rainfall amounts from Gauge-adjusted radar rainfall (from Advanced Hydrologic Prediction Service, NWS) Washington Post Article: How and why the D.C. area was deluged by a month’s worth of rain in an hour Monday (July 8th, 2019)
- 6. Tucker Avenue and Surrounding Neighborhoods Stormwater Management Recent Storm Response and Stormwater Drainage Issues 6 Service inquiries prior to July 2019 Input from 2018 community meeting July 2019 flood response
- 7. Tucker Avenue and Surrounding Neighborhoods Stormwater Management Updates on Sewer Backup and Overflow issues 7 Wastewater Inspection: • 7/8/19 Trouble Response Staff dispatched for initial wastewater backup inspection. Staff provided “backup” information packets to impacted residents. • 7/10/19 CCTV staff completed inspections to determine the cause wastewater backups in multiple homes. Staff found no defects such as roots, debris, fats-oil-grease (FOG) or breaks which may have contributed to the backups. • CCTV staff dispatched a second time to conduct dye testing of area way drains at homes to confirm connection to wastewater pipes.
- 8. Tucker Avenue and Surrounding Neighborhoods Stormwater Management Updates on Sewer Backup and Overflow issues 8 Next Steps: • Back Flow Valve (BFV) packages were mailed to all the impacted residents after the storm event – Option for residents for backup protection. – BFV is a flap-type device on private lateral to prevent wastewater backup if pipe surcharges. – Requires an agreement with the County per code 67.1-2-1(b)(12) which prohibits discharging surface or ground water into a wastewater system. Therefore, area way drains at the home must be disconnected. – BFV requires periodic maintenance by homeowner.
- 9. Tucker Avenue and Surrounding Neighborhoods Stormwater Management Updates on Sewer Backup and Overflow issues 9 Next Steps: • Level Monitoring – County has installed level sensor at the manhole (030-4-212) close to the intersection of Tucker and Somerville Dr. The level of water in the manhole will continued to be monitored for several months.
- 10. Tucker Avenue and Surrounding Neighborhoods Stormwater Management Neighborhood Stormwater Improvement Projects • Identify and evaluate house flooding and public safety concerns • Improve drainage conditions • Reduce and treat stormwater runoff at the source • Improve water quality and stream protection • Use innovative & functional designs • Make improvements compatible with characteristics of neighborhood • Partner with community to develop sound, cost effective solutions that can be collaboratively implemented and maintained • Build on lessons learned to help improve site development process for infill development 10
- 11. Tucker Avenue and Surrounding Neighborhoods Stormwater Management Neighborhood Stormwater Improvement Project: Update 11 DESIGN TASK STATUS Topographic (Land) Survey Complete Utility Designation Complete Sub-surface borings to locate utilities and classify soils Begin 9/23 Stormwater drainage analysis and report Ongoing Concept design Ongoing Easement needs and acquisition Next Steps
- 12. Tucker Avenue and Surrounding Neighborhoods Stormwater Management Project Updates – Existing Drainage Conditions 12
- 13. 13 Tucker Avenue and Surrounding Neighborhoods Topographic Survey and Drainage Evaluation Tucker Avenue Example Overland Relief Flow Path DRAFT
- 14. 14 Tucker Avenue and Surrounding Neighborhoods Existing Utilities Gas line Water line Sanitary sewer line Storm sewer line Telephone and electric The placement of numerous existing utilities will influence the design solution
- 15. 15 Upper Tucker Middle Tucker Lower Tucker The goals and solutions for each of the three areas may be different Tucker Avenue and Surrounding Neighborhoods Conceptual Solutions
- 16. 16 Tucker Avenue and Surrounding Neighborhoods Conceptual Solutions – Level 1 Improvements Channel capacity improvements Infrastructure capacity upgrades Infrastructure capacity upgrades Channel capacity improvements Infrastructure capacity upgrades Decision Point!
- 17. 17 Tucker Avenue and Surrounding Neighborhoods Conceptual Solutions – Level 2 Improvements Enhanced swales New infrastructure New infrastructure New infrastructure from private systems Road improvements
- 18. 18 Tucker Avenue and Surrounding Neighborhoods Conceptual Solutions – Level 2 Improvements Pavement reduction Road re-profiling Level spreader Floodplain regrading and vegetation Pavement reduction Road re-profiling Minor floodplain grading Level spreader Pavement reduction New infrastructure
- 19. 19 Tucker Avenue and Surrounding Neighborhoods Conceptual Solutions – Features Additions and upgrades to existing infrastructure will intercept and convey stormwater within an enclosed system. Infrastructure capacity upgrades and new infrastructure Infrastructure capacity upgrades and new infrastructure Curb Inlet
- 20. 20 Tucker Avenue and Surrounding Neighborhoods Conceptual Solutions – Features Channel capacity improvements will be graded and sized to better direct the flow of stormwater while permitting infiltration Channel capacity improvements Channel capacity improvements
- 21. 21 Tucker Avenue and Surrounding Neighborhoods Conceptual Solutions – Features Channel capacity improvements Channel capacity improvements Amended Swales Infiltrating Trenches
- 22. 22 Tucker Avenue and Surrounding Neighborhoods Conceptual Solutions – Features Enhanced swales with infiltration Enhanced swales
- 23. 23 Tucker Avenue and Surrounding Neighborhoods Conceptual Solutions – Features New infrastructure that provides conveyance and infiltration Where soil conditions are favorable, options to convey stormwater while permitting infiltration will be considered Check Dams Imbricated Stone Check Dams Enhanced swales
- 24. 24 Tucker Avenue and Surrounding Neighborhoods Conceptual Solutions – Features A level spreader reduces the energy of stormwater runoff, converting it to sheet flow. Reforestation increases plant cover that further diffuses the flow of stormwater, stabilizes the soil, and increases uptake of water. Road improvements at Somerville Drive Minor floodplain grading and reforestation Level spreader Pavement reduction
- 25. Tucker Avenue and Surrounding Neighborhoods Easements: Land Rights Review • Review of existing easements • Determine need for additional easements to construct and maintain improvements • Work with individual homeowners • Land rights needed before proceeding with final design and construction 25
- 26. Tucker Avenue and Surrounding Neighborhoods Stormwater Management Homeowner Improvements 26 HOW CAN YOU HELP? In addition to project elements, here are a few ideas that individual homeowners can do to help contribute to improving neighborhood drainage goals. LID practices Compost Blanket Infiltration trench Rain garden Rain barrels Conventional practices French drain Yard inlet (will not prevent flooding from a storm like July 8th) Fence design Increased gaps Landscaped drainage swales
- 27. Example Homeowner Improvements Stormwater Management French Drain | Rain Garden 27 French drains and rain gardens aid in directing water away from foundations and increase filtration into the ground
- 28. Example Homeowner Improvements Stormwater Management Infiltration Trench| Compost Blanket 28 Compost blankets are effective at reducing runoff, improving soil structure, and aid in establishing vegetation Infiltration trenches are designed to receive stormwater runoff and allow that runoff to infiltrate into the ground
- 29. Example Homeowner Improvements Stormwater Management Rainwater Harvesting 29 Rain barrels provide an opportunity to capture and store roof runoff and come in an ever-increasing variety of styles to match any preference
- 30. Example Homeowner Improvements Stormwater Management Privacy Fence Design 30 Increase openings in fence design while maintaining privacy Provide gaps at ground level to permit water to flow past Incorporate swales and French drains adjacent to fence lines Options in the design of privacy fences can help improve the flow of stormwater and reduce damming
- 31. Tucker Avenue and Surrounding Neighborhoods Project Schedule & Next Steps • Concept design plan: December 2019 • County to review and formally start the easement process: – The process takes anywhere from 4 to 6 months – Land rights must be completed before final design and construction • Community Meeting: February 2020 • Final Design and Permitting • Community Coordination • Utility Relocation • Construction 31 Gas Line Relocation
- 32. Tucker Avenue and Surrounding Neighborhoods Stormwater Management Additional Information For additional Information, please contact 32 Agency Inquiry Phone Stormwater Planning Division Stormwater Capital Projects 703-324-5500 Maintenance and Stormwater Management Division Drainage Complaints 703-877-2800 Land Development Services Proposed and Active Development 703-324-1780 VDOT Road Repair and Stormwater Maintenance in ROW 1-800-FOR- ROAD (800-367-7623). Northern Virginia Soil and Water Conservation District Homeowner support with drainage problems 703-324-1460 To request this document in an alternate format, call 703-324-5500, TTY 711, or email SWPDmail@fairfaxcounty.gov. https://www.fairfaxcounty.gov/publicworks/stormwater/plans-projects/tucker-avenue- neighborhood-stormwater-improvement-project For project updates, visit the project webpage:
Notes de l'éditeur
- Subdivisions: Chesterfield (Tucker Ave) Chesterbrook Gardens (South) Grass Ridge (North)
- One quite simple approach would be to talk about how much a given storm amount compares with the minor and major system capacities. So, in general, the minor system is sized to handle approximately 2.4” in 1.5 hours and the major system 3.6” in 1.5 hours (these are the current NOAA Atlas 14 rainfall amounts average of the 1-hour and 2-hour amounts for the 10-year and 100-year storms, respectively). The July 8 storm we got in the band with the heaviest rainfall ranged from 3-5” in 90 minutes (with isolated amounts of 6”). Therefore we could describe the July 8th storm as of a magnitude that exceeded the minor system capacity by between 1.3 and 2.1 times i.e 130% and 210%. The storm rainfall was also between 0.9 and 1.4 times the major system capacity i.e. 90% to 140%. I think presenting the magnitude of a storm as a percentage of the minor and major system capacity may be something to consider.
- Maintenance and Stormwater Management Division Received approximately 400 service request countywide Over 120 reported house floodings Site visits and evaluation of existing drainage systems
- Upper Tucker: Birch Rd. to Barbee St. Yard flooding Middle Tucker: Barbee St to Youngblood St. Yard flooding Lower Tucker: Youngblood St to Somerville Dr. Yard Flooding Road flooding Travel Time
- We do allow fences in our easements. We discourage fence posts within storm drainage easements with buried pipes, but recognize that it is necessary in many cases. We do caution property owners to avoid using fence material that blocks the surface flow around and through the fence. In other words, in areas where surface runoff is expected, i.e. through floodplains, they should not use a solid board or board on board fence material. In some cases, the property owners have been advised to cut off the bottom of those types of fences. Each situation is different, and is very dependent on topography and surrounding land use. A property owner is not allowed to block surface runoff by ordinance. We will replace non-permanent fence types if we have to take them down for maintenance/construction access. My comments: The fence being placed along the rear lot line would be just as critical as a fence placed along either or both of the two side lot lines. During a large storm event, water will flow in the direction of the concrete channel and outside its banks, along the rear properties of 6533 Mulroy St and their neighbors along that street. Blocking the flow with a fence along the side yard lines will impact flood levels on adjacent properties. I definitely do not support using either of the last two fence configurations. The first one would be better without the bottom rail. We would advise the property owner to cut 3-6” off the bottom of the solid board fences. Val Tucker Chief, Stormwater Infrastructure Branch Maintenance and Stormwater Management Division Here is what we suggest: Fences in an RPA should maintain the functional value of the vegetated buffer, should be designed so that they do not inhibit or alter surface flow (i.e., water must be able to flow under and through the fence unimpeded), and vegetation may only be removed to provide for the actual placement of the fence. With that guidance we would suggest either a chain link fence or an “open” wooden board-on-board fence with openings between each board (see images below) and at least a + 3-inch gap between the bottom of the fence and the ground. This would allow water to flow under and through the fence relatively unimpeded.