Reston Section 24  Regional Stormwater ManagementFacility Repair & Rehabilitation Project           Hunter Mill District  ...
Project DetailsDescription and Overview:This stormwater management facility (Facility ID 0067DP) is located on Reston Home...
Twin Branches Road - Tax Map No. 27-1              Stormwater Management Facility ID 0065DP                               ...
Pre-existing Condition: No adequate access              for maintenance
Post Construction: New permanent access          road for maintenance
Pre-existing Condition: Fair Weather Crossing
Post Construction: New Fair Weather Crossing
Pre-existing Condition: Sediment accumulation in pond and   blocked principal spillway pipe. Pond was originally    constr...
Post Construction: New Control Outlet 6’X6’ Riser Structure,     disturbed areas were planted with native seed and        ...
Pre-Existing Condition: End Section of the Principal           Spillway 48” Corrugated Pipe
Post Construction: Endwall of the New 60”      Principal Spillway Pipe Culvert             Dissipater pool
Pre-Existing Condition: Severely Eroded          Emergency Spillway
Post Construction: Emergency Spillway             after Repairs
For additional Information, please call   Irene Haske, Public Information Officer          703-324-5821, TTY 711       SWP...
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Reston/Hunter Mill Stormwater Facility Repair and Rehabilitation

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Reston Section 24
Regional Stormwater Management
Facility Repair and Rehabilitation Project
Hunter Mill District

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Reston/Hunter Mill Stormwater Facility Repair and Rehabilitation

  1. 1. Reston Section 24 Regional Stormwater ManagementFacility Repair & Rehabilitation Project Hunter Mill District Project No. FX4000-DF006
  2. 2. Project DetailsDescription and Overview:This stormwater management facility (Facility ID 0067DP) is located on Reston Homeowner Association property withinthe Difficult Run Watershed. The pond was originally built without adequate access to perform non-routine maintenancesuch as sediment removal and structural repairs. This project was initiated because the existing facility was overtoppedduring a storm event and severely eroded the emergency spillway and portions of the dam embankment. Also, theupstream inundation area is wooded and the outfall structure tends to clog with debris and requires frequentmaintenance. To stabilize the emergency spillway and reduce the chance of dam failure, the capacity of the principlespillway is increased by installing a larger size pipe and the emergency spillway is armored. To control the frequentmaintenance a larger size BMP trash rack is installed. A permanent maintenance road is installed to provide access forall types of future maintenance work.Project Scope of Work:• The eroded emergency spillway was reconstructed and armored with CL-II rip-rap.• The eroded dam embankment was reconstructed.• The existing 48” corrugated principal spillway pipe was replaced with a larger 60” CL-III RCP.• The existing riser structure was replaced by a large size (6’ x 6’ and 8’ high) structure.• The pond was graded and sediments were removed to achieve the original storage capacity.• Installed a 0.4 mile long permanent access road for future maintenance.• Installed a Fair Weather Crossing capable for vehicular access.• Restored the disturbed area using seeding and covering with coir fiber matting on all embankment slopes.DPWES Project Team:• Project Manager - Dipmani Kumar• Construction Manager - Yousef Rayyan• Project Inspectors - Yudhie Brownson & Jack Schambach• Land Acquisition Agent - Carol L. Kresge• Survey Analyst - Gregory Harper
  3. 3. Twin Branches Road - Tax Map No. 27-1 Stormwater Management Facility ID 0065DP Site Limits 6’X6’ Riser Site Entrance Fair Weather Crossing LocationThis stormwater management facility is located near Twin Branches and Snakeden Branchin a low density residential area of Hunter Mill District and receives runoff from a 236 acredrainage area. The access Road meanders through the woods along an existing pedestrian trail.
  4. 4. Pre-existing Condition: No adequate access for maintenance
  5. 5. Post Construction: New permanent access road for maintenance
  6. 6. Pre-existing Condition: Fair Weather Crossing
  7. 7. Post Construction: New Fair Weather Crossing
  8. 8. Pre-existing Condition: Sediment accumulation in pond and blocked principal spillway pipe. Pond was originally constructed with an outlet control structure (riser).Dam Embankment Pond Inflow
  9. 9. Post Construction: New Control Outlet 6’X6’ Riser Structure, disturbed areas were planted with native seed and protected with Coir matting cover Pond Inflow Debris Screen
  10. 10. Pre-Existing Condition: End Section of the Principal Spillway 48” Corrugated Pipe
  11. 11. Post Construction: Endwall of the New 60” Principal Spillway Pipe Culvert Dissipater pool
  12. 12. Pre-Existing Condition: Severely Eroded Emergency Spillway
  13. 13. Post Construction: Emergency Spillway after Repairs
  14. 14. For additional Information, please call Irene Haske, Public Information Officer 703-324-5821, TTY 711 SWPDmail@fairfaxcounty.gov www.fairfaxcounty.gov/dpwes

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