Royal Lake Dredging and Restoration Project Update-June 2014
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Royal Lake Dredging and Restoration Project Update-June 2014

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Royal Lake Dredging and Restoration Project Update-June 2014

Royal Lake Dredging and Restoration Project Update-June 2014

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  • 32,500/160,000 = 20.3% <br /> <br /> Land Use in Drainage Area by Type, Acres and Percentage <br /> Residential/Business, 522 acres, 70.5% <br /> Woodland, 118 acres, 15.9% <br /> Transportation, 79 acres, 10.7% <br /> Water, 13 acres, 1.8% <br /> Grassland, 8 acres, 1.1% <br /> Total = 740 acres <br /> Floodpool of Woodglen Lake = 36 acres <br /> <br /> Land Ownership: <br /> Upstream of dam: 79% private, 21% public <br /> Downstream of dam: 47% private, 53% public <br />
  • 65,000 CY/295,000 CY = 22 percent full <br />
  • 32,500/160,000 = 20.3% <br /> <br /> Land Use in Drainage Area by Type, Acres and Percentage <br /> Residential/Business, 522 acres, 70.5% <br /> Woodland, 118 acres, 15.9% <br /> Transportation, 79 acres, 10.7% <br /> Water, 13 acres, 1.8% <br /> Grassland, 8 acres, 1.1% <br /> Total = 740 acres <br /> Floodpool of Woodglen Lake = 36 acres <br /> <br /> Land Ownership: <br /> Upstream of dam: 79% private, 21% public <br /> Downstream of dam: 47% private, 53% public <br />
  • Built in 1973 as a flood-control dam
  • Built in 1973 as a flood-control dam
  • Built in 1973 as a flood-control dam

Royal Lake Dredging and Restoration Project Update-June 2014 Presentation Transcript

  • 1. Royal Lake: Meeting Agenda  Introductions and Opening Remarks  Project Goal and Status  Royal Lake Conditions  Project Overview  Site Access  Dredging – Phase I and Phase II – Dredging Alternatives  Lake Habitat and Shoreline Restoration  Project Timeline  Questions and Answers
  • 2.  Restore Sediment Pool Capacity – Downstream water quality benefits – Lake water quality – Aesthetics  Improve Lake Water Quality and Habitat  Provide Long Term Maintenance Improvements Project Goals and Benefits
  • 3.  Completed Data Collection  Completed Lake Dredging and Management Plan  Design Plans and Specifications – Preliminary Design – Completed – Final Design – Current design phase  Permitting – In Progress  Late 2014/Early 2015 – Complete Final Design and Permitting  Dredging Projected to Start in Late Summer, 2015 Royal Lake: Project Status
  • 4. Royal Lake Facts  Drainage Area = 2,477 acres (3.67 square miles)  Lake Surface Area = 37.5 acres  Sediment Pool Capacity = 416,000 cubic yards (CY)  Current Sediment in Lake = 103,000 CY*  Estimated Annual Sediment Load = 4,400 CY 50 feet 103,000 CY * Based on a 2013 bathymetric survey
  • 5. Royal Lake: Sediment Thickness
  • 6. Royal Lake: Water Depth
  • 7. Royal Lake: Sediment Sampling Results  Samples were analyzed for chemicals found in typical urban environments  All tests indicated significantly lower concentrations than state limits except for Arsenic  Nitrogen and Phosphorous levels were elevated  With dredging of 103,000 CY: – Approximately 8,500 lbs of Phosphorous will be removed – Approximately 102,000 lbs of Nitrogen will be removed
  • 8.  Total Wetlands Impact: – 0.85 Acre  All impacts within original footprint of lake Royal Lake – Wetland Impact
  • 9. Project Overview Staging Areas Sediment Forebays Lake grading to restore the original bottom elevation
  • 10. Site Access and Staging
  • 11. Access During Construction Public Access: The park will remain open and existing parking lot will be available.
  • 12. Access During Construction Public Access: Pedestrian gates will be provided. Access through work areas and trails around the lake will be possible after work hours.
  • 13. Staging Area 1 Potential Expansion Berm/Cofferdam to be built Area to be dewatered and backfilled to expand staging area after berm/cofferdam is built
  • 14. Royal Lake: Dewatering Basin Inactive dewatering basin to be filled in and restored Staging area potential expansion
  • 15. Phase I and Phase II Dredging PHASE II 48,000 CY PHASE I 15,000 CY PHASE I 40,000 CY
  • 16. Dredging Alternatives 1. Wet Dredging: Mechanically dredge deposited sediment and haul wet. Normal pool maintained. (Note: This option will still require lake drawdown for a short period of time to build the forebay berms) 2. Dry Dredging: Drain the lake and dry deposited sediment in place prior to hauling 3. Project will be bid out with the option to dredge wet or dry Partial drawdown for Phase I dry dredging: drawing the lake partially to the Phase I dredging limits would leave a 15 acre pool; sediment would be dried in the dewatered section of the lake in place prior to hauling. Approximately 1/2 of the deposited sediment volume would be removed.
  • 17.  General Sequence – Establish access and staging areas – Conduct dredging utilizing barges – Haul wet sediment to disposal site for drying  Pros – Less weather dependent – Quicker initial start to dredging – Less potential for schedule extensions or delay  Concerns – Increased sediment handling effort at disposal area – Potentially higher cost Wet Dredging
  • 18.  General Sequence – Initiate drawdown of lake – Establish access and staging areas – Establish diversion channels within lake – Conduct dredging  Benefits – Higher daily sediment removal rates – Minimal sediment handling effort at disposal area – Potentially lower cost  Concerns – Very weather dependent – Higher potential for delays due to weather – Even with a reduced pool, there will be a need to relocate/salvage fish Dry Dredging (Full or Partial Drawdown)
  • 19. Royal Lake: Partial Drawdown  A partial drawdown would leave 15 acre pool with a maximum depth of 8 feet  Sediment to be removed = 55,000 CY DRAW-DOWN 55,000 CY
  • 20. Huntsman Lake (29 acres) Huntsman Lake – Currently being dredged in the dry
  • 21. Huntsman Lake Dam Rehabilitation Project Fish Relocation (May, 2013)
  • 22. Huntsman Lake Improvements forebay forebay berms dam embankment Phase I dredging limits (34,500 CY) Huntsman Lake Improvements
  • 23. Huntsman Lake Dredging June, 2014
  • 24.  In-lake forebay  Wetland planting  Shoreline stabilization  Fish habitat  Fish stocking Royal Lake Restoration Fish habitat created from salvaged trees Lake Barton: Fish stocking by Virginia Game and Inland Fisheries
  • 25. Royal Lake: Shoreline Restoration
  • 26. Shoreline Protection
  • 27. Fish Habitat Structures
  • 28.  Community coordination at design and construction phase – Pardon Our Dust meeting to be scheduled after contractor selection  Late 2014/Early 2015: Complete final design  Spring 2015: Bid advertisement  Late summer 2015: Begin dredging  Project Duration: – Phase 1, Base Dredge: Dredge approximately 55,000 CY = 5 to 6 Months – Phase 2, Full Dredge: 9 to 12 Months (total)  Lake may be drained/partially drained for project depending on bid results  For the wet dredge option, the lake will still require lowering for a short period to construct the forebays Royal Lake Dredging and Restoration Project Timeline and Coordination
  • 29. Contacts: Martin Chang martin.chang@fairfaxcounty.gov Dipmani Kumar dipmani.kumar@fairfaxcounty.gov Matt Meyers matthew.meyers@fairfaxcounty.gov Stormwater Planning Division Fairfax County DPWES (703)324-5500, TY 711 Partners: Royal Lake Dredging and Restoration