 Dredging Program and Project Background Project Benefits Royal Lake Conditions Phased Approach Dredging Methods and ...
 History– Lakes previously dredged by DPWES Stormwater– Limited to small quantities– Dewatered on site Lake Barton compl...
 Completed Data Collection Developing Lake Dredging and Management Plan Community coordination at design and constructi...
 Restore sediment pool capacity– Downstream water quality benefits– Lake water quality– Aesthetics Improve lake water qu...
Lake Barton Dredging and RestorationArea Treated(acres)Phosphorous Removal Nitrogen Removal Sediment Removal544 77,000 lbs...
Royal Lake Facts Drainage area =2,477 acres (3.67 square miles) Lake surface area =37.5 acres Sediment pool capacity =4...
Royal Lake
Royal Lake: Sediment Thickness
Royal Lake: Water Depth
Royal Lake: Dredging Areas Phase 1: Base Dredge = 40,000 CY Phase 2: Up to an additional 60,000 CYZone D12,400 CY
Royal Lake: Partial Drawdown
Dredging Methods and Alternatives1. Mechanically dredgedeposited sediment andhaul wet2. Drain lake and drydeposited sedime...
PRE-DREDGING:An estimated35,000 cubic yardsof sediment hadaccumulated inthe lake, formingislands andreducing waterlevels t...
Lake Barton Example: Pre-Dredging
LakeBartonExample: DredginginProgressDredging:Dredging tookplace withoutdraining the lake.
LakeBartonExample: DredginginProgress
Lake Barton Example: Disposal Site
North Park Lake Example Allegheny County, PennsylvaniaDredging:The lake was drainedand the sediment wasdried in-place.
North Park Lake Example Allegheny County, PennsylvaniaTemporary DiversionChannelsEquipment Workingon Next Slide
North Park Lake: Dredging Allegheny County, PennsylvaniaTruck WashTemporaryDiversion ChannelLow PressureExcavatorBulldozer...
 General Sequence– Establish access and staging areas– Conduct dredging utilizing barges– Haul wet sediment to disposal s...
 General Sequence– Initiate drawdown of lake– Establish access and staging areas– Establish diversion channels within lak...
 In-lake forebay Wetland planting Shoreline stabilization Fish habitat Fish stockingLake RestorationFish habitat crea...
Royal Lake: Shoreline Restoration
Royal Lake: Shoreline RestorationRoyal LakeExistingConditions
Shoreline Protection Options
Fish Habitat Structures
Royal Lake: Site Access and StagingOptional?
Royal Lake: Site Access and Staging
Staging Area 1 Potential ExpansionBerm/Cofferdamto be builtArea to be dewatered andbackfilled to expand stagingarea after ...
Royal Lake: Dewatering BasinInactiveDewatering Basin
Access During ConstructionPublic Access:The park will remainopen and existingparking lot will beavailable.
Access During ConstructionPublic Access:Pedestrian gates will beprovided. Accessthrough work areas andtrails around the la...
 Community coordination at design and construction phases– Preliminary Design (65%)– Final Design (95%)– Preconstruction:...
Contacts: Martin Chang, Project Manager703-324-5825 | Martin.Chang@fairfaxcounty.gov Dipmani Kumar, Section Chief703-324...
Royal Lake Dredging and Restoration
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Royal Lake Dredging and Restoration

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Royal Lake Dredging and Restoration

Fairfax County Department of Public Works and Environmental Services

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Royal Lake Dredging and Restoration

  1. 1.  Dredging Program and Project Background Project Benefits Royal Lake Conditions Phased Approach Dredging Methods and Alternatives Park Access and Community Coordination Next StepsRoyal Lake: Meeting Agenda
  2. 2.  History– Lakes previously dredged by DPWES Stormwater– Limited to small quantities– Dewatered on site Lake Barton completed in 2011 Currently working on:– Huntsman Lake, Woodglen Lake, Royal LakeDredging and Lake Restoration Program
  3. 3.  Completed Data Collection Developing Lake Dredging and Management Plan Community coordination at design and constructionphases– Preliminary Design (65%)– Final Design (95%)– Preconstruction: Pardon Our Dust meeting December 2013: Final Design Construction in Fiscal Year 2015 (July 2014)Royal Lake Dredging and RestorationProject Timeline and Coordination
  4. 4.  Restore sediment pool capacity– Downstream water quality benefits– Lake water quality– Aesthetics Improve lake water quality and habitat Provide long term maintenance improvementsProject Goals and Benefit
  5. 5. Lake Barton Dredging and RestorationArea Treated(acres)Phosphorous Removal Nitrogen Removal Sediment Removal544 77,000 lbs dredged 115,500 lbs dredged 38,500 tons dredgedAnnual benefit fromincreased trappingefficiency130 lbs/year 200 lbs/year 65 tons/year
  6. 6. 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 =100,400 CY Estimated annual sediment load =4,400 CY50 feet100,400 CY
  7. 7. Royal Lake
  8. 8. Royal Lake: Sediment Thickness
  9. 9. Royal Lake: Water Depth
  10. 10. Royal Lake: Dredging Areas Phase 1: Base Dredge = 40,000 CY Phase 2: Up to an additional 60,000 CYZone D12,400 CY
  11. 11. Royal Lake: Partial Drawdown
  12. 12. Dredging Methods and Alternatives1. Mechanically dredgedeposited sediment andhaul wet2. Drain lake and drydeposited sediment inplace before hauling
  13. 13. PRE-DREDGING:An estimated35,000 cubic yardsof sediment hadaccumulated inthe lake, formingislands andreducing waterlevels to less thanthree feet in mostareas.Lake Barton Example
  14. 14. Lake Barton Example: Pre-Dredging
  15. 15. LakeBartonExample: DredginginProgressDredging:Dredging tookplace withoutdraining the lake.
  16. 16. LakeBartonExample: DredginginProgress
  17. 17. Lake Barton Example: Disposal Site
  18. 18. North Park Lake Example Allegheny County, PennsylvaniaDredging:The lake was drainedand the sediment wasdried in-place.
  19. 19. North Park Lake Example Allegheny County, PennsylvaniaTemporary DiversionChannelsEquipment Workingon Next Slide
  20. 20. North Park Lake: Dredging Allegheny County, PennsylvaniaTruck WashTemporaryDiversion ChannelLow PressureExcavatorBulldozerBulldozerExcavatorand DozerTruck AccessStaging
  21. 21.  General Sequence– Establish access and staging areas– Conduct dredging utilizing barges– Haul wet sediment to disposal sitefor drying Benefits– Less weather dependent– Quicker initial start to dredging– Less potential for scheduleextensions or delay Concerns– Increased sediment handling effortat disposal area– Potentially higher costDredge Alternative – In the Wet
  22. 22.  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 disposalarea– Potentially lower cost Concerns– Very weather dependent– Higher potential for delays due to weather– Typically more odor from sediment exposed– Need to relocate/salvage fishDredge Alternative – In the Dry
  23. 23.  In-lake forebay Wetland planting Shoreline stabilization Fish habitat Fish stockingLake RestorationFish habitat createdfrom salvaged treesLake Barton:Fish stocking by Virginia Game and Inland Fisheries
  24. 24. Royal Lake: Shoreline Restoration
  25. 25. Royal Lake: Shoreline RestorationRoyal LakeExistingConditions
  26. 26. Shoreline Protection Options
  27. 27. Fish Habitat Structures
  28. 28. Royal Lake: Site Access and StagingOptional?
  29. 29. Royal Lake: Site Access and Staging
  30. 30. Staging Area 1 Potential ExpansionBerm/Cofferdamto be builtArea to be dewatered andbackfilled to expand stagingarea after berm/cofferdamis built
  31. 31. Royal Lake: Dewatering BasinInactiveDewatering Basin
  32. 32. Access During ConstructionPublic Access:The park will remainopen and existingparking lot will beavailable.
  33. 33. Access During ConstructionPublic Access:Pedestrian gates will beprovided. Accessthrough work areas andtrails around the lakeafter work hours.
  34. 34.  Community coordination at design and construction phases– Preliminary Design (65%)– Final Design (95%)– Preconstruction: “Pardon Our Dust” meeting December 2013: Final Design Construction in Fiscal Year 2015 (Starts July 2014) Project Duration:– Phase 1, Base Dredge: Dredge 40,000 CY = 5 to 6 Months– Phase 2, Full Dredge: 9 to 12 MonthsRoyal Lake Dredging and RestorationProject Timeline and Coordination
  35. 35. Contacts: Martin Chang, Project Manager703-324-5825 | Martin.Chang@fairfaxcounty.gov Dipmani Kumar, Section Chief703-324-4612 | Dipmani.Kumar@fairfaxcounty.gov http://www.fairfaxcounty.gov/dpwes/stormwater/Royal Lake DredgingandRestorationhttp://www.fairfaxcounty.gov/NVSWCD/ http://www.fairfaxcounty.gov/parks/

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