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
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
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
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
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
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 PressureExcavatorBulldozerBulldozerExcavatorand DozerTruck AccessStaging
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
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
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
Staging Area 1 Potential ExpansionBerm/Cofferdamto be builtArea to be dewatered andbackfilled to expand stagingarea after berm/cofferdamis built
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 lakeafter work hours.
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
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/