royal lake dredging and restoration project: pardon our dust meeting may 9, 2016
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A Fairfax County, VA, publication
Department of Public Works and Environmental Services
Working for You!
Royal Lake Dredging and Restoration ProjectPardon Our Dust Meeting
May 9, 2016
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Royal Lake Dredging and Restoration
Agenda • Opening Remarks – Supervisor Cook
• Project Background - Stormwater Planning Division– Background– Major Project Elements– Summary of previous Pohick watershed dredging projects –
Lake Barton, Huntsman Lake, and Woodglen Lake
• Maintenance of Traffic, Trail Management, Tentative Construction Schedule – ASI Constructors
• Royal Lake Biology and fish save efforts – Stormwater Planning Division
• Construction Timeline Summary and Safety during construction – Stormwater Planning Division, Utilities Design and Construction Division, Park Authority
• Q&A
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Royal Lake Dredging and Restoration
Royal Lake – Quick 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 CY / year 50 feet
100,400 CY
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Royal Lake Dredging and Restoration
Items of Work Dredging up to 51,220 CY of sediment (Phase I area) Access road improvement Demolition of the existing decanting basin fence and dewatering
structures Regrading of the existing decanting basin Temporary construction of a staging area and safety fence E&S and Control of Water measures Construction of two sediment forebay berms/weirs Construction of 340 feet of shoreline stabilization Construction of 130 feet of stream bank stabilization Installation of one new ACB ramp Replacement of an existing boat ramp with ACB ramp Installation of 65 fish habitat structures Restoration, seeding and landscaping of disturbed areas
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Royal Lake Dredging and Restoration
Scope of Work
A1 A2
B2B1
Zone Volume (CY)
A1 33,500
A2 5,600
B1 12,000
B2 3,800
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Royal Lake Dredging and Restoration
Water Depth
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Royal Lake Dredging and Restoration
Grading Plan
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Royal Lake Dredging and Restoration
Grading Plan
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Royal Lake Dredging and Restoration
Sediment Disposal Site – I-95 Landfill Complex
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Royal Lake Dredging and Restoration
Alternate disposal site – Noman Cole Pollution Control Plant
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Royal Lake Dredging and Restoration
Decanting Basin Restoration
Restored Decanting Basin
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Royal Lake Dredging and Restoration
Royal Lake – Riser Modifications, Existing and Proposed Lake Bottom
• The riser modifications will facilitate drawdown for future maintenance dredging and also includes a deep water release mechanism for improving downstream water quality.
• Proposed lake bottom will restore the estimated original contours and depth of the lake (in Phase I area).
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Royal Lake Dredging and Restoration
Shoreline Restoration: Existing Condition
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Royal Lake Dredging and Restoration
Shoreline Protection
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Royal Lake Dredging and Restoration
Placement of Fish Habitat Structures
TREE BRANCH PILES
Rock Rubble Piles
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Royal Lake Dredging and Restoration
Stream Stabilization
Pohick Creek Dredging and Lake Restoration Projects
Project Goals• Restore sediment pool capacity
– Downstream water quality benefits– Aesthetics
• Improve lake water quality and habitat• Provide long term maintenance improvements
Lake Barton: 2011Huntsman Lake: 2014Woodglen Lake: 2015Royal Lake: 2016
Sources of Sediment
Dredging Alternatives
1. Mechanically dredge deposited sediment and haul wet
2. Drain lake and dry deposited sediment in place before hauling
Lake Barton Dredging in Progress
Disposal Site – Sediment Reuse
• Topsoil for landfill cover• Topsoil product for resale
Huntsman Lake Dam Rehabilitation Project Fish Relocation (May 2013)
Huntsman Lake - Forebays
bank stabilizationaquatic bench
forebay
forebay berms
maintenance access
sanitary sewer
dam embankment
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Royal Lake Dredging and Restoration
Some Photos from the Huntsman Lake Dredging Project
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Royal Lake Dredging and Restoration
Some Photos from the Huntsman Lake Dredging Project
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Royal Lake Dredging and Restoration
Some Photos from the Huntsman Lake Dredging Project
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Royal Lake Dredging and Restoration
Some Photos from the Huntsman Lake Dredging Project
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Royal Lake Dredging and Restoration
Some Photos from the Huntsman Lake Dredging Project
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Royal Lake Dredging and Restoration
Some Photos from the Huntsman Lake Dredging Project
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Royal Lake Dredging and Restoration
Some Photos from the Huntsman Lake Dredging Project
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Royal Lake Dredging and Restoration
Some Photos from the Huntsman Lake Dredging Project
Woodglen Lake Dredging and Restoration
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Major Project Elements
Improved access road
Sediment forebayLake dredging,
shoreline restoration, lake habitat improvement
Removal and restoration of decanting
basin
Reforestation areas
Stream stabilization
Riser modifications
Woodglen Lake Dredging and Restoration
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Lake Drawdown
Woodglen Lake Dredging and Restoration
The Lake After Draining
Woodglen Lake Dredging and Restoration
Capital Facilities / Utilities Design and Construction Division / Transportation and Stormwater Construction Branch
Sediment Near the Forebay – To Be Removed
Woodglen Lake Dredging and Restoration
Capital Facilities / Utilities Design and Construction Division / Transportation and Stormwater Construction Branch
Sediment Being Loaded
http://www.pwmag.com/erosion-control/dredging-up-savings_o_3.aspx
Woodglen Lake Dredging and Restoration
Capital Facilities / Utilities Design and Construction Division / Transportation and Stormwater Construction Branch
Forebay Berm
Woodglen Lake Dredging and Restoration
Modifications & Repairs – Principal Spillway Riser
Woodglen Lake Dredging and Restoration
Capital Facilities / Utilities Design and Construction Division / Transportation and Stormwater Construction Branch
Stream Restoration Work – Lake Inlet
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Royal Lake Dredging and Restoration
Site Access and Maintenance of Traffic Plan
Pommeroy Drive Access Point
Gainsborough Drive Access Point
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Royal Lake Dredging and Restoration
Neighborhood Truck Route
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Royal Lake Dredging and Restoration
Trail Management Plan
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Royal Lake Dredging and Restoration
Royal Lake Biology • Reptiles and Amphibians• Fish• Benthic organisms (bottom layer)
– Birds & mammals feeding on mussels
Frogs and Toads
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http://www.fcps.edu/islandcreekes/ecology/bullfrog.htm
https://www.flickr.com/photos/dah_professor/3674098110/
http://capeannvernalpond.org/american-toad/
http://www.virginiaherpetologicalsociety.com/identification-keys/id-keys-frogs/Pseudacris.html
Frog/toad response to prior lake de-watering
• Huntsman Lake– “Never have I seen such a plague of toadlets.”
(Resident in Huntsman area)
• Bradley Acres Pond– Retrofitted SWM Wet pond– “It’s biblical,” said a resident
• Predaceous diving beetles• Toads and toadlets• 5-lined skinks
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Turtles
48http://www.virginiaherpetologicalsociety.com/reptiles/turtles/yellow-bellied-slider/Yellow-bellied%20Slider%20(Trachemys%20scripta).jpg
http://www.virginiaherpetologicalsociety.com/reptiles/turtles/northern-red-bellied-cooter/northern_red-bellied_cooter.php
http://www.virginiaherpetologicalsociety.com/reptiles/turtles/turtles_of_virginia.htm
http://www.virginiaherpetologicalsociety.com/reptiles/turtles/red-eared-slider/red-eared.JPG
Fishes – Electrofishing
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Fishes – Electrofishing
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Fishes – Electrofishing
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Fishes
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Fishes
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Fishes
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Fishes - Release
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Freshwater Mussels – Mussel Life Cycle
http://www.fishwild.vt.edu/mussel/research/life_history.html
Pyganodon cataracta and Utterbackia imbecilis
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Eastern FloaterP. cataracta
Paper PondshellU. imbecillis
Woodglen Lake Dredging and Restoration
Project Benefits
• Removed over 40,000 CY of sediment• Facilitated future maintenance dredging operations by:
• Providing a 9,000 CY sediment forebay• Improving the existing access road• Providing truck staging areas
• Provided improvements and repairs for the principal spillway riser• Installed fish habitat structures within the lake• Provides the following annual (estimated ) reductions in the downstream
sediment and nutrient loadings:• Total Suspended Solids (TSS) 14.6 tons/year• Total Nitrogen (TN) 1,075 lbs/year• Total Phosphorus (TP) 67 lbs/year
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Royal Lake Dredging and Restoration
• Lake drawdown Scheduled to begin week of May 9th (this week!)
• Dredging activities to commence by mid-June, 2016• Project duration: 12 months• Lake will remain mostly drained for entire project• Lake filling after project completion is dependent on
rainfall conditions, and it is expected filling will be initiated by June, 2017
Summary of construction timeline
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Royal Lake Dredging and Restoration
Lake Drawdown and Safety
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Royal Lake Dredging and Restoration
Lake Drawdown and Safety
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Royal Lake Dredging and Restoration
Safety During Construction
• Contractor is required to comply with Fairfax County’s Construction Safety Resolution.
• For all residents, keeping safe means following two simple rules:
1. Please stay outside the construction limits at all times!2. Observe construction activities from a safe distance.
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Royal Lake Dredging and Restoration
Contact information
Stormwater Planning Division 703-324-5500, TTY 711 or by email: Joe Riley-Ryan: Joseph.Riley-Ryan@fairfaxcounty.gov Dipmani Kumar: Dipmani.Kumar@fairfaxcounty.gov
Utilities Design and Construction Division703-324-5111, TTY 711 or by email:Bill Nolan: William.Nolan@fairfaxcounty.gov
Thank you.
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