Royal Lake Dredging and Restoration Project: Pardon Our Dust Meeting May 9, 2016
1. A Fairfax County, VA, publication
Department of Public Works and Environmental Services
Working for You!
Royal Lake Dredging and Restoration Project
Pardon Our Dust Meeting
May 9, 2016
2. Royal Lake Dredging and Restoration
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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
3. Royal Lake Dredging and Restoration
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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
4. Royal Lake Dredging and Restoration
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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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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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Sediment Disposal Site – I-95 Landfill Complex
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Alternate disposal site – Noman Cole Pollution Control Plant
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Decanting Basin Restoration
Restored Decanting
Basin
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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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Shoreline Restoration: Existing Condition
17. 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: 2011
Huntsman Lake: 2014
Woodglen Lake: 2015
Royal Lake: 2016
23. Huntsman Lake - Forebays
bank stabilization
aquatic bench
forebay
forebay berms
maintenance access
sanitary sewer
dam
embankment
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Some Photos from the Huntsman Lake Dredging Project
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Some Photos from the Huntsman Lake Dredging Project
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Some Photos from the Huntsman Lake Dredging Project
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Some Photos from the Huntsman Lake Dredging Project
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Some Photos from the Huntsman Lake Dredging Project
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Some Photos from the Huntsman Lake Dredging Project
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Some Photos from the Huntsman Lake Dredging Project
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Some Photos from the Huntsman Lake Dredging Project
32. Woodglen Lake Dredging and Restoration
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Major Project Elements
Improved access
road
Sediment forebay
Lake dredging,
shoreline restoration,
lake habitat improvement
Removal and
restoration of decanting
basin
Reforestation areas
Stream stabilization
Riser modifications
35. Woodglen Lake Dredging and Restoration
Capital Facilities / Utilities Design and Construction Division / Transportation and Stormwater Construction Branch
Sediment Near the Forebay – To Be Removed
36. Woodglen Lake Dredging and Restoration
Capital Facilities / Utilities Design and Construction Division / Transportation and Stormwater Construction Branch
Sediment Being Loaded
39. Woodglen Lake Dredging and Restoration
Capital Facilities / Utilities Design and Construction Division / Transportation and Stormwater Construction Branch
Forebay Berm
40. Woodglen Lake Dredging and Restoration
Modifications & Repairs – Principal Spillway Riser
41. 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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Site Access and Maintenance of Traffic Plan
Pommeroy Drive
Access Point
Gainsborough
Drive Access Point
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Royal Lake Biology
• Reptiles and Amphibians
• Fish
• Benthic organisms (bottom layer)
– Birds & mammals feeding on mussels
47. 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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56. 56
Freshwater Mussels – Mussel Life Cycle
http://www.fishwild.vt.edu/mussel/research/life_history.html
57. Pyganodon cataracta and Utterbackia imbecilis
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Eastern Floater
P. cataracta
Paper Pondshell
U. imbecillis
58. 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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• 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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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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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 Division
703-324-5111, TTY 711 or by email:
Bill Nolan: William.Nolan@fairfaxcounty.gov
Thank you.