royal lake dredging and restoration project: pardon our dust meeting may 9, 2016

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 – 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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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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Water Depth

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Grading Plan

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Grading Plan

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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

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Shoreline Protection

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Placement of Fish Habitat Structures

TREE BRANCH PILES

Rock Rubble Piles

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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

http://www.google.com/url?sa=i&source=images&cd=&cad=rja&docid=9ZWE66pLHMnG_M&tbnid=A_FqgcFYmqYzjM:&ved=0CAgQjRwwAA&url=http://wduqnews.blogspot.com/2010/04/sediments-to-be-captured-in-north-park.html&ei=p6ONUeHUKtSy0AG5jYGYDw&psig=AFQjCNHzNADNB8iWxRlIXa0cq7r_-eXvmA&ust=1368323367737787

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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Some Photos from the Huntsman Lake Dredging Project

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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


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Lake Drawdown


The Lake After Draining


Capital Facilities / Utilities Design and Construction Division / Transportation and Stormwater Construction Branch

Sediment Near the Forebay – To Be Removed



Sediment Being Loaded

http://www.pwmag.com/erosion-control/dredging-up-savings_o_3.aspx

http://www.pwmag.com/erosion-control/dredging-up-savings_o_3.aspx



Forebay Berm


Modifications & Repairs – Principal Spillway Riser



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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Neighborhood Truck Route

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Trail Management Plan

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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

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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


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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Lake Drawdown and Safety

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Lake Drawdown and Safety

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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: [email protected] Dipmani Kumar: [email protected]

Utilities Design and Construction Division703-324-5111, TTY 711 or by email:Bill Nolan: [email protected]

Thank you.

mailto:[email protected]



http://www.fairfaxcounty.gov/

royal lake dredging and restoration project: pardon our dust meeting may 9, 2016

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