Woodglen Lake Dredging and Restoration Department of Public Works and Environmental Services Project Update, September, 2013

1. Woodglen Lake Dredging and Restoration
Department of Public Works and Environmental Services
Project Update, September, 2013

2. Woodglen Lake: Meeting Agenda
 Project Goals and Status
 Woodglen Lake Conditions
 Project Overview
 Site Access and Decanting Basin Restoration
 Dredging Approaches
 Streambank Stabilization
 Lake Habitat Restoration
 Project Timeline
 February Meeting highlights
 Questions and Answers

3. Project Goals
 Restore sediment pool and create in-lake forebay
 Aesthetics
 Long-term downstream water quality benefits
 Improve lake water quality and habitat
 Stabilize two stream locations to protect access
road
 Remove existing decanting basin and provide long
term maintenance improvements

4. Woodglen Lake: Project Status
 Data collection completed
 Lake dredging and management plan completed
 Design plans and specifications
 Preliminary design – completed
 Final design – current design phase
 Permitting
 Late 2013: complete final design
 Begin construction in spring 2014

5. Woodglen Lake Facts
 Drainage area =
740 Acres (1.15 square miles)
 Lake surface area =
12.5 acres
 Sediment pool capacity =
160,000 cubic yards (CY)
 Current sediment in lake =
29,300 CY
 Estimated annual sediment load =
1,200 CY / year
16.6 feet
29,300 CY

6. Woodglen Lake: Sediment Depth

7. Woodglen Lake: Water Depth

8. Woodglen Lake: Project Overview
Staging Area
Improved access
road
Sediment forebay
Lake dredging,
shoreline restoration,
lake habitat improvement
Removal and
restoration of decanting
basin
Potential
reforestation areas

9. Dredging Approaches
1. Wet Dredging: Mechanically dredge deposited
sediment and haul wet. Normal pool maintained.
(Note: This option will still require lake drawdown for
a short period of time to build the forebay berms)
2. Dry Dredging: Drain the lake and dry deposited
sediment in place prior to hauling
3. Project will be bid out with the option to dredge wet
or dry
Partial drawdown option for dry dredging: drawing the
lake down by 9 feet would leave a 3.5 acre pool; sediment
would be dried in the dewatered section of the lake in
place prior to hauling. Approximately 1/2 of the deposited
sediment volume would be removed.

10. Woodglen Lake: Site Access and Staging

11. Woodglen Lake: Decanting Basin Restoration
Realigned access
road and restored
decanting basin

12. Wet Dredging
 General Sequence
 Establish access and staging areas
 Conduct dredging utilizing barges
 Haul wet sediment to disposal site
for drying
 Pros
 Less weather dependent
 Quicker initial start to dredging
 Less potential for schedule
extensions or delay
 Cons
 Increased sediment handling effort
at disposal area
 Potentially higher cost

13. Dry Dredging (Full or Partial Drawdown)
 General Sequence
 Initiate drawdown of lake
 Establish access and staging areas
 Establish diversion channels within lake
 Conduct dredging
 Pros
 Higher daily sediment removal rates
 Minimal sediment handling effort at
disposal area
 Potentially lower cost
 Cons
 Very weather dependent
 Higher potential for delays due to weather
 Even with a reduced pool, there will be a
need to relocate/salvage fish

14. Huntsman Lake Dam Rehabilitation Project Fish Relocation (May, 2013)

15. Woodglen Lake: Partial Drawdown
Staging Area
 A partial drawdown would leave a 3.5
acre pool with a maximum depth of 5
feet with an average depth of 1 to 2 feet.
 Approximate volume of sediment to be
removed 15,000 CY

16. Lake Restoration
 In-lake forebay
 Wetland planting
 Shoreline stabilization
 Fish habitat
 Fish stocking
Lake Barton:
Fish stocking by Virginia Game and Inland Fisheries
Fish habitat created from
salvaged trees

17. Chesapeake Bay Preservation Areas
 Buffer restoration in
deficient areas

18. Woodglen Lake: Shoreline Restoration
 Existing Shoreline Condition

19. Woodglen Lake: Shoreline Protection
Image Courtesy of North Fork Native Plants

20. Fish Habitat Structures
Photos Courtesy of the Pennsylvania Fish and Boat Commission
Nesting Structure
Porcupine Crib Jr.
Rock Rubble Piles
Post Clusters

21. Stream Stabilization
North Stream Stabilization Area
South Stream Stabilization Area

22. Stream Stabilization
Log Vane
Geolift
Imbricated Rock Wall

23. Access During Construction
 Pedestrian
access to
lake from
Zion Drive
will be
maintained
(after hours)
 Lake Barton
example

24. Woodglen Lake: Project Status and Timeline
 Data collection completed
 Lake dredging and management plan completed
 Design plans and specifications
 Preliminary design – completed
 Final design – current design phase
 Permitting
 Late 2013: complete final design
 Begin construction in spring 2014

25. Woodglen Lake Dredging and Restoration
Project Timeline
 Early 2014: construction bid advertisement
 Spring 2014: begin dredging
 Dredging method will depend on bid results
 Project duration: 6 to 7 months

26. February Meeting Discussion Highlights
 Dry/Wet dredging: in order to ensure a competitive
bidding environment, both options have to be allowed,
with partial drawdown an option for dry dredging
 Cheapest dredging method: depends on disposal site
identified, either method could be cheaper
 Project cost-effectiveness: forebay and maintenance
enhancements make this project cost-effective from the
viewpoint of downstream water quality improvements
and long-term costs

27. Huntsman Lake (29 acres)

28. Woodglen Lake Dredging and Restoration
Contacts
 Dipmani Kumar, Project
Manager
 703-324-4612
 Dipmani.Kumar@fairfaxcounty.gov
 Matt Meyers, Branch Chief
 703-324-5651
 Matthew.Meyers@fairfaxcounty.gov
 Partners: