The meeting agenda covered the Royal Lake restoration project, including dredging phases to remove sediment, alternatives for wet or dry dredging, and habitat and shoreline restoration. The project goals are to restore sediment capacity, improve water quality and habitat, and provide long-term maintenance. Final design is underway with dredging projected to start in late summer 2015.

2. Royal Lake: Meeting Agenda
 Introductions and Opening Remarks
 Project Goal and Status
 Royal Lake Conditions
 Project Overview
 Site Access
 Dredging
– Phase I and Phase II
– Dredging Alternatives
 Lake Habitat and Shoreline Restoration
 Project Timeline
 Questions and Answers

3.  Restore Sediment Pool Capacity
– Downstream water quality benefits
– Lake water quality
– Aesthetics
 Improve Lake Water Quality and Habitat
 Provide Long Term Maintenance Improvements
Project Goals and Benefits

4.  Completed Data Collection
 Completed Lake Dredging and Management Plan
 Design Plans and Specifications
– Preliminary Design – Completed
– Final Design – Current design phase
 Permitting – In Progress
 Late 2014/Early 2015 – Complete Final Design and Permitting
 Dredging Projected to Start in Late Summer, 2015
Royal Lake: Project Status

5. 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 = 103,000
CY*
 Estimated Annual Sediment Load =
4,400 CY
50 feet
103,000 CY
* Based on a 2013 bathymetric survey

6. Royal Lake: Sediment
Thickness

7. Royal Lake: Water Depth

8. Royal Lake: Sediment
Sampling Results
 Samples were analyzed for chemicals found in typical urban
environments
 All tests indicated significantly lower concentrations than state
limits except for Arsenic
 Nitrogen and Phosphorous levels were elevated
 With dredging of 103,000 CY:
– Approximately 8,500 lbs of Phosphorous will be removed
– Approximately 102,000 lbs of Nitrogen will be removed

9.  Total Wetlands
Impact:
– 0.85 Acre
 All impacts
within original
footprint of
lake
Royal Lake – Wetland Impact

10. Project Overview
Staging Areas
Sediment Forebays Lake grading to
restore the original
bottom elevation

11. Site Access and Staging

12. Access During Construction
Public Access:
The park will remain
open and existing
parking lot will be
available.

13. Access During Construction
Public Access:
Pedestrian gates will be provided. Access through work areas and trails around the lake will
be possible after work hours.

14. Staging Area 1 Potential
Expansion
Berm/Cofferdam
to be built
Area to be dewatered and
backfilled to expand staging
area after berm/cofferdam
is built

15. Royal Lake: Dewatering Basin
Inactive dewatering basin
to be filled in and restored
Staging area
potential
expansion

16. Phase I and Phase II Dredging
PHASE II
48,000 CY
PHASE I
15,000 CY
PHASE I
40,000 CY

17. Dredging Alternatives
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 for Phase I dry dredging: drawing the
lake partially to the Phase I dredging limits would leave a
15 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.

18.  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
 Concerns
– Increased sediment handling effort
at disposal area
– Potentially higher cost
Wet Dredging

19.  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 disposal
area
– Potentially lower cost
 Concerns
– Very weather dependent
– Higher potential for delays due to weather
– Even with a reduced pool, there will be a need
to relocate/salvage fish
Dry Dredging (Full or Partial
Drawdown)

20. Royal Lake: Partial Drawdown
 A partial drawdown would leave 15 acre
pool with a maximum depth of 8 feet
 Sediment to be removed = 55,000 CY
DRAW-DOWN 55,000 CY

21. Huntsman Lake (29 acres)
Huntsman Lake – Currently being dredged in the dry

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

23. Huntsman Lake Improvements
forebay
forebay berms
dam
embankment
Phase I dredging limits (34,500 CY)
Huntsman Lake Improvements

24. Huntsman Lake Dredging
June, 2014

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

26. Royal Lake: Shoreline
Restoration

27. Shoreline Protection

28. Fish Habitat Structures

29.  Community coordination at design and construction phase
– Pardon Our Dust meeting to be scheduled after contractor selection
 Late 2014/Early 2015: Complete final design
 Spring 2015: Bid advertisement
 Late summer 2015: Begin dredging
 Project Duration:
– Phase 1, Base Dredge: Dredge approximately 55,000 CY = 5 to 6 Months
– Phase 2, Full Dredge: 9 to 12 Months (total)
 Lake may be drained/partially drained for project depending on bid results
 For the wet dredge option, the lake will still require lowering for a short
period to construct the forebays
Royal Lake Dredging and Restoration
Project Timeline and Coordination

30. Contacts:
Martin Chang
martin.chang@fairfaxcounty.gov
Dipmani Kumar
dipmani.kumar@fairfaxcounty.gov
Matt Meyers
matthew.meyers@fairfaxcounty.gov
Stormwater Planning Division
Fairfax County DPWES
(703)324-5500, TY 711
Partners:
Royal Lake Dredging and
Restoration