Huntsman Lake “Pardon Our Dust”
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Huntsman Lake Dam Rehabilitation Huntsman Lake Dredging and Restoration Department of Public Works and Environmental Services Pardon Our Dust Meeting Fairfax County, VA
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Huntsman Lake “Pardon Our Dust”
- 1. Huntsman Lake Dam Rehabilitation Huntsman Lake Dredging and Restoration Department of Public Works and Environmental Services Pardon Our Dust Meeting Fairfax County, VA A Fairfax County, VA publication, October 2013
- 2. Huntsman Lake Dam Rehabilitation Huntsman Lake Dredging and Restoration Pardon Our Dust Outline • • • • • Dam Rehabilitation – Background – Project Status – Sequence of Work – Major Project Elements Lake Dredging and Restoration – Background – Project Status – Dredging Phases – Lake Restoration Construction Timeline Summary Safety Q&A
- 3. Huntsman Lake Dam Rehabilitation Project Background • • • Huntsman Dam is operating under a conditional Operation & Maintenance (O&M) Certificate from the Virginia Department of Conservation and Recreation, Division of Dam Safety, because its auxiliary spillway can only convey about 50 percent of the flows from the design storm. Planning and design for this project was completed in February 2013, and Fairfax County and Northern Virginia Soil and Water Conservation District (NVSWCD) entered into a cost-share agreement with the Natural Resources Conservation Service (NRCS) to rehabilitate the facility in June, 2013. Project was advertised for construction on September 9, 2013.
- 4. Huntsman Lake Dam Rehabilitation Project Status • Bid opening: October 2nd, 2013 • Two bids received; apparent low bidder is ASI Constructors, Inc. • Construction contract will be managed by the Utilities Design and Construction Division (UDCD), Fairfax County • UDCD is completing safety, qualification and reference checks • Target date for contract execution*: November 16, 2013 • Notice to Proceed (NTP): First week of December, 2013 • Performance time: 240 days * Before a contract can be awarded, Natural Resources Conservation Service (NRCS) will review and concur with proposed construction schedule, subcontractors and performance bond.
- 5. Huntsman Lake Dam Rehabilitation Project Summary of rehabilitation plan
- 6. Huntsman Lake Dam Rehabilitation Project Major Design Elements
- 7. Dam Rehabilitation General Sequence of Work • • • • • • • • • • • • Drawdown lake and flag limits of construction Install perimeter controls Clear some trees Install Erosion and Sedimentation (E&S) controls Rough-grade the area Install cofferdam for diversion of water Demolish the riser Final-grade the area Install Articulated Concrete Blocks (ACBs) Build concrete structures (riser, cutoff wall system) Lay topsoil and seed the area Remove E&S controls
- 8. Huntsman Lake Dam Rehabilitation Project Spillway realignment and armoring
- 9. Huntsman Lake Dam Rehabilitation Project Spillway realignment and armoring
- 10. Huntsman Lake Dam Rehabilitation Project Spillway realignment and armoring
- 11. Huntsman Lake Dam Rehabilitation Project Riser replacement
- 12. Huntsman Lake Dam Rehabilitation Project Riser replacement
- 13. Dredging and Lake Restoration Project Status • • • • Bid advertisement: October 14th, 2013 Mandatory pre-bid meeting: October 30th, 2013 Bid opening: November 13th, 2013 Contract execution: middle of December, 2013 to early January, 2014 • Notice to Proceed (NTP): typically 2 weeks after contract execution • Performance time: – Phase I : 150 days – If Phase II is authorized: Additional 120 days Note: For dredging, contract specifications state that the lake will be fully drained. The dam rehabilitation contractor will be responsible for lake drawdown, which is expected to take approximately 4 weeks.
- 14. Background • • • • • Drainage area = 1,482 acres (2.3 square miles) Lake surface area = 28.6 acres Sediment pool capacity = 295,000 cubic yards (CY) Current sediment in lake = 65,000 CY Estimated annual sediment load = 2,970 CY 32.5 feet 65,000 CY
- 15. Huntsman Lake Dam Rehabilitation Project Fish Relocation (May 2013)
- 17. Huntsman Lake Site Access and Staging Area
- 18. Huntsman Lake - Forebays maintenance access bank stabilization aquatic bench forebay berms forebay sanitary sewer Phase I dredging limits (34,500 CY) dam embankment
- 19. Dry Dredging Lake Needwood in Montgomery County, MD
- 20. Dry Dredging
- 21. Dry Dredging Lake Needwood in Montgomery County, MD 21
- 22. Lake Restoration • • • • • In-lake forebay Shoreline stabilization Fish habitat Fish stocking Reforestation Fish habitat created from salvaged trees Lake Barton: Fish stocking by Virginia Game and Inland Fisheries
- 23. Shoreline Restoration Huntsman Lake Existing Conditions
- 26. Reforestation
- 27. Huntsman Lake Dam Rehabilitation Huntsman Lake Dredging and Restoration Summary of construction timeline • Lake drawdown and dam rehabilitation construction activities to start in December, 2013 • Dredging activities to commence after lake is fully drawn down by January, 2014 • Project duration: 9 months (both projects) • Lake will remain drained for entire project • Dam rehabilitation and dredging projects have been coordinated to minimize the time lake is empty • Lake filling after project completion is dependent on rainfall conditions, and it is expected filling will be initiated in September, 2014
- 28. Huntsman Lake Dam Rehabilitation Huntsman Lake Dredging and Restoration SAFETY • Contractor is required to comply with Fairfax County’s Construction Safety Resolution. UDCD performs a review of the contractor’s safety record during the past 3 years. • 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.
- 29. Huntsman Lake Dam Rehabilitation Huntsman Lake Dredging and Restoration
- 30. For more information or questions, call the Stormwater Planning Division at 703-324-5500, TTY 711 or email: Dipmani Kumar: dkumar@fairfaxcounty.gov Matt Meyers: mmeye1@fairfaxcounty.gov Utilities Design and Construction Division 703-324-5111, TTY 711 or email: Bill Nolan (Dam Rehabilitation): wnolan@fairfaxcounty.gov Mannan Qureshi (Dredging): mqures@fairfaxcounty.gov A Fairfax County, Virginia, publication October 2013 To request this information in an alternate format, call 703-324-5500, TTY 711. Thank you.
Notas del editor
- Built in 1973 as a flood-control dam
- 1. Armor the control section 2. Extend the training dikes 3. Change the AS alignment
- Built in 1973 as a flood-control dam
- Built in 1973 as a flood-control dam
- Built in 1973 as a flood-control dam
- Built in 1973 as a flood-control dam
- Built in 1973 as a flood-control dam
- Built in 1973 as a flood-control dam
- 65,000 CY/295,000 CY = 22 percent full
- Built in 1973 as a flood-control dam
- This project was Lake Needwood in Montgomery County, MD (Redland). We dredged 100,000 cy of sediment. We did a partial drawdown. The drawdown took about 2 weeks - they only needed to drawdown the lake about 4 feet; however, the County started the drawdown in September, after the main recreation season, and the pre-construction meeting wasn't until the beginning of November. They wanted to let the sediment naturally dewater as much as possible. Initially, they had a lot of rain and didn't get as much dewatering as desired, but eventually, the sediments dewatered enough to truck them to the disposal area. They did have to mix the sediments with a drier material for placement at the disposal area. There was no real additional dewatering -- they filled the disposal area and the end result was a filled in and mounded area (with slopes of 3:1). The mound ended up being 25 high with a big flat top! Not our design - we had a design that maximized the available land footprint, had 4:1 and 5:1 slopes and kinda blended into the area. We didn't want it to look like a big out of place mound of dirt! The contractor requested a field change for the disposal site which the County finally agreed to. They were lucky they had a big open space available that was used as a fill source for a recent highway construction project. The project pre-construction was November 3, 2010. They actually started dredging right after Christmas are completed the project just after July 4th 2011 -- so it took about 9 months. Marlene MartinFX Browne
- Built in 1973 as a flood-control dam
- Built in 1973 as a flood-control dam
- Built in 1973 as a flood-control dam