Lake Jackson Dam
Updated: January 27, 2014
Work on the dam repairs continues, however there have understandably been a few delays due to the recent winter weather we have experienced. Due to the bitter cold and snow, the contractor is unable to work at this time. Once the extremely low temperatures begin to rise and the weather improves, the contractor will re-commence work on the repairs.
Unfortunately, a specific timeline for completion of the repairs is not available, however the contract for the repairs concludes May 15, 2014, and per the specifications of the contract, the repairs must be complete at that time. It is important to note that the nature of outdoor public works construction projects make them highly dependent upon weather conditions and as such, it may become necessary to delay work if, as we have experienced lately, the weather does not cooperate. There is also always the possibility of unforeseen circumstances that create delays. The contractor and consultant remain as committed as the County to move the project forward as quickly as possible and are working diligently to do so.
As a reminder, please be aware that citizens are not allowed in the fenced area around the dam nor on the dam for safety reasons. It is also very important that the workers on-site be allowed to do their work without interruption. Please direct any questions you have to my office at (703)792-4621 or ColesDistrict@pwcgov.org and my staff will respond as quickly as possible.
The County has received questions from residents about whether there is an opportunity to dredge the lake and/or remove vegetation as part of the dam repair project. At this time, the County has no plans or funding to dredge the lake, make any improvements to the shoreline, or remove vegetation. Residents can certainly address those issues now themselves on their own property when the water level is low, being sure to follow any applicable county, state and federal guidelines. County staff can assist residents in figuring out which guidelines may apply to their particular situation, but unfortunately the funding approved by the Board of County Supervisors is not sufficient to cover any additional efforts beyond the dam repair.
ADVISORY: Please be aware that no repairs have taken place, and residents are still advised to stay clear of the area in and around the dam due to the small whirlpool in the water. It poses a significant safety hazard so please do not swim or boat anywhere near the dam.
In May of 2012, County staff observed the activation of two “toe” drains on the downstream side of the Lake Jackson Dam (see photo) that are releasing a significant amount of water. The County is closely monitoring the flow from the toe drains, as well as researching the purpose of the toe drains and the significance of the water flow. The toe drains are believed to drain water from the inside of the dam, however the dam was built in 1928 and there are no construction plans or as-builts to reference to confirm this conclusion. If the drains are active because of water in the core of the dam, this is a possible concern for dam safety. Since the toe drains are draining water, this would also explain the low lake water levels water front owners are experiencing. Other factors could also be contributing to low lake water levels as well.
The County engaged the services of a nationally known dam consultant, the Michael Baker Corporation, to investigate the cause(s) of the toe drain activation, and consulted with the State Dam Safety Engineer for the NOVA region. The investigative work included:
- underwater diving investigation of both the upstream and downstream face of the dam
- coring holes into the dam crest to investigate the dam interior with remote control cameras
- dewatering the interior of the dam with pumps
- use of dye tracer tests to determine seepage areas.
Please note this work was exploratory in nature and did not include any repairs or remediation. The Michael Baker Corporation has submitted their final report which contains information on the investigation of the dam as well as several rehabilitation options. The report can be viewed and downloaded by clicking the links below:
- Lake Jackson Dam Investigation and Conceptual Rehabilitation Report, Phase 1
- Lake Jackson Dam Investigation and Conceptual Rehabilitation Report, Phase 1, Attachments 1 & 2
- Lake Jackson Dam Investigation and Conceptual Rehabilitation Report, Phase 1, Attachment 3
- Lake Jackson Dam Investigation and Conceptual Rehabilitation Report, Phase 1, Attachment 4
- Lake Jackson Dam Investigation and Conceptual Rehabilitation Report, Phase 1, Attachment 5
- Lake Jackson Dam Investigation and Conceptual Rehabilitation Report, Phase 1, Attachment 6
- Lake Jackson Dam Investigation and Conceptual Rehabilitation Report, Phase 2
- Lake Jackson Dam Investigation and Conceptual Rehabilitation Report, Phase 2, Attachments
Please note that the report is very large and as such, had to be uploaded into many sections. Please be aware that the report may take some time to download as it contains numerous graphics.
On April 23, 2013, the Board of County Supervisors approved the County’s FY14 budget which provides full funding to repair the Lake Jackson dam. The funding will cover the cost to repair the dam as recommended in the consultant’s report as Alternative A: Fill All Chambers with Concrete.
An Invitation for Bid (IFB) to repair the Lake Jackson dam was issued in August 2013 and the contract has been awarded.
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