Is Dredging Lake Barton’s Dam Solution?

Is Dredging Lake Barton’s Dam Solution?

Federal aid to rehab 30-year-old retention lake, county examining possible future dredging.

Braddock residents met with federal, state and local government officials on Wednesday, Nov. 14 to discuss upcoming state-mandated improvements to Burke’s Lake Barton dam. The improvements would increase the dam’s flood prevention ability, sediment retention capacity and the possibility of sediment dredging.

The first official meeting of the Lake Barton Task Force, formed of Burke residents interested in the rehabilitation of the 30-year-old retention man-made lake, focused on the improvement of its auxiliary drainage pool and overall sediment capacity, but also included discussion on removing several years worth of sediment deposits in the lake.

"The problem that we have seen is that during probable maximum precipitation [Lake Barton Dam] … needs to be able to handle that," said Alica Ketchem of the United States Department of Agriculture’s Natural Resources Conservation Service in Richmond. "They’re held to such stricter standards because these dams need to protect property and life, and they need to be able to operate safely under all probable circumstances."

One of three Braddock District lakes created in the late 1970s with federal conservation money to prevent residential flooding, Lake Barton and its dam work to prevent flooding of the Pohick Creek watershed, according to information from the USDA. The other two are Lake Braddock, completed in 1970, and Royal Lake, finished in 1977. All were built in a cooperative agreement between Fairfax County and the federal government.

AS DAM TECHNOLOGY has improved over time, safety standards applied to dam viability have increased, putting Lake Barton’s auxiliary drainage capabilities at risk, said Ketchem. Concern for the stability of the dam’s auxiliary drainage spillway, designed to hold excess storm water during heavy rainfall, has initiated a federal examination for upgrades.

"The way the dam is now, conceivably, you could have a serious flooding issue," said Supervisor Sharon Bulova (D-Braddock). "The excess water [in the auxiliary pool] can work its way into this soil and ultimately that could get into the embankments and cause the damn to fail."

The problem could be in the looser soil of the auxiliary pool floor becoming eaten away by water seepage during a period of major rain, causing erosion of the embankment walls of Lake Barton, and possibly initiating major flooding, Bulova said.

The project takes on greater urgency as the Lake Barton dam is considered "high hazard," due to the potential damage that could be caused during a breach. The USDA has placed higher priority on the project, according to Ketchem.

"If we don’t do something in the future, we could have a flood risk," said Bulova. "Now that we know that, it’s not imminent … but we are required to do something to meet the problem."

The plan described to residents last Thursday involved the installation of articulated concrete blocks to be laid out on the ground of the auxiliary pool, covered eventually by normal grass and vegetation. The concrete blocks would then work to limit soil erosion in the pool for several years, according to Bulvoa.

THE FEDERAL government is prepared to pay about 65 percent of the project’s estimated price tag of $3 million, which would be matched by county money, according to Ketchem. If approved through the design process, the project should start sometime in 2010.

But if the federal government is going to invest money into the dam rehabilitation, under its regulations, the dam must be able to carry a minimum of at least 50 years of allowable sediment runoff, she added. As of right now, Lake Barton sits with about 39 years of sediment space remaining.

While some residents have expressed a desire for extensive dredging of the existing sediment in Lake Barton, the federal government would look to the less expensive alternative of building a higher principal dam water riser, according to Ketchem. The result would be in an increase of surface space at Lake Barton by nearly half an acre, she added.

"Legally, that is the option that must be chosen if we are going to fund a cost-sharing project like this rehab," Ketchem said. "We expect no real visual effects of the water level, and it will have no adverse effect on the walking paths."

STILL, SEDIMENT removal must be completed if the problem of a larger lake is going to be addressed properly, said retired Air Force veteran Warren "Parke" Parkerson, a 27-year resident of Burke.

"I don’t think they need to raise the dam any, they’re up high enough as it is," Parkerson said. "If they’re looking for the real solution that will give benefits to the fish, the plant life, they’ll need to dredge that silt."

While the dredging project, currently estimated at about $736,000, is obviously a necessary improvement to the Lake Barton dam, the federal government cannot cover the bill, Ketchem said.

"They obviously don’t want a mudflat, it’s an aesthetic quality, it’s not very beautiful to live right near a mudflat," she said.

With no help from the federal government, the county is looking for ways of funding the project sometime in the future, although nothing has been officially slated as of yet, said Bulova.

"I know that a lot of residents on the task force are really pushing hard for this dredging," she said. "But I think that we’re going to need to see what we can do about funding it and make some plans from there."

Expensive dams and retention lakes might cause some politicians pause, especially considering the potential long-lasting effects, according to Parkerson.

"It may be more expensive, but they always say, ‘pennywise, pound foolish,’" he said. "I think that they will benefit more from dredging the lake than they would from raising it."