Let the Dredging Begin

Let the Dredging Begin

FCPA Board approves dredging contract.

Lake Accotink lovers can rest assured that the 55-acre centerpiece of park activity will be around for many more sunrise and moonlight outings.

The Fairfax County Park Authority Board voted at its July 27 meeting to approve the contract award of $7.25 million to Mobile Dredging and Pumping Co. of Chester, Pa., to go forward with the lake dredging project.

The total cost is an estimated $8.4 million, which includes administrative and contingency costs.

Though the board has given its blessing, the action is only preliminary, according to FCPA spokeswoman, Judy Pederson. The project needs approval from the Fairfax County Board of Supervisors before it can proceed.

Mannan Qureshi, Department of Public Works and Environmental Services project engineer, said the board is expected to vote the last week of September but he could not provide a firm date because some parts of the contract are still in negotiations.

The contract the FCPA board approved contains plans for a less expensive method for collecting and draining the dredge material than was first proposed.

The original plan called for a geomembrane collecting system at an estimated $9.56 million by Mobile Dredging, the project’s lowest and only bidder.

Qureshi said the method, which uses woven geotextile bags to collect and drain the material, is more expensive because it’s new and very few companies have experience using it.

The least expensive way would have been to collect and drain the material at the lake and truck it out, Pederson said, but to keep the peace in the park and surrounding neighborhoods, that option was discarded.

DPWES HIRED independent construction cost estimator, McDonough Bolyard Peck, to review the bid documents. MBP found that a mechanical system would produce the same results at a 25 percent savings.

If the two-phase project is approved, Mobile Dredging will start Phase I this fall by installing the dredging pipeline along the Norfolk Southern Railroad right of way and prepping the disposal site to receive the sediment, John Lehman, of the Park Authority planning division, said.

The 20-inch, above-ground pipe will be laid parallel to the track as far away as possible so that it does not interrupt park activities, Qureshi said.

Pipe installation will likely take most of the fall to complete and dredging will begin in the spring, probably sometime late March, once the chance of freezing has ended, Lehman said.

After the pipe, dredging machine and hydraulic pumps are installed, the material will be pumped 2.8 miles to the Virginia Concrete Construction property, located at the Shirley Park Industrial Complex.

Once the dredge material reaches the site, it will be collected through a mechanical system and filtered into a small, enclosed area, where it will be drained.

After it’s dry enough, it will be used for depression grading and filling at the industrial complex.

THE ENTIRE dredging process, which should be completed by fall 2006, should not interfere with park activities or endanger park wildlife, Lehman said.

However, some noise disturbance associated with the dredging may occur, particularly along the pipeline at areas where the pumps are located but the disruption should be minimal, he added.

Park Manager Tawny Hammond said the park will remain open to the public as long as it is deemed safe but an isolated day here or there may occur when it is closed for workers to bring in or remove equipment.

“There might be some safety fencing right around the lake where there may be a pump or a dredge but that shouldn’t affect any of the parks programs or activities,” she said. “We’d only suspend a program temporarily if it was affected by the dredging but it’s not expected to disrupt the entire lake, only those parts they’re working on.”

Lehman said they’re not sure at this point how much and when the lake might have to be restricted and that will be determined as the work is being done.

The result of dredging usually lasts between 10-15 years and makes a considerable difference, primarily in keeping the lake from becoming a wetland.

“Every year, the sediment comes into the lake and the holding capacity is reduced,” Qureshi said. “If the whole lake filled with silt, water wouldn’t stop coming into the area. It would spread all over, causing flooding and more problems, so it has to be done.”

Currently, some areas of the lake are as shallow as two feet, but once the project is completed the water in most of those areas will rise at least two to four feet, Lehman said. Citizens have repeatedly expressed to Hammond that they value Lake Accotink because it enhances the quality of their lives.

“Over and over people say what a gem it is,” she said.

The lake is nestled inside a 500-acre park that is surrounded by a dense residential population. The park, Hammond said, is deeply ingrained into the lives of the people in the community.

“They look at it as a getaway, a slice of countryside where they can hike and bike and recreate with family and meet their fitness and recreational needs,” she said. “It’s a huge part of people’s lives.”