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Monday, March 16, 2020

Lake Accotink pipeline could threaten park's habitat

County officials and community residents take a "pipeline walk" in Lake Accotink Park, accompanied by the sounds of spring peepers, wood frogs, and birds.
When Fairfax County officials announced a plan in September to install a pipeline to haul dredged sediment away from Lake Accotink, many community members were happy that the lake would be saved.

But now that the pipeline project – which would include five acres of cleared woods in Wakefield Park – has been somewhat more fleshed out, there is concern about environmental damage.
Erosion along Accotink Creek.
“This is not what the neighborhood expected as the price to keep the full lake,” states the Friends of Accotink Creek. “The industrialization of our parks is not acceptable.”

According to FAC, this project would remove forested habitats, damage wetlands, impede floodwater flows, and block the movement of wildlife. It will be a “hideous eyesore, negating the aesthetic value of retaining the full lake.”

County officials and environmentally minded residents took a “pipeline tour” March 14 along the Cross County Trail to see where the pipeline might be installed and how the project could affect the habitat of Lake Accotink Park.

Related story: County proposes $30.5 million plan to save Lake Accotink

The group – about 30 people in all – included Braddock Supervisor James Walkinshaw, staff from the Fairfax County stormwater department and Park Authority; members of FACC and Friends of Accotink Lake, naturalists, and people who live nearby.

Braddock Supervisor James Walkinshaw (center) listens to community members' concerns about the pipeline project.
The project calls for the dredging to be done from a barge floating in Lake Accotink. A machine “like a big vacuum cleaner” will suck up sediment into a plastic 18-inch pipe, said Charles Smith, branch chief for watershed projects in the County’s Stormwater Planning Division.

The pipeline will carry the sediment two miles to a pad site somewhere in Wakefield Park where it will be “dewatering.” The dried-out material will then be hauled away by truck.

The pipeline project was approved by the Board of Supervisors after a study of several alternatives to repair the sediment-choked lake. If nothing is done, the lake would eventually disappear. The pipeline project would restore the lake to an eight-foot average depth.

The goal of both the county and the community is “to have the dredging done in a way that has the least environmentally and socially negative impact,” said Smith.

Philip Latasa of FAC urged the county to raise the pipeline a few increase off the ground so as not to impede the movement of small animals, such as frogs, toads, and salamanders. Larger animals, like foxes, could jump over it.

Lake Accotink is filling up with sediment.
Fairfax County hasn’t decided which side of the lake the pipeline should be installed or where two booster pumps should be located. That would depend on such factors as where flooding occurs and how the water moves, Smith said. A contractor hired by the county will submit an analysis next month addressing those details.

The county also hasn’t determined where the pipeline would end and where the dewatering pad should be built. That site could not be a in flood zone; would have to be accessible to trucks, a crane, and heavy equipment; and couldn’t be too close to the power lines, Smith said.

Construction could start in 2022 at the earliest and would take three years, he said.

The first dredging is expected to remove 350,000 cubic yards of sediment from the lake. The subsequent dredging would most likely remove half as much sediment. Smith hopes it could be 10 years between dredgings, but that depends on how many big storms there are.

FAC prefers a less intrusive dredging operation, with a shorter or rerouted pipeline, even if it results in a smaller lake

An erosion control project in Wakefield Park. 
Most of the sediment is washed into streams from developments miles away, causing erosion of the stream banks. About  45,000 to 50,000 cubic yards of material is dumped into the lake every year, mostly during “high-intensity storms,” Smith said.

The Ravensworth Farm community, which is adjacent to Lake Accotink Park, was built in 1961, before stormwater controls were required, Walkinshaw noted. “That’s a good example of what we’re dealing with across the county.”

Walkinshaw hopes the entire lake won’t have to be closed during the dredging. The trails and marina area would remain open, although parts of the park might have to close during construction of the pipeline. The pipeline would be removed between dredging operations.

Smith and other county leaders plan to meet with environmental and community groups this year to hear their concerns.

To fund the pipeline project, Fairfax County is applying for a $30 million state loan. The county plans to apply for the loan in July, and should hear whether it’s approved by the end of the year, Walkinshaw said. Loan repayments would come from the county’s stormwater fees.

Related story: Supervisors approve funding plan for Lake Accotink

Another project to start soon is construction of an elevated walkway below the dam, Walkinshaw said. That area tends to flood, and thus becomes hazardous for pedestrians.

In a separate but related issue, the Park Authority is restarting the process to revise the Lake Accotink Park Master Plan. The plan will address what should happen to the park in 10, 20, and 30 years. A community meeting on the Master Plan originally scheduled for March 31 has been postponed.

2 comments:

  1. If it is to be a temporary instal how in the world is that a problem? Alternatively perhaps they lake is allowed to continue to fill and return to a natural swamp area, great for studies of marsh and wetlands but very poor for recreation.
    I hope they find a logical path.

    ReplyDelete
  2. The public engagement that brought about the plan to retain Lake Accotink was an admirable example of local civic action at its best.

    However, a main motivation for retaining the full lake is its aesthetic value. Now we learn that there is a high aesthetic cost attached in the form of an aboveground, 18 to 24 inch pipeline from Lake Accotink into Wakefield Park, routed along the Cross County Trail and Accotink Creek, plus 5 acres of woods cleared for a dewatering site.

    This cost of what is lost is not what the neighbors expected and seems too high for what is being kept.

    Issues with the pipeline:
    • Industrialization of our parks in not acceptable
    • The sacrifice of our dwindling forested habitats is not acceptable
    • The pipeline, combined with its pumping stations and with the 5-acre dewatering clearing, will be a hideous eyesore, negating the aesthetic value of retaining the full lake
    • No matter how carefully laid, the pipelaying heavy equipment will impair wetlands and habitat.
    • The pipeline will block the movement of wildlife
    • The pipeline will be 100% in the floodplain. Its interaction with the high water after heavy rain will not be good.

    Possible alternatives to the pipeline:
    • Dewater sediment on barges in the lake
    • Mechanical dewatering to eliminate the need for offsite dewatering
    • Adapt the methods employed by Lake Barcroft, with lesser infrastructure needs.
    • Route the pipeline alongside the railroad for dewatering in one of several industrial parks along the tracks.
    • Reconsider the smaller lake option

    ReplyDelete