The Northern Virginia Daily

Article Date: September 25, 2007

 Miles of sewer lines being removed from former Avtex Plant

Second phase halfway done with focus on southern part of the site

By: Robert King

Officials aren’t just dismantling buildings at the former Avtex plant; they’re also removing miles of sewer lines.

The plant that produced rayon and other synthetics from 1940 to 1989 was declared a Superfund site by the U.S. Environmental Protection Agency in 1986.

FMC a former plant owner, is funding and leading the cleanup with assistance from the EPA.

Buildings at the plant are completely demolished, and cleanup of various chemical basins and landfills continues.  When completed, the area will house a conservancy area and industrial park called Royal Phoenix.

The EPA and FMC agreed to remove all sewer lines and manholes and dispose of them offsite, said John G. Torrence, an environmental contractor for FMC.

FMC is halfway done with the three-phase excavation, he added.

The first phase was completed in 2005 and centered on sewer lines in the site’s northern part.  “The reason we went for the northern half first is we wanted to help redevelopment efforts,” Torrence said.

FMC is in the middle of its second phase, which focuses on the southern part of the site.  The third phase will focus on lines going toward the facility’s former wastewater treatment plant.

Torrence said refitting the lines instead of destroying them would be too time consuming and expensive.

The integrity of the sewers is another reason for their removal.  Some sewers were built in the 1940’s and could leak, Torrence said,  adding that some contain harmful chemicals.

“Some of these sewers were used for storm water and are clean,” Torrence said. 
Other sewers were used as process lines. [It] could mean any type of the materials used in the manufacturing of rayon, such as acid, would travel through these sewers as a waste product.”

Torrence said cleanup officials determined what materials the sewers contain through soil testing.

Officials test soil all around the lines for any soil contamination.

Sometimes the location of a sewer line can tip off officials to the materials it once carried.  For example, PCBs, a harmful organic compound, were present at the plant’s powerhouse area.

“If it is present in the powerhouse area, then a sewer runs past it,” Torrence said.

When officials excavate a pipe, they remove surrounding soil.  That soil is tested, and any contaminated material is taken to an appropriate disposal site like an incinerator or landfill, Torrence said.

The excavation does have its obstacles.

“The sewers range in depth and in size,” Torrence said.

The shortest could be 4 to 6 feet underground while the deepest is 30 feet, he said.  The lines width varies from 4 inches to 5 feet.

FMC uses trackhoes – excavators that have tracks on the bottom – to remove the pipes.

“The larger trackhoes are the more powerful and used to get the bigger, heavier sewer pipes out of the ground,” Torrence said.

Sewer lines that are not mapped provide another obstacle.

For the first phase, FMC thought it would need to excavate only 8,000 feet of sewer  lines, but ended up pulling out 13,500 feet, Torrence said.

Workers are usually able to find undiscovered sewers as they excavate known lines, he said.

FMC increases the number of soil samples in an area that could have unknown sewers, he added.

“It depends on the sewer,” Torrence said.  “We look at where the sewer is going and where it is tied in and collect the soil samples at an appropriate distance or volume.”

Any discovered sewers get a separate sample to make sure there are no leaks, he added.

Instinct plays a part in determining where to sample.

“You have to use a lot of gut-feeling judgment in the field,” Torrence said.