Silt Fence and Wattles Stay the Course – Part 2

Replacing a Water Main
Another site that combines a variety of techniques, including silt fencing and wattles, is an ongoing water main instillation project at Fort Belvoir military base in Virginia.

Work at the 80,000-acre site began in 2010, stopped briefly, and resumed in August 2011. Sediment control at the site where 144,000 feet of water main is being replaced had been a challenge. George Galachiuk, superintendent at the site for Indianapolis-based Bowen Engineering, says the company tried several erosion control methods before selecting Gator Guard Environmental Products’ Gator Guard reusable sediment control wattle to be used in coordination with silt fence and straw. He says that while several previous methods of sediment control disintegrated when vehicles on the busy base rolled over them, this was not the case with the Gator Guard.

“We’re able to reuse them,” says Galachiuk. “The Gator Guards are extremely tough and hold up really well. We use them on the downside of all of dirt and soil piles. This way any rain that gets on top of the pile goes into the Gator Guard and not into any of the other areas we’re working in.”

The area is rife with construction—hotels, child development centers, hospitals—and the sediment control methods chosen have to respond to heavy traffic while the water main is being replaced in phases.

“The [base] size is the challenge. We’re not doing the whole thing all at once, but we’re all over the place,” says Galachiuk, noting that the replacement is anticipated to be completed in 2013. “We have areas on the north side of the base, south side of the base—we’re getting the worst pipes first. There are some areas that are higher up and significantly lower areas. We’ve used 4,000 linear feet of Gator Guard onsite because it works so well.

“We use straw bales to protect the catch basins and fabric for the catch basins,” he adds.

With a UV-resistant geotextile as its outside wrap and filled with recycled foam, the Gator Guard has an anticipated life span of five years. The units are cut to fit and connect end to end. Each has an apron that should be pinned approximately every 3 feet with an inch of dirt covering the apron, according to the company.

In addition to the Gator Guard, a variety of silt fence and super silt fence was placed in large areas such as swamp areas and wetlands.

“You have to disturb more ground than with the Gator Guard,” says Galachiuk, referring to the instillation of silt fence. “We will be using seed and straw for revegetation. We’re using contractor [grass] mix while the plants are removed, watered, and replanted.”

The project is about 40% completed, and the work that is remaining is being completed more quickly. “We’re in areas where there’s less disturbance, where it’s more open.,” says Galachiuk. “We’re able to get pipe in quicker now.”

Workers monitor the site each week as well as after significant rains, such as one that took place on June 29.

“The wind made significant damage; it took down trees, roofs. People were without power for five days,” says Galachiuk, noting that the Gator Guards remained staked down. “Between the stakes and the dirt, they worked really well. They held up fine.”

Installation Techniques
Proper installation is vital in creating a stable silt fence barrier in any setting. Terry Venteicher, owner of 3D Erosion Control in Des Moines, IA, has installed more than 4 million feet of silt fencing during his lifetime. He currently uses Ankeny, IA–based Devon Distributing’s tommy Silt Fence Machine on sites that range from residential to rural.

“The tommy has a narrower knife. I can get it in faster,” he explains. “It makes a J that runs along the wheel. You get about 18 inches in the ground and about 18 inches out of the ground.”

“The vertical wheel, positioned between two narrow parallel panels, is a moving pivot where the horizontal silt fence fabric is converted to a vertical position between the panels,” according to the manufacturer. The fabric is “simultaneously pulled off the roll by the vertical wheel, funneled into the apparatus, converted to a vertical position between the panels, and inserted into the soil” that has been opened by the panels. The soil will then collapse on the fabric, securing it.

Other machines Venteicher says he has used required more horsepower in the form of a larger tractor than he uses to pull the installer.

A 30-horsepower utility or larger tractor, or a 60-horsepower or larger skid-loader, is needed to pull the tommy through the soil. It uses what’s known as a static-slicing method.

“I have more maneuverability with a smaller tractor that can pull the tommy,” says Venteicher. Bouncing from site to site, he says, he can install as much as 2,150 feet of silt fence in a single day by himself. One particularly challenging site is Windmill Farm in Mecina, IA, which produces corn and soybeans on 300 acres; installation sites at the farm can be very spread out. “They have windmills, but the site where the windmill is might only be a half an acre.”

Venteicher often combines silt fencing with another sediment control method. He takes wood chips and places them in a heavy fabric. This “works in the same way a filter sock” would, he says.

The tommy works well on housing development sites as well, where the project “requires all four sides of [the site] to be protected. In a smaller tractor, you can keep that tighter to the lot line as you need,” says Venteicher. “If you have a bigger tractor, you are about 4 feet off the boundary.”