Silt Fence and Wattles Stay the Course – Part 3
Streambank Stabilization
On another project also located in a residential area, the Filtrexx Bank Stabilization system was used on a streambank restoration project that took place last April in Charlotte, NC.
“The backyard of a residential property near downtown Charlotte was being washed away during rain events due to recent construction upstream that was increasing the amount of water that was being distributed into the stream,” explains J.R. Stewart, a Filtrexx representative who helped oversee the installation by Eco-FX Environmental, a certified Filtrexx instillation team. “The client wanted to go with a green approach to stabilizing and reclaiming her fence and yard. Also, the extremely limited accessibility hindered the use of heavy equipment for any type of concrete product to be utilized.”
The client’s house is located on a lot that backed against the stream. Houses nearby were built close together and that, in combination with a narrow driveway and excessive grades into the backyard, made the area inaccessible for heavy equipment, says Stewart. “The Filtrexx Bank Stabilization product allowed for the bank to remain stable while germination was achieved,” he says. “The mesh material filled with compost and seed mix helps to stabilize the bank prior to germination. Germination is the long-term fix.”
The weather provided another challenge. “During rain events, the water level rises extremely high on this channel, so the work needed to be performed in a very timely manner to avoid a rain event washing away or damaging an unfinished project,” he notes. Using vegetation that grows within the tubular mesh nettings, the Filtrexx Bank Stabilization system creates a natural anchor to stabilize waterway banks and prevent future erosion of riparian areas. The soft-armor system sometimes includes geogrid for structural stability.
In addition to the system, Eco-FX Environmental used SiltSoxx above the bank to control sediment during construction at the site. The palletized SiltSoxx were delivered and installed there before construction began. SiltSoxx provide filtration as water flows through the compost-filled tubes that are designed to trap sediment. When a project site surface is sloped and SiltSoxx are used, the tubes also naturally slow down water velocities. Each month, Eco-FX Environmental visits and monitors the site.
Repurposing a Plant
Sediment control in urban areas brings its own unique challenges. In Newark, DE, the site of a former Chrysler plant is evolving. A local university is planning to find a new use for the site; now that the plant itself has been torn down, the school contracted Lindstrom Excavation to begin installing a gas main in mid-June 2012. Runoff at the site, which has approximately 60 acres of blacktop, had been an initial concern in terms of sediment control during construction.
“The original design for the project included silt fence,” says Duane Lindstrom, president of Lindstrom Excavating Contractors Inc., based in Worton, MD. He suggested using Erosion Eels, from Friendly Environment in Shelbyville, TN, which he felt were more suited to this particular site. “Since you have a hard surface, it’s beneficial to use the Erosion Eel so you don’t have to disturb anything. At the end, it’s less expensive compared to putting silt fence in and pulling silt fence out.”
The erosion control budget for the project is approximately $50,000 and includes the Erosion Eels, which are distributed on the East Coast by Richmond, VA–based ACF Environmental. Lindstrom had used them on a project in the past where workers were dredging a harbor, and he found the product useful for protection at that location. At the former industrial site, Lindstrom says, the Eels would not destroy the existing blacktop. “Some of the pavement goes back, some gets filled in with stone,” he says. “No one knows what is going to be built there in the future.
The gas line is approximately 4,000 feet, and the Erosion Eels were placed around the area of disturbance. The ease of moving the Eels was also appealing.
“When you have done a certain area, you can move the Erosion Eels very easily,” notes Lindstrom, who said the site does have slopes affecting runoff in a rain event. “We’re able to line the catch basins as a secondary defense against erosion.”
Following a powerful storm that caused extensive damage and took out power along the east coast on July 29, the product held up very well, he says.
The Erosion Eels served as the primary sediment control method and were approved for use at the site by the state. The product is filled with shredded rubber from used tires. When a project is completed, this filler is then reused in new Erosion Eels after it has been cleaned. The geotextile wrap is recycled for use in automobile plastics, according Friendly Environment.
In this field, sediment and erosion control requirements have become stricter, says Lindstrom, and are actively being enforced. The Erosion Eels have helped the project meet requirements. State representatives come to inspect the site weekly, he says.