Two Ways to Install Silt Fence
The many functions and forms of an evolving standby
There are two ways to install a silt fence—the right way and the wrong way.
The right way, it turns out, has a lot of variables, as any contractor knows. The choices are dictated by the type of soil, the slope gradient, and the length of time a job may take, as well as other influences. The wrong way often has to do with contractors using unfit materials and with lack of inspection and enforcement to correct installation errors.
|Photo: Burchland Manufacturing
|Preventing sediment runoff is silt fence’s biggest job.
While it’s not news that silt fences are a first-rate form of erosion control, what’s new is the growth of options and new products for the job. And contractors, young and older, new to the business or old hands, are using a variety of equipment to install silt fences.
Joe Johnson, 25, is a contractor just starting his own business in Hot Springs, AR. He learned the business of erosion control when he went to the southwestern coast of Florida after high school where he worked on jobs for the state department of transportation (DOT).
After five years, he wanted to return to his roots and start his own business. “I got homesick and decided to go back home to Hot Springs,” says Johnson. “In Arkansas, I feel that everything’s in its infancy. A lot of people don’t know what a silt fence is.”
He surfed the Internet to get pointers about writing his business plan, and he got an old hay blower, reworked it, and made a new machine out of it. He spoke with DOT contractors who said they installed silt fences with a silt fence plow.
“In Florida, we put things in with a trencher,” Johnson says. “Here, I’ve pretty much had to learn on my own. I didn’t have any mentors, and the Internet has been a great big help—finding the resources to start up and also tools.”
His first big purchase was a McCormick silt fence plow while his business—Integrity, Erosion Control & Landscaping—continues to grow by word of mouth.
He’s also learning about a different level of enforcement, more lax than what he experienced in Florida. “If you have less than 1 acre and don’t have any controls, you’re not in violation,” he says. “The problem is that the soil washes out on somebody else’s property. In Florida, just a half-acre lot had to have perimeters. Here in Arkansas people don’t even know they’re in violation. The specifications are here but are not being enforced.”
What is required in Hot Springs, he says, are wire-back fences. A problem, however, is that the wooden stakes break a lot and people want to use T-posts.
“There are a lot of variables that govern a job. The terrain here in central Arkansas has a lot of hills, and I’m used to a perimeter control all the way around a job site. That’s not needed here in some instances,” Johnson says.
“On one job, this place was washed out. It was a dirt parking lot on the edge of a field. The problem was the rain, and the customer waited too long after stabilizing the fence and to install permanent vegetation to slow down the flow,” Johnson explains. “There were rills and gullies across the 3-acre field that was a temporary parking lot. I had to regrade this surface. All the sediment had washed downhill, and it didn’t contaminate anything but their property. But they had waited months until they took care of the problem.”
The biggest problem is that people don’t know there’s a problem, which creates more of a problem, as far as Johnson is concerned.
On this parking lot job, he had to replace the fence and the hay bales used to reinforce the fence. The owners didn’t know their fence wasn’t going to last forever, which provides an example of people not knowing about a problem.
“First I had to get rid of the bales, and then we replaced the silt fence and made a series of rock check dams before I could regrade the slope,” Johnson says.
He goes on to say that one set of best management practices (BMPs) is not going to be effective in every situation—a slope gradient will be different, there will be different terrain, and the runoff factor is always different. “No one control fits all,” Johnson says.
|Photo: Raygn Alexander
|Raygn Alexander, who has his own business in Stillwater, OK, installs a fence with his McCormick silt fence plow.
Same Problem, Different Approach
David Minter of Houston is a co-owner of Construction EcoServices. He started his business five years ago with Bob Adair, a long-time friend, and has a different approach to sediment control.
“Most silt installers use a trench method, and when you trench a silt fence in, it disturbs a lot of the soil,” says Minter. “What we try to do is keep dirt and dirty water from leaving a construction site. So we use the tommy Silt Fence Machine. We found it to be a superior machine.”
If the contractor doesn’t compact the ground where the silt fence is installed, the water that’s trying to leave the site will try to underrun the soil. Water wants to run down and follow the line of gravity. Minter says that the tommy uses a static slicing method to install the fence so the soil is not disturbed or lifted up.
“It just goes into the ground with the J-hook in the ground, and we drive over and insert the silt fence material. Once the silt fence is installed, we drive back over it with our tractor and it fully compacts the soil. Water can’t underrun the silt,” Minter explains.
He says he’s seen some installations where people try to use the trench method. That aerates the soil, and the water takes the soil offsite. “That’s what we’re trying to do, keep the soil onsite,” he says.
The Houston-area soil, heavy clay or sandy, is not a problem. More often, a challenge comes in the form of a physical restriction on a site, like a fence or a building. “When the silt fence has to be right up against a building, then you have to put the fence in by hand,” Minter says.
Another challenge is getting people to accept a method other than trenching. “Many of the jobs are wire-back silt fences. We found that sometimes engineers ask for the wire back thinking that would add strength to the installation. But when you install wire-back silt fence, that creates more underrun,” he says. “In addition, when the job’s over, you have to take the wire out, and it’s more bulk to go to the landfill. That’s not very ecological.”
What Minter prefers is using synthetic hay bales, made from recycled carpet fibers, which run from $5 to $8 a bale. “We use them in deep swales where there’s a high flow and a high velocity. Natural hay bales have a limited life. And on long-term jobs that may run 18 months or two years, the synthetic bales last longer,” he says.
Minter says he recently discovered that Wal-Mart has adopted the slicing method for silt fence installation. For a long time, the big company, which does a lot of building, would accept only wire-back fence.
“I think it’s a positive move because it’s a superior method. We’ve been a believer in this method since we started five years ago,” Minter says. “When we started this business, we were looking for innovative and cost-effective ways to install BMPs, and our research led us to the slice silt machines. It not only does a proper job but also saves our clients money.”
|Adam Popenhagen, a compliance inspector with Bonestroo, checks the installation of a silt fence on a job site.
Another point of view about erosion and sediment control comes from a man who does compliance inspections. Greg Halverson, 30, works for Bonestroo, a private company in St. Paul, MN. Bonestroo is one of several firms doing this work in the St. Paul/Minneapolis area. In addition to doing civil engineering work for municipalities, the company has a water and natural resources group that checks inventory, water quality, storm sewer design, and stormwater compliance. The latter is governed by the National Pollutant Discharge Elimination System (NPDES).
“Municipalities have to have one of these permits from the state or feds in order to discharge pipes. Contractors need them in order to discharge water from construction sites. We help municipalities and contractors with compliance,” says Halverson. “We contract with municipalities and residential contractors to enforce the regulations.”
Halverson absolutely agrees with Johnson, the contractor from Arkansas, about the most common problem being a lack of knowledge.
“A lack of knowledge creates problems,” Halverson says. “In this area contractors can enroll in a statewide program on erosion control run by the University of Minnesota. Our company has pushed a lot of training in the past few years. But now I’m seeing more enforcement and less training.”
The point is not what product is being used, he notes. The biggest need is to stabilize the site to prevent sediment runoff. The second need is proper documentation, according to Halverson.
“In some cases, contractors may be taking care of things properly but lack paperwork to prove it,” he says. “We may recommend certain products for certain situations. For instance, some contractors have gotten away with cheap products, products that are not acceptable. This is where enforcement comes in.”
The High-Priced Spreads
Joe Palka Jr., 48, is the executive vice president of land development for Horsham, PA–based Toll Brothers, the nation’s eighth largest builder and the leading builder of luxury homes. Palka doesn’t believe in using low-priced erosion control products for his high-priced projects.
“We develop communities as small as 15 to 20 lots in the Pennsylvania and New Jersey areas. And we have a community in Loudoun County, Virginia, in excess of 5,500 homes,” says Palka.
At Toll, the erosion/sediment control plan is designed by the engineer in cooperation with the land development manager for the community. Then the contractors execute the plan first by establishing a perimeter silt fence on the downhill side of the site, where the runoff leaves the disturbed area.
“The standard silt fence is filter fabric between wood stakes. A reinforced silt fence also has a wire back or plastic-mesh back for more severe conditions. A super silt fence is a fabric fence backed with chain-link fence, even more effective than reinforced fence,” says Palka.
He explains that an effective silt fence design considers the slope rating of the product, the percent grade and the length of the slope on the uphill side of the fence, and soil type. Problems can arise with colloidal soils, very fine-grained soils that are difficult to filter. “That’s when you use a combination of chemical treatment or polymers to make the silt fence more effective,” says Palka. “Small particles are definitely a problem with silt fence.”
What he’s found effective for lot perimeter controls during homebuilding operations is SiltShield. “The beautiful thing about SiltShield is that if someone drives over it inadvertently, it rebounds and doesn’t break or need to be reinstalled,” he says. “That’s a recurring issue on homebuilding sites everywhere. SiltShield is a filter fabric sandwiched in between a quarter-inch of cross-linked polyethylene foam. You can use fiberglass stakes for extra support where you expect heavier stormwater or sediment loading. It’s a pretty innovative product, and we’ve been using it on various projects with great success.”
Palka says the new product is not yet in many states’ BMP manuals, and therefore it does not have blanket approval for use, but it can be used anywhere a contractor would ordinarily use a silt fence. Once a conservation district sees the product in action, the district generally allows its use in lieu of conventional silt fence.
“It’s rated for fairly high flows, and we find it stands up better to the rigors of homebuilding than a regular silt fence,” Palka says. “It’s a more expensive product on initial install, but if you’re going to replace your silt fence during the life of a construction project, the cost difference becomes negligible.”
The product can also be reused after removal, while a typical silt fence is not reusable.
Another person who knows about big developments is John M. Jones, 49, the manager for the Wayne County Erosion Control Program. That’s the regulating authority for the Detroit, MI, area, and Jones often inspects sites for multifamily residential projects, which includes checking that the silt fences are being maintained properly.
“One common problem is with multifamily residential projects, like condominiums. There’s so much construction traffic and so many people involved, like subcontractors and trades people, that it’s difficult to maintain sediment control, especially on backup curbs in front of new homes,” Jones explains. “Those silt fences tend to have a short life expectancy because they tend to get run over by construction traffic. I think it’s a universal problem where you have a lot of single homes going up at the same time. It’s very chaotic. That’s why I was willing to work with SiltShield.”
Jones says he’s seen the SiltShield used on corner lots, which typically get the most damage from traffic. “What we liked about it is that it functions as well as a silt fence, but it was more likely to be standing up when it rains or after it was knocked over. And it’s easier to pick it back up, as opposed to a traditional silt fence when it’s run down and torn and the pickets are down,” he says. “And it’s difficult to give a citation to a builder for something he can’t always control, like when a fence gets run over.”
Back to the Small Contractors, the Backbone of the Trade
Raygn Alexander, 27, started his business, Oklahoma Erosion Control, in Stillwater about two years ago. In this region of the country, erosion control is not at the top of the list for builders.
Photo: Joe Johnson
|Contractors use a silt fence plow to install wire-back silt fence in Arkansas.
Photo: Burchland Manufacturing
|Slicing or plowing silt fence into the ground allows for secure installation.
Photo: Devon Distributing Co.
|The tommy Silt Fence Machine disturbs an area of only about 4 inches.
“It’s a difficult business to market,” Alexander says. “Contractors don’t view erosion control as a primary concern. Basically a guy buys a house. He’s got to have a frame, a water line. Why would he have the soil tested? It’s an added cost that people don’t take seriously.”
Before returning home to start his own company, Alexander worked in Oregon and Illinois where erosion control was taken seriously. So it is discouraging to run into indifference on what he considers an important part of building. He also recognizes that the Oklahoma Department of Environmental Quality doesn’t have the manpower to enforce all the regulations.
Even so, he likes owning his own business. “Every single job is different and has a different challenge. It’s one of the reasons I like the business,” he says. “It’s a challenge for me to get the job done and get it done right.”
Two frustrating things he deals with are finding labor and seeing contractors sometimes get away with doing erosion control incorrectly because of lack of regulation. “The most challenging thing is encountering contractors who don’t plan ahead, don’t have things installed properly, and don’t maintain their silt nets,” Alexander says. “I’ll go to a site that has PVC pipes and other equipment stacked up against the fence.”
One thing he has no quarrel with is his equipment. “I use the McCormick silt fence plow,” he says. “It is the best piece of equipment for the job. It does a great job of putting in a silt fence.”
Joey Marquez works in a different part of the country and under different conditions. One of 25 employees who work for Gallion Erosion Control in Santa Paula, CA, the 26-year-old has been doing silt fence work for eight years.
“We work in Ventura County and Los Angeles County, and sometimes the soil isn’t very good. It has too much clay, so it doesn’t absorb water well,” Marquez says. “If you have a heavy storm, there’s a lot of water.”
Right now, however, southern California is classified as being in an “extreme drought” by the US Drought Monitor, a partner with the US Department of Agriculture. So excess water’s not a problem at the moment, but controlling dry dirt is still a necessity.
“Soil has a lot to do with how you’re going to put the fence in. You compact it with wheel rolling. We use the tommy Silt Fence Machine,” Marquez says. “The tommy does it without the poles, which makes the silt fence tighter. It also buries the fence without the trenching, so the disturbed area is only about 4 inches.”
Up in Nebraska, there’s a different set of circumstances, according to contractor Jason Henderson. Henderson, 25, co-owns three-year-old Green Thumb in Nehawka, NE, which is 45 miles south of Omaha. “We do a lot of private work and a lot of state reclamation work, and the problems we have around here, especially around western Nebraska, come from the sandy soil,” Henderson says. “We have problems with the fence blowing out because of erosion occurring underneath the fence. We’ve also had problems in one area, in Broken Bow, that’s had 30 inches of rainfall this year, compared with the usual annual 15 inches.”
While Broken Bow is located in the center of the state, there’s a big difference between the eastern and western parts of Nebraska because of the types of soil. “The eastern part of the state has soil that is good clay, and there’s hardly any sand there. But you get west of Grand Island, and there are sand hills in western Nebraska. And you can’t compact sand very well.”
Henderson says his company has jobs on both sides of the state but that Green Thumb uses the McCormick silt fence plow, east and west. “We like the way it’s designed and heavy built, and we’ve been using the McCormick about three years,” Henderson says.
The company does, however, use different methods for installing silt fence in the western part of the state because of the sandy soil. “We plow it deeper, about 8 inches, and we bury it deeper, at the 12-inch mark. And we put our key posts together, spacing them every 4.5 to 5 feet instead of 6 feet,” Henderson explains.
He also takes extra measures in Broken Bow and other areas experiencing unusually heavy rainfall. “What we’ve done is put a silt fence in the middle of the slope to slow down the water and keep the silt from sliding downhill. Putting the silt fence in the middle slows down the runoff, and we catch sediment mid-slope.”
And Green Thumb takes it one step higher: recycling the silt. “We take this silt to and reuse it to compact the road bed,” he says.
Now that’s erosion control at its smartest.
Author's Bio: DeWitt Smith is a journalist and features writer who lives in Ojai, CA.