By Janis Keating

Some contractors believe that silt fences make bad neighbors. Across the nation, alternative best management practices are being sought and found—ranging from the “low tech” yet highly biodegradable straw wattle to plastic barrier and drain systems that not only catch sediment but also are strong enough to stand up to construction-site abuse and can be reused on subsequent projects.

Cost-Effective and Fail-Safe
Stokes Construction Co. of Covington, GA, installs sewer, water, and storm drains for subdivisions. To keep sediment from running off the site during work, Stokes relies on Silt-Saver devices that attach to catch basins. “They save us a lot of time and work,” Owner George Stokes notes. “We have 75 or 80 of them, and we remove them when the curb installers begin their work.”

Photo: Gator Guard

Gator Guards create a sturdy barrier against silt.

Stokes’s company, which was incorporated in 1980, has been using the products for about five years. “We started using them right after they came out. We haven’t had to replace any of the plastic ones yet; we’re putting 16 catch basins in right now. Silt-Savers are the best thing for catching sediment I have ever found. They save so much time. I don’t put in any silt fences; those are usually put up on the work site by a separate company, if they’re used.”

On most projects, Stokes uses the Silt-Saver SS-100A (round) or SS-200A (square) frame and filter assembly that attaches to catch basins. The two-piece unit—a polyurethane frame that fits over stormwater pipe openings—provides structural integrity. The frame is covered with a non-woven geotextile fabric, which is the sediment-filtering medium. The units’ HDPE frames are reusable. No stakes are required for installation, and the device’s size makes it difficult to miss, so workers shouldn’t stumble—or drive—over it.

“We can use the plastic part over again; we can also reuse the filter part as long as workers don’t tear it when they come in to do concrete work. We can turn them inside out and reuse them,” Stokes says. Another cost saving: No special training is required for workers to install the Silt-Savers. “They’re very simple to put in. When we get done with building the concrete drains, we put 4-foot-diameter Silt-Savers atop them, then drape cloth over that, and put in gravel, to hold the cloth down.”

No heavy equipment is needed to transport and install them on a site. “They are stackable—we can get 15 or so on the back of a pickup truck. Plus, they’re really light—each weighs maybe 20 pounds. One man can handle that really easily,” he adds.

What percentage of the cost of a typical Stokes job is spent on sediment control? “The Silt-Savers are not really budgeted because they’re reusable,” Stokes says.

Silt-Saver Inc. also manufactures filters for curb inlets (SS-300), protection for pedestal top inlets (SS-400), and a bottom drain attachment (SS-500) that works with a Silt-Saver to create a self-contained filtration system. For stabilizing construction exits, the company offers SS-600, a 200-pound fabric underlayment.

Photo: Gator Guard

Stapling the apron every 3 feet keeps the wattle secure.

Photo: EarthCo

A powerful wash of mud can take a silt fence down easily.

Since the advent of National Pollutant Discharge Elimination System (NPDES) Phase II, Stokes has observed stricter enforcement of sediment control practices. “There’s a lot of construction work around Atlanta, and the state’s really watching it close; they come out and take samples of the runoff.” He adds, “There’s a lot of this mica in the Georgia dirt, and when it gets wet it runs like a river. We only hear from citizens’ groups if there’s a problem downstream, a pond turning red [from silt]. Thus far, we haven’t had that problem; Silt-Saver takes care of that.”

So, the solution is “set it and forget it?” “No,” Stokes explains. “Silt-Savers have to be maintained like anything else. I’ve seen a unit with water and mud to the top of it, yet the filters catch all this stuff. Then we have to go back and clean it out, but it’s better than getting the mud out of the creek, which would be my job to clean up if it happened. I’ve never had one fail—and they take a lot of punishment on the job site.”

High Praise for Low Maintenance
Maintenance of sediment control products can cost a contractor a lot of time, and therefore money. Vice President Will Casey of Boise (ID) Excavation favors Gator Guard Environmental Products because the brand requires very little maintenance.

“We inspect our Gator Guards weekly, and after rain events, but they require very little extra maintenance,” Casey says. “That’s one reason we’ve been using them for the past few years, in direct replacement of silt fences or wattles—it requires little or no maintenance. The products are also reusable, and we use them a lot in high-traffic areas, because they won’t be damaged by vehicles or equipment. With wattles and other straw products, if you run over it one time, or hit it with a backhoe, it breaks apart—the same happens with silt fences.”

Billed as a “reusable sediment control wattle,” Gator Guards are constructed from UV-resistant geotextile and stuffed with recycled foam. A new 25-foot roll weighs but 7 pounds; and, because it’s made of sturdier components, it supposedly can survive more vehicle “accidents” (trucks and tractors running over it). Once cut to fit a particular area, the Gator Guard’s ends can be repaired with simple caulk.

Do customers, who might miss seeing more traditional silt fences or wattles, readily accept alternative products? “Once in a while a client will ask about fences or wattles, but once we explain why we’re using Gator Guard the client is very supportive,” says Casey. As the Gator Guard company is located in Boise, the products are gaining wider acceptance: “Locally, Gator Guard has been spec’d out as a direct replacement for wattles,” Casey adds.

 It’s difficult to pin down “typical” sediment control costs for a job. “It depends on the project,” Casey says. “On average, it’s probably 2% to 5% of the overall project cost, but that varies on terrain and location. Actually, Gator Guards are cheaper than the other products we use—the budget is probably 1% spent on Gator Guard versus 3% on other products.

“We install them in the initial phase of a project, and then we take them away when that phase is finished. They can be reused; as for their average life—we can probably do up to three projects with the same ones.”

He continues, “The whole erosion control industry is changing dramatically now, based on new implementation and new products. The field is changing all the time. We don’t see public groups checking on, or inspecting, our sites, but the state and local governments are seeing more public awareness of the need for erosion control and for keeping silts out of waterways. And there are many waterways to protect around here; we have a lot of rivers, streams, and irrigation canals. The state also contains a variety of landscapes that need to be protected—from steep mountains to flatlands.”

Wattles Work in the Wild
In the Columbus and Franklin County (OH) Metro Parks, straw wattles are still the preferred sediment stopper, because the bulk of the park district’s work is performed in natural settings, and the wattles can be left in place after the construction work is completed.

Photo: Gator Guard

Shoveling 1 inch of dirt on the Gator Guard's apron helps keep it in place.

“Sometime we take the wattles out when the job is finished, sometimes not,” explains Steve Brown, chief landscape architect. “If we’re not planning on mowing, we leave them there. Ground cover can grow around it and make it less noticeable, and the wattle can degrade after it’s served its purpose.” If the site to be worked on has greater than a 6% to 8% slope, wattles can still be used, he says, “but then you need to use more than one row. We might put two to three rows of wattles progressively up the slopes.”

The county uses wattles from EarthCo Inc., available in three sizes: 25 feet long and 9 inches in diameter; 20 feet long and 12 inches in diameter; and 10 feet long and 18 inches in diameter. In some instances, the wattles may be removed to another location; in most cases, however, vegetation grows into the wattles, blending them into the landscape. Even wattles that may have been destroyed onsite serve a purpose, as the straw can readily be used for mulching newly seeded areas.

Brown notes that wattles have “good” and “bad” points. “Wattles aren’t highly visible, so you can leave them there—whereas a silt fence, you can see it really well, which is not great for a park setting. On the other hand, as wattles do blend into vegetation, those people concerned with erosion control might wonder, ‘Are there really controls in there?’—whereas the silt fence is obvious. But then we can leave wattles in place; they have more capabilities to hold back erosion, and they’re not unsightly. Wattles are nearly maintenance free—and some silt fences get knocked over.”

Metro Parks generally uses wheat straw wattles (“We specify that it have no weed seed in it,” Brown says) in 8- and 10-inch diameters. “Wattles are constructed of netting filled with straw materials,” Brown explains. “Made in 20-foot lengths, you cut them to fit. They’re fairly durable; you can move them around, even run over them with a truck—you don’t want to do that, but it doesn’t destroy the wattle. With a little reshifting of its contents, it bounces back. We also use them for ditch checks that are used adjacent to bike paths we may have created. These ditch checks are just used during construction, and they can stay in place anywhere from a month to six months or so until we get good vegetative cover, which will curb erosion.”

Photo: EarthCo

EarthCo's straw wattles are dense enough to hold water back.

Wattles are Brown’s leading weapons for preventing sediment runoff in area water sources. “Our area is part of a drainage basin of the Olentangy River. The Scioto River, and the Big and Little Darby creeks on the west side, are also of concern; they’re state and national scenic rivers. The Ohio and USEPA, as well as public groups, keep their eyes on these waterways. We have to maintain them—they’re popular fishing areas, which require good water quality.”

Brown also uses other EC measures. “Wattles are not the only thing we use; we also use some silt fences, depending upon applications, straw bales for ditch checks, and retention ponds, and we’ll often temporarily seed sites that will be barren for some period.”

During a typical parks project, what percentage of its cost is earmarked for erosion control? “That depends on the site—a lot of projects we do are situated along streambanks and adjacent to creeks and streams, which we need to protect. They’re nearly the entire edge of the construction site,” Brown says. “I would say, in recent jobs, if the total cost is $800,000 to $1 million, about $40,000 to $50,000 is spent on erosion control, once you include all the temporary seeding and so on.”

Some of these projects in the Metro Parks, which include 23,000 total acres of land, take from three months to a year to complete. “Most work is done by outside contractors. They install and maintain the wattles, but we tell them how the project should be done,” Brown explains. The average Columbus and Franklin County Metro Park is in the 1,000-acre range, and most are natural area parks for conservation, preservation, and passive recreation, such as nature trails and picnic areas; there is no playground equipment or baseball diamonds.

In addition to the regulations in place due to NPDES Phase II, Brown’s parks come under the close scrutiny of local and state governments (Columbus is Ohio’s capital), as well as citizen groups. “I don’t know that NPDES Phase II has increased public concern, but it put more restrictions on what you can do, what measures, and it has added to people being more aware that erosion control has to be in place. There were some recent ODOT construction jobs in Columbus during which the public questioned the erosion control work that was being done,” he says.

“We work around a lot of waterways, which have spawned many neighborhood watch groups—‘Friends of whatever creek or stream.’ Once in a while, a public group will say, ‘Gee, this erosion control needs to be improved.’ People are more aware of erosion control overall.”

Janis Keating is a frequent contributor to Forester Communications publications.

EC - November/December 2006