The job sounded simple enough. Matt Patterson and the rest of his crew from the Irving, TX, office of American Civil Constructors were called in to restore the eroding banks of a creek that ran along the property of a large residential estate in the northern section of Dallas.
The job turned out to be anything but ordinary. Patterson, a superintendent with American Civil Constructors, and his crew had to deal with stands of mature trees that the property’s owners wanted to protect. They also had to work around existing bridges and retaining walls, which the owner also didn’t want damaged or removed.
The biggest challenge, though? To firmly attach the coir mats they were using, crew members had to first drill dozens of holes into the creek’s limestone bottom. This took six days.
“That was certainly time consuming,” Patterson says. “We had to drill along about 400 linear feet in about a 25-foot width. That wasn’t the easiest, or quickest, part of the job.”
Still, Patterson and his crew did finish the work successfully. “The mat is working really well right now,” Patterson notes. “It’s strong stuff. We use a lot of rolled erosion control products. They’re flexible, the ones we use biodegrade naturally, and they do a good job.”
Patterson is far from the only erosion control expert turning more frequently to rolled erosion control products. Engineers, highway department officials, builders, and developers are all adding rolled products-blankets and turf reinforcement mats (TRMs), mostly-to their project specifications.
There are many reasons for the growing popularity of these products. The tougher National Pollutant Discharge Elimination System (NPDES) Phase II regulations have driven many contractors and developers to turn to rolled products to prevent erosion and to help establish permanent vegetation as a post-construction erosion control measure. At the same time, more states are writing rolled products into their best management practice (BMP) specifications.
Then there’s the fact that builders, especially those tackling residential projects, are more frequently constructing their new housing subdivisions on hilly and sloped land. They need mats and blankets to keep soil in place on such difficult building sites.
The manufacturers of blankets, mats, wattles, and other rolled products say they expect even more engineers, developers, and builders to call for the products.
“NPDES provided a snowball effect,” comments Lynne Finney of North American Green. The Evansville, IN, company produces a variety of temporary erosion control mats and TRMs. “Contractors are seeing that the regulations are enforced; there are fines and court orders actually being placed on companies and contractors for not following the rules. They were kind of forced to try these blankets, see what it’s all about, rather than blowing straw or using hay bales. And then all of a sudden they realize, “˜Hey, I’m not going back two or three times to this certain project because these blankets actually work.'”
This growth, however, brings both good and bad news. More demand, for example, also brings out more competitors.
“There are a lot of blanket manufacturers out there now,” says Bob Moran of Belton Industries in Norcross, GA. “It’s a growing marketplace, and one that’s grown very competitive. Five years ago, it seemed, there were only about four of us. Now there are 18 or 19. It’s not hard for these new competitors to see that this is a growth market. There’s not a huge financial barrier to getting into the market in terms of dollars. And with business increasing, a lot of people are giving it a chance.”
With the demand for rolled products steadily increasing, here’s a look at how blankets, mats, coir logs, and related products are used; what benefits they bring to a project; and what factors have influenced their growing popularity.
Products for All Projects
Rolled products are nothing new. Engineers and builders have been using them for decades to control erosion on their construction sites. But the products today have gained a firmer footing in the industry, especially among those developers seeking to control erosion effectively without spending a small fortune.
“Rolled products are durable, they last long, and they perform well,” says Lanka Santha, chief executive officer of RoLanka International Inc., a manufacturer of biodegradable blankets in Stockbridge, GA. “So many other erosion control products are temporary applications. At the end of a project, the crew members have to remove it and take it to a landfill. We try to avoid that. Our products are biodegradable and earth-friendly. That is the main focus of our product line.”
Blankets and mats are also flexible, products that contractors can use on a variety of projects. And that more than anything-more than NPDES Phase II regulations and BMP requirements-may explain their rising popularity.
Consider erosion control blankets. These lightweight products, often with photodegradable or biodegradable netting and filled with materials like straw or wood excelsior, protect the ground well, even on difficult, sloping sites. Blankets provide seeds with time to become established-often in one growing season-before they completely degrade. Then, once natural plant life has taken hold, a natural erosion control protection is firmly in place.
Turf reinforcement mats are heavier products, usually made out of nylon or plastic net and mesh and durable fiber such as coir. Engineers call for mats when they need a product that will last several years, even after vegetation has become established on the site. Contractors will often call for turf reinforcement mats in drainage channels as substitutes for concrete or riprap, for example. The mats are a more aesthetically pleasing option when aesthetics is a prime concern.
Other contractors rely on a combination of products, both synthetic and natural. They may use everything from old logs to thick bushes to supplement the protection provided by mats or blankets.
“We work with departments of transportation, with private companies, and in environmentally sensitive areas,” Moran says. “We get called in when people need something effective but also biodegradable. More contractors today are aware of the government legislation out there, and we’re often working on land that is far from flat. A lot of that good, flat land is gone. It’s already been built on. You have a lot of steep slopes now on housing sites. They need products like ours to control the erosion and to avoid sometimes heavy fines.”
For Patterson, erosion control blankets and turf reinforcement mats were the obvious choices for his creek restoration in Dallas, a project wrapped up early this year after 18 months of work. American Civil Constructors chose to use mainly RoLanka International’s BioD-Mat 70, a semi-permanent coir woven mat designed to last four to six years before biodegrading. Patterson’s crew also relied on 12-inch coir wattle logs to complete its work.
The owner of the 4-acre property called in American Civil Constructors because heavy rains had slowly but steadily eroded the banks of a creek snaking through his estate’s grounds. Patterson and his crew’s job was to restore the banks and keep the rising waters in place.
“With the amount of money being spent on the property, it was illogical not to address the condition of the banks,” Patterson says.
The biggest challenge came from drilling the small holes in the creekbed. To do this, crew members used an air-compressed pneumatic drill to create a series of holes each measuring an inch-and-three-eighths. Workers then fixed the RoLanka mats in place by tying them into the fresh holes with zip ties.
Once workers had laid this base material, they were then able to add soil, live plant material, and hardwood mulch to the banks. American Civil Constructors choose such plant material as wild honeysuckle and sumac, plants that traditionally do well in the poor-quality north Dallas soil.
Before doing any of this, though, Patterson had to gain approval from the City of Dallas, which meant following its extensive list of stormwater control measures. For instance, Patterson had to first get approval from the city to enter the creek with drilling machinery before the workers could bore their securing holes. Workers also had to install silt fence around the site as a temporary sediment control measure to prevent soil from being dumped into the creek during the restoration process.
In all, workers went through 15 rolls of mats, with each roll containing 1,072 square feet of material.
“Overall, this material is some pretty strong stuff,” Patterson says. “We’re very happy with how it worked. It’s done the job we’ve asked it to do.”
The crew also significantly reduced the grade slope of the creek, something that’s important to prevent future erosion. It is far less likely for the creek’s waters to gouge the bank when its slope is on less of an incline, Patterson says.
Unfortunately, there were several factors that limited the amount of creek slope that Patterson and his crew members could reduce. The property’s owner had several manmade structures in place that he didn’t want removed or damaged. This meant that crews, when installing the mats, had to work around small retaining walls and bridges.
The crews also had to work around several large and mature trees that the owner wanted to preserve. Again, this posed another challenge. Workers had to install some of the coir mats around the bases of these trees. In other instances, they had to first prune away some of these trees’ roots to properly attach the material.
“We had to work with what we had, in the conditions that were set for us,” Patterson says. “But that’s OK. The work has definitely paid off. It was a nice project for us. We restored the banks and protected the property. Everybody is happy with the way things turned out.”
A Varied Approach
Patterson isn’t the only erosion control specialist who is turning more frequently to rolled products. Far from it.
Kent Campbell, vice president of Covington, GA-based EcoSouth Inc., an environmental consulting and design/build firm, counts blankets and mats as key tools in his company’s efforts to restore eroding banks.
In January of this year, EcoSouth finished the restoration of a stream in Cleveland, GA. A large commercial developer called on Campbell and his company to stabilize the highly eroded banks of a degraded stream that ran alongside the future site of a large commercial development. From October through late January, EcoSouth workers installed coir fiber rolls to shore up 1,300 linear feet of banks.
Besides the manmade blankets, EcoSouth’s workers also relied on several natural items to help stabilize the stream’s banks. These included large pieces of woody debris, root logs, and logs cut from large trees. Workers placed chunks of native stone along the stream, too. They also planted native plantings to provide longer-term protection.
Campbell says that this combination of rolled erosion control products and natural buffers provides the most stability for streams and rivers. “We use the natural elements as structure,” Campbell explains. “They provide a diversity of potential habitat for aquatic fauna.”
The logs, for example, work as cover for the stream’s banks. They also serve as veins that redirect the water flow to minimize the amount of stream that pushes up against the banks, thus protecting them from future erosion. The rocks, in combination with the logs, help create in-stream habitats.
“A year from now, when you go out to the site, what will stand out most will be the manmade products that you installed,” Campbell says. “Hopefully, the vegetation will have succeeded in covering the banks. Once you are down in the channel, the natural materials will blend in much faster than will the manmade materials.”
Campbell says it’s this combination of manmade and natural elements that provides the best possible protection against erosion.
“The manmade items, such as the blankets, provide the better short-term stability. They don’t look as natural, though, so we use the natural elements for more of the longer-term protection,” Campbell says. “We are looking for function, of course, not just aesthetics. When you are dealing with streambanks that are highly erosive, you need to maximize the functional capability with the manmade products.”
Increasing Demand
The manufacturers of rolled erosion control products point to the success contractors such as Campbell are having with blankets and mats to explain why their industry is growing so quickly. Success, they say, is the best advertisement.
Of course, increased state and federal pressure to control erosion and prevent sediment runoff doesn’t hurt, either.
“We’ve grown our company every year for the past five years,” says Luke Snyder of Western Excelsior Products, a manufacturer of erosion and sediment control products. “Most of the increase stems from the widespread greater knowledge of the products and how they work. More municipalities and state organizations are getting organized and actually going to these job sites and inspecting them to make sure they are following the erosion control plans that the engineers specify. You combine the regulations, the education about these products, and the organized inspection programs, and that’s where most of the increase stems from.”
If blankets didn’t work well, though, Snyder says, the industry would falter. Engineers would simply find another product that prevented erosion more effectively.
Blankets are an effective alternative to the traditional method of using blown straw to battle erosion, Snyder says. The main problem with blown straw is that contractors have so much leeway in how thick of a blanket of it they can apply, he notes. Some may be tempted to use as little straw as possible to avoid regulation but not quite enough to successfully halt erosion on a job site. When using blankets, though, these sometimes tough decisions no longer rest in the hands of contractors.
“Engineers want the insurance that whatever it is they specify on the job-site plan is going to work and protect the channel or slope from a rain event,” Snyder says. “They know exactly what they are getting when they use an erosion control blanket.
“When using blown straw or hydromulch, depending on how thick the applicator puts the product down, you are going to get varying results,” he says. “With a blanket you can feel confident that what the spec sheet says is what is actually going on the job site. You are going to get better results, more protection. You will see better stands of vegetation when you are using an erosion control blanket.”
Knowing how to use the products effectively is critical, notes Finney of North American Green. The company provides design software to help engineers and project managers design slope, channel, and shoreline protection projects, allowing them to enter their parameters and providing recommendations. North American Green also provides assistance with installation of blankets and mats, both through printed materials and sometimes with onsite assistance through their distributors. “Our specialists will even be available to go onsite after they’ve designed a project for somebody, on the initial installation to help teach them and make sure they understand. It’s a hands-on experience. We feel education is really the key-proper installation, the types of products that are out there, how to use them, when to use them, where to use them, why to use them. We do a lot of brown-bag seminars and are always doing educational presentations to customers.”
The one factor holding back even further growth of the rolled erosion product industry may be cost, says Mark Kimberlin of Greenfix America, a manufacturer of erosion control blankets that is soon moving its headquarters to Woodland, CA.
Kimberlin says that there is little debate that rolled products generally provide more protection than do other less expensive products such as sandbags. But that doesn’t mean, unfortunately, that contractors will always choose rolled products, unless, of course, a job’s specifications or local regulations require it.
“If a developer or contractor has a financial decision to make that is offset with minimal risk, they will obviously turn to a lesser-cost management practice,” Kimberlin says. “We see people putting cost above everything else a lot.”
When his company is asked to evaluate a job’s specifications, Kimberlin says, engineers will recommend the product that will work most effectively. At times, that may mean a more expensive product, he says. Often, contractors or developers will ignore such recommendations and instead opt for a less expensive product that may not work as well for their particular job site, he notes.
“They’ll go with something that is not appropriate for the application, the region, or the area,” he says. “Something that is appropriate for southern California in the summer is not necessarily appropriate for the Pacific Northwest in the summer.”
Even those contractors and developers who do opt for the more costly protection of rolled products don’t necessarily do so for altruistic reasons, Kimberlin says.
“The majority of the time, in my opinion, I see the objective being strictly driven by compliance,” he says. “People want to stay out of trouble. They want to know the lowest-cost way to stay out of trouble. We’ll help people do this, but we won’t compromise the quality of our product. We’ll stick to the select fibers we use in our products. They do come at a little bit of a premium.”
About the Author
Dan Rafter
Related
