Not Just Temporary Solutions
Rolled EC products are used in combination with other techniques as part of long-term designs.
By
Donna Gordon Blankinship
Engineers and managers of erosion control projects are finding new and creative ways to use erosion control blankets and turf reinforcement mats, and not just as temporary solutions. As products improve and new installation techniques are developed, these mats and blankets make it possible to give sites the erosion protection they need while maintaining a beautiful green façade.
Other trends include the increasing popularity of using native plants and the combining of hard- and soft-armor techniques in many projects. In some cases, engineers and project managers who had originally planned to use a hard-armor technique changed their minds and went for these rolled erosion control products. They switched gears because of the ease of installation and the way blankets and mats can help jobs look and feel finished faster.
A good example of this change in direction midway through the planning process is a project recently completed in Springfield, MO. Civil engineering firm URS and contractor Hartman & Co. Inc. were hired by the City of Springfield to line a stormwater channel upstream from a sinkhole that was being protected as part of an underground cavern system. The challenges included keeping as much silt and as many pollutants out of the sinkhole as possible. The city also wanted to create a natural setting inside this residential area.
“We have to be careful about what stormwater goes down [the sinkhole] because it eventually ends up in the groundwater,” explains Michael Holesapple, a design engineer from URS’s Springfield office.
Project managers originally looked at using cement blocks chained together in a mat to replace the existing concrete-lined channel. Holesapple says they first considered just two options: another concrete-lined channel or the cement-block mat. They chose the block mat, but then changed their minds in the middle of the design stage after seeing a presentation of Erosion Solutions’ StayTurf. Instead of adding concrete to the area, they decided to pull out all the existing concrete and use the prevegetated erosion mat to create a little park for area residents that would serve as a pond as large as 2 acres during the rainy season.
“It upset some of the skateboarders around there,” says Larry Henderson, estimator and project administrator for Hartman & Co. Inc., but everyone else involved thinks the project—installed in a buffer zone between commercial property and a residential area in early November 2005—was a big success.
Henderson says they decided on StayTurf because the relatively new prevegetated mats had already proven their ability to stay put and because they start doing their sediment filter work right away. There was no need to wait for plants to grow before the sediment work could begin. Henderson says they seeded some other parts of the project that would not experience the fast-flowing water they expect in the channel. “We might be lucky to get some growth this year. We had an unseasonably warm November, but it will probably be next summer before the grass has a good stand,” he notes.
In comparison, the 28-foot-wide, 850-foot-long channel was installed in one day, and after 10 days of water it was “pretty much established,” Henderson says. That’s 2,700 square yards of erosion mat installed in one day. He also cites economics as another reason for the choice—not because the mat was less expensive than other options but because he expects it will last longer and not need replacing or fixing as would other approaches.
Jon Crider of Erosion Solutions says StayTurf has been tested at the Texas Transportation Institute to withstand 12 pounds per square foot of shear force, which is why it can be used in situations where riprap or other hard armor would have been the previous choice. He says the product is fairly flexible: The client can choose any kind of vegetation it wants in the mat. The product was developed about 20 years ago in Australia and has been sold in this country only in the past few years. It includes the vegetation, a jute blanket that is almost entirely biodegradable, and UV-treated polymer netting. The plants are allowed to grow in the mat for up to 10 weeks before the mat is cut into 10-foot-wide by 40-foot-long rolls and installed.
Crider says it hasn’t been easy getting his new product to the market, but he believes its strength will be its biggest selling point as an alternative to concrete or riprap. The turf mats are produced on a farm in Rossville, KS, but Erosion Solutions sells to companies all over North America.
A native fescue was used to seed the mat for the Springfield project. It’s a common plant for the area and well suited to the climate, Holesapple notes. He says the success of a product like this depends a lot on site preparation, including the amount of topsoil on the ground and the right mix of dirt and water. Very dry or very wet conditions make the installation more difficult, he says, adding that the unusually nice November weather was just right for this installation.
“From what I saw, it seemed very easy to install. They appeared to be moving very quickly through the project,” Holesapple says.
A $1 Million ProjectFor some jobs, speed is not even a consideration. The Leona Quarry project, for example, is such a massive undertaking that speed of completion is barely on the list of concerns. Peter Helseth, project engineer for DeSilva Gates Construction of Dublin, CA, says erosion control efforts have totaled more than $1 million at this future home site that for years was the region’s major rock quarry.
The quarry opened in 1904 and was the main quarry for the Bay Area for more than half a century. Every big construction project in the Oakland area included rocks from Leona Quarry. Later, it slowly transitioned out of the rock-cutting business and focused mainly on materials recycling. Until The DeSilva Group, the company’s development arm, began transforming the quarry into home sites, it was known by everyone who grew up in the area as the ugly brown scar on a hill of green.
David Chapman, project manager with The DeSilva Group, believes this project is unusual in many ways, including holding the distinction of being one of the only working quarries in the nation to go directly from quarry to end use without sitting for a while in a reclamation stage. Because the quarry has never been officially closed down, it is still considered by the government to be a working quarry even though no one has cut rock there in decades. The transition from quarry to development must include leaving the property in a clean-draining and safe situation.
“Anyone would have to be impressed to see what we’ve done there,” Chapman says with the pride of getting close to finishing a job that has been a real challenge for years, including more than a year fighting a lawsuit to prevent the project from going forward. It will be another three to five years before the estimated 427 homes—including houses, townhouses, and condos—are complete. The schedule of completion will depend on how quickly the units sell.
Before a single home could be sold at the Leona Quarry site, a whole lot of regrading and erosion control work had to be done, which took about 18 months. Helseth says that during those 18 months, 3.6 million cubic yards of dirt were moved. “We moved it onsite from top to bottom, and shuffled it all around to make this work.” He adds that they came within about 10,000 cubic yards of balancing.
Next, workers installed more than 41,000 feet of sub-drain and almost 27,000 feet of concrete ditches and put down 6,000 tons of asphalt and 18,000 tons of aggregate. The biggest challenge of the project, however, is not its size but its slope, which includes 750 feet of elevation change from top to bottom at about a 3:1 slope. To keep the dirt in place and to cover up the bare rock with vegetation, several different erosion control approaches were taken.
Helseth says about 150,000 square yards of Western Excelsior’s erosion control blankets were installed on this project. The product used was a coconut straw blanket with a burlap weave. Next, more than 6,000 plants were planted to revegetate the slopes. All the plants were native and were taken as seeds and cuttings from local plants in 2004, a year before they were planted at the quarry.
One special consideration of this project was the requirement by state and national laws to provide habitat for the Alameda whipsnake, which is on the threatened species list. Helseth says some people believe the snake disappeared during the days the quarry was operating. “If there is one that wasn’t killed by the quarry, it will have a habitat,” he says. “We are creating another 27 acres of habitat in case the snake ever does get reintroduced.”
A large variety of native plants were used in the project, including nearly 20 species from California sagebrush to orange bush monkey flower to Mexican rush. Helseth expects the area to be lovely after the plants are well established.
 |
PHOTO: PROPEX FABRICS |
| A slope at the Lakeside development in Oklahoma City |
To revegetate the cut slope, more than 2,000 planting holes were drilled into the rock. Then a compost and hydroseed mixture was applied, and the area was covered with erosion control blankets and about 45,000 square feet of straw wattles. A water-detention pond, which can hold up to 26 acre-feet of water, was designed for a 100-year flood. A filtration system was installed for the water in this system.
Helseth says it was necessary to use a variety of erosion control solutions for this project, varying the choices according to the individual topography of the site and the future use of the land. For example, more temporary and less attractive solutions were used on the house pads, such as straw “glued” together with a tackifier. “Our goal was to have 100% of the slopes treated with something,” Helseth says of the 128-acre site.
Mixing It UpFinding the right combination of erosion control products was one of the biggest challenges for Tallgrass Environmental Solutions when the company signed on as a subcontractor on the Lakeside of Oakdale housing development project in Oklahoma City, OK. At the center of the project was a 23-acre recreational lake bordered by a 1,400-foot dam. The bank around the lake was a 3:1 or greater slope. “We had some pretty gnarly slopes out there,” says Joshua Rasp, vice president and project manager of Tallgrass, a company he started more than a year ago after moving back home to Oklahoma from Colorado.
Tallgrass was contracted to find the best management practices to make sure the slopes at the site were stabilized and vegetated as the lake filled with water and home construction began. Alan Berry with Propex of Austell, GA, notes that this site had “ample opportunities for soil erosion.” Rasp had worked with Propex products in the past and called the company for help because he planned on using its SuperGro erosion control fabric again.
Rasp first had to do a bit of a sales job convincing the developer that it was a good idea to ignore conventional wisdom and not just put down a bunch of Bermuda grass sod and call the job finished. He admits he brought some western ideas back with him to Oklahoma. One was the value of using native grasses to seed an area because they are more beautiful, do a better job of erosion control, help filter silt out of stormwater, and are much easier to maintain than conventional grass, which must be mowed and weeded.
The next challenge was to convince people involved in the project that they needed to do a thorough job and not just the bare minimum of seeding and slope reinforcement. “If you want peace of mind, there’s no substitute for doing things right from the start,” Rasp says. “That gives you peace of mind when the thunderstorms start rolling in.”
 |
PHOTO: TENNESSEE DOT |
 |
PHOTO: TENNESSEE DOT |
| A roadside swale during construction and after vegetation has grown in |
After the mulch and turf reinforcement fabric were installed on this project in spring 2005, the weather gave Rasp an opportunity to thoroughly test his work. Three big rainstorms in a row dropped 4 inches over a few days. “The products were really put to a test not long after being installed. I sweated some bullets.” But he adds that the project held up just fine even though the native grasses had just begun to grow. “An ounce of prevention is worth a pound of cure,” he says.
Rasp used a variety of products on the project, but most of his work involved paper mulch from Mat Inc. of Floodwood, MN, topped by rolls of SuperGro. The seed mix he used included more than 60 varieties of grasses and wildflowers. After the slopes were hydroseeded, about 15,000 square yards of the reinforcement fabric were installed over the mulch and seeds.
“Due to the geometry of the slopes, it was decided to install SuperGro parallel to the slopes. This is an acceptable method of installation because SuperGro does not require check trenches like most rolled erosion control products,” Berry explains. By installing the fabric “sideways,” the workers saved time and effort.
Rasp says the project was a great opportunity for his company to try out some new things and to showcase the newest erosion control products. “I was able to show my developer exactly what we can do with a lot of the innovations that are out there.”
 |
PHOTO: TENNESSEE DOT |
| Erosion control fabric staked on a roadside slope |
By the end of the season, the grass was already looking like the native prairie it was planted to imitate and had grown up to 4 feet tall by the end of August.
The downside to this approach is the extra time needed to learn how to install the various products. Rasp says he probably wouldn’t try so many new things on one job again, but when you’re new to the neighborhood, sometimes you have to do some extra work to demonstrate how capable your company is.
“From a productivity standpoint, we do need to find the products that work best and stick with them,” he says, adding that Tallgrass took what it learned at the Lakeside project and applied those lessons to the rest of its work last season. One change he’s made is to now use a wood-paper combination mulch instead of the paper mulch. Both products are made by Mat Inc.
Rasp hopes to use projects like this to establish his company as the most innovative and effective erosion control business in his area. “If you can build a reputation for your company, you don’t need to be the cheapest guy on the block,” he says.
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His goal is to get contractors in Oklahoma to think more about the future and a little bit less about the immediate cost of things. Rasp admits that’s not a very easy sell in Oklahoma, where water is still not a precious resource the way it is in much of the West. “People are more worried about today and not so worried about the future,” he says.
He’s hoping his work can turn some heads and change some minds.
March-April 2006
Not Just Temporary Solutions
Rolled EC products are used in combination with other techniques as part of long-term designs.
By
Donna Gordon Blankinship
Engineers and managers of erosion control projects are finding new and creative ways to use erosion control blankets and turf reinforcement mats, and not just as temporary solutions. As products improve and new installation techniques are developed, these mats and blankets make it possible to give sites the erosion protection they need while maintaining a beautiful green façade.Other trends include the increasing popularity of using native plants and the combining of hard- and soft-armor techniques in many projects. In some cases, engineers and project managers who had originally planned to use a hard-armor technique changed their minds and went for these rolled erosion control products. They switched gears because of the ease of installation and the way blankets and mats can help jobs look and feel finished faster.
A good example of this change in direction midway through the planning process is a project recently completed in Springfield, MO. Civil engineering firm URS and contractor Hartman & Co. Inc. were hired by the City of Springfield to line a stormwater channel upstream from a sinkhole that was being protected as part of an underground cavern system. The challenges included keeping as much silt and as many pollutants out of the sinkhole as possible. The city also wanted to create a natural setting inside this residential area.
“We have to be careful about what stormwater goes down [the sinkhole] because it eventually ends up in the groundwater,” explains Michael Holesapple, a design engineer from URS’s Springfield office.
Project managers originally looked at using cement blocks chained together in a mat to replace the existing concrete-lined channel. Holesapple says they first considered just two options: another concrete-lined channel or the cement-block mat. They chose the block mat, but then changed their minds in the middle of the design stage after seeing a presentation of Erosion Solutions’ StayTurf. Instead of adding concrete to the area, they decided to pull out all the existing concrete and use the prevegetated erosion mat to create a little park for area residents that would serve as a pond as large as 2 acres during the rainy season.
“It upset some of the skateboarders around there,” says Larry Henderson, estimator and project administrator for Hartman & Co. Inc., but everyone else involved thinks the project—installed in a buffer zone between commercial property and a residential area in early November 2005—was a big success.
Henderson says they decided on StayTurf because the relatively new prevegetated mats had already proven their ability to stay put and because they start doing their sediment filter work right away. There was no need to wait for plants to grow before the sediment work could begin. Henderson says they seeded some other parts of the project that would not experience the fast-flowing water they expect in the channel. “We might be lucky to get some growth this year. We had an unseasonably warm November, but it will probably be next summer before the grass has a good stand,” he notes.
In comparison, the 28-foot-wide, 850-foot-long channel was installed in one day, and after 10 days of water it was “pretty much established,” Henderson says. That’s 2,700 square yards of erosion mat installed in one day. He also cites economics as another reason for the choice—not because the mat was less expensive than other options but because he expects it will last longer and not need replacing or fixing as would other approaches.
Jon Crider of Erosion Solutions says StayTurf has been tested at the Texas Transportation Institute to withstand 12 pounds per square foot of shear force, which is why it can be used in situations where riprap or other hard armor would have been the previous choice. He says the product is fairly flexible: The client can choose any kind of vegetation it wants in the mat. The product was developed about 20 years ago in Australia and has been sold in this country only in the past few years. It includes the vegetation, a jute blanket that is almost entirely biodegradable, and UV-treated polymer netting. The plants are allowed to grow in the mat for up to 10 weeks before the mat is cut into 10-foot-wide by 40-foot-long rolls and installed.
Crider says it hasn’t been easy getting his new product to the market, but he believes its strength will be its biggest selling point as an alternative to concrete or riprap. The turf mats are produced on a farm in Rossville, KS, but Erosion Solutions sells to companies all over North America.
A native fescue was used to seed the mat for the Springfield project. It’s a common plant for the area and well suited to the climate, Holesapple notes. He says the success of a product like this depends a lot on site preparation, including the amount of topsoil on the ground and the right mix of dirt and water. Very dry or very wet conditions make the installation more difficult, he says, adding that the unusually nice November weather was just right for this installation.
“From what I saw, it seemed very easy to install. They appeared to be moving very quickly through the project,” Holesapple says.
A $1 Million ProjectFor some jobs, speed is not even a consideration. The Leona Quarry project, for example, is such a massive undertaking that speed of completion is barely on the list of concerns. Peter Helseth, project engineer for DeSilva Gates Construction of Dublin, CA, says erosion control efforts have totaled more than $1 million at this future home site that for years was the region’s major rock quarry.
The quarry opened in 1904 and was the main quarry for the Bay Area for more than half a century. Every big construction project in the Oakland area included rocks from Leona Quarry. Later, it slowly transitioned out of the rock-cutting business and focused mainly on materials recycling. Until The DeSilva Group, the company’s development arm, began transforming the quarry into home sites, it was known by everyone who grew up in the area as the ugly brown scar on a hill of green.
David Chapman, project manager with The DeSilva Group, believes this project is unusual in many ways, including holding the distinction of being one of the only working quarries in the nation to go directly from quarry to end use without sitting for a while in a reclamation stage. Because the quarry has never been officially closed down, it is still considered by the government to be a working quarry even though no one has cut rock there in decades. The transition from quarry to development must include leaving the property in a clean-draining and safe situation.
“Anyone would have to be impressed to see what we’ve done there,” Chapman says with the pride of getting close to finishing a job that has been a real challenge for years, including more than a year fighting a lawsuit to prevent the project from going forward. It will be another three to five years before the estimated 427 homes—including houses, townhouses, and condos—are complete. The schedule of completion will depend on how quickly the units sell.
Before a single home could be sold at the Leona Quarry site, a whole lot of regrading and erosion control work had to be done, which took about 18 months. Helseth says that during those 18 months, 3.6 million cubic yards of dirt were moved. “We moved it onsite from top to bottom, and shuffled it all around to make this work.” He adds that they came within about 10,000 cubic yards of balancing.
Next, workers installed more than 41,000 feet of sub-drain and almost 27,000 feet of concrete ditches and put down 6,000 tons of asphalt and 18,000 tons of aggregate. The biggest challenge of the project, however, is not its size but its slope, which includes 750 feet of elevation change from top to bottom at about a 3:1 slope. To keep the dirt in place and to cover up the bare rock with vegetation, several different erosion control approaches were taken.
Helseth says about 150,000 square yards of Western Excelsior’s erosion control blankets were installed on this project. The product used was a coconut straw blanket with a burlap weave. Next, more than 6,000 plants were planted to revegetate the slopes. All the plants were native and were taken as seeds and cuttings from local plants in 2004, a year before they were planted at the quarry.
One special consideration of this project was the requirement by state and national laws to provide habitat for the Alameda whipsnake, which is on the threatened species list. Helseth says some people believe the snake disappeared during the days the quarry was operating. “If there is one that wasn’t killed by the quarry, it will have a habitat,” he says. “We are creating another 27 acres of habitat in case the snake ever does get reintroduced.”
A large variety of native plants were used in the project, including nearly 20 species from California sagebrush to orange bush monkey flower to Mexican rush. Helseth expects the area to be lovely after the plants are well established.
|
PHOTO: PROPEX FABRICS |
| A slope at the Lakeside development in Oklahoma City |
To revegetate the cut slope, more than 2,000 planting holes were drilled into the rock. Then a compost and hydroseed mixture was applied, and the area was covered with erosion control blankets and about 45,000 square feet of straw wattles. A water-detention pond, which can hold up to 26 acre-feet of water, was designed for a 100-year flood. A filtration system was installed for the water in this system.
Helseth says it was necessary to use a variety of erosion control solutions for this project, varying the choices according to the individual topography of the site and the future use of the land. For example, more temporary and less attractive solutions were used on the house pads, such as straw “glued” together with a tackifier. “Our goal was to have 100% of the slopes treated with something,” Helseth says of the 128-acre site.
Mixing It UpFinding the right combination of erosion control products was one of the biggest challenges for Tallgrass Environmental Solutions when the company signed on as a subcontractor on the Lakeside of Oakdale housing development project in Oklahoma City, OK. At the center of the project was a 23-acre recreational lake bordered by a 1,400-foot dam. The bank around the lake was a 3:1 or greater slope. “We had some pretty gnarly slopes out there,” says Joshua Rasp, vice president and project manager of Tallgrass, a company he started more than a year ago after moving back home to Oklahoma from Colorado.
Tallgrass was contracted to find the best management practices to make sure the slopes at the site were stabilized and vegetated as the lake filled with water and home construction began. Alan Berry with Propex of Austell, GA, notes that this site had “ample opportunities for soil erosion.” Rasp had worked with Propex products in the past and called the company for help because he planned on using its SuperGro erosion control fabric again.
Rasp first had to do a bit of a sales job convincing the developer that it was a good idea to ignore conventional wisdom and not just put down a bunch of Bermuda grass sod and call the job finished. He admits he brought some western ideas back with him to Oklahoma. One was the value of using native grasses to seed an area because they are more beautiful, do a better job of erosion control, help filter silt out of stormwater, and are much easier to maintain than conventional grass, which must be mowed and weeded.
The next challenge was to convince people involved in the project that they needed to do a thorough job and not just the bare minimum of seeding and slope reinforcement. “If you want peace of mind, there’s no substitute for doing things right from the start,” Rasp says. “That gives you peace of mind when the thunderstorms start rolling in.”
|
PHOTO: TENNESSEE DOT |
|
PHOTO: TENNESSEE DOT |
| A roadside swale during construction and after vegetation has grown in |
After the mulch and turf reinforcement fabric were installed on this project in spring 2005, the weather gave Rasp an opportunity to thoroughly test his work. Three big rainstorms in a row dropped 4 inches over a few days. “The products were really put to a test not long after being installed. I sweated some bullets.” But he adds that the project held up just fine even though the native grasses had just begun to grow. “An ounce of prevention is worth a pound of cure,” he says.
Rasp used a variety of products on the project, but most of his work involved paper mulch from Mat Inc. of Floodwood, MN, topped by rolls of SuperGro. The seed mix he used included more than 60 varieties of grasses and wildflowers. After the slopes were hydroseeded, about 15,000 square yards of the reinforcement fabric were installed over the mulch and seeds.
“Due to the geometry of the slopes, it was decided to install SuperGro parallel to the slopes. This is an acceptable method of installation because SuperGro does not require check trenches like most rolled erosion control products,” Berry explains. By installing the fabric “sideways,” the workers saved time and effort.
Rasp says the project was a great opportunity for his company to try out some new things and to showcase the newest erosion control products. “I was able to show my developer exactly what we can do with a lot of the innovations that are out there.”
|
PHOTO: TENNESSEE DOT |
| Erosion control fabric staked on a roadside slope |
By the end of the season, the grass was already looking like the native prairie it was planted to imitate and had grown up to 4 feet tall by the end of August.
The downside to this approach is the extra time needed to learn how to install the various products. Rasp says he probably wouldn’t try so many new things on one job again, but when you’re new to the neighborhood, sometimes you have to do some extra work to demonstrate how capable your company is.
“From a productivity standpoint, we do need to find the products that work best and stick with them,” he says, adding that Tallgrass took what it learned at the Lakeside project and applied those lessons to the rest of its work last season. One change he’s made is to now use a wood-paper combination mulch instead of the paper mulch. Both products are made by Mat Inc.
Rasp hopes to use projects like this to establish his company as the most innovative and effective erosion control business in his area. “If you can build a reputation for your company, you don’t need to be the cheapest guy on the block,” he says.
His goal is to get contractors in Oklahoma to think more about the future and a little bit less about the immediate cost of things. Rasp admits that’s not a very easy sell in Oklahoma, where water is still not a precious resource the way it is in much of the West. “People are more worried about today and not so worried about the future,” he says.
He’s hoping his work can turn some heads and change some minds.