Where the Sediment Went
A variety of tools for construction sites
Keeping soil where it belongs is more than just a good erosion control practice—it saves money for contractors in the long run, because they don’t have to purchase truckload after truckload of topsoil for residential developments to replace the soil that escaped. In addition, federal and state regulations are in place to preserve natural waterways; excess sediment can harm wildlife and freshwater resources. Cities and towns want to keep storm sewer lines clear; sediment buildup requires costly mucking out, and, again, many storm drains eventually end up in natural waterways. Although sediment can develop nearly anywhere, anytime, as new construction stirs up quite a bit of dirt, sediment control is usually put in place on day one, and contractors across the nation choose a variety of tools for the purpose.
Getting the Clay Out of the Way
Oxford, GA’s G.K. Walton & Associates Inc. has been using Silt-Saver products to solve its sediment problems.
“We’ve been using Silt-Saver products from the time our company went into business,” says Vice President Todd Christian. “It’s a no-brainer—-there are no failures with their products. Their new BSRF [belted strand retention fence] is one of the best products on the market right now. A lot of companies in the state put in the type C wire-back silt fence, but it doesn’t work as well as the BSRF.”
Silt-Saver, located in Conyers, GA, produces various storm drain and curb inlet filters, as well as the BSRF.
Christian explains differences between the “old” silt fences and the BSRF. “A silt fence is there to ensure that runoff water is as clean as possible. Georgia’s Soil and Water Conservation Commission [GSWCC] writes the state manual of regulations and BMPs, and they expect clear water to exit through silt fence. The water clarity is measured in NTUs [nephelometric turbidity units], and the manual requires runoff water from the site to be 80 NTUs. Oddly enough, while the GSWCC enforces this requirement, the old-style silt fence can’t provide that. After a hard rain, water coming through the BSRF is significantly cleaner—you wouldn’t mind drinking it. Meanwhile, the old standard silt fence has muddy water flowing out.”
Research conducted by the University of Georgia included extensive lab and field testing of the BSRF. “This is the only fabric that has credentials,” Christian explains. “The first time I saw the BSRF and regular silt fences side by side was when we did the installation at the University of Georgia test site. We opened up fire hydrants to the mud, which applied a lot of water pressure.”
G.K. Walton & Associates has done demonstrations of the new fence. “We’re trying to put it on some DOT [department of transportation] jobs here so that people can see it and get behind the product when they understand how well it works. We are installing it now, even though the old style is recommended,” Christian says. “We have done some new Super Wal-Mart sites with the BSRF, and they love it. We’re putting the normal BMPs [best management practices] onsite, then the BSRF behind it to catch the silt the other fence allows through. Customers ask, ‘How can this not already be approved for use in Georgia?’
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Photo: G.K. Walton & Associates Inc. |
| A Georgia site with BSRF installed |
“We have a relationship with many Georgia inspectors,” he goes on. “They’ll say, ‘We’ll let you put it up here,’ and then after they see the results, we have one more person who believes in it. Florida is on board with BSRF. Georgia is going to have to step up because they’re seeing the proven results of it.”
Christian also notes that how a BMP is installed can make a difference for the contractor. “In this business, you lose or make money on the labor. The BSRF can go up using only two people instead of three. You can get BSRF with the wood posts already attached, but we have found we get a better looking installation when we roll it in a mass roll and install it using our own stakes onsite. By comparison, the most time-consuming part of installing a regular silt fence is putting out the wire—we call it hog wire, a mesh metal wire. It’s a three-step process, and it takes much longer.”
When the site is finished, the EC contractor also has to disassemble those fences. “All DOT and commercial sites require removal and disposal of all erosion control products when the project is complete. I would rather take and pay for a half-ton of this waste material instead of a full ton of trash that includes the wire, which adds much more weight,” he says.
On many sites, a variety of ESC measures are used throughout the life of the project. Christian describes a typical job: “Erosion control is a group effort. There is no one thing that does the job. First task on the site is to surround the perimeter with silt fence. This must be done before the construction crew begins grading. In metro Atlanta, all fence has to be installed and inspected before any dirt is moved. We always install the inlet covers, too. We also put in temporary hydroseeding where the grade will be undisturbed for 14 days or more. We add polymer tackifier to hydroseed mix and install straw matting on slopes. The job doesn’t end with those installations. We are onsite until the notice of termination is filed.”
Along with the state inspectors, any firm such as Christian’s is under more scrutiny. “Erosion control is a huge thing in Georgia -- even regular citizens drive around to inspect sites, not just the city and state. I can understand their concern; drainage goes to a retention pond, which eventually goes off site. Property owners are supposed to maintain the pond when it gets to a certain level, but that doesn’t always happen.”
Skimming Off the Bad, Saving the Good
In the town of Cary, NC, Stormwater Field Services Administrator Tom Horstman includes the Faircloth Skimmer surface drain in his EC programs.
“My department oversees projects in this area,” he says. “I have two inspectors in the field making sure erosion control projects are done correctly. The product has been around for a number of years. Faircloth himself used to manage the local EC program at nearby Orange County, and the skimmer was developed from his experience in his field—common sense says if you pull water from the top, you get cleaner runoff. We want the best for our citizens—about two years ago North Carolina made the skimmer one of its BMPs, although we used it about four or five years before then.”
Produced by J.W. Faircloth & Son of Hillsborough, NC, Faircloth Skimmer surface drains float on the surface of a basin, releasing the cleanest water, instead of draining from the bottom as conventional outlets do. The product is available in eight sizes, designed to handle specific flow rates and amounts of water to be skimmed.
Horstman explains some of his department’s tasks: “Private developers submit a plan for a site, whether it’s commercial or residential construction. Our requirements mandate that they use the skimmer, and my people make sure they are installed and used correctly.
“Of course, other EC measures are also used onsite—silt fences, diversion ditches—and, of course, seeding is the best EC measure to use. My guys go out weekly or twice a week—they make the decision on how many times they need to go out—and make sure the denuded areas are being taken care of. Usually, early construction needs more oversight than later stages of construction.”
Cary, a town of 130, 000 people, has also used various other ESC techniques, such as sediment basins with washed stone, but the surface drains are now a standard BMP. “It’s important to note the skimmer requires more maintenance, but construction companies like to work here, so they use it; they’re ready to do what has to be done to make things work. Anything that works better will take a little more maintenance, and they’re ready to step up to the plate,” Horstman says.
The devices are only temporary. “After final seeding, when the asphalt’s down, and the building’s up—then the skimmer’s not needed. It’s installed at the beginning of the project and removed once the site is stabilized.” The Faircloth Skimmer surface drain is reusable.
“If the site encompasses only a quarter-acre, only a silt fence might be required. Any larger than that, though, and you need skimmers. For a big site, several will be needed. Most of the time, they’re put on the lower end of the site, but you do have to guide the water; that’s what a diversion ditch does. The location of these ditches can change on a daily basis—and often a site will need more ditches. Once you put in storm drains, they discharge to a temporary or a permanent device and then to a skimmer. When the site is finished, drains are connected to the stormwater system.”
Better Control Through Chemistry
A large residential subdivision not only stirs up a lot of soil during its construction; such developments are also often sited near water features for aesthetic reasons. Such a project requires quite a bit of erosion control, as Scott Thorne, CPESC, division compliance manager for Centex Homes’ Sacramento Division in Roseville, CA, knows well.
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Photo: SpreadRite Organics |
| The tubes can be left in place; these have been seed-injected and filled with compost. |
 |
Photo: SpreadRite Organics |
| Palletized Filtrexx SiltSoxx at SpreadRite Organics’ Chelsea Recycling Yard, ready for delivery to the job site |
“Usually there’s drainage of some sort around all our projects,” he says. “Once we put in roads and underground utilities, the water goes back to where it used to run. This drainage could be natural, or a city or county system. Most are storm drain systems—metal, concrete, or plastic pipes which drain into a basin or diversion channels.”
Centex Sacramento uses Fairfield, CA’s Protech General Contracting Services for many of its EC maneuvers. Protech, a full-service environmental compliance company, specializes in water treatment for stormwater control, sediment or contaminant removal, and pollution prevention. “Protech provides us with materials for lining channels and BMPs,” notes Thorne. “Usually we use them for large water treatment, when we have to filter runoff water, to put it back in the creeks. Protech has a good staff—engineers who have education behind their words—and they’re open to using more than one just type of product.”
Thorne details how sediment is removed from runoff on his sites: “The whole process of getting soil out of the water—it’s at the micron level. One has to change the polarity of silt, to bond the molecules and get them out. First we treat the runoff, which is located in a temporary retention pond, with chemicals. We then skim the water off the top and treat it with a series of filters before releasing it to the environment. The mud sinks to the bottom; we’re catching just those silt particles in suspension.
“The whole point of this procedure is to keep turbidity levels down,” he goes on. “But if you set the filter to zero, you have too many chemicals in the water. So you ramp it down a bit. The filter doesn’t remove the chemicals but the dirt particles that have the chemicals in it. We have to take lab tests of the materials to show it’s not causing problems. California hasn’t endorsed chemicals for water treatment, but some companies use them. Protech works with whatever works best for the soil. We often use chitosan, an organic or natural product made of seashells—it’s primarily calcium and sand. It works well in some soils and not in some others.”
Centex’s procedures work well now, but as Thorne explains, “California is currently revising stormwater guidelines. To date, checking the turbidity has been a visual rating. Now, they don’t have effluent numbers—XX NTUs—that we have to meet, but there’s a basin plan. What you put back into the creek can’t be any worse than what [the turbidity level] is now. I’m imagine California’s eventual guidelines will probably be similar to Washington’s, which is 25 NTUs.”
Sediment control starts early: “We use Protech products during early development of the site, when we’re setting in the streets,” Thorne says. “Such systems don’t work very well once streets have been paved; you typically don’t want to hold water in your street drains.” He outlines the typical development process: “You start with a bare field; then you mass grade. The streets are cut out; water, sewer, and storm drains are installed; then you build streets up to pavement. At that point, underground power, phone, and gas lines go in. Ninety-eight percent of the time, this is all done before we break ground for individual foundations, except for any model homes.”
Various ESC tools are used. “We’re supposed to use a combination of sediment and EC tools, such as straw spread out on ground, filter fabric—these are laid out on fronts of the pads, so the soil doesn’t move, yet foot traffic can go over it. We undercut driveways to garages and put gravel there so soil doesn’t get into the street. Other EC contractors install erosion blankets, wattles, filter bags, and gravel bags as needed. Gravel bags are much like sand bags, but are composed of three-quarter-inch gravel. With sand, if the bags break—it’s a sediment. We put gravel bags in gutters, making a levy or dike, and they hold the sediment.”
When the project is completed, sediment control tools are removed. “Usually when houses are ready to move in, the storm drains take over the drainage system. Our developments often have holding ponds if we’re draining to a creek, which are then usually made part of the landscape.”
Over its 50-year lifespan, Centex Homes has seen a great deal of change in how it does business, and Thorne himself has seen a great deal of that change. “Procedures have changed a lot in just the last 10 years. This is my eighth year; when I first started, regulations about holding back the sediment were just coming in.”
Everything’s Dandy in Ohio
Grove City, OH’s East Jordan Iron Works sells Dandy products in conjunction with its own. “We are a manufacturer of construction castings, like manhole covers and catch basin lids,” explains Greg Probasco, branch manager. “When a contractor puts in underground sewers, he installs Dandy products and catch basin grates, which keeps dirt, mud, and sediment from getting into underground lines. The Dandys go hand in hand with our grates.”
The Dandy products are temporary, installed on grates during the construction phase of subdivisions or commercial projects. “Where new streets are going in, Dandy products prevent sediment from washing down into new sewer systems. When the project is completed, the contractors remove Dandy products and put back the grates. Dandys can be reused—contractors can clean them out and use them again. They seem to last; I have seen some that have been down for a year or more.”
Located in Westerville, OH, Dandy Products Inc. produces various sediment control and inlet protection devices, such as the Dandy Bag, Curb Sack, Pop, Dewatering Bag, and Skimmer. The sack device is designed to attach underneath catch basin inlet grates, catching any drainage sediment; the bag straps atop the grates, to block sediment from getting into the grate.
Why did East Jordan Iron Works choose Dandy? “At the time, this was a new product they came out with some years ago. They asked if we wanted to be a distributor for them. Now, over the years , inlet filters have become a requirement, especially here in the Columbus area,” says Probasco.
Greenwaste Put to Good Use
In Alabama, sediment control eventually also adds organic material to the soil. “What we put in Filtrexx SiltSoxx is local greenwaste,” says Vice President/Technical Engineer Hunter Bruce, P.E., of Alabaster, AL’s SpreadRite Organics. “Thus far, we’ve put more than 100,000 yards of greenwaste back into the state’s soil. Although some contractors will remove the items when the site is completed, some cut them, spread the composted material inside around, and only dispose of the netting. As it seems that every site here has a slope in it, typically the items are left in place, even though the slope is stabilized.”
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Photo: SpreadRite Organics |
| Filtrexx Siltsoxx can be stacked; this triple stack of 9-inch product secures a yard inlet. |
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Photo: SpreadRite Organics |
| A BMP for the birds, and other wildlife |
Filtrexx International LLC of Grafton, OH, produces a line of netting products that can be used for erosion and sediment control, including Filtrexx SiltSoxx, a silt fence alternative; InletSoxx; and Ditch Chexx, a straw bale alternative.
SpreadRite, which was established four years ago, is one of Filtrexx’s biggest users. “Filtrexx SiltSoxx are 30% of our overall business, whether we’re using them for a curb inlet, placing them at the perimeter, or getting creative with them and growing media [compost], allowing us to put vegetation in them. Filtrexx even made us green netting to help us stand out, and it matches our company colors.”
Many of his firm’s clients are commercial developers, and Bruce has seen his company’s role change over the years. “We still do a lot of silt fencing, but it’s not the end-all. We have moved to more of a hybrid approach, utilizing Filtrexx SiltSoxx for higher flow rates and fence to capture and hold runoff. We used to be called in as a service installer-supplier of what had been prescribed; however, now we’re sitting with the site owner and the contractor at the first, doing environmental consulting at the site.”
Bruce’s firm handles jobs in Alabama, Florida, Georgia, and Mississippi. “We’re the licensed Filtrexx installer for Alabama and the Florida panhandle. We also distribute the product and sell it to other firms. We produce it on pallet form in a wattle; some people come from out of state to pick it up. It is heavier than a wattle and lasts longer. Some contractors we do work for move and reuse them until they fall apart.”
And the product’s “falling apart” takes some time: “When vegetation grows around them, they eventually photodegrade and you can leave them. However, we often reuse the material the product captures and the wood fiber that’s inside. We cut open the inlet filters, screen the sediment out, and put it into a topsoil mix. We then reuse the wood fiber in another Filtrexx SiltSoxx.”
Filtrexx Certified Installers (there are over 100 installers in the US) use several different types of “soxx,” or netting, when doing custom installations onsite. Many installations require long-lasting netting, while others’ clients are interested in completely biodegradable options that degrade faster.
“You can express-blow the filter or compost product into it,” Bruce explains. “That gives us an advantage, because we can install Filtrexx SiltSoxx around wetlands where you can’t drive heavy machinery. We can fill the netting from as far away as 600 feet from the truck, or we can use or Filtrexx’s FX machine, which works off hydraulics, to stuff the netting. We don’t have to clear brush to make way for a big piece of equipment.
Bruce likes Filtrexx SiltSoxx’s versatility, noting that the tubes come in 9-, 12-, 18-, and 24-inch diameters, and when one fills with silt another can be staked on top. “We have stacked them as high 4 or 5 feet. With a silt fence, you’d have to muck them out.” The Filtrexx SiltSoxx are held down with 2- by 2-inch pencil-tipped stakes. “Compared to a straw wattle, the staking is the biggest advantage; they won’t want to move on that first flush of water and silt; it’s designed to let water pass through its whole length.”
Another difference from silt fence: “It’s animal-friendly,” Bruce reports. “Animals can climb over it. On one Lake Seminole job site, we saw that raccoons actually ate through the silt fence barrier that had been placed near the lake, 5,000 feet around the project. If you use a silt fence, animals can’t get over it; I have seen paw prints of animals trying to climb and get over on silt fences.”
On a recent project, SpreadRite Organics installed 22,000 linear feet of Filtrexx SiltSoxx. “This was a residential development next to the Cabaha River, which is a huge watershed through Birmingham. We worked during the sixth phase of a total development, where home lots were situated right on the river. Lots of people keep watch over the river, so we had to be extra careful.
“We wrapped the perimeter, which drains toward the river, protecting valley ways—maybe a third to one-half of the property. We don’t have to, but we do put a temporary or a seasonal grass on both sides of the [perimeter] as a grass filter strip.”
Bruce says the site determines which ESC tools are used. “We will sit and consult with the client, even if the project is just one lot, to analyze what he’s looking for—it may be a filter strip, Filtrexx SiltSoxx, a silt fence, a Mud-Dry mud strip—whatever’s needed. On a flat lot, perhaps all one would need is a lot of grass filter strips or Mud-Dry.”
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Alabama’s soil is “red clay chert, which makes for phenomenal compaction,” Bruce explains, “although we occasionally find loamy soil. Filtrexx SiltSoxx captures finer particles than woven materials do. We often leave a pallet of them for the contractor’s use, in case he finds some area that needs more protection. Installing them takes less than five minutes, rather than the length of time it takes to dig a trench and backfill silt fence.”
The year 2007’s weather brought additional challenges to Bruce’s firm: “The drought has made dust control a big problem; it’s definitely affected our business. We developed Mud-Dry—an engineered blonde wood fiber to cover construction sites, and a Dry Koat additive. We developed Mud-Dry for wet months, but we have seen increased success in protecting against airborne dust as well. If you use these to cover a muddy or dusty site and use Filtrexx Siltsoxx, you’ll have a solid construction site."
May 2008
Where the Sediment Went
A variety of tools for construction sites
Keeping soil where it belongs is more than just a good erosion control practice—it saves money for contractors in the long run, because they don’t have to purchase truckload after truckload of topsoil for residential developments to replace the soil that escaped. In addition, federal and state regulations are in place to preserve natural waterways; excess sediment can harm wildlife and freshwater resources. Cities and towns want to keep storm sewer lines clear; sediment buildup requires costly mucking out, and, again, many storm drains eventually end up in natural waterways. Although sediment can develop nearly anywhere, anytime, as new construction stirs up quite a bit of dirt, sediment control is usually put in place on day one, and contractors across the nation choose a variety of tools for the purpose.
Getting the Clay Out of the Way
Oxford, GA’s G.K. Walton & Associates Inc. has been using Silt-Saver products to solve its sediment problems.
“We’ve been using Silt-Saver products from the time our company went into business,” says Vice President Todd Christian. “It’s a no-brainer—-there are no failures with their products. Their new BSRF [belted strand retention fence] is one of the best products on the market right now. A lot of companies in the state put in the type C wire-back silt fence, but it doesn’t work as well as the BSRF.”
Silt-Saver, located in Conyers, GA, produces various storm drain and curb inlet filters, as well as the BSRF.
Christian explains differences between the “old” silt fences and the BSRF. “A silt fence is there to ensure that runoff water is as clean as possible. Georgia’s Soil and Water Conservation Commission [GSWCC] writes the state manual of regulations and BMPs, and they expect clear water to exit through silt fence. The water clarity is measured in NTUs [nephelometric turbidity units], and the manual requires runoff water from the site to be 80 NTUs. Oddly enough, while the GSWCC enforces this requirement, the old-style silt fence can’t provide that. After a hard rain, water coming through the BSRF is significantly cleaner—you wouldn’t mind drinking it. Meanwhile, the old standard silt fence has muddy water flowing out.”
Research conducted by the University of Georgia included extensive lab and field testing of the BSRF. “This is the only fabric that has credentials,” Christian explains. “The first time I saw the BSRF and regular silt fences side by side was when we did the installation at the University of Georgia test site. We opened up fire hydrants to the mud, which applied a lot of water pressure.”
G.K. Walton & Associates has done demonstrations of the new fence. “We’re trying to put it on some DOT [department of transportation] jobs here so that people can see it and get behind the product when they understand how well it works. We are installing it now, even though the old style is recommended,” Christian says. “We have done some new Super Wal-Mart sites with the BSRF, and they love it. We’re putting the normal BMPs [best management practices] onsite, then the BSRF behind it to catch the silt the other fence allows through. Customers ask, ‘How can this not already be approved for use in Georgia?’
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Photo: G.K. Walton & Associates Inc. |
| A Georgia site with BSRF installed |
“We have a relationship with many Georgia inspectors,” he goes on. “They’ll say, ‘We’ll let you put it up here,’ and then after they see the results, we have one more person who believes in it. Florida is on board with BSRF. Georgia is going to have to step up because they’re seeing the proven results of it.”
Christian also notes that how a BMP is installed can make a difference for the contractor. “In this business, you lose or make money on the labor. The BSRF can go up using only two people instead of three. You can get BSRF with the wood posts already attached, but we have found we get a better looking installation when we roll it in a mass roll and install it using our own stakes onsite. By comparison, the most time-consuming part of installing a regular silt fence is putting out the wire—we call it hog wire, a mesh metal wire. It’s a three-step process, and it takes much longer.”
When the site is finished, the EC contractor also has to disassemble those fences. “All DOT and commercial sites require removal and disposal of all erosion control products when the project is complete. I would rather take and pay for a half-ton of this waste material instead of a full ton of trash that includes the wire, which adds much more weight,” he says.
On many sites, a variety of ESC measures are used throughout the life of the project. Christian describes a typical job: “Erosion control is a group effort. There is no one thing that does the job. First task on the site is to surround the perimeter with silt fence. This must be done before the construction crew begins grading. In metro Atlanta, all fence has to be installed and inspected before any dirt is moved. We always install the inlet covers, too. We also put in temporary hydroseeding where the grade will be undisturbed for 14 days or more. We add polymer tackifier to hydroseed mix and install straw matting on slopes. The job doesn’t end with those installations. We are onsite until the notice of termination is filed.”
Along with the state inspectors, any firm such as Christian’s is under more scrutiny. “Erosion control is a huge thing in Georgia -- even regular citizens drive around to inspect sites, not just the city and state. I can understand their concern; drainage goes to a retention pond, which eventually goes off site. Property owners are supposed to maintain the pond when it gets to a certain level, but that doesn’t always happen.”
Skimming Off the Bad, Saving the Good
In the town of Cary, NC, Stormwater Field Services Administrator Tom Horstman includes the Faircloth Skimmer surface drain in his EC programs.
“My department oversees projects in this area,” he says. “I have two inspectors in the field making sure erosion control projects are done correctly. The product has been around for a number of years. Faircloth himself used to manage the local EC program at nearby Orange County, and the skimmer was developed from his experience in his field—common sense says if you pull water from the top, you get cleaner runoff. We want the best for our citizens—about two years ago North Carolina made the skimmer one of its BMPs, although we used it about four or five years before then.”
Produced by J.W. Faircloth & Son of Hillsborough, NC, Faircloth Skimmer surface drains float on the surface of a basin, releasing the cleanest water, instead of draining from the bottom as conventional outlets do. The product is available in eight sizes, designed to handle specific flow rates and amounts of water to be skimmed.
Horstman explains some of his department’s tasks: “Private developers submit a plan for a site, whether it’s commercial or residential construction. Our requirements mandate that they use the skimmer, and my people make sure they are installed and used correctly.
“Of course, other EC measures are also used onsite—silt fences, diversion ditches—and, of course, seeding is the best EC measure to use. My guys go out weekly or twice a week—they make the decision on how many times they need to go out—and make sure the denuded areas are being taken care of. Usually, early construction needs more oversight than later stages of construction.”
Cary, a town of 130, 000 people, has also used various other ESC techniques, such as sediment basins with washed stone, but the surface drains are now a standard BMP. “It’s important to note the skimmer requires more maintenance, but construction companies like to work here, so they use it; they’re ready to do what has to be done to make things work. Anything that works better will take a little more maintenance, and they’re ready to step up to the plate,” Horstman says.
The devices are only temporary. “After final seeding, when the asphalt’s down, and the building’s up—then the skimmer’s not needed. It’s installed at the beginning of the project and removed once the site is stabilized.” The Faircloth Skimmer surface drain is reusable.
“If the site encompasses only a quarter-acre, only a silt fence might be required. Any larger than that, though, and you need skimmers. For a big site, several will be needed. Most of the time, they’re put on the lower end of the site, but you do have to guide the water; that’s what a diversion ditch does. The location of these ditches can change on a daily basis—and often a site will need more ditches. Once you put in storm drains, they discharge to a temporary or a permanent device and then to a skimmer. When the site is finished, drains are connected to the stormwater system.”
Better Control Through Chemistry
A large residential subdivision not only stirs up a lot of soil during its construction; such developments are also often sited near water features for aesthetic reasons. Such a project requires quite a bit of erosion control, as Scott Thorne, CPESC, division compliance manager for Centex Homes’ Sacramento Division in Roseville, CA, knows well.
|
Photo: SpreadRite Organics |
| The tubes can be left in place; these have been seed-injected and filled with compost. |
|
Photo: SpreadRite Organics |
| Palletized Filtrexx SiltSoxx at SpreadRite Organics’ Chelsea Recycling Yard, ready for delivery to the job site |
“Usually there’s drainage of some sort around all our projects,” he says. “Once we put in roads and underground utilities, the water goes back to where it used to run. This drainage could be natural, or a city or county system. Most are storm drain systems—metal, concrete, or plastic pipes which drain into a basin or diversion channels.”
Centex Sacramento uses Fairfield, CA’s Protech General Contracting Services for many of its EC maneuvers. Protech, a full-service environmental compliance company, specializes in water treatment for stormwater control, sediment or contaminant removal, and pollution prevention. “Protech provides us with materials for lining channels and BMPs,” notes Thorne. “Usually we use them for large water treatment, when we have to filter runoff water, to put it back in the creeks. Protech has a good staff—engineers who have education behind their words—and they’re open to using more than one just type of product.”
Thorne details how sediment is removed from runoff on his sites: “The whole process of getting soil out of the water—it’s at the micron level. One has to change the polarity of silt, to bond the molecules and get them out. First we treat the runoff, which is located in a temporary retention pond, with chemicals. We then skim the water off the top and treat it with a series of filters before releasing it to the environment. The mud sinks to the bottom; we’re catching just those silt particles in suspension.
“The whole point of this procedure is to keep turbidity levels down,” he goes on. “But if you set the filter to zero, you have too many chemicals in the water. So you ramp it down a bit. The filter doesn’t remove the chemicals but the dirt particles that have the chemicals in it. We have to take lab tests of the materials to show it’s not causing problems. California hasn’t endorsed chemicals for water treatment, but some companies use them. Protech works with whatever works best for the soil. We often use chitosan, an organic or natural product made of seashells—it’s primarily calcium and sand. It works well in some soils and not in some others.”
Centex’s procedures work well now, but as Thorne explains, “California is currently revising stormwater guidelines. To date, checking the turbidity has been a visual rating. Now, they don’t have effluent numbers—XX NTUs—that we have to meet, but there’s a basin plan. What you put back into the creek can’t be any worse than what [the turbidity level] is now. I’m imagine California’s eventual guidelines will probably be similar to Washington’s, which is 25 NTUs.”
Sediment control starts early: “We use Protech products during early development of the site, when we’re setting in the streets,” Thorne says. “Such systems don’t work very well once streets have been paved; you typically don’t want to hold water in your street drains.” He outlines the typical development process: “You start with a bare field; then you mass grade. The streets are cut out; water, sewer, and storm drains are installed; then you build streets up to pavement. At that point, underground power, phone, and gas lines go in. Ninety-eight percent of the time, this is all done before we break ground for individual foundations, except for any model homes.”
Various ESC tools are used. “We’re supposed to use a combination of sediment and EC tools, such as straw spread out on ground, filter fabric—these are laid out on fronts of the pads, so the soil doesn’t move, yet foot traffic can go over it. We undercut driveways to garages and put gravel there so soil doesn’t get into the street. Other EC contractors install erosion blankets, wattles, filter bags, and gravel bags as needed. Gravel bags are much like sand bags, but are composed of three-quarter-inch gravel. With sand, if the bags break—it’s a sediment. We put gravel bags in gutters, making a levy or dike, and they hold the sediment.”
When the project is completed, sediment control tools are removed. “Usually when houses are ready to move in, the storm drains take over the drainage system. Our developments often have holding ponds if we’re draining to a creek, which are then usually made part of the landscape.”
Over its 50-year lifespan, Centex Homes has seen a great deal of change in how it does business, and Thorne himself has seen a great deal of that change. “Procedures have changed a lot in just the last 10 years. This is my eighth year; when I first started, regulations about holding back the sediment were just coming in.”
Everything’s Dandy in Ohio
Grove City, OH’s East Jordan Iron Works sells Dandy products in conjunction with its own. “We are a manufacturer of construction castings, like manhole covers and catch basin lids,” explains Greg Probasco, branch manager. “When a contractor puts in underground sewers, he installs Dandy products and catch basin grates, which keeps dirt, mud, and sediment from getting into underground lines. The Dandys go hand in hand with our grates.”
The Dandy products are temporary, installed on grates during the construction phase of subdivisions or commercial projects. “Where new streets are going in, Dandy products prevent sediment from washing down into new sewer systems. When the project is completed, the contractors remove Dandy products and put back the grates. Dandys can be reused—contractors can clean them out and use them again. They seem to last; I have seen some that have been down for a year or more.”
Located in Westerville, OH, Dandy Products Inc. produces various sediment control and inlet protection devices, such as the Dandy Bag, Curb Sack, Pop, Dewatering Bag, and Skimmer. The sack device is designed to attach underneath catch basin inlet grates, catching any drainage sediment; the bag straps atop the grates, to block sediment from getting into the grate.
Why did East Jordan Iron Works choose Dandy? “At the time, this was a new product they came out with some years ago. They asked if we wanted to be a distributor for them. Now, over the years , inlet filters have become a requirement, especially here in the Columbus area,” says Probasco.
Greenwaste Put to Good Use
In Alabama, sediment control eventually also adds organic material to the soil. “What we put in Filtrexx SiltSoxx is local greenwaste,” says Vice President/Technical Engineer Hunter Bruce, P.E., of Alabaster, AL’s SpreadRite Organics. “Thus far, we’ve put more than 100,000 yards of greenwaste back into the state’s soil. Although some contractors will remove the items when the site is completed, some cut them, spread the composted material inside around, and only dispose of the netting. As it seems that every site here has a slope in it, typically the items are left in place, even though the slope is stabilized.”
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Photo: SpreadRite Organics |
| Filtrexx Siltsoxx can be stacked; this triple stack of 9-inch product secures a yard inlet. |
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Photo: SpreadRite Organics |
| A BMP for the birds, and other wildlife |
Filtrexx International LLC of Grafton, OH, produces a line of netting products that can be used for erosion and sediment control, including Filtrexx SiltSoxx, a silt fence alternative; InletSoxx; and Ditch Chexx, a straw bale alternative.
SpreadRite, which was established four years ago, is one of Filtrexx’s biggest users. “Filtrexx SiltSoxx are 30% of our overall business, whether we’re using them for a curb inlet, placing them at the perimeter, or getting creative with them and growing media [compost], allowing us to put vegetation in them. Filtrexx even made us green netting to help us stand out, and it matches our company colors.”
Many of his firm’s clients are commercial developers, and Bruce has seen his company’s role change over the years. “We still do a lot of silt fencing, but it’s not the end-all. We have moved to more of a hybrid approach, utilizing Filtrexx SiltSoxx for higher flow rates and fence to capture and hold runoff. We used to be called in as a service installer-supplier of what had been prescribed; however, now we’re sitting with the site owner and the contractor at the first, doing environmental consulting at the site.”
Bruce’s firm handles jobs in Alabama, Florida, Georgia, and Mississippi. “We’re the licensed Filtrexx installer for Alabama and the Florida panhandle. We also distribute the product and sell it to other firms. We produce it on pallet form in a wattle; some people come from out of state to pick it up. It is heavier than a wattle and lasts longer. Some contractors we do work for move and reuse them until they fall apart.”
And the product’s “falling apart” takes some time: “When vegetation grows around them, they eventually photodegrade and you can leave them. However, we often reuse the material the product captures and the wood fiber that’s inside. We cut open the inlet filters, screen the sediment out, and put it into a topsoil mix. We then reuse the wood fiber in another Filtrexx SiltSoxx.”
Filtrexx Certified Installers (there are over 100 installers in the US) use several different types of “soxx,” or netting, when doing custom installations onsite. Many installations require long-lasting netting, while others’ clients are interested in completely biodegradable options that degrade faster.
“You can express-blow the filter or compost product into it,” Bruce explains. “That gives us an advantage, because we can install Filtrexx SiltSoxx around wetlands where you can’t drive heavy machinery. We can fill the netting from as far away as 600 feet from the truck, or we can use or Filtrexx’s FX machine, which works off hydraulics, to stuff the netting. We don’t have to clear brush to make way for a big piece of equipment.
Bruce likes Filtrexx SiltSoxx’s versatility, noting that the tubes come in 9-, 12-, 18-, and 24-inch diameters, and when one fills with silt another can be staked on top. “We have stacked them as high 4 or 5 feet. With a silt fence, you’d have to muck them out.” The Filtrexx SiltSoxx are held down with 2- by 2-inch pencil-tipped stakes. “Compared to a straw wattle, the staking is the biggest advantage; they won’t want to move on that first flush of water and silt; it’s designed to let water pass through its whole length.”
Another difference from silt fence: “It’s animal-friendly,” Bruce reports. “Animals can climb over it. On one Lake Seminole job site, we saw that raccoons actually ate through the silt fence barrier that had been placed near the lake, 5,000 feet around the project. If you use a silt fence, animals can’t get over it; I have seen paw prints of animals trying to climb and get over on silt fences.”
On a recent project, SpreadRite Organics installed 22,000 linear feet of Filtrexx SiltSoxx. “This was a residential development next to the Cabaha River, which is a huge watershed through Birmingham. We worked during the sixth phase of a total development, where home lots were situated right on the river. Lots of people keep watch over the river, so we had to be extra careful.
“We wrapped the perimeter, which drains toward the river, protecting valley ways—maybe a third to one-half of the property. We don’t have to, but we do put a temporary or a seasonal grass on both sides of the [perimeter] as a grass filter strip.”
Bruce says the site determines which ESC tools are used. “We will sit and consult with the client, even if the project is just one lot, to analyze what he’s looking for—it may be a filter strip, Filtrexx SiltSoxx, a silt fence, a Mud-Dry mud strip—whatever’s needed. On a flat lot, perhaps all one would need is a lot of grass filter strips or Mud-Dry.”
Alabama’s soil is “red clay chert, which makes for phenomenal compaction,” Bruce explains, “although we occasionally find loamy soil. Filtrexx SiltSoxx captures finer particles than woven materials do. We often leave a pallet of them for the contractor’s use, in case he finds some area that needs more protection. Installing them takes less than five minutes, rather than the length of time it takes to dig a trench and backfill silt fence.”
The year 2007’s weather brought additional challenges to Bruce’s firm: “The drought has made dust control a big problem; it’s definitely affected our business. We developed Mud-Dry—an engineered blonde wood fiber to cover construction sites, and a Dry Koat additive. We developed Mud-Dry for wet months, but we have seen increased success in protecting against airborne dust as well. If you use these to cover a muddy or dusty site and use Filtrexx Siltsoxx, you’ll have a solid construction site."