Saving money, saving time, and saving the environment are the driving factors behind the choices being made in short-term and temporary sediment control best management practices (BMPs) these days.
There are several products on the market now that can be used to address one situation on a job site and, after it has served its temporary function, can be removed to serve another purpose.
Case in point: Gator Guard wattles, a UV-resistant geotextile stuffed with recycled foam. In Chugiak, AK, the Granite Construction Co. of Watsonville, CA, is using the product to provide sediment control on a highway project.
The Old Glenn Highway/South Birchwood/Peters Creek project entails a 4-mile-long road reconstruction effort involving widening, adding shoulders, and adding 8- to 10-foot-wide bike paths, as well as a bridge reconstruction.
The project began in spring 2010, with the work halted for the winter as freezing conditions set in. It is expected to be completed by fall 2011 as the bridge is reconstructed, followed by the completion of one more mile of the road.
Matt Young, a field/office engineer for Granite Construction Co., says previous use of Gator Guard wattles on bridge project in Alaska convinced him the product would be equally effective for this job.
“We researched it and tried it for the first time in Alaska for perimeter control on the bridge project,” he says. “We liked the ease of access. You could drive over it with excavators, there’s low maintenance, and the installation costs are pretty low.”
The Alaska state government approved its use on the Old Glenn Highway project. A big selling point was that the product can be reused, says Young. His company has about 6 miles of the product and is able to reuse it again and again.
Other products are destroyed once they are removed, but with Gator Guard, “you can install it several times and it will still be equally effective,” Young says.
Granite Construction Co. installed the wattles one mile at a time.
“We were stabilizing behind where we were paving, so we have an unpaved surface for only a mile,” he explains, adding that nearby water bodies intensified the importance of effective BMPs. “Once we had the first phase done and stabilized, we could pull up all the Gator Guard, inspect it, and move it to the next stage where we needed to put our BMPs down.
“We’ve been able to reuse the Gator Guard quite a few times,” says Young. “We’ve been stockpiling it, and as we need it we grab a few more rolls and reinstall it at the next location.”
Young says the Gator Guard was easy to install. “There are some things we’ve been working on to maximize its effectiveness, such as using a staple gun to make it level. When we install the Gator Guard, we’ll shoot it and make it level to the slope the water will be running down, instead of making it an arch so it spills over one spot,” he says. “Now we have the majority of it level, and we have a 20-foot-long spillway with 2 feet on each end, curving up, so it can retain the water before it spills over the Gator Guard.”
The ease of any installation project depends on soil type, Young points out. “It takes a little more care if it’s real soft, silky material versus gravel,” he says. “You have to take more care that the tail is embedded a little deeper-otherwise it’ll undercut the Gator Guard. The same thing applies to silt fence. You have to make sure it’s buried a little deeper, depending on the soil.”
This particular project encompasses clay, silt, sand, and gravel-type soils.
The job doesn’t have many inherent challenges, other than the usual: to manage where the water flows.
“You make sure you’re treating the water before it leaves the site,” says Young, adding that his company will use the Gator Guard to create a settling pond by digging trenches and using the Gator Guard as a spillway so the water can run through the product at each level.
“By the time it gets to the end, the water is clear,” he says.
Another product that helps contractors serve multiple purposes is Erosion Eel, a sediment control device made of woven polypropylene geotextile exterior and filled with washed shredded rubber. Erosion Eel is designed for flow control and capture of suspended particles. It can be used to replace silt fence, rock check dams, temporary diversion berms, and inlet drain protection.
Landsaver Environmental in Richmond, VA, a division of ACF Environmental, supplies and installs erosion control and hydroseeding materials. The company recently used Erosion Eel at a retrofit project executed during summer 2010 at Fort Eustis, a US Army base in Newport News, VA.
The job called for silt fence to be placed around the perimeter of the job site. There was existing concrete and asphalt on the site.
“But you can’t drive silt fence into asphalt or concrete, so we took the areas that did not have it and trenched in the silt fence around the chain link fence. In the area where we could not trench in the silt fence, we took the 10-foot Erosion Eels and stacked them end-to-end, overlapping them on the end, so they could be used as a perimeter barrier where silt fence couldn’t be trenched into the ground,” explains Doug Evans, territory manager for erosion control for Landsaver Environmental.
One aspect of the job was particularly pleasing to the contractor-the fact that after the Erosion Eels served their purpose for about five months, they could be removed, hosed down, and used for inlet protection afterwards.
Also on the job site was a large area being used as a dirt stockpile. One option would have been to vegetate and fertilize it or install silt fence around it, but this area also was located on concrete and asphalt. Landsaver laid a circumference of Erosion Eels around the dirt pile, keeping soil from washing out and preventing sediment-laden runoff.
Time limitations proved to be another challenge on the job.
“This was something that needed to be done quickly,” says Evans. “We mobilized our silt fence crew down there. After they installed all of the silt fence that they could, they took a measurement with a wheel. We came back the next day with the Erosion Eel. Time was a factor; they weren’t going to be able to break ground on the job site until the site was secure.”
The company also used Erosion Eels at a job at the University of Virginia. Landsaver Environmental worked with C.T. Purcell Excavating & Grading on installing silt and safety fence during summer 2010.
Twenty drop inlets were located in the middle of the campus. Original plans called for the creation of stone baskets made of chicken wire and hardware cloth and wrapped in silt fence.
Instead, Landsaver Environmental installed 18 structures using Erosion Eel, Gutter Gators, and ACF’s Siltsacks, a sediment control device mounted under catch basin grates made of a permeable geotextile that allows water to pass but prevents silt and sediment from clogging the drain. The approach saved time and labor.
“This is a busy street that was never shut down,” says Evans. “They were going to have to come back in there with shovels and pieces of equipment. By using the Erosion Eels and the Siltsacks, they could basically pick them up and load them on the back of their truck.”
A product’s success at filtering water is one of the prime factors contractors consider when choosing BMPs on construction sites. B.G. Biscoe, vice president of Sioux Construction, a full-service erosion control company in Weatherford, OK, also favors materials that can be reused.
The company provides complete erosion control services, employing silt fence, hay blowing, seeding, sod, watering, hay bales, straw wattles, and hydroseeding. The company’s primary supplier is Triangular Silt Dike in Luther, OK. “We use them for all of our silt fence materials, and we also use their material for our hydroseeding,” says Biscoe.
Triangular Silt Dike is a reusable, lightweight, multipurpose alternative to rock check dams. Weighing in at 7 to 9 pounds per 7-foot section, it has a protective apron on both sides of the dike to prevent undercutting and failure. It is installed with U-shaped wire staples and can conform to curves and rough terrain. After being cleaned, the product can be reused.
“We use a lot of Silt Dike,” says Biscoe. “We bought a semi load of it this year. We use silt fence and Silt Dike on every project.”
One such project is on Oklahoma’s Highway 70. Sioux Construction has used about 1,500 feet of Silt Dike and 12,000 feet of silt fence in this ongoing, two-year project.
The company is using both Silt Dike and silt fence as temporary BMPs as the work goes progresses, then pulling them out before each area receives sod.
“When Silt Dike is used, it absorbs all of the silt. It’s heavy. But we reuse a lot of it. We pile it up and haul it on the back of a trailer and reuse the ones that didn’t get that much water or silt on the next project,” he says.
The company will typically install three pieces in a ditch; the middle piece is usually the one that gets the most impact, while the end parts are the most likely pieces to be reused.
Sioux Construction was recently enlisted to handle a 150-acre job at a wind farm under construction, followed by another 100-acre job at the same site. Biscoe used Triangular Silt Dike products for the project. The company hydroseeded with rye grass and was set to follow up in the spring with a native grass blend.
Soil-Tek of Mid-America in Lake St. Louis, MO, provides a complete line of erosion control services, including stormwater pollution prevention plans (SWPPPs), installation and maintenance of BMPs, inspections, and post-storm cleanup. Clients are typically commercial builders for cities and counties, with some work done for the home construction industry.
Soil-Tek almost exclusively uses Filtrexx products as its preferred BMP for the majority of its projects.
“We’ve found over the past seven years that they give us better utility. They’re more efficient because they’re more effective, and that’s the reason we concentrate on those devices,” says IECA member Rob Carrothers, the company’s owner. “Most of our projects are commercial building projects. The thing we like about it is if we can’t put anything else in, we can always use a filter sock, no matter how steep the slope.”
Case in point: The company recently worked on a campus expansion project for the brokerage house Edward Jones. The project presented challenges: The company had to relocate all of the utilities to construct a new building. In order to do so, a 2:1 slope was created above a creek.
“We used Filtrexx 18-inch sock at the creek’s edge and back up the slope,” Carrothers says. “We cut the slope in three different places with Filtrexx socks to hold the slope while they were waiting to move the utilities.”
The utility relocation was supposed to have occurred within 30 days of the project’s start. At least five months later, the utilities still had not been moved.
“The only thing that would have lasted there until they could get a permanent solution in place would have been a Filtrexx sock,” Carrothers says. “First of all, it’s heavy enough to stay in place when staked properly, and secondly, you’re able to filter the water and dam it up behind.
“Because we’ve got a decent slope, the sock doesn’t get pushed and the creek is saved. It doesn’t end up with a sediment load because of the multiple layers of socks that filter the water.”
Sometimes Soil-Tek will use other BMPs in conjunction with the Filtrexx socks.
“We do install silt fence when a customer requires it or an engineer thinks it’s important for a particular solution,” says Carrothers.
In his marketplace, it also becomes a preferred solution against the backdrop of pending numeric effluent guidelines from the EPA.
Although its new rule of limiting turbidity of stormwater discharges from many construction sites to 280 nephelometric turbidity units (NTU) was supposed to take place in phases, it has recently been challenged in court; further changes may ensue in the coming months. Nonetheless, Carrothers says he’s prepared for anything.
“Rather than damming an area up and letting things settle out, or using a flocculent, we can get 10 gallons per minute through a filter sock and clean the water at the same time.”
While there isn’t much training required for his employees to install filter socks, especially because his company doesn’t have a lot of turnover, there sometimes can be an education involved for clients, says Carrothers.
“When you’re looking at a project and we’re having to spec the products, that takes a bit of a learning curve because most people want to treat all BMPs the same-they want to treat them like a silt fence,” he says.
Durability-and the fringe benefits of saving downtime and money-is the driving factor in choosing the tommy Silt Fence Machine, says Carl Ondrus, owner of Ohio Ground Control in Avon, OH. His company specializes in installing silt fence, and Ondrus has been using the tommy for nearly six years in his work as a subcontractor on commercial and residential sites up to 40 acres.
Ondrus, who used to work for an excavating company, now works by himself. As such, he favors the “simplicity and speed” of the tommy.
“There’s not much of a learning curve,” he says. “It was pretty simple and, being around equipment all my life, it wasn’t too hard to figure it out.”
Recently, Ondrus had to replace a bearing on the machine. In all of the time he’s used the tommy, that was the first repair, he says.
IECA member Danny Reynaga owns Watershed Resources in San Diego, CA, and serves as a consultant for Reed & Graham in Sacramento. He also helps companies comply with the construction permit in California. Reynaga utilizes Hydrosorb products such as Soilfloc PAM polymers in his work.
“One of my erosion control contractors whom I’ve done business with over the years was looking to stop erosion on some slopes for a housing development project in San Diego. They were looking for something temporary that would last three to six months during the 2009 rainy season,” says Reynaga.
“I helped the contractor out by servicing him with a 100% wood mulch, and he also needed a tackifier for the mulch, so that’s when I used the Hydrosorb product.”
The contractor found the polymer product easy to use and was satisfied with how it reacted with the soil, Reynaga adds.
Reynaga is getting an increasing number of requests from customers for assistance in complying with effluent guidelines, especially as they relate to California’s new construction general permit for stormwater.
“You have to be qualified as having some experience and showing you have certification as a CPESC, stormwater quality professional, or civil engineer,” says Reynaga, who is a CPESC (Certified Professional in Erosion and Sediment Control).
“A lot of these rules are coming into play, and owners and engineers are looking for different BMPs that can help to comply with the regulations,” he adds. “From a supply standpoint, it’s good because it helps to facilitate the need for different products and the education about what products are out there. Manufacturers are always coming out with new products to help the end user comply, whether it be for erosion control or stormwater management.”
StormKlear manufactures a chitosan-based polymer for flocculation to treat stormwater runoff and dewatering from construction sites. Among the products offered by the company is StormKlear LBP-2101 and DBP-2100.
At a recent job site for Tennessee Department of Transportation’s State Route 385, DBP-2100 and GelFloc geosynthetic socks were used along with a StormKlear dewatering bag BMP to dewater dirty ponds.
In an effort to reduce the initial turbidity, water was recirculated from the end pond through the StormKlear dual polymer sock chambers and then discharged onto riprap to prevent further erosion.
A second set of socks was added to each chamber to reduce pump flow, resulting in clearer water cascading from an upper pond to a lower pond.
The sock chamber was connected to a geotextile dewatering bag, which was positioned on crushed rock to prevent blinding of the material that occurs when placed on dirt. The filtrate from the bag was discharged through several transition areas before leaving the site into the wetlands, resulting in near drinking water clarity.
Dale Kraus is a supervisor with Green Thumb, an erosion control company owned by his wife Phyllis in Dyersburg, TN. The company uses Silt-Saver products on all its jobs, which are primarily on commercial and state transportation sites.
Silt-Saver’s products include the Frame and Filter Assembly for storm drain inlet protection. It’s a dome-shaped HDPE frame that fits over the storm drain opening, eliminating the need for posts.
The Curb Inlet Filter and the Curb and Grate Inlet Filter are designed with polymeric coils that lend stability to the devices as they sit in front of curb inlet openings. They differ from coir logs or wattles in that they are designed to last for the duration of a project.
The company also will be introducing the Belted Silt Retention Fence.
“We put Silt-Saver BSRF in with the tommy and try to put it in 4 to 6 inches deep,” says Kraus. “We drive a tractor tire back over it afterward to secure the ground back to normal standards. We use a hydraulic jack to hammer the posts in and a staple gun to staple the strip on there. Sometimes we have to use a trencher or backhoe where we can’t get a tractor and the tommy in.”
Kraus says his company usually runs three-person crews, and as long as there’s nothing major wrong or steep slopes or tree roots, it’s not a problem to install 2,000 to 3,000 feet of fence a day.