By Bill Tice

Natural and synthetic polymers can play a significant role in the ongoing battle against dust and sediment movement. But with a huge array of options on the market users are often faced with a maze of choices.

Dave Smith, a Carson City, NV–based regional range land management specialist for the Bureau of Indian Affairs (BIA), has been using polymer products for emergency stabilization and rehabilitation work for a number of years. “Mostly where I get involved with polymers is when we are dealing with highly erosive soil situations and where there are downstream values at risk,” he says.

Photo: Southwest Desert Images

Polymers are a big part of dust control measures, especially on building lots and roads.

Smith has spent 22 years of his career working for the BIA, returning to the organization this year after a four-year hiatus, during which time he worked for the US Fish and Wildlife Service. While with Fish and Wildlife and prior to taking his current position with the BIA, Smith was also one of two leaders with a national fire rehabilitation team for the Department of the Interior. In this role, he visited areas all over the country to help determine ways to stabilize and rehabilitate natural areas that had been damaged by fire.

Smith says using polymers for stabilization is not the least expensive method, but he adds in some cases it is the only way to go, especially when the public can be in danger if a situation is not corrected.

“Although polymers can be more expensive than other soil stabilization methods, it comes back to what it is you are trying to protect,” he explains. “When it comes to protecting human lives, that is something you can’t put a price on,” he adds, pointing to “brownouts” as an example of life-threatening conditions. “In one case, I was treating an area of Aeolian dunes that had experienced a fire. These sand dunes form a wind-positive dune system, and when the vegetation burns off, they are very moveable. An adjacent heavily traveled highway was susceptible to brownouts from the moving dunes, so I needed a solution that would hold down the soil.”

Brownouts can be very dangerous for motorists as visibility can be reduced to zero in just a matter of seconds, with the potential to cause serious multi-vehicle accidents. In the area of dunes Smith worked on, some 5,000 acres were affected and he needed to treat 500 acres of that land base. He called for part of the area to be treated with a polymer-based tackifier from Ranchester, WY–based Rantec Corp. that was mixed with a hydromulch product and applied from the air using a fixed-wing aircraft. The mulch was a mixture of paper and wood fiber and included a native grass seed mix and water as well as the tackifier. For the balance of the 500 acres to be treated, he specified drill-seeding. “Drill-seeding costs about $85 to $100 per acre, while treating with hydromulch can be as much as $2,000 per acre,” he notes. “In the area that we drill-seeded, we were getting some erosion just from the drilling process, while the area we treated with the hydromulch worked tremendously well. Right after the treatment, we had wind speeds of over 50 miles per hour with little or no erosion on the dunes treated with hydromulch. If I had the funding, I would have gone back and treated other areas with the same hydromulch mix.”

In the southern California wildfires, Smith says they applied hydromulch with SoilSET, which works in a similar way to a polymer but is a natural guar-based product that uses organic biodegradable ingredients to create a nano-structured matrix as a soil binder. “In this case we successfully treated 1,500 acres on one of the Indian reservations, including one slope that was above a water bottling plant,” he says.

Photo: Highland Environmental Control

Copolymer application can keep a site dust free for a year or more.

Smith says every treatment is site specific and what works for one situation may not work for others. “What we use really depends on the soil type, the slope, and the topography,” he says. “But we are finding in most cases following a fire, the most effective treatment is to put some kind of mulch on the surface of the soil.”

Rob McGann, an estimator with Hydro-Plant Inc. in San Marcos, CA, says his company uses polymers and other stabilization products in many areas of its business, which is primarily hydroseeding and hydromulching for the erosion control industry. “We work on highways, box stores, commercial developments, and master plan home communities,” he says. “Most of our business is in southern California, Arizona, and Nevada, but we have also worked on projects in Hawaii and Mexico.”

For some of the master plan communities that are developed in phases, Hydro-Plant can be onsite for periods of up to five years. Two large projects the company has been working on for some time now are Scripps Ranch near San Diego and Rolling Hills Ranch near Chula Vista, CA. Each project—both are for the same developer—has required upwards of 3 million square feet of application to date.

“The developer calls us in after certain parts of the project are graded, and they generally have us spray on a guar and nonirrigated vegetative cover, which includes grasses and native flowers like California poppies,” McGann explains. “In most cases, we do this work in the fall so that the pads or lots are buttoned up for the winter. Eventually, sometimes four to six months later, we will go back in and hydroseed the final landscape mix for the landscaping contractor.”

For Hydro-Plant and the areas it works in, McGann prefers the plant-based guar gum products, which the company sources from Rantec. “The guar gum is not a polymer,” he says. “We do use some polymers, but we have found with some of the true polymers they break down from the rain and ultraviolet rays. We find the guars, which are a gel-type material, tend to hold the soil in place a little longer, at least in terms of sediment control.”

Other stabilization solutions used by Hydro-Plant include polyacrylamides, which are called PAMs for short and come in a dry or emulsified form, and bonded fiber matrix products. “There really is a wide range of products out there,” adds McGann. “For cost, PAMs are on the low end of the scale at between 3 and 3.5 cents per square foot, guar products typically are a little higher at 4 to 4.5 cents per square foot, and bonded fiber matrix products tend to be the high end at 7 to 8 cents per square foot. We consider bonded fiber matrix solutions when we need to protect areas for longer periods, such as nine to 12 months.”

Bob Kirk, a principal with Sierra Vista, AZ–based Southwest Desert Images LLC, is finding polymers are starting to play a major role in his company’s dust control measures, especially on roads and building lots. And although to date he has not seen a major push toward polymers for sediment control, it is something he says his clients are interested in.

Presently, water has been the main method of dust control used by Kirk’s company, which is the largest landscaping company in southeast Arizona with about 100 employees. But with water being a precious commodity, especially in the southern Arizona area, the move to polymers has become increasingly popular. “When we are using water on its own for dust control, we will have to spray several times a day, which consumes a large volume of water. With the polymers, we mix them in with the water and a one-time application can last from weeks to several months,” he says.

“For dust control, we primarily use Soiltac and Durasoil from Soilworks LLC in Gilbert, Arizona,” says Kirk. “The Soiltac is a liquid copolymer soil hard-crust stabilizer that we can apply as a temporary or permanent measure, while on dirt roads that have a lot of traffic, we will generally use the Durasoil, which is a synthetic organic dust control agent. How we use the Durasoil really depends on how often the road is used and to what extent. We generally find that an application will last about six months, but if we have heavy machinery using the road, we may have to spot spray to maintain an acceptable level of dust control.”

For sediment control, Kirk says the company uses many of the standard best management practices (BMPs) that are available, including “tootsie rolls” (rolled netted straw) and silt fence. Additionally, crews normally construct one or two sediment trenches before the manmade BMPs. “We are not seeing a lot of demand for spray-on products for sediment control, primarily due to cost, but it is something our customers are interested in, especially when they are working on slopes,” says Kirk.

In addition to the company’s mainstay business, which includes housing and commercial developments, Kirk says it is finding another market for dust control products in the aviation business. “Airports and landing strips have specific rules for foreign object debris that state the runway has to be clear of any debris or foreign matter that could damage an aircraft if it gets caught up in the engines. If we coat an entire dirt runway or landing strip with a polymer product, it binds any small debris to the dirt, making it safe enough for planes to take off and land. We can even make the surface hard enough that a C130 transport plane could land and take off on it.”

A little farther north in Phoenix, AZ, Highland Environmental Control LLC offers clients a full-service dust control and stormwater management program. “We are the largest dust control company in the Phoenix area,” says John Nagel, one of the partners in the company. “We work with many of the top 10 homebuilders in the area, providing them with a complete package of services. This includes a compliance officer, a water truck, water towers, and track-out devices. We use a proactive approach and manage each site from the risk standpoint of the developer, eliminating unnecessary exposure for their company. Our services include working with the county and ADEQ [Arizona Department of Environmental Quality] officials to stay on top of all the EPA and ADEQ requirements.”

Another service Highland offers is the application of Soiltac from Soilworks, a copolymer emulsion designed for soil stabilization and dust control. “Longevity is the main factor for us and our clients,” explains Nagel. “We can apply this copolymer product and it can last up to a year or more, depending on the application rate used. This makes it very cost-effective for our clients.”

When developers are building large subdivisions or master plan communities, they generally work in phases, completing all of the dirt work at one time. This means a number of house pads can sit vacant for several months before homes are actually built on them. “We spray these vacant lots in order to prevent the soil from becoming airborne or eroding away,” explains Nagel. “Some of these lots might not be built on for three, six, nine, or 12 months, so we need to cap them off and keep the developer in compliance.”

Mining companies in Montana and other areas have found an interesting use for polymer-based dust control products—topping ore concentrate that is transported in open-top railcars.

“We supply a number of different chemical products to our mining customers, including EarthChem’s Earthbound, which is used for dust and sediment control,” says Greg Peterson, president of Chemical Montana Co., a Helena, MT–based distributor of chemicals to industrial markets. “We support about six major industries, including mining, agriculture, laundry and dry cleaning, and water treatment. The polymer-based products from EarthChem are used for many applications within mining and agriculture, but the railcar application is one of the most unique.”

Most of the mining in Montana is for copper, zinc, lead, gold, molybdenum, and other metals. These minerals are extracted from a pit or quarry and then processed through some kind of grinding system, followed by a flotation mill and a filtration system. The resulting product is a concentrate, which is dried and loaded onto open-top railcars for shipment to refineries in Canada and other parts of the United States, or to a West Coast port for shipment to Asia.

Before the railcar leaves for its destination, the ore concentrate is treated with Earthbound. The product is applied by either moving the railcar through an overhead spray bar, or by spraying with a hand wand from an overhead catwalk. Earthbound comes in a liquid or powdered form and is diluted with water. “Basically, as the railcar rolls down the tracks, the Earthbound product prevents the ore from blowing off, which not only keeps the product in the car, but also helps our customers stay in compliance with air-quality regulations,” summarizes Peterson.

When it comes to sediment control, manmade BMPs and spray-on products are not the only solution available to developers, contractors, and erosion control experts. In most cases, especially on construction sites, any sediment must be removed from water that is being carried off the site. In these situations, a biopolymer or synthetic polymer flocculent product in gel or liquid form can be the answer.

“These products are added to the stormwater prior to being discharged, and they work by getting the silt particles to flocculate and gather together so that they can settle by weight or filtration,” explains Alex Zimmerman, CPESC, an erosion and sediment control services manager with Vancouver, WA–based CSI Geosynthetics. “If you only used gravity filtration, the particles would not settle in a time frame that is conducive to construction-site time schedules.”

CSI is a distributor of geosynthetic construction products from fabrics to grids, silt fence, landfill covers, turbidity curtains, and sediment control products such as the ones Zimmerman describes. “We offer all kinds of products to help contactors get their projects done, and as part of my job, I assist our customers with sediment and erosion control issues.”

For flocculant products, CSI is a local distributor and service provider for Natural Site Solutions in Redmond, WA, which is the exclusive North American distributor of Storm-Klear Gel-Floc and Storm-Klear Liqui-Floc. Both products are manufactured by Vanson HaloSource Inc. and use the natural biopolymer chitosan, which is derived from crab and shrimp shells. In turbid water, chitosan causes coagulation of the sediment particles, which then allows for gravity settling, biofiltration, sand filtration, or cartridge filtration.

“The Washington State Department of Ecology is very strict when it comes to permits and guidelines for construction-site discharges, and that was one of the driving factors behind the development of these products,” says Zimmerman. “Chitosan is also used in bandages as it can encourage the blood to coagulate, reducing bleeding, and it is also used by aquariums because it makes the water extremely clear, creating excellent visibility.”

In addition to the Natural Site Solutions products, CSI uses other polymers, including a liquid synthetic product from Environmental Polymers in Vancouver, WA, that was specified for a large combined sewer overflow (CSO) pipeline project the company is currently involved with in Portland, OR. The almost $300 million West Side CSO project is part of a 1991 initiative by the city’s environmental services division to reduce its CSOs from the nearby Columbia and Willamette rivers over a 20-year time span. CSOs occur because existing combined sewer pipes are not large enough to carry stormwater and sanitary flows to the treatment plant, especially during the Northwest’s rainy winter season when stormwater fills the combined sewers. Bacteria, untreated sewage, and other stormwater pollutants can be carried directly into the river during a CSO.

Photo: Southwest Desert Images

A company's dust control method of choice may depend on how often a surface is used.

“During the construction of the tunnel for the West Side project, the soil was liquefied by the tunnel boring machine,” says Zimmerman. “When it was brought to the surface as a sludge, the liquid polymer was used to separate the water from the sludge, creating a soil that could be conveyored to a barge and sent offsite for disposal.”

Zimmerman says injecting the sludge with the polymer and then running it through a hurricane centrifuge accomplished the separation. “When using polymers, every situation will be different, but you want to get the most bang for your buck,” he notes. “Testing and sampling in order to find out which one is going to work the best for your project is essential.”

Zimmerman explains that the chitosan-based products are natural polymers. He says synthetic polymers are also safe, providing dose rates are correct. “The concern with any polymers is that they can be toxic at varying levels to fish,” he says. “You want to use just enough polymer so that all of the hooks in the polymer chain catch sediment particles. If all the hooks are taken, the polymer and attached sediments can be removed from the water and there is nothing left to be toxic, but if too much polymer is added to the water, then you have empty hooks and you can have a toxicity problem. In Washington state, there is a limit on how high you can turn up the polymer to control toxicity.”

Onsite at the Seattle Tacoma International Airport (SeaTac), another Washington state company, Clear Water Compliance Services Inc. (Clear Water) of Lynnwood, WA, is using a chitosan-based product from Natural Site Solutions to treat runoff from the construction of the airport’s third runway project. Clear Water has been in business since 1998, and in addition to its main office in Lynnwood, it also has branch offices in Auburn, WA, and Sacramento, CA. “We focus primarily on water treatment and work in the industrial and construction stormwater and wastewater markets,” explains Jason Ziemer, the company’s chief operating officer. “We work on large infrastructure projects across the country, but 80% of our work is on the West Coast from Alaska to California. Our projects can be as small as 1 or 2 acres right up to thousands of acres.”

In many cases, Clear Water provides customers with “start to finish” services when it comes to water quality. “We can do everything from evaluation and design of stormwater systems and project engineering to sediment and erosion control maintenance and site water treatment services,” adds Ziemer. “We also manufacture water treatment equipment, which is primarily for our own use, but we will provide this equipment to customers on request.”

Ziemer notes that most of the company’s work is related to treating captured water before it is discharged. “This is where we use the biopolymers and filtration devices,” he says. “We have to look at each project and evaluate what needs to be done. Only then can we develop an approach and move forward. The SeaTac project is one of the largest stormwater treatment projects in the nation right now, and it is very complex.”

Photo: Southwest Desert Images

Choose a polymer that best suits your situation.

For the SeaTac project, Clear Water designed, manufactured, and installed specialty equipment for monitoring and operating the stormwater treatment system during construction. “We started this project in December 2005, and we expect to be here for three years,” says Ziemer. “We worked with the engineering team to help design site drainage and the pond locations and sizes. Whenever it rains, the water runs off and collects in the ponds. We monitor the levels in the ponds and when they fill up, the computer automatically dials us and we come out and run the treatment system. In the summer months, that can be once a month, but during January when we have a lot of rain, it can be 24/7.”

When the system is operating, a programmable logic controller, which is essentially a computer control system, monitors the water to be treated for flow and turbidity. Based on these two pieces of information, the technician sets the chemical injection pump’s dosage rate of the chitosan-based biopolymer at where it needs to be in order to reach the proper level of treatment. In addition, the computer automatically sends treated water back to the pond if water-quality standards are not met.

“We use a variety of different polymers, but we specify chitosan the most,” adds Ziemer. “Chitosan does have limitations and there are certain types of water that don’t treat well with it, so we have to screen and make sure we always use the right polymer for the situation. Where chitosan doesn’t work well is when we have organic material interference, which can be caused from any type of plant material. The water goes a dark, tea-like color, but if we use an aluminum-based polymer in conjunction with chitosan, we can rectify this.”

Bill Tice is based in Blaine, WA.

An Industry Insider’s Perspective

How they are made and how they work

By Chad Falkenberg

Synthetic copolymer emulsions are emerging as one of the most advanced and versatile materials successfully being utilized throughout the dust control, erosion control, and soil stabilization industries.

There are a variety of synthetic copolymer emulsions, but the majority consists of acrylic and vinyl acetate–based latex polymers in a concentrated liquid emulsion. Synthetic copolymer emulsions are environmentally safe, are nontoxic to both plants and animals, and have no negative impact on water quality. Upon drying, the emulsion cures transparent and will not significantly alter the appearance of the natural soil or aggregate.

Photo: Southwest Desert Images

Using polymers for dust control is popular in areas, such as Arizona, where water is scarce.

Any equipment capable of spraying water can be used safely to apply the copolymer dilution to the application site. Copolymer emulsions are noncorrosive to equipment and are safe for operators to handle. To apply the concentrated emulsion, it is diluted in the field with water from 1 to 40 parts depending on the application type and the manufacturer’s recommendations. It can be used to treat almost any soil or aggregate type under a wide temperature range.

Once applied topically or mixed into the soil/aggregate, the polymer molecules coalesce and crosslink, forming bonds between the soil or aggregate particles. As the water dissipates from the soil or aggregate, a durable matrix of solid mass is created. When compared to the molecular structure of traditional materials such as bitumen, lignosulfonate, chlorides, and non-various resins, copolymers can be up to 10,000 times larger in size. The key advantage of copolymers originates with their long, relatively straight molecular structure consisting of up to 1 million molecules in length that are linked and crosslinked together. Light application rates are useful for dust suppression and erosion control by creating a three-dimensional cap or surface crust. Heavier rates can generate qualities similar to cement, which are useful for soil solidification and stabilization. By adjusting the application rate, copolymer emulsions can remain effective from weeks to several years.

Copolymers were originally introduced into the dust control market as a cost-effective way to dispose of large volumes of waste “white water” and other various byproducts that were generated from the adhesives and coatings industry. Traditionally, these materials were disposed of through water treatment plants at a significant expense. It was more cost-effective to use the byproducts for dust control. Today, many copolymers in the marketplace are still blends of waste copolymer emulsions spanning from contact adhesive to floor polish. Unfortunately, this wide spectrum of materials results in a range of results for the end user. Typical byproduct copolymers have solids content below 50% with significant variances from batch to batch including tensile strength, bacterial resistance, elasticity, UV-resistance, dry tack, viscosity, pH, water resistance, and many other important factors influencing performance.

“Prime” engineered copolymer emulsions such as Soiltac can be manufactured with no dependence on byproducts, allowing for production in unlimited quantities with consistent performance and properties.

Chad Falkenberg is with Soilworks LLC and has been involved in the industry for a number of years.

EC - November/December 2006