Grading and Excavation Contractor | Reduce, Recycle … and Reap Rewards

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Contractors tell how they are converting greenwaste from construction sites into material that benefits both the environment and their bottom lines.

By Greg Northcutt

Disposing of greenwaste cleared from commercial building sites, road building projects, and golf course construction jobs can be a daily grind for Lee Sharp, president of Sharp Contracting, Knoxville, TN. Rather than burning or burying logs, stumps, and branches from trees cleared from construction sites, he runs them through a hammermill, knocking them into bits and pieces. In the process, he’s cutting the costs of hauling the material off the site and helping the environment, while producing material that’s worth some real money.

Once considered a waste disposal problem, slash from land clearing projects is now being recovered and recycled as mulch for landscaping or controlling erosion, and as fuel to fire boilers for producing steam used for heating or generating electricity using machines that grind woodwaste into small bits and pieces.

As in many areas of the country, air-quality regulations have eliminated the option for Sharp to remove the wood waste simply by lighting a match to it. What’s more, increased pressure on landfill space has added to the time and expense of dumping the material in a landfill.

Getting Ahead
Putting bulky green woodwaste in a landfill that will accept it is a costly proposition, Sharp notes. “It can be a long way to one of these landfills and then you have the expense of diesel for your trucks and the tipping fees,” he explains. “I’m money ahead to grind the woodwaste and recycle it.”

As Sharp notes, grinding offers a way to reduce the cost of transporting stumps and brushy treetops by increasing the amount of wood that can be hauled in a truck. For example, grinding can reduce 600 cubic yards of brushy material to as little as 100 cubic yards of ground wood, say experts. For logs and stumps, the reduction is more like a 3:1 or 2:1.

Then there’s the value of the recycled wood itself, even if it is relatively modest. “If you’re hauling 20-ton truck loads of ground wood priced at $10 a ton as fuel, that load is worth $200,” observes Tim Wenger, president of grinder maker CW Mill Equipment Co. Inc. “While $200 doesn’t buy a lot of transportation, it does get the material offsite.”

Another contractor who is benefiting from grinding greed woodwaste is Richie Trammel. He’s an assistant vice president of Phillips and Jordan Inc., a heavy grading and earth moving company based in Knoxville, TN. Trammel is in charge of the company’s land clearing operations in the Charlotte, NC area.

“Back in the 1980s, when we cleared a tract of land, we’d simply burn the waste wood in the open,” he says. “Then, in the 1990s, we switched to pushing the wood into a pit, where we burned it. Now, in some areas where we operate, local ordinances don’t allow us to burn at all.”

These days, the emphasis is on recycling, Trammel says.

“Now, we make use of all the wood. All the timber that we can’t log and sell is ground up and removed from the site. Even though we might not make that much money from the wood chips, by reducing the volume, grinding knocks down some of the costs to haul it away,” he says. “We sell some of material to power plants that use it to fuel boilers and we give the rest away to landscape supply yards, who regrind it for landscaping uses.”


	New Mobile Shredder Drives to the Job Site

More Green Operations
Over the years, the Bob Ray Co., Louisville, KY, has expanded its residential tree care business into clearing land for rights-of-way in residential, commercial, and industrial development sites.

“Before we got into land clearing, we’d dump waste wood where we could, either on our land or a customer’s property,” says Tee Ray, president of the company. “Now, because we make our living in the green business, we want to be environmentally friendly and do our part to recycle timber that we can’t market otherwise.”

His company uses the Beast Recycler from Bandit Industries Inc. to grind the waste wood into 6-inch or smaller material. Some of this is sold and delivered to a local company as fuel for cogeneration of electricity. The remaining waste wood is reground into 2-inch or smaller pieces for mulch and sold to a subsidiary of the Bob Ray Co. This mulch is colored with various dyes and sold to wholesalers and retailers for use in landscaping projects.

Purchasing a grinder also made sense for Dan Dykstra with Trillium Corp., a land development company in Bellingham, WA. Several years ago, the company had planned to burn all the slash it was going to remove from a 600-acre land development project. Then, its burning permit was unexpectedly revoked. This left the company two choices: buy 20 trucks and haul the waste wood to a yardwaste landfill or invest in a grinder. “The costs of trucking and dumping the material would have killed us,” says Dykstra, who’s in charge of the grinding operations. “Because of the size of this project, it was more economical for us buy a grinder and give the recycled wood away.”

He bought a Peterson model 6700B grinder. Last year (2007), Dykstra completed his second season of grinding. Until he could find a cogeneration plant that would haul the free material away for use in its boiler, he used an 80-yard chip wagon truck, a 40-ton articulated dump truck, and a dozer to place the ground up wood into three 80,000-cubic-yard stockpiles. “After the first year of taking the material for free, the plant wanted us to offset their truck fuel costs by paying them to take our wood.”

So, last year, Dykstra found another co-gen plant that would plant wanted us to offset their truck fuel costs by paying them to take our wood.” So, last year, Dykstra found another cogen plant that would haul the wood at no charge.

With about 95% of the clearing work completed at the end of 2007, he plans to complete the grinding work this year (2008). “Then, we’ll park the machine until the next big land clearing project,” Dykstra says. “In the meantime, we might do some custom grinding.”


	Check Out Some of the Latest in Grinding Technology

Market Prospects
Land-clearing contractors and those who specialize in grinding aren’t the only ones finding opportunities for recycling wood waste into mulch and fuel. “Grading and excavating contractors have represented a good percentage of our business over the years,” says Wenger.

“Some of the larger grading and excavation contractors have set up their own mulch operations and become wholesalers and distributors,” says Jerry Morey, president of Bandit Industries Inc., a grinder manufacturer. “Some may have contracts with large home improvement retailers. Smaller contractors usually sell their recycled wood mulch to wholesalers who remarket it.”

He expects the market for mulch to continue growing as more homeowners hire professional landscapers and as drought continues in some areas. “Mulch not only helps control weeds, but it also retains moisture for trees, shrubs, and flowers.”

The appeal of grinding waste wood for mulch varies from one market to the next.

“In the Carolinas, the supply of wood exceeds demand,” says Wenger. “In the Chicago area, mulch producers are barging in wood from Arkansas to meet the demand for wood fiber. And, in New England, the demand for wood chips exceeds supply. As a result, mulch producers, and those who make fuel, are competing for the same waste wood.”

Rising oil prices are boosting the market for wood fuel, Morey notes. “Power plants and cogeneration operations, especially in the Northeast and the South are using more recycled wood,” he says. “Near our factory in Michigan, a university gets about half its power for heat and air conditioning from burning wood chips.”

The ability to recycle woodwaste may not necessarily be the only reason to own a grinder, either. Wenger reports selling grinders to grading and excavation contractors in Georgia and the Carolinas several years ago when they were left without a way to grind up wood cleared from their sites as many of their grinding contractors went south to clean up storm debris left by a series of hurricanes.

“These buyers couldn’t move dirt until they could get the waste wood ground up,” he says. “Owning a grinder can improve a grading and excavation contractor’s competitiveness. It allows them to keep margins they pay to a grinding contractor. Plus, it allows them to grind on their own schedule rather than waiting for someone else to do it. Also, it’s a way to keep employees busy when the dirt work slows.”

Grinder Choices
Depending on make and model, grinders feature a mill with various types of hammers or teeth to cut, split, or grind green wood and different sizes of screens to reduce the wood to pieces as long as 6 inches or as fine as sawdust, depending on use.

“You can put bigger material into a grinder than a chipper,” says Morrey. “A grinder also produces a more stringy material, which is more desirable for mulch. For fuel use, you want pieces less than 2 inches long, with as few fines as possible.”

Wood pellets are emerging as another form of fuel. In this case, wood ground as fine as flour is run through a die and processed into pellets for fuel used in stoves for heating homes.

Depending on use of the processed wood, the ability to control the size of the end product can be an important factor in selecting a grinder. Peterson grinders, for example, feature a three-stage grinding process. “It consists of an up-turning rotor and a large grate area that allows you to produce materials to exact specifications,” Cody Peterson says. “A quick-change multiple grate system makes it easy to customize grate configurations to produce a wide variety of finished materials.”

Grinders are available in two basic styles. Tub models use a revolving tub and rely on gravity to feed the mill. They handle just about any size material that can fit inside the tub, which can range up to about 10 feet in diameter. Horizontal models use a conveyor to feed waste wood into mill openings measuring as large as about 50 by 80 inches.

“Both types of grinders excel in conditions and applications that match up with their capabilities,” says Jerry Roorda, a grinder specialist with Vermeer Manufacturing Co. “Tub grinders generally perform better with heavy, large-diameter material such as stumps and root balls. However, unlike a horizontal grinder, logs have to be cut to fit inside the tub. Because you can fill the tub all the way to the top, the same amount of material is presented to the mill at any one time. As a result, you end up with a more consistent size of product.

“A horizontal grinder is better for longer, bushier woodwaste because you can feed over-length material into it without the need to cut it into shorter lengths. Horizontal models have the long feed table and conveyor that guide material into the grinder. This eliminates the sometimes tedious task of placing and manipulating material when feeding a tub grinder.”

More Mobility
Originally developed to be towed behind a truck, more and more grinders are being mounted on tracks for remote-controlled, self-propelled operation. Tracks can add to a grinder’s versatility. For example, a track-mounted unit eliminates the time and effort to tow a grinder for short distances if you’re processing several piles of debris on a job site. Also, tracks may enable the grinders to reach places inaccessible that machines rolling on tires can’t reach.

“These models are becoming much more popular since they were introduced six years ago,” says Wenger. “Using the remote control, an excavator operator can maneuver the grinder over wet or rough terrain to the desired location and then operate the grinder from the cab of their excavator.”

Land clearing contractor Trammel has been using two HogZilla HTC-1464T track-mounted self-propelled tub grinders for the past two years along with a smaller model HTC-1462T track-mounted unit. “They’re a big advantage for getting around the site in wet, winter weather,” he says. “You don’t have to build roads to move them and you’re not tearing up the rear end of a truck trying to pull them over rough terrain. Because we can walk the grinder right next to the excavator as we’re moving to the next pile, we cut the time to move a towed unit in half, at least. It’s easier to reposition the self-propelled grinder to keep dust from blowing off the grinder and into the machine’s radiator when the wind shifts direction. Also, it might be a little safer to operate and move a self-propelled grinder, because the excavator operator controlling the grinder remains inside the cab of the excavator.”

Selection Considerations
Grinders suitable for reducing tree trunks, branches, and stumps cleared from land development projects range in size from 440-horsepower tub grinders weighing 45,000–110,000 pounds to heavier, horizontal grinders that produce as much as 1,500 horsepower for grinding tree trunks, branches, and stumps. When selecting the best size for your needs, Roorda suggests considering the amount and size of material to be processed and necessary mobility. “If a high daily volume of material can be expected in one central location, setup and mobility of the unit is not nearly as important as the necessary capacity,” he says.

Trammel, for example, uses his HogZilla 1,000-horsepower HTC-1464T and 1,000-horsepower HTC-1462T models to grind larger hardwood tree species and smaller, soft woods.

Regardless of type and model, grinders are specialized machines that call for special care and operation, says Sharp, who has owned and operated grinders for 20 years. Currently, he has an 800-horsepower Morbark 1200 horizontal grinder, used for smaller projects and a 1,000-horsepower HogZilla model HTC-1462T tub grinder for high production work.

“Grinding is an expensive operation and if you’re not a quick learner you can lose a lot of money quickly,” he says. “Only people who have been specially trained operate our grinders. If the operator is sick, the machine doesn’t run.”

Production Figures
It takes a certain level of production, of course, to pay the costs of buying, operating, and maintaining a grinder. Cody Peterson figures that a $600,000 grinder should operate at least 700 hours a year to justify its expense.

“If you can keep the machine busy at that level, it’s probably more effective to own it and do the work yourself than to hire a grinding contractor,” he says.

The amount of woodwaste processed per hour depends not only on the capacity of the grinder but also on other factors, such as type of raw material, proximity of the waste to the grinder, and the number of available trucks for hauling the recycled product.

For example, using an excavator to feed his 1,000-horsepower horizontal portable grinder and trucks parked under the discharge chute, Dykstra reports that he can produce anywhere from about 450 to 600 cubic yards of processed green wood per hour. “That’s with the machine operating at full capacity and burning about 43 gallons of fuel per hour,” he says. “Under these conditions I can fill an 80-yard chip truck and have it pulling away in less than 10 minutes.”

Trammel’s crews move their 1,000-horsepower, self-propelled, track-mounted tub grinder from pile to pile around the project site. In a day, they can grind an average of four acres of cleared hardwood waste, filling twenty 100-yard live-floor trailers.

“On storm cleanup jobs involving soft woods, where the material is already cut up and brought to the grinder, we can process as much as 500 to 600 yards per hour,” he says.

Sharp keeps production up on the tub grinder by using a trackhoe equipped with a shear to cut up and split logs before placing them in the grinder.

“That preparation keeps the tub running like a sewing machine,” Sharp says.

Easy Does It
One critical consideration in selecting a grinder is the ease of performing proper preventive maintenance. It’s the key to keeping these machines up and running.

Hammers, teeth, hammer shafts, anvils, and screens are high wear items.

For example, if hammers are allowed to wear without proper maintenance, the hammermill could go out of balance and its vibration will cause excessive bearing wear and other vibration-related issues. That’s why Roorda recommends checking the hammers and teeth every day to spot and repair any problems that can lead to a loss of productivity or unnecessary wear.

Because of the difference in types of grinding materials and varying amounts of use from one operator to another, it’s difficult to come up with specific “rule of thumb” for average wear or longevity, say the manufacturers. Much depends on how finely the material is ground, and how the material is prepared for grinding and the extent to which dirt, rocks, and other foreign objects are mixed in with the woodwaste.

“Sometimes when we’re grinding wood cleared from heavy rock ground, we may go through 10 bits in a six-hour period,” says contractor Dykstra. “However, if we’re working on a part of the project where the ground is strictly dirt, we may be able to grind for three days without burning up a bit.”

“If you don’t stay on top of maintenance, you’ll be out of business real quick,” adds Sharp. “We also keep a laborer on the ground when grinding to spot and remove any foreign objects, like steel posts or concrete, that can cause a lot of damage if they get into the mill.”

Try a Demo
While manufacturers continue to improve the performance, reliability, and durability of grinders, there’s probably no better way judge how well a particular machine will measure up to your needs than to see one in action. In fact, the results of demonstrations of several different makes on his job site sold Dykstra on the machine he purchased.

“Every grinder we tested had its pros and cons,” he says. “There’s nothing like seeing how a machine performs under your actual conditions for a day or two to make your
buying decision.”

Greg Northcutt writes on construction and business issues.

GEC - March/April 2008

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