Whether it’s a 5-foot diameter tree trunk, chain-sawed limbs, shrub trimmings, or even grass clippings, all such products have become more and more essential in growing new plants. Municipalities are finding that regardless of the initial size, such items help make a terrific mulch. That mulch not only reduces plant water use but also leads to reduced herbicide application. Plus, mulch is an attractive ground cover that helps public and private areas show their best faces. Essential to the success of a mulching operation is the grinder or shredder used to help keep the cost of producing mulch as low as possible.
“We process anywhere from 78,000 to 92,000 tons of recyclable green waste a year,” reports Matt Wood, green waste recycling coordinator for the Urban Forestry Division of the Los Angeles Bureau of Street Services. “We will grind whatever they bring us, with logs as big as 50 inches in diameter. Most are brought in an unchipped form but trimmed, and we take the trunks and grind them up.”
The operation includes six heavy-duty equipment operators, seven truck drivers, 18 maintenance laborers, and two supervisors. “Curbside-collected yard trimmings is another part of the operation. We’ll process about 150 tons per day of curbside. We don’t have any storage or composting permit on our 61⁄2-acre site in the northwest end of the city, so everything we produce is hauled out as we make it. We’re operating solely under a chipping and grinding permit.”
Wood, who has been dealing with recycling operations for 21 years, reports the city has three tub grinders at that facility. “We have a trammel screen to screen curbside collected and another trammel screen to screen the mulch to make the finished product. For the curbside we use a 2-inch screen and for mulch we use a 1⁄2-inch screen. The finished product we do sell to wholesalers and nurseries, primarily as a soil amendment.” He adds that community and botanical gardens inside the city get it free as a bedding mulch. Tree fruit farmers report the mulch has helped reduce water usage by 15-25%.
Wood comments that his division’s grinders are all manufactured by Morbark Inc. The oldest one, an 1100 model has been in use since 1994, he says, while one of the division’s 1300 models is seven years old, and the other 1300 was purchased last summer. “Our machines are self-propelled,” Wood says. “We do that because we don’t have to get a truck to move around the site and it helps with air quality. Also, we don’t have to go through the stationery permitting process, which makes it a little easier for us to operate on the same site throughout the year.”
Parts replacements are typically through the manufacturer, and delivery takes just a couple of days, unless it has to be sent from company headquarters in Michigan. “We’ve had good luck with the machines, but another benefit is the city has assigned regular operators to my operation. I’m able to train each operator on the function of the machine. They’re very familiar with how their machine works, and they perform a lot of the daily maintenance themselves. They’re aware of what’s going on with that machine all the time.”
Another advantage is that the grinders work on an asphalt pad. “By putting the grinders on asphalt, the cutting inserts last longer. There are no dirt or rocks against the screen. We start with a clean surface, which makes material going through the machine that much cleaner. Even during the rainy season, we’ve been able to run the operation 24 hours a day. That’s when we get more downed trees.”
Wood adds that they don’t get a lot of root buttresses. When they get a downed tree complete with root ball, the operator simply picks it up 2–3 feet off the macadam and drops it a few times. “It’s easy to pick up the soil left by that procedure, and we can grind the tree without causing problems to our machines. The biggest problem, though, is trapped metal. If there’s no way to get the pipe out, we’ll haul the root ball to the dump. It doesn’t take a lot of time to check for metal and the operator needs to pay attention. It’s the operator’s attention that makes the difference.”
Another strategy, on or off the site, is to locate the machine for easy PM, so that PM downtime is next to nothing. “Each day we have about an hour’s worth of PM, including greasing, tightening bolts, installing new cutting inserts. It takes the operator just 5 minutes to replace a worn insert. Our older machines have 24 inserts and the newest one has 20. They’re double-sided, so we get two uses out of them.”
A final strategy is they have a parts contract with the manufacturer of the machines. “That way we don’t have problems with parts not fitting or not lasting as long as expected,” Wood comments.
As with other machines, an essential element for increasing production while reducing cost and complexity of operation comes from the suppliers. Says Dan Brandon, marketing manager for the Winn, MI-based Morbark: “Some of the more apparent trends in the past decade are for larger machines, greater horsepower, more productivity. Also, control panel computerization has helped boost both simplicity and safety of operation while increasing production. In the past, grinders had a lifespan of 3-5 years; you’re now looking at 7-10 years in a municipal operation. The city of Los Angeles, for example, should get close to double the life of the older machine with the new one they put in this summer.”
The need, Brandon says, is for users to find other uses for the grinder/shredder as well as avenues for marketing the product. This can include bedding soft playground material, compost, soil amendments, even colored mulch. “Time is money these days, and fuel is expensive. I expect we’ll see continued improvement to make grinders and shredders more operator-friendly as well as more productive. The more productive we make these machines, the happier the customers will be.”
Manufacturers are working with steel vendors to use the best possible grade of steel so the machines will last longer, no matter what type of climate they’re operating in. “A couple of our patented items include a torque limiter which instantaneously disengages the drive line, which saves the engine from bogging down. The last thing you want to do is ruin a $150,000 engine because you’ve caught a piece of steel. The torque limiter disengages the driveline, yet the engine continues running so the operator only has to remove the foreign object and he’s back to work.”
As with other vendors, another major effort is promptness of parts replacement, again to avoid costly downtime.
While large operations such as Los Angles are year-round, grinders and shredders have a niche in smaller communities, especially when the population fluctuates tenfold during the year. One such is Worcester County, MD, which has a modest 45,000 permanent residents but a summer population that peaks at 450,000. Ron Taylor is landfill supervisor and recycling coordinator for Worcester County Public Works, Solid Waste Division. “Growth starts in May and ends sometime in October,” he says. “We’re in a building boom, but we’ll take in 700–800 tons a day in the summer and 400–500 tons a day in winter.”
The county’s operation produces ground mulch for sale as well as for erosion control measures on the landfill, and also is used to beautify county property. “Keeping material out of the landfill is the biggest benefit at this point. We’re using a Morbark, Model 1100 tub grinder to grind all of our yardwaste, including stumps. In 2005, we received over 62,000 tons of demolition and used a Morbark Predator, which is a high-torque shredder, to grind this material. This machine shreds the material and helps reduce volume by at least 50%.”
Selling Mulch Is A Natural
While many municipal operations tend to focus on the part of the grinding equation that helps the community deal with greenwaste, Mike Byram, senior director of the environmental business segment for Vermeer Manufacturing Co., located in Pella, IA, emphasizes, “There’s less and less desire to take organic waste to the landfill, so the need is to find a market for the processed material, whether as playground mulch, as compost, or as fuel. If someone will pay for the end product, it should help reduce the cost of operation. Trends are that customers are a lot more aware of and making decisions on the cost of operation, such as maintenance, fuel costs, service intervals and extended life of the machines they buy.” Productivity is also part of the cost of operation. Vermeer designs its grinder control systems to help obtain efficient machine output while operating in ranges that protect machine component life.
As with other successful manufacturers, Vermeer uses innovation to enhance their products. All Vermeer horizontal grinders feature the patented Vermeer Duplex Drum cutting system which offers optimum cutting performance and simplified maintenance. The maintenance time is reduced by easy hammer and cutter-block change-out. In addition, the hammers and cutter blocks are reversible, therefore nearly doubling hammer life.
He adds that an experienced equipment operator can learn the basics of a new grinder in a relatively short period of time. However, if an operator has never worked on large mobile equipment before, it can take several weeks of training before becoming proficient in loading, running, and maintaining a grinder.
Byram adds that another Vermeer innovation is the patented thrown-object restraint system (TORS) on its tub grinders. “One issue with grinders is thrown objects. The Vermeer TORS controls the quantity and distance of thrown material.” In addition, Vermeer horizontal grinders feature the thrown-object deflector.
West of Chicago in Lockport, IL, Todd Hahn, director of operations for Homer Industries LLC, says this private operation handles 300,000 yards of green wood waste annually, using two Vermeer TG 9000 grinders. “We sell the resulting mulch to landscapers, supply yards, schools, and cities. During the summer months, we get the product out the same day it’s ground. However, we do strategically stockpile during the winter months to prepare for a busy spring.”
Hahn says the company’s source is from its land clearing operations. “We don’t dig the trees out; we cut them at the base. We buy our replacement parts from the manufacturer for two reasons. First, I can usually get the item needed in five minutes. Second, the quality is much better than with the nonbranded part. We have four operators and four mechanics that handle both maintenance and repairs. Plus, Vermeer’s mechanics help us quite a bit. If there’s something major, they come from their store and have the repair made within a couple of hours. Their quick reaction helps us keep the operation profitable.”
Concerning safety, Hahn concludes, “We have a strict safety policy and educate our guys on safety. We typically hire people experienced with the type of equipment we use. Safety is never a big issue if you know what you’re doing. Do your job right, work smart, and you don’t have to worry about safety.”
Horizontal Or Tub, Stationary Or Mobile?
Down in Murfreesboro, TN, the street services and mulching operation, overseen by Joey Smith, handles 27,000 tons of yard waste annually. Says Smith, “We grind it, then give it away on a first-come, first-served basis. We don’t have a disposal fee, either. It all comes out of the general fund, including weekly pickup for curbside collection.” Furthermore, this city of 75,000 has an intercity agreement with surrounding towns as well as an agreement with Rutherford County.
“We’re working on changing our location 9 miles to include a scale house at a new site that has 44 acres and room for us to use 51⁄2 acres for the mulching operation. We have a tub grinder and a horizontal grinder. We’ve had the horizontal, a Morbark 1300—which we use as a stationary unit—for 10 years. On July 27, 2005, we added a CW Mills Manufacturing HogZilla mobile tub grinder.”
He says that adding the second grinder came after a series of windstorms blew down so many trees in 2003 that they had to rent a tub grinder to handle the extra work. “It took us almost six months. We had 45,000 tons of yard waste that year just because of storms. Both types of grinders have their place. There are spots we can move the mobile grinder to if we have to, which reduces the cost of hauling trees to the landfill itself. It makes for faster recovery after a storm.”
The challenge is being able to anticipate day-to-day demand. “The smaller machine makes it easier to handle volume changes. We do haul brush directly to it right now, but when there’s a major storm it saves the city money by hauling to another location for centralized processing. We have 20-yard haulers in the city’s truck fleet. Centralizing the grinding operation saves time and fuel for the city’s fleet and encourages more citizen participation.”
Smith also agrees that grinders require intensive maintenance: “If you don’t grease it or make sure there’s oil, it’s not going to operate. Like any other machine, if you don’t maintain it you’ll have bigger bills. So our people check both grinders three days a week to be sure no problems are developing.
“Even though the site is dedicated to organic waste, we still have to watch for concrete, tires, plastic bottles, aluminum cans and other foreign materials. We take trees only, no posts, treated lumber, and stuff like that.” Smith reports they plan to develop a composting operation but haven’t set a specific date.
Since 1947, West Salem Machinery Inc., of Salem, OR, has been supplying screening and size-reduction machinery, both stationary and portable, and is heavily involved in the recycling scene involving wood products as an alternative fuel source. “Thanks to our 60 employees, we can supply an individual component such as a grinder or even a complete processing system. For example, one of our customers has a wood recycling operation in North Carolina. He came to us nine years ago. He had a diverse mix of woodwaste material and was trying to come up with a system to minimize labor and energy costs and produce a recyclable, saleable product out of his woodwaste material.”
So the folks at West Salem Machinery designed a horizontal-feed grinding system with a disc screener to process 30–40 tons per hour. This included conveying equipment and an automatic truck loading system, which greatly reduced the need for a front-end loader or other rolling stock. “It can be operated by a single person,” Lyman explains.
He then comments, “The trend we see is more on stationary electric equipment. Electricity is less expensive than diesel power. Another good area of savings is in operating and maintenance. Diesel engines are more complicated than electric motors and require a much higher level of maintenance. The switch to electric drive simplifies the equipment. It’s easier to operate and easier to care for, yet offers improved reliability. That all translates into lower cost of production.”
Regarding stationary machines, he comments, “You can expect your grinder to last 20, 30, even 40 years—with proper maintenance. Since the machine stays in place, you can build it heavier to provide a long life.”
Jerry Morey, president of Bandit Industries Inc., Remus, MI, sees chippers as an effective way to turn a waste product into a valuable commodity that a waste processing operation can sell.
“High energy costs are opening up opportunities,” Morey says. “There is a growing demand for wood mulch by the landscape industry and an increase in the use of wood mulch in the ag industry. Years ago, greenwaste occupied as much as 40%–50% of some landfills. That’s gone now; they’ve turned that waste into mulch and other products.”
For him, the future also includes developing even better machines for processing material at a lower cost. “Improved electronics will help control all operational functions to maximize the use of fuel. We’ve been making our Beast Recyclers for nine years, and none have ever been retired. Yet we’re seeing older machines being turned in with just 6000–8000 hours on them after 3–4 years in service. Those people are trading for the advantages that come with newer models.”
Morey points out that the latest introductions are so simple to operate that they can be readied for transport in less than 10 minutes and set up for operation in less than 20 minutes after arriving at the worksite.
Tim Wenger, president of CW Mill Equipment Co. Inc., Sabetha, KS, reports that his firm began building tub grinders in 1974. “We built our first HogZilla in 1988 because larger grinders provide a better investment value. There is value in size, room for an operation to grow before it outpaces the capacity of a smaller machine. Municipalities particularly are realizing the grinder they bought 5–10 years ago may not have been the best value.
“Those using smaller grinders may take 6-inch wood and the rest ends up in the landfill. Others may take 8-inch, and others 12-inch before the wood has to go to the landfill. It makes sense to get the larger machine to lengthen the life of the landfill, especially since more and more communities are expected to accept everything and grind it into mulch and give that mulch back to the customer.”
Wenger, who has been head of the family firm since 1985, adds that with the company’s latest line it’s relatively simple to turn a greenwaste grinder into one that accepts tires, then switch back to wood. “It takes two people just five hours to make the changes for switching that tub grinder from wood processing to tire processing. The city of Brownsville, TX, was forced to deal with a tire problem. They’re shredding their tires, but others are using tires in cogeneration plants.”
Meanwhile, in Brownsville
There is one catch with buying a monster machine to handle whatever comes through the gate or past the scale house, and that’s the cost. “That’s why we bought a used grinder,” explains David Ivory, director of public works for the city of Brownsville, TX.
He candidly comments, “These machines can cost $1 million, and we don’t grind enough material to justify such a large expenditure. I felt a brand-new machine for us might be overkill, yet we needed something that could handle the tires as well as the woodwaste. So, we saved 60% when we got the used machine.”
Ivory, who has been with the city 12 years, adds that another specific challenge for the green division of Brownsville’s public works involves palm trees. “They are so fibrous that when you try to process palms with a smaller machine they turn into ropes. You need the hp capacity to cleanly cut and grind the fibers.”
Noting that 10 employees deal with recyclable waste, he says the used machine has benefited the citizens in many ways. “We use mulch and compost in parks and a lot in-house to generate vegetation, to establish grass on slopes and paths, which reduces erosion. Using mulch, or compost, or both for maintaining the common areas has beautified Brownsville.”
He candidly comments, “We bought our machine four years ago. By nature, it requires a lot of maintenance. A lot of things can go wrong. The secret is to have a mechanic onsite that is dedicated to the machine. Then, when we’re grinding tires, palm trees, or whatever else, that machine is checked twice a day by the mechanic. He’s spending less than 90 minutes keeping that machine working.”
The general secret, though, is for prospective users to consider all of their needs and challenges and develop an operation designed to deal with the waste involved, and make room for future needs.
This helps ensure that after buying a grinder or shredder, the user will be satisfied with the performance of the machine, and with the long-term success of the operation.