• Hathaway Tree Service makes colored mulch from trees and brush cuttings

    1431by Mary Weaver

    photos by William Weaver

    Hathaway Tree Service’s colored and natural mulch sales are booming, so much so that Rick Cordie, president of the family-owned Minnesota business said, “I need more trees than I’m getting.” The tree service, land clearing, and mulch-producing business employs 18, twelve full-time employees and the rest part- time college students.

    “We do a lot of land clearing,” said Cordie. “Most is commercial and road construction in the Rochester area. We’ll go 30 miles from Rochester to clear land. I have 5 crews out right now taking down hardwood.”

    Cordie grinds brush and wood for mulch with a portable Morbark 1300 tub grinder, powered by a 1000 HP CAT motor. The Morbark has an attached cab and Morlift 400 loader. Together make it a compact, highly mobile unit.

    “I bought the Morbark 5 years ago,” Cordie continued. “Before that I used a lighter machine. We had a large fire start because of the dust retained in that grinder. I like the Morbark because a reverse fan clears the dust. It’s a very efficient machine. I also like that it’s built very heavy. It has lots of moving parts, but the local warehouses stock the parts, and I can get them overnight. If a piece of metal would get into the machine, the Morbark would automatically shut the clutch down immediately. Huge augurs grab the mulch and pull it out of the grinder tub.

    The Morbark’s sturdy build can be both a positive and a negative because of its weight. Due to Minnesota road weight limits and seasonal road restrictions, they need a ‘heavy use’ permit to take it on the road. “We can’t move it at all when winter and spring road restrictions are on.”

    As part of their regular maintenance, they find that this tub grinder takes frequent servicing. “We use long-lasting diesel oil, but every four hours we run the machine, we have to grease it and check that none of the teeth are broken.”

    Hathaway’s wood grinding is impressive to watch. The Morbark 1300 has a 13-foot diameter tub, which makes surprisingly short work of logs, stumps and brush. Material is fed in large “bites” by the attached loader and an auxiliary loader on a tripod, which is also easy to transport when necessary. A CAT front-end loader helps to move material within in reach of these. Care is always given when using the machine since the grinder’s high rpm can expel debris from time to time. “It can start throwing big chunks of wood 100 yards out if the machine catches them just right,” commented employee Jesse Powell.

    The Morbark comes with five screens, but Cordie only uses two: a 3-inch and a 5-inch. Most of the time he uses the 3-inch for mulch. “A 3-inch grind meets the specs for Emerald ash borer-infested trees, both for mulch and for biofuel,” he said. “The city requires that borer infested trees be ground up within 20 days. We have a lot of emerald ash borer and in Minnesota about 30% of our trees are ash.” Borer infested wood that comes into the yard through their tree service is marked with orange paint for easy recognition.

    Of course, the mulch would process more quickly with the 5-inch screen. “We sometimes use the 5-inch screen when on land- clearing jobs. That way, we can get a lot of material ground, loaded into the semis, and hauled back to the yard more quickly. We sell the 5-inch mulch for walking trails where a rougher grind is needed. The city buys a lot of that sized mulch for making rain gardens at the ends of parking lots to help recycle rainwater. They use special plants in the rain gardens, and put mulch in the bottom. This is becoming very common around here.”

    Hathaway’s sells mulch in 100 cu. yd. batches to landscapers and 10 cu. yd. batches to the public. “We don’t have enough product and materials to sell wholesale to garden centers. We’ve never quite actually run out of mulch to sell, but we’ve come close.” Toward the end of May, Cordie commented, “Each of the past two Saturdays, we’ve had 60 to 70 vehicles come to our yard to pick up mulch.” (That is in addition to the mulch Hathaway delivers.

    Colored Mulch

    Although about 80% of the mulch sold is natural in color, the remaining 20%, sold in four colors: red, chocolate, light brown, and cedar. Hathaway’s colored mulch is very popular, in part because it holds its color so well.

    “Some companies just spray the color on the mulch,” explained Cordie. “We actually soak the mulch in Colorbiotics colorant, and it is agitated by a series of augurs in the vat. That gives the colorant time to soak in, and gives it good penetration of the mulch. Customers appreciate vat-dyed mulch. We go through about eight drums of BASF’s Colorbiotics colorant each year. It’s a good product.”

    Employee Jesse Powell has been in charge of mulch coloring for three years. He is an expert with the operation’s 20-year-old Fecon vat-coloring machine. Because the unit only colors about five cubic yards of mulch at a time, building a stockpile is not a quick process. During the coloring process, Powell changes jobs frequently. First, he jumps into the driver’s seat of the CAT 928G loader to put 2 buckets of mulch into the Fecon. Then he hops down to recheck the computerized automated dials on the machine. Next, he monitors the colored mulch being discharged from the door on the back of the vat. When necessary, he breaks up jams with a pitchfork.

    From there, the well-soaked, colored mulch is conveyed by a Finlay 524 conveyor into its proper bin. This particular morning, Powell was coloring dark chocolate mulch, so dark it looked almost black. This is currently Hathaway’s most popular color.

    When Powell initially adjusts the mix of water and colorant, he first sets the Fecon’s computer controls on “manual” to purge the water from the lines and to get the dye flowing into the bottom of the pump, where it’s mixed with the water. When the color is right, he turns the computerized controls to automatic. The automatic feature ensures that the correct color is produced. It also hydraulically opens and then reseals the discharge door on the back of the while it controls the discharge augurs and the conveyor.

    Nevertheless, the controls need to be rechecked regularly, even when set on automatic because of the machine’s vibrations, which can dislodge the settings. Powell regularly checks the settings, maintaining the proper amounts of water and Colorbiotics, to make sure the vibrations have not changed them.

    For the dye to work properly, clean water is needed, Cordie explained. The clean water is trucked to the site in milk trucks from a dairy, and stored in a 10,000-gallon tank on site. It costs about $800 for the two milk tanker loads of water needed to fill the tank, which adds significantly to their cost of producing colored mulch. “I’ve already emptied the water tank once this season,” commented Powell in late May.


    The Colorbiotics/water mixture enters the Fecon, traveling through recycled milk house hoses, to two sets of sprayers, one at the front and one at the back of the vat. The mulch is agitated around in the vat to absorb the color with a series of three augurs. A lower augur returns the mulch, which has been pushed to the back of the vat to the front again. That ensures the mulch and colorant have been mixed thoroughly.


    When the batch is complete, a door in the back of the vat opens hydraulically, and an augur moves the sopping wet mulch from the vat and onto the conveyor. Powell finishes emptying the vat with the pitchfork. Then the exit door is automatically closed and sealed, ready to be loaded with the next 5 cubic yards of mulch.


    Cordie is careful which ground-up wood he uses for the colored mulch. ”We wait for two weeks after the mulch is ground, until the moisture level is lower so it will absorb the colorant,” he explained. “However, if the mulch gets too old and dry, the wood cells can’t accept the color at all.”


    Other incoming material

    Although Cordie also runs a tipping yard on site where homeowners and businesses can get rid of yard waste, wooden skids and softwoods, he does not grind that material himself with his Morbark. That pile is saved for a Saint Paul, MN utility that uses it for biomass fuel. They grind the wood with a Vermeer horizontal grinder. “The utility would like me to grind it for them, but I’m afraid of wrecking my Morbark with metal contaminants,” Cordie explained. ”Repairs would be too costly.”


    To obtain more material for mulch making, Cordie does allow three other tree care companies to drop off chipped material at his yard that he will grind into mulch. “These companies are careful about keeping out metal contaminants. My tipping fees for this are only about ¼ of what they used to be,” he explained. “Twenty years ago, not many people around here used mulch. We had to spread the ground-up wood on cornfields in the winter to get rid of it. Today we can use it to produce a salable product. So we lowered our tipping fees to these tree companies, to give some of the savings back to the producers.” For more information on Hathaway Tree Service, visit their website at www.hathawaytreeservice.com .

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