Un proyecto de demolición de una vivienda ofrece muchas oportunidades de reutilización y reciclado con la ayuda de un triturador que esté hambriento de materiales.
By Daniel C. Brown
Construction & Demolition Recycling, cdrecycler.com
For Kevin Reese, sustainability is not just a buzzword. He is dead serious about it, and so is David Cloutier, director of renovation and construction for Balfour Beatty Communities (BBC), Newtown Square, Pennsylvania.
Reese, owner of Reese Equipment Co. LLC, Dixon, Missouri, is recycling and reusing 94 percent of the content and structure of 30 single-story houses that were formerly used by the U.S. Department of Defense (DOD) at Whiteman Air Force Base in Knobnoster, Missouri. Reese has a contract with BBC to strip the houses of all reusable content and to grind up any wood and drywall in the remaining structures. BBC delivers development, design, financing, construction, renovation, property and facilities management services in the multifamily, student and military housing sectors. The company currently has more than 44,000 residential units and $5.7 billion in real estate assets under management.
"Once we discussed and verified the possibilities of grinding the houses, we realized the benefits. The days are gone when we would take down a house with a bulldozer, put it into a 5-ton dump truck and drive it down the street. We're able to safely recycle or reuse just about everything on the project. This is a win-win for the entire community."
Little time to waste
Reese's contract extends to 126 military housing units at White Sands Missile Range, New Mexico. "The first thing is that we take all the copper out," says Reese. "Then we take off all of the siding, aluminum or not, and recycle it. All light fixtures come out and get resold. The refrigerators, dishwashers, furnaces and all of that gets taken out and resold. Sometimes we even resell the carpet if it is in good shape."
Once the house is stripped of usable contents, Reese brings up his new 5710C horizontal grinder from Peterson Pacific Corp., Eugene, Oregon, and begins grinding up the wood and drywall that’s left in the shell. An excavator tears down the houses and feeds the material into the grinder. In turn, a conveyor on the grinder feeds the ground mulch into a walking floor trailer.
"Our walking floor trailer is a 100-cubic-yard trailer, and I can load it in 20 minutes," says Reese. "With my old grinder it took 45 minutes to an hour to load the trailer. This new grinder is twice as fast as my old one. We never run the Peterson for a steady hour because we have the truck loaded. But it would probably grind 50 to 60 tons per hour of this house material. We've got 3-inch screens in it, which means the material comes out fine. You hardly see a piece any bigger than a quarter coming out of it."
"This new grinder is twice as fast as my old one. We never run the Peterson for a steady hour because we have the truck loaded. But it would probably grind 50 to 60 tons per hour of this house material."
The resulting mulch is used as top cover to contain solid waste at the landfill. In a conventional landfill, dirt gets pushed over the solid waste every day to contain it. Ground-up house mulch saves the use of soil for cover at the landfill.
"The finer we keep the mulch, the more we can put on a trailer," says Reese. "And that's the whole idea: to cut down on the number of trips. One of these houses takes two walking floor trailer loads to haul one off. If you hauled it with an end-dump, you'd be looking at 20 loads to haul one off. We're cutting down our travels by 90 percent, so that saves on fuel, greenhouse gas emissions and wear and tear on the roadways.
Indeed, Cloutier and his staff at BBC expect to divert from the landfill 111 tons of common components and materials in the houses they demolish. "That includes furnaces, doors, air conditioning units, copper, aluminum, storm doors, water heaters, light fixtures, kitchen appliances, toilets, mirrors, electrical outlets, breaker boxes, shelving, laminate floors and more," says Cloutier.
For larger and specialty materials such as concrete, asphalt, street signs and electrical transformers, BBC is diverting 3,738 tons from the landfill. "We are working with our partners to divert 2,700 tons of concrete and 1,000 tons of asphalt from the landfill and using it in the construction of a parking lot at a local pumpkin patch," says Cloutier. "Additionally, the project will be donating 38 street lights to the city of Dixon, Missouri, and electrical transformers to the local public works department. Once the homes are ground to mulch, the 780 tons of materials will be used as daily cover at the local landfills."
Cloutier is enthusiastic about the house-grinding operation. "By grinding the existing structures, the transportation of C&D waste is accomplished in just two walking floor trailers per duplex," he says. "That's fantastic. Typically you would need 20 5-ton dump trucks per duplex. With the landfill 5 miles away, the fuel savings and greenhouse gas reductions add up very quickly," he adds.
Reese says while his truck travels to the landfill, unloads and returns, he is tearing down another house with the excavator. "We're hauling about six loads per day," he says. "In total it takes about an hour to grind up one house."
At the heart of the operation is the workhorse, the 5710C horizontal grinder from Peterson Pacific. Reese says he particularly appreciates the remote control on the grinder. “With the remote, you can control every function on the machine except for starting the engine and turning on the mill itself. Everything else—all the belts on and off, the feed on and off, the conveyor flow, the track mobility —everything can be done with the remote control,” says Reese.
"With the remote, you can control every function on the machine except for starting the engine and turning on the mill itself. Everything else-all the belts on and off, the feed on and off, the conveyor flow, the track mobility -everything can be done with the remote control," says Reese.
Reese also comments on the size of material the grinder will handle. Backed up by a 1,050-horsepower Caterpillar engine, the 60-inch by 55-inch in-feed opening on the grinder can grab and grind a 50-inch tree. Reese also will use the machine for grinding trees and brush in right-of-way clearing operations. For that application, the grinder is mounted on tracks and can follow an excavator around rough terrain. A magnetic head pulley at the end of the machine will recover ferrous materials including door hinges and screws in the houses.
Additionally, the machine has a complete dust suppression system, says Derek Izworski, regional sales manager for Peterson Pacific. "We spray water in front of the grinding chamber, into the grinding chamber, and onto the discharge belt," says Izworski. "When you're grinding up the brittle wood in old houses, it gets quite dusty, but our system knocks it down."
With a side removal grate system, maintenance of the machine is easy. The grates pull out of the side of the machine; omitting the need to climb into the machine to remove the grates. It also has a patented Peterson impact cushion. The shock load of the wood going through the grinding chamber is a violent event, but one urethane block on each side of the chamber cushions all of those impacts, says Izworski. "It's a no-maintenance shock absorber," he says. "It cushions everything up on top there. None of our competitors have that."
Working in green waste, the Peterson 5710C grinder can handle on the order of 120 tons per hour, according to Izworski. "It's kind of like a cross-training shoe," he notes. "You can do more than one thing with it. You can do the houses today, and yet go grind trees tomorrow with it. There are no changes required for that machine to go from houses to trees. The possibilities with that machine are endless."
Leader of the pack
Reese Equipment has won an award as one of BBC's sustainability leaders. "We encourage and receive input from our contractors and from our employees," says Cloutier. "We're always looking for input and creative solutions as to how we can improve our operations because when it comes to the demolition of existing houses, we're all looking to safely reduce our impact on the landfills, community and the environment.
"When Reese introduced us to 'green demolition' by grinding the houses, we really took a look at it," says Cloutier. "We asked, 'Is it safe? Is it sustainable? Is it environmentally friendly?' Once we discussed and verified the possibilities of grinding the houses, we realized the benefits. The days are gone when we would take down a house with a bulldozer, put it into a 5-ton dump truck and drive it down the street. We're able to safely recycle or reuse just about everything on the project. This is a win-win for the entire community."