C&D Recycling Technologies

BioCycle December 2006, Vol. 47, No. 12, p. 35

Two Massachusetts facilities process loads using a system of conveyors, screens, manual picking and grinders while recovering wood for use as boiler fuel.

Robert L. Spencer


AFTER MORE than four years of planning and working with a 160 member Construction & Demolition (C&D) Debris Advisory Committee, a state-imposed ban on disposal of C&D debris in landfills took effect July 1, 2006 in Massachusetts – the first state to promulgate such regulations. Hoping the adage “Build it and they will come” applies to C&D processing facilities, private companies have been investing heavily in development of state-of-the-art, enclosed C&D plants.

There are numerous variables to factor into the design of a C&D processing facility: Volume of material, its composition, the end products, and markets for those products. One of the most difficult assumptions is to determine the processing capacity considering that seasonal and economic variables greatly impact generation of the feedstocks. This article takes a look at New England Recycling’s facility that opened in January, 2006 in Taunton, as well as ABC&D Recycling’s facility in Ware, which opened this March (both in Massachusetts).

Both facilities process loads of mixed C&D using a system of conveyors, screens, manual picking and grinders to recover newly banned materials. Currently, these plants manufacture alternative daily cover (ADC) for use on landfills, their largest market at this point. However, as landfills continue to close in the Northeast, both facilities are looking to expand the range of materials they process to replace ADC. Both facilities are also designed to recover wood for use as boiler fuel, another market that is in flux due to varying regulations from state to state, and more stringent air emission requirements.

ABC&D RECYCLING, WARE
Building on his experience recycling motor vehicles at his car salvage yard in this rural town in central Massachusetts, Dick O’Riley was convinced by a friend that they should expand into recycling of C&D. Six years ago, O’Riley set out to permit and develop a 750 tons/day C&D processing facility. As President and CEO of the company, O’Riley has been intimately involved with design and development of the $12 million facility, as well as its start-up and operation. “I wanted a turnkey processing facility, and worked with Continental Biomass Industries (CBI) to design a system with all of the components needed to process mixed loads of C&D,” says O’Riley.

“The permit process took two years longer than we had planned since we went to court to appeal some of the restrictions put on the project by the Town of Ware Board of Health that made the project just not feasible,” explains O’Riley. After 22 months in court, ABC&D Recycling was successful in winning modifications and removal of some of the more onerous restrictions.

O’Riley recounted the extensive site preparation work, which included removal of junk cars at the old automobile salvage yard, testing of the soil (it passed), seeking approval to cross a railroad track and establish a rail siding, installing public water service from the road to the site, installation of an electrical transformer, and construction of a storm water collection and treatment system with oil/water separator. The 14-acre facility includes a row of vegetation to screen it from the highway, fencing, truck staging area before the scales, parking areas, two truck scales, and the rail siding. “We made our own crushed gravel to be used in the asphalt paving,” says O’Riley, pointing to a series of outside bunkers where concrete, brick and asphalt are kept separate from the processing facility.

A 24,400 square foot metal building keeps all processing operations inside, a regulatory requirement. On the tipping floor, truckloads of C&D are dumped, inspected and if necessary, sorted by an excavator with a grapple, plucking off metal, aluminum, plastic and gypsum, prior to being loaded into the primary shredder (CBI Annihilator). From there, the shredded mix of wood, rocks, bricks, metal and miscellaneous materials is conveyed to a screen to drop out the 3-inch minus fraction, primarily wood and dirt fines, which are conveyed to a storage bunker until removed for use as ADC. These first steps are designed to remove rock and abrasive dirt prior to the final shredder, and to present the remaining material in smaller sizes so wood and recyclable materials can be more easily picked out by hand.

Awaiting the picking challenge are six employees in a climate controlled platform 16 feet above the tipping floor. Six bays, three on each side of the conveyor belt, have open bins for up to 12 employees to drop recyclable materials down chutes into bunkers beneath the platform, primarily ferrous metal, nonferrous metal, rock/stone, and cardboard.

Another feature of the sorting platform is a second conveyor running under a portion of the chutes, which can be accessed as needed. This will eventually be used to sort wood that will be conveyed to a second grinder and then to a bunker to be sold as fuel. O’Riley explains that the reason they are not currently sorting wood is that there is not sufficient capacity in the existing wood storage bunker. Once a new conveyor is installed to move shredded wood to a larger storage bunker outside, they plan to divert wood from the ADC stream. “We are allowed by our permits to store wood outside, and one of our future markets is wood fuel,” he says. Another major reason for the shift to boiler fuel is that his primary landfill customer for ADC will be closing in the next few months, and new outlets for ADC, wood and other materials will be required. “We have a company that will broker our C&D fines to markets served by rail car once our main landfill closes,” says O’Riley. The rail siding is within the building, and has a scale built into the tracks so the weight of each rail car is recorded when it leaves the site.

Following hand sorting, material is conveyed into a third grinder, followed by an overband magnet to pull out ferrous metal, and then to a large bunker from which the “fines” are loaded into trailers in an enclosed loading dock, and hauled to landfill. All of the CBI equipment is electrically powered rather than diesel due to fewer air and noise impacts. To better control electrical power surges that can shut down the equipment, and to reduce electricity consumption, O’Riley recently installed a power factor connection system which levels out electrical energy flow to the equipment.

FIRE AND DUST CONTROL
Above the tipping floor, mounted on a platform, is a water cannon, ready to spray a powerful stream of water in case of fire from hot loads, or to quell a dusty load. The entire processing building is outfitted with a water spray misting system in a series of independently operated zones (Air One Inc.). Tad Wollenhaupt, Air One President, describes the dust control system as a combination of spray nozzles suspended from the ceiling and rotary foggers, each providing consistent sized water droplets targeted primarily at nuisance dust particulate matter up to 100 micron in size. The system is supplemented with several rotary atomizers that produce 50 micron droplets in a large volume of mist using only one gallon per minute of water.

“For effective dust control, we design sprayers that generate water droplets that are slightly larger than the dust particles so the water and its captured dust drop to the floor,” explains Wollenhaupt. In order to minimize water use, a remote control is located in the cab of the excavator for use by the operator when more dusty loads are delivered. Air One also has odor control agents for injection into the water spray system as required. A fire suppression sprinkler system is also installed in the ceiling of the main processing building, and adjoining mechanical and employee break rooms. Currently, there are 12 employees, including a production manager that oversees the entire operation.

Published tipping fees are $95/ton, including roofing, and $125/ton for loads with more than 20 percent gypsum. The facility price sheet states that “gypsum (sheetrock) must be separated from load when dumping.” Loads of source separated concrete larger than 24 inches, with steel, are charged $15/ton, concrete with wood or debris $20/ton, and clean brick and asphalt, $6/ton. Currently no reduced rates are offered for source separated wood since it is processed through the facility into ADC, and soon, boiler fuel.

O’Riley is concerned that mixed loads of C&D are going to out-of-state landfills, material and revenue his company could use. According to the Massachusetts Department of Environmental Protection (DEP), mixed loads of C&D cannot be legally transferred out of the state, and DEP waste ban inspections at transfer stations are intended to minimize such diversion.

NEW ENGLAND RECYCLING, TAUNTON
Development of an enclosed C&D processing facility was a natural expansion for NER and its sister company G. Lopes Construction Inc. considering their existing operations processed and recycled brush, stumps, aggregates and C&D at two locations, one in nearby Raynham, and the other in Taunton. The new $5 million C&D processing building and equipment utilizes 5 out of 16 acres of a site already permitted and in use for processing C&D.

As with the Ware facility, a similar CBI processing system is utilized, and the two plants, although owned by different companies, are very similar. On the tipping floor, an excavator with grapple sorts out unwanted materials such as insulation, as well as large recyclable items such as metal and plastic pipe. The excavator is also used to crush the materials by driving up on the piles prior to loading on a 60-inch wide conveyor that feeds a 30-foot long trommel with one-half inch screens, generating “fines” that are used as ADC at a number of landfills.

Several major differences in the NER facility compared to the ABC&D facility are that NER does not use a shredder ahead of the sorting platform, relying instead on the excavator to break up the material. NER also uses a trommel screen instead of a vibrating screen to sort out the fines.

Although the NER facility has a smaller permitted capacity at 550 tons/day than ABC&D’s 750 tpd facility, there are twice as many picking stations, with 24 employees picking materials off the belt. Other staff includes four operators, a maintenance manager, and facility manager, Paul Correia.

“We want to get out more wood and more plastic, and we are planning on installing a new, larger baler to process even more plastic and OCC,” says Correia. He explains that the company is making the transition from manufacturing ADC, which is currently 47 percent of the processed material, to a greater percentage of boiler fuel than its current 17 percent, as well as other value-added materials such as baled plastic and OCC.

Economic drivers for the ADC to boiler fuel transition are the higher cost of ADC based on paying a tip fee of $40/ton at the landfill, plus $12/ton transportation, for $52/ton. Compared to getting paid $40/ton for fuel wood, minus trucking costs to power plants in Maine, it is significantly more economical for NER to produce boiler fuel at this time. Wood chips are loaded into trailers using a screw conveyor to evenly distribute the load.

Correia says that taken together, these steps will to reduce facility residual trash from its current nine percent, resulting in additional significant savings by diverting more material from costly landfills.

NER is also evaluating a range of mechanical sorting systems to not only recover more materials, but to make its boiler fuel cleaner in response to more stringent power plant requirements.

Published tipping fees at NER’s Taunton facility are $100/ton for residential and commercial C&D, as well as roofing shingle debris. NER is also looking into a recycling technology for shingles. The company directs clean, dimensional lumber to its Raynham facility where it is processed into mulch and a feedstock for a wood pellet plant in New Hampshire.

Bob Spencer is a Contributing Editor to BioCycle.

Q&A ON MASSACHUSETTS C&D SITES
EDMUND COLETTA, of the Massachusetts Department of Environmental Protection (Mass DEP) provided these responses to questions about the state’s construction and demolition debris facilities.

Q: How does the ban contribute to construction of new C&D sites?

A: Massachusetts has 12 existing C&D processing facilities. There also is one C&D processing facility in New Hampshire (ERRCO) that takes 65 percent of its material from Massachusetts sources.These facilities have a total permitted capacity to handle approximately 2.1 million tons per year of C&D debris. In addition, there are currently 3 new proposed facilities in various stages of permitting that will add over 1 million tons per year of processing capacity. Massachusetts has sufficient capacity online and coming online to process all the C&D waste generated and divert banned material from disposal.

Q: Given that alternative daily landfill cover is the primary product currently used by many facilities – and landfills are closing, what are DEP’s recommendation for developing other markets?

A: MassDEP has always encouraged that processing facilities work to develop higher use markets for C&D materials than use as daily cover or grading and shaping material at landfills. MassDEP has had numerous discussions with companies looking at other beneficial uses of C&D materials. In addition, MassDEP’s C&D subcommittee developed several “case studies” documenting the costs/benefits of separating material at the point of generation and diverting the material to various end markets.

Q: Regarding wood for boiler fuel, what is DEP’s regulation on burning C&D wood in boilers?

A: MassDEP regulations would allow C&D wood to be burned in a properly designed boiler with state of the art air pollution controls. Wood that was not clean wood, in order to be used as a fuel, would require a Beneficial Use Determination under the solid waste regulations in addition to the air permit for the facility. Currently, there are no facilities in Massachusetts that burn C&D wood.

Q: Are there any DEP proposals to allow mixed wood to be burned in boilers with certain air quality controls, other than in MSW combusters?

A: MassDEP does not have any current permit applications to allow mixed wood to be burned in boilers.

Q: What is the DEP policy on use of clean wood for mulch?

A: There are numerous technologies Results of a demonstration project, conducted by several C&D processing facilities, to divert clean construction wood to a mulch product are being reviewed. If MassDEP approves this activity, C&D processors will be required to follow a stringent sampling and analytical protocol to generate this product and ensure it consists only of clean wood.

Q: Are the recovery rates at the C&D processing facilities tracked by DEP?

A: MassDEP tracks annual recycling and other forms of diversion from C&D processing facilities and other recycling companies, as well as C&D disposal data from disposal facilities. This information is reported in the Solid Waste Master Plan 2006 Revision, which is available on our web site at http://www.mass.gov/dep/recycle/priorities/dswmpu01.htm#swmp. A list of all processing and transfer stations is posted on the web site at www.mass. gov/dep/recycle/solid/swfacil.htm.

Q: What is the current DEP policy on gypsum in alternative daily cover?

A: As a condition of a processors C&D Fines Beneficial Use Determination Permit, C&D processors must remove gypsum wallboard prior to any processing of C&D debris for alternative daily cover.

Q: Is DEP following development of technologies that may be able to convert wood to ethanol, and do you think this could be a significant market for recovered wood as ADC markets diminish, and boiler fuel markets get tighter?

A: There are numerous technologies that could result in beneficial uses of C&D wood and be a significant market for recovered wood.

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