When municipalities make commitments to reach zero-waste-to-landfill goals and increase diversion rates, they must look at their waste stream and determine what materials can be diverted. Usually, municipalities target food waste and construction and demolition (C&D) debris.
“C&D represents a large fraction of the total MSW (municipal solid waste) in a region and provides a large chunk of potential recovery to improve overall recycling numbers,” Bradley Kelley, senior project engineer at Gershman, Brickner & Bratton (GBB), a McLean, Virginia-based consulting firm, says.
One project that GBB helped design, procure and start up was the C&D debris processing system at Corral Farm, a MSW facility in Fauquier County, Virginia.
“The C&D landfill was out of capacity and closing, so the county decided to maximize recycling and minimize the disposal of this waste stream,” Mike Dorsey, Fauquier County director of environmental services, says. There were also no other C&D recycling options available at the time in the region.
The system processes mixed C&D debris, such as dimensional lumber, scrap metal, vinyl siding, rigid plastics and drywall, and bales cardboard and plastic on-site to sell directly to buyers.
According to GBB, the site has increased recycling, maximized landfill life and generated more than 50 percent of the funds needed to provide the county’s solid waste services since the facility began operations.
Doing more than most
GBB partnered with Draper Aden Associates (DAA), a consulting engineering firm based in Blacksburg, Virginia, for the Fauquier County project. DAA was already a consultant with the county for one of its landfills.
GBB worked with the county to draft a request for proposal describing the needs for processing equipment and gave the option to bidders of either operating the facility on county land or supplying the equipment for the county to operate. GBB then reviewed the six proposals it received with the county and decided a county owned and operated facility would be best.
Kelley says GBB and county representatives visited several reference facilities from proposers and eventually settled on Sherbrooke OEM Ltd., headquartered in Sherbrooke, Quebec.
“Sherbrooke was chosen as the best solution based on the criteria set forward in the request for proposals,” Kelley says. “GBB sent a representative to an existing facility with Sherbrooke equipment to confirm that the new facility would perform as expected.”
Planning for the $1.2 million system began in 2005, Dorsey says, and operations began in July 2007. According to Dorsey, the C&D facility receives 50 to 100 tons per day and operates once or twice per week.
An excavator is used to load materials onto an apron conveyor, which moves the material to an incline conveyor. The material moves through the only piece of equipment not manufactured by Sherbrooke, a Finger Screen from General Kinematics, Crystal Lake, Illinois. The Finger Screen sorts through material that is 0 to 8 inches. The material is then moved through a magnet to pull metals, and a star screen is used to pull 2-inch-minus material. Hand sorters separate any material 2 to 8 inches or more.
After the material goes through the system, the drywall is shipped to a gypsum facility, the lumber is ground on-site for mulch and a stockpile of scrap metal is loaded and sold directly through the county. Dorsey says vinyl siding and rigid plastics are baled and sold on-site, as is cardboard.
Inerts sorted from the line are stockpiled and sometimes used on-site, depending on the county’s needs.
“We have 300 acres with recycling programs and a landfill disposal operation,” Dorsey says. “And we run a transfer station, collection system and bulk system. For as small as we are as a county, we do more things than most.”
Kelley says one of the obstacles GBB had to overcome was working with Sherbrooke to fill out the paperwork needed for installation.
“Many turnkey equipment manufacturers are used to working with private entities where the up-front requirements and paperwork are not as strict,” Kelley says. “Understanding that, as a municipality, everything needs to be spelled out and written, and who is responsible for what can sometimes be an additional headache for manufacturers, but it is certainly something that is necessary.”
Dorsey says the county encountered some normal challenges when installing and implementing the C&D system, such as training staff and learning efficient operating procedures, maintenance requirements, material management strategies and contamination best practices. They also had to deal with a few requisite repairs (including worn-out belts, sprockets and bolts), but the system’s cost effectiveness quickly became evident.
“Recycling tipping fees and sales revenue are consistently cost effective compared to the disposal alternative,” he says. “The county initiated a pilot program for landfill mining of C&D materials that would not have been feasible without the system in place.”
The mining has since been discontinued because of the county’s decision to reduce on-site landfill disposal and transfer municipal solid waste.
Keys to success
Municipalities can improve their recycling rates, recovery number and improve landfill space, when implementing a C&D program, Kelley says.
“In certain cases, there may also be local demand for certain feedstock, such as clean wood for chips or biomass fuel, that a C&D processing facility can provide,” he says. Local MSW landfills can also use fines from C&D processing as alternative daily cover if there is a dirt or cover shortage.
“This may not always count as recovery or reuse, but may help extend the life of the landfill or prevent having to haul in dirt from elsewhere as the needed cover,” Kelley says.
Kelley says the number of C&D programs in municipalities is growing, but in many instances, the debris is already handled by private entities and most larger municipalities may already have a program in place that is private, public or both. Regardless of who is handling the waste, Kelley says a C&D program must have the necessary tonnages to be successful.
“C&D processing facilities operate on efficiencies of scale and have minimum tonnages and throughputs necessary to work out economically,” he says. “Understand that just because you have C&D material doesn’t necessarily mean it makes sense to process it—there can be a lot of other factors involved.”
If a municipality wants to implement a C&D program, Kelley says the best road to success starts with mapping out any goals, looking at what is going on locally and not being afraid to ask for help.
“Understand your tonnages and goals,” he says. “Is [your goal] to save landfill space? Improve recovery tonnages? Provide local builders with LEED certification (Leadership in Energy and Environmental Design) potential? Also, understand regional influences from other C&D locations and recovered materials markets. Having a knowledgeable third party help guide you through this is very helpful, as there can be a lot of confusing information and pitfalls.”
To have a successful municipal C&D program, Kelley says municipalities must be aware that markets for recovered materials are erratic and that market needs are always changing. He says to avoid any negative consequences, contracts and equipment must reflect that uncertainty and be versatile.
“A successful C&D program needs to be sustainable for the long term to provide recovery options for contractors and builders and to keep recyclable material from landfill,” Kelley says. “This may mean surviving some lean years when the economics are not favorable. In many cases, a municipality is in a better position to survive these downturns than a private entity, but these downturns should be anticipated, and the municipality should be patient.”