IN 1998, the city of San Jose, California conducted a waste composition study to determine what materials were still going into landfills in its jurisdiction. Construction and demolition (C&D) debris comprised the largest percentage (31 percent), followed by organics (24 percent) and paper (22 percent). The city followed up the waste composition study with a gate survey at four landfills to find out the sources of the materials. “The top three categories were businesses (38 percent), self-haul (26 percent) and single family (21 percent),” says Stephen Bantillo of the San Jose Environmental Services Department. “We then did some further research into the self-haul category via a gate survey in 1999, as we believed the self-haul category was linked to C&D materials — primarily loads brought in by the contractors themselves versus franchised haulers. Not surprisingly, the gate survey, which focused on roll-off boxes, open top containers and trucks, showed that at least 70 percent of the waste ending up in these loads was C&D. There was no program in place to ‘incentivize’ self-haul activity. C&D generators and the self-haul community were virtually unaffected by the city’s financial incentive structure to divert waste from landfills.”
City staff and its consultants estimated that about 160,000 tons/year of C&D were being landfilled, and that between 50 and 70 percent were recoverable. Materials included concrete, asphalt, masonry, dirt, metal, cardboard, wood, drywall/wall coverings, roofing and carpet. Much of the C&D was coming in mixed loads, e.g. wood, concrete, metal and dirt from a demolition job. “Basically, we found that under the economic/ market conditions, segregated loads were being recovered on a more consistent basis than mixed loads,” says Bantillo.
After studying its options, San Jose zeroed in on a diversion deposit strategy for C&D materials. “We really did not want to fiddle with fees at the facilities, mainly because we didn’t want to cause the generators to seek cheap disposal out-of-town where we had no control over it and the disposal could be attributed to San Jose via the state’s Disposal Reporting System,” says Bantillo, who manages the city’s Construction & Demolition Diversion Deposit Program (CDDD). “The deposit incentive seemed more reasonable than other options. We performed an economic study in order to develop the rates to assess for the deposits. The study primarily focused on determining what amount we needed to assess on a square foot basis for a particular type of job to provide an incentive to make the costs of recycling competitive with disposal.”
Minimizing paperwork for all parties involved also was a primary consideration. “Through the economic study, it was determined that we could have in excess of 8,000 projects each year to process,” he adds. “We obviously wanted a relatively simple administrative process that required little work on the part of the applicant and a simple review by the city.” To calibrate the amount of material generated per square foot of project type for the San Jose area, the city’s consultant looked at five years of permit data and performed an analysis against the waste composition, gate surveys, and rates at the various processing facilities and landfills, and came up with a rate matrix (Table 1). “The difference in the rates for the listed project types is a clear indication of the type of materials generated and the effort required to process/recover them,” explains Bantillo. “For example, nonresidential demos are believed to have a relatively high percentage of concrete and steel, and thus have one of the lowest rates. Residential alterations, on the other hand, were found to generate a high percentage of mixed loads that required more processing and whose processed materials tended to have lower value in the market place.”
The CDDD program became effective on July 1, 2001. Roofing projects with tear-offs are exempt until July 2002. All residential and nonresidential new construction, alteration and demolition projects require a CDDD Clearance and Deposit before a building permit is issued. The original exemptions were: New residential construction projects of less than $115,000 in value; new nonresidential construction projects of less than $135,000 in value; residential alteration and nonresidential alterations of less than $2,000 and $5,000 in value respectively; and work for which only a plumbing, electrical or mechanical permit is required.
Recently, several more exemptions were added. “After six months of taking deposits, we found a number of project types that we missed in our initial research that generate very little excess materials, i.e., seismic tie-downs and premanufactured accessories such as signs and patio covers,” says Bantillo. “We changed the code to reduce our workload and make our customers happy. We’ll probably have more updates in late spring.”
The other key piece of the CDDD program is having certified facilities where generators can take the C&D to be processed, and receive the necessary receipts to retrieve their deposits. The two types of certification are: Administrative, which applies to inert processors recovering at least 90 percent of the incoming C&D; and Full, which applies to mixed C&D facilities recovering at least 50 percent of the incoming C&D. The administrative certification is for operations that take a single material, such as concrete, asphalt or metal. “These companies have been operating and recycling for years,” says Bantillo. “We do a qualitative analysis on-site to verify that they are diverting more than 90 percent of the incoming material. Basically, we wanted to be sure we had them on the certified facility list for the CDDD customers already using them.” Facilities handling mixed C&D loads are subject to a qualitative and quantitative analysis. “We wanted to perform a more extensive review of their operations and related data to better understand how they would achieve the requisite diversion level,” he adds.
To date, San Jose has certified 22 facilities that will recover at least 50 percent of the C&D materials received. At least seven of the 22 accept mixed loads of C&D, notes Bantillo. “With the number of options available to C&D generators, many of them are able to take their loads to the same facility they are accustomed to using. Taking their loads to a certified facility and submitting the receipt(s) with their refund request is the easiest way for generators to demonstrate they have diverted their materials.” The main motivation for the C&D processing facilities to get certified is competition. “If the facilities don’t get certified, the generators will take their loads to a competitor that is certified,” he adds. “To date, we haven’t refused any refund requests, although we’ve had to make extra efforts with some customers to see that they get their refund, mainly because they initially neglected to provide receipts or adequate documentation.”
The municipal code also allows for alternative construction methods as a means of diversion. For example, an architect who is building a rammed earth house is also using some recovered building materials from another project, so he expects to generate much less waste than the standard project. “He provided a write-up of his project as part of his CDDD clearance application and we are looking forward to completion of his project and processing his refund request,” says Bantillo. “We tell our customers, ‘The measure of our success is not how much money we keep, but how much money we give back.’ And the contractors seem to appreciate that.”
The CDDD program started in July and San Jose has calculated the following data for the first six months: Total project value — $432,454,000, with the average project value at $247,000 (median at $25,317); Total square feet – 5,126,000, with the average of 2,900 sq. ft. (median at 400 sq.ft.); and Total deposit value — $1,430,000, with the average deposit of $815 (median at $350). Though several very large projects have skewed the averages upward, the data so far indicates that the CDDD program has been effective at capturing the projects that generate the majority of the self-haul mixed C&D loads.
To encourage processors to invest in C&D sorting capabilities — thus maximizing the quantities recovered — San Jose created a C&D Infrastructure Grant program to purchase equipment or establish innovative diversion processes. The grant program was funded at $750,000. The Zanker Materials Processing Facility in San Jose, profiled in Part I of this article (see “Advances In Sorting Mixed Loads of C&D Debris,” February 2001), received a total of $193,000 in funding — $64,000 for its “Rocket” water separation system, and $129,000 to install an air knife. The Guadalupe Landfill, owned by Waste Management, received $140,000 for the mixed debris sorting line described below. “Some of the facilities have been somewhat effective with ground sorts, but clearly the most efficient and safest way is with mechanized separation enhanced with sort lines,” says Bantillo.
MIXED C&D LINE AT GUADALUPE
When Alex Gabel began working at the Guadalupe Landfill in San Jose seven years ago, he was told the remaining capacity was 20 to 25 years. Today, the landfill still has the same amount of capacity, due in large part, says Gabel, to its recycling programs, including wood and yard trimmings diversion and more recently, mixed loads of C&D debris. Last December, Guadalupe’s $600,000 mechanical and hand sorting line designed to process 200-plus tons/day began operating. The equipment was supplied by Lubo USA, who engineers and distributes C&D recycling machinery from Lubo in Europe.
The 1999 gate survey of self-haul loads conducted over a one week period by the city of San Jose found that Guadalupe Landfill received 624 loads of C&D — over 75 percent of the C&D loads going into the four landfills surveyed. The 624 loads represented a little over 1,000 tons being landfilled. More than half of that amount was mixed loads of C&D. Therefore when San Jose created the CDDD program and the accompanying grants, Waste Management decided to invest in the C&D sorting system. “Incentives provided by communities are what is changing the landscape and improving opportunities for waste management companies to invest in these operations,” says Joel Corona, Northern California region recycling manager with Waste Management.
The sorting line is enclosed in a 20,000 square foot steel building. Trucks with C&D debris unload and an excavator pulls out oversized items that would either bog down the starscreen or should be disposed. “That excavator plays a critical step,” says Gabel, who oversees C&D recovery. “It has a clam on it that is used to break up long pieces of wood, sheets of plywood and concrete. Essentially, it preps material for the sort line.”
With this type of operation, safety is a top priority. “Our number one concern at Guadalupe and Waste Management is safety,” says Gabel. “We have gone over 400 days without a lost time accident. I want everyone of my crew and customers to go home in one piece at the end of the day.”
A bucket loader pushes the material into the building, where another excavator loads it onto a vibratory infeed chute. The key to this processing step is to load an appropriate blend of materials that will maximize sorting efficiency. “We’re trying to make a C&D soup, a mix that includes a complete variety of the materials pickers are looking for,” he adds.
The blending step maximizes the efficiency and throughput of the line. “The worst thing you can do to a sorting line like this is put on segregated loads,” notes Willfred Poiesz, vice-president for Lubo USA’s western region. “If you have a dirt load that just got pushed into the building, or one with a high amount of fines, the operator should dump a pile of that on top of a pile of wood, then load it together into the feeder. The weight per cubic yard goes up and the sorters are more effective because they can all work at the same time. For example, if the operator grabs a load that is only wood and dumps it into the feeder, the screen isn’t used efficiently and there may be ten sorters and only four will be needed to remove the wood. Conversely, if you take a grapple of only fines, dirt and small items, the screen will work and the sorters won’t have anything to remove.”
From the infeed chute, materials are conveyed to a presort table where crews pick out plastic, wire, trash and other items that would get caught in the starscreen. “There are six people at that presort station who concentrate on removing trash and metal,” says Gabel. Material then goes to a 20-foot starscreen set at about two-inch minus. The two-inch fraction is mostly dirt and small stones. The overs go onto the postsort belt, where 12 to 14 people pull off clean wood, concrete, rocks and cardboard. What isn’t pulled off of the line — roofing materials, small pieces of metal, tar paper and painted wood — is used at the landfill for alternative daily cover (ADC). The ADC fraction comprises about 24 percent of the recovered materials.
Wood is the most marketable material recovered, followed by metal and cardboard. The concrete and starscreen fines are used as construction materials on the landfill. Guadalupe is looking into installing a concrete crushing operation. The wood is processed through a Morbark grinder and then screened to a variety of sizes, depending on the market. There is a landscape supply yard at the landfill, where mulch and wood/compost blends are sold.
The current recovery rate, not counting ADC, is 68 percent, says Gabel. Including ADC it is 92 percent. The remaining eight percent is a C&D residue that is disposed. Increasing numbers of loads are coming in as a result of the CDDD program. “We’re still in the building stages,” notes Gabel. “We get more phone calls each week asking about the deposit, how to get it back, etc. If we weren’t certified and didn’t have this operation, those loads would be going someplace else, so in that sense, the CDDD program is bringing more material in the door. And it’s helping to extend the life of our landfill.”
Working with the private sector to foster an environment that favors diversion over disposal has been a cornerstone of San Jose’s solid waste management program. “In the nearly 12 years that I have been developing and managing programs for San Jose, one of the constants is that the city asks for more diversion and the solid waste companies ask for more incentives to make it worth their while,” says Bantillo. “Offering $750,000 in C&D grants and implementing the CDDD program went a long way toward getting buy-in from the companies and enhancing the C&D processing infrastructure in San Jose. Overall, when it comes to diversion, we know that the success of the local solid waste companies translates directly into success for our programs. And our greatest successes have been achieved through establishing public/private partnerships and working toward common goals.”