MSW Management | A Closer Look at the Puente Hills MRF

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This Sanitation Districts of Los Angeles County facility is geared for the future.

By Lynn Merrill

At the foot of the western slope of the second-largest landfill in the US, nestled in an industrial area and adjacent to a busy rail line, sits the future for Los Angeles County’s solid waste management needs. While other area material recovery facilities (MRFs) operate at near capacity, like a sleeping giant, the Puente Hills Material Recover Facility is gearing up for a future of 4,400-ton-per-day recyclables processing and rail-hauled solid waste.

The Puente Hills Landfill, located in the City of Industry, originally opened in 1957 and was acquired by the Sanitation Districts of Los Angeles County in 1970. As the county grew, the districts began planning for new disposal capacity and ran smack into the NIMBY syndrome.

“Earlier in the ’80s we had tried to permit six different landfills in county, and that was unsuccessful,” states John Cosulich, supervising engineer and the districts’ project engineer for the MRF. “They basically got shot down one by one. [The planning for the MRF] started back in 1988. At the time, the board of directors wanted us to take all of the waste out of the basin on a train. It was a long-planned activity.”

According to Cosulich, the decision to site the facility adjacent to the Puente Hills Landfill grew out of a variety of factors. “We’re kind of at the northeastern end of most of the waste shed. Puente Hills takes about a third of Los Angeles County’s waste, so this is a cornerstone facility. We had the availability of land at the bottom of the landfill. We bought an additional 17-acre parcel so that we could have enough land for a MRF, and we knew we had the rail access right across the street.”

Habib Kharrat, supervising engineer for the Puente Hills MRF as well as two other facilities owned by the districts, emphasizes the value of the location. “The fact that you have 13,000 tons coming into this facility at the Puente Hills Landfill that will not be available anymore [when the landfill closes] for the adjacent residents or the waste shed, like John mentioned, you’d think you’d want to capture at least part of that. The Puente Hills MRF, which is a 4,000-ton-per-day facility, will capture that within this area and keep it here. So in addition to having the land and the proximity to the rail, it’s again the location.”

Pushing the districts even more toward the reality of waste-by-rail is the looming closure of the landfill itself in 2013. “There’s been more push by the regulators to help waste-by-rail,” says Kharrat. “They actually wrote it in the latest CUP issued by the county for the Puente Hills Landfill, which is requiring deadlines for waste by rail to be implemented. If not, the Puente Hills will be penalized by reducing the amount of tonnage allowed to the landfill. Obviously, we had the foresight before the permit in 2003 to start up a MRF, but even more so it confirmed what we had planned by putting a requirement of closure in 2013 and putting these requirements in the CUP to get waste by rail going.”

Construction of the site required a significant amount of dirt movement to make this plot buildable. “We moved 2 million cubic yards in a project called the lower western cut,” says Cosulich. “We used that soil for cover for the landfill, so it was a win-win situation. But this land was not buildable initially, because it was a landslide. If we had a major earthquake, theoretically we could have had an engulfment issue. The Department of Public Works wouldn’t have issued a building permit for this site if we didn't move that earth.”

Final design of the MRF commenced in 2000, and the facility opened in July 2005. In designing the MRF, the districts built on the design lessons of others. “We were looking at a complete transfer and recycling facility,” says Cosulich. “In touring and interviewing MRF operators, we realized that the bigger you made the building, the more recycling you can do. Most every transfer station and recycling facility we went to, they said we wish we had more land and bigger space. With that in mind, and as a public agency in our dedication to recycling, we did size a very large facility. We have 215,000 square feet under roof. The basic box is 750 feet long by 300 feet wide. That’s a clear span. We decided to make a very large building so that we could do a lot of recycling with 4,000 tons per day.”

In addition to the MRF itself, the districts constructed a 24,000-square-foot administration building to house all field staff for solid waste operations throughout the county, as well as a 10,000-square-foot building to maintain the district’s vehicles. Ample parking allows the districts to park all of the transfer rigs while an onsite LNG facility provides clean fuel for the district’s equipment.

Several key features were incorporated into the design of the building in order to minimize fugitive dust and odors. For example, a limited number of doors were specified, and the entrance and exit doors were placed at right angles to one another in order to contain odors and prevent a “wind tunnel” effect. All doors are designed with rapid open/close doors to assist in containing dust and odors within the building. A negative pressure ventilation system draws air into the building from the front and exhausts it through roof fans located primarily on the back of the building. Roof fans over potentially odorous areas are ringed with stainless steel tubing with nozzles to distribute odor-neutralizing chemicals into the exhaust air.

In keeping with the districts’ commitment to the environment, green building design features and materials were used during construction. High-efficiency air-conditioning systems and lighting, installation of over 500 skylights, and use of occupancy sensors minimizes electricity use. Reclaimed water is used for site irrigation and in employee restrooms to reduce potable water use. Recycled materials were used throughout the project from structural and reinforcing steel to toilet partitions, carpeting, insulation, ceiling and floor tiles, and car parking lot wheel bumpers.

The design of the processing line required a comprehensive look at the wastestreams coming into the facility, the existing recycling facilities and activities already occurring in the county, and the changes to the waste and recycling streams once the landfill closes. “We made the decision up front that you target what waste you want to recycling,” stated Cosulich. “You can go after construction-and-demolition [C&D] waste, select commercial waste, or go after household waste. Each would have a different design configuration. Early on, we did a waste study at Puente Hills, and we do have a fair amount of select commercial where there’s a high amount of recoverable paper and cardboard. So that’s what we designed the line for. It’s a 25-ton-per-hour line designed for select commercial.”

“It’s a commercial MRF as opposed to a residential MRF,” says Matt Zuro, senior engineer and the facility manager. “At a residential MRF you get certain types of commodities, and at a commercial MRF you get certain types of commodities. It doesn’t say that you don’t get some of those same types of commodities that you’d see at a residential MRF, it’s just not in as large of quantities as a residential MRF would be. We do some carpet recycling here and then the dry commercial.”

Currently the facility is operating at 350 to 400 tons per day, with a ramp up to 4,400 tons per day. “We have no flow control, and we have to compete with the privates,” says Cosulich. “We do have economies of scale—at 4,000 tons per day we can be somewhat competitive. We built this as part of the waste-by-rail facility. We oversized the building to allow for a lot of floor sorting in order to have a safe operation. The actual equipment line, as a public agency, we’re required to bid, so we made the decision to go for a select commercial waste. We drafted a specification to do that. We received three bids. CP Manufacturing submitted the lowest, responsive, responsible bid.”

Commercial loads enter the facility through a set of high-speed roll-up doors located at the north end. The trucks enter into a large tipping area where they are directed by a spotter to dump at a designated area. Information regarding each load is entered into a handheld data unit by the spotter, and in many cases the characteristics of the load are already known due to the repeat business by the haulers. Once the load information has been entered, the load is dumped on the sorting floor and teams of floor sorters operating in concert with wheel-loader operators, will either remove contaminants or segregate recyclables. Materials that are destined for processing on the commercial sort line are then moved to a staging area prior to loading onto the in-feed conveyor.

“From the in-feed conveyor, it goes first to a presort area,” says Cosulich. “The presort area is to take out anything that might foul the screens or gunk up the processing line that can be removed there. They do pick out plastics and select commercials at the presort station. Next it goes to an oversize screen that takes out corrugated cardboard. Then it goes to a fines screens. Anything that falls through the fines screen is basically trash. Then we have this middle-sized screen that is picked through by sorters manually. They pick out paper, plastics, cardboard—all sorts of things. We have approximately twenty sorters on that line.” Materials are sorted into separate bunkers and then directed to a baler through another feed conveyor. Baled materials are then moved to an enclosed holding area until shipped to market.

While most of the C&D wastes that are received at the Puente Hills facilities go directly to the landfill, some clean materials, such as concrete, can be crushed at the landfill and used as base materials. “We get a fair amount of woodwaste in this MRF that could also be part of the C&D wastestream,” reports Zuro. “The woodwaste, we either take it to our Commerce WTE [waste-to-energy] facility. Some of that woodwaste, if it’s clean enough, we’ll take it up to our landfill, grind it and use it for daily cover.” According to Zuro, over the past 15 months the MRF has averaged a 48% recovery rate on the processing line while the facility achieved a 23.5% diversion overall. Woodwaste contributed 17.4 % overall diversion.

In designing the MRF, every effort was made to incorporate the best technology available. “We talked with other MRFs, and we talked with the actual recycling equipment manufacturers, and we tried to get their best ideas and their latest ideas,” says Cosulich. At the time the MRF became operational, the sort line was the latest and greatest. “But that technology is changing quite a bit,” adds Zuro. “There’s other things, like optical sort, that we could possibly add onto our system that we haven’t done at this point in time. Optical sort has come a long way in the last five years.”

Like any good facility, there are opportunities to enhance and improve on performance. “There’s a lot of things that we’re thinking about that we might want to change,” says Kharrat. “Adding an item like a metering drum at the initial feed of the equipment would help out in terms of streamlining what’s coming in and eliminating any blocked belt on the sort lines. That’s one thing we’re looking into. The other thing is the optical, knowing that it’s at a stage that it maybe is functional. The idea of having that would eliminate a big bulk of the manual labor on the sort line. But it’s not as simple as just adding one machine. There will be modifications to the belt lines to redirecting that stuff on our sort lines. We are very limited in our presort area. We would like to have a bigger presort area. We’re realizing that we have a lot of the plastic film that can get in the disks and can stop them. We’re not having enough space to put additional man labor to remove that. Floor sorting is very inefficient—you just walk around the pile and pick stuff here and there. You put that on a portable conveyor belt on the floor and you can probably recover a lot more. It’s safer for the employees and more efficient in that sense.”

Although the Puente Hills Landfill is not scheduled to close for five years, Kharrat and his staff are gazing into the crystal ball and trying to determine which directions the MRF will need to take in order to meet the challenges of a changing wastestream. “Obviously, when the Puente Hills Landfill closes, or even before that, we’re going to be getting all kinds of things, so I don’t know if we want to continue being the commercial MRF or suddenly now we want to be both [residential and commercial]. If we want to process that type of material, the good thing with what John did in his design is that he allowed space in the equipment room to add another train of sorting equipment. Maybe we can look into getting a residential line to ‘dirty-MRF’ whatever comes into the lines. We see a lot of the facilities going to dirty MRF-ing. They’re eliminating the three-barrel programs that they have before, and they’re just bringing everything in. They're realizing that, with the three-barrel program, the barrels that they thought would be rich in recoverable material, people are throwing trash in. When you have that, you need a large prescreen area and a lot of through put to get that stuff through.”

Consultant and writer Lynn Merrill is a frequent contributor to Forester publications.

MSW - March 2008