Playing an integral role in the overall efficiency of a material recovery facility (MRF), tipping floors are an intermediate step between collecting materials and delivering them to end markets.
While the best tactics for designing and managing a tipping floor generally depend on the site, Robert Craggs, solid waste and resource recovery manager at Kansas City, Missouri-based engineering firm Burns & McDonnell, shares some universal best practices to get the most out of this space.
Because of the harsh conditions many tipping floors face day to day, such as impact loads, abrasive elements and damage from heavy processing equipment, Craggs says a safe environment is a key element to smooth operations.
“One of the [main] concerns is all the dust,” he says. “When you drop recyclables on the floor, it’s a very dusty environment. Most of the time the building is enclosed. So, to ensure that your employees are safe, there’s a couple different things that can be done relative to the dust.”
Dust can irritate lungs, create choking hazards, irritate eyes, reduce visibility and contaminate machinery’s moving parts. The enclosed nature of a tipping floor prevents these particles from escaping the facility, resulting in a high concentration of dust. To mitigate this issue, a MRF operator can use dust-suppression systems in the tipping floor area and outfit employees with proper personal protective equipment (PPE).
In addition to dust suppression, Craggs mentions the need for efficient traffic flow when looking at safety. “You have vehicles that are coming in and out, and you have individuals who are operating equipment, so you have to have clear communication and staff that have very designated roles,” he says.
With a wide variety of vehicles ranging from collection trucks to large transfer trailers entering a facility, a well- designed tipping floor generally will have multiple bays for unloading different kinds of vehicles. By establishing a pattern to control traffic flow, a facility can reduce the risk of accidents and keep workers and customers safe throughout the day, Craggs says.
“There are two schools of thought as it relates to the most optimal [traffic flow] approach,” he says. “Some believe if you have a separate exit from the entrance that that’s the most efficient way to do it because you come in, dump your materials and then you go out a different exit. Others suggest that having multiple bays where trucks pull in and then back out is fine. It’s really site-specific. It depends on how large your site is and how many physical limitations [it has].”
The challenging environment of a tipping floor necessitates extra precautions. “It’s about having [these safety practices] work together and having people trained appropriately,” Craggs adds.
From an engineering perspective, Craggs says rules of thumb are associated with designing adequate space to handle materials on the tipping floor. The kinds of materials being delivered, the types of vehicles coming into the facility and how much material is received daily are factors that determine space requirements.
“You need to have the flexibility, which translates into adequate storage space,” Craggs says. “An efficient tipping floor needs [to be able] to handle the storage of enough materials when it’s at the high end as opposed to just a normal day or a low end.”
"To ensure that your employees are safe, there’s a couple different things that can be done relative to the dust,” – Robert Craggs
Storage space should be based on the amount of volume you anticipate receiving and how much variance you expect to occur, he says. To handle an influx of material during peak times, an operator should look at the MRF’s records over time to determine how much the facility can accommodate.
To calculate the area needed for a tipping floor, an operator can use material characterization data and convert the anticipated recyclable weights into loose volumes. By adding up the daily volumes of commodities that are expected to be processed, the throughput for the facility can be estimated, he says.
Having enough space on your tipping floor also can make it easier to handle loads that might be contaminated. “If you have to drop a load of materials on the ground or on the tipping floor, and it’s contaminated, you want to have a tipping floor that’s big enough to address the contamination in that load and still have a tipping floor big enough to drop another load of recyclables next to it or in the same general area,” Craggs says.
With the need to store some incoming material on the tipping floor prior to processing, installing a push wall can help alleviate a crunch for space. Placement of push walls varies by facility, but Craggs recommends having one on at least two sides of the building to better reinforce stacked materials and to benefit wheel loaders when moving recyclables to designated infeed areas.
He adds that having the flexibility to keep source-separated material, such as cardboard, from curbside- collected recyclables, which go to different infeed systems, is important.
Know your haulers
Haulers have certain expectations of MRFs. A primary goal of any facility is efficiency, so by understanding a customer’s needs in relation to the tipping floor, an operator can manage the space to meet those goals.
“When you have haulers that are driving transfer trailers versus driving regular recycling vehicles, they are going to have different expectations on how to get in and out or different expectations in terms of being able to stop and look at their equipment before they get out the door,” Craggs advises.
Maintaining communication with haulers can give MRF operators insights into their schedules as well as to whether they are having troubles during the transport of materials. By understanding customers’ situations, a MRF operator can better accommodate their needs and estimate tipping floor traffic.
A tipping floor that is well-designed facilitates traffic flow, enables adequate storage space and allows material to be delivered to the processing system quickly. “Having an efficient tipping floor where vehicles get in and get out will ensure that the materials get on the floor, get in the system and are processed in a timely manner,” Craggs says.