Tipping floors are an intermediate position between a garbage source, such as a dense suburban community, and a landfill. Rather than 15 or 20 small garbage trucks making daily trips to the landfill, the trucks go to a central transfer station once they have finished their route. At the transfer station, the trucks “tip-out” the garbage onto the floor — hence the name “tipping floor.”
Tipping floors are subject to extreme and harsh conditions. They are exposed to a daily barrage of aggressive chemicals, impact loads, abrasive elements, and damage from heavy processing equipment. Crucial to the successful operation of a transfer station is keeping these tipping floors in good shape while minimizing downtime and optimizing return-on-investment. Tipping floors normally have a finished concrete surface. But concrete does not hold up well under the heavy abuse of a high-volume transfer station and is prone to cracking and fracturing. In high-volume transfer stations, the surface of the tipping floor can lose from one-half to 1 inch of concrete every year. In these cases, the tipping floor may need replacing every two years. Not only is this costly, but a facility can be out of operation for two weeks or more while the concrete floor is being repaired.
Alternatively, new installation technology and advances in material performance allow a better solution. High-performance, cement-based products provide improved durability with quick installation. This minimizes downtime impact to facility operations, as well as reduces the overall cost of floor maintenance. By increasing abrasion resistance, compressive strength, and impact distribution along with low permeability, high-performance floor toppings are well suited to the tough working environment of tipping floors.
Tipping floor locations
The most efficiently designed transfer stations have a tunnel or drive-through area below the tipping floor. Larger waste transfer trucks drive into the tunnel under a large hole at the end of the tipping floor. After the garbage is tipped-out onto the floor, heavy front-end loaders push the garbage into the hole where it falls into the larger trucks. Now, instead of 15 or 20 trucks going to a landfill, only three or four of the larger trucks are needed. This saves money on transportation costs and eliminates excessive truck traffic through a community.
Because of the constant pushing and scraping of the front-end loaders, tipping floors are often exposed to continual stress. While some facilities might process only 500 to 1000 tons per day, larger facilities might handle from 3000 to 5000 tons of garbage and refuse per day. Not only does this refuse contain glass and metal pieces that gouge the floor, it also contains chemicals and liquids that degrade the floor.
Tipping floors have also become integral to the recycling process at material recovery facilities (MRFs). As community regulations are enforced for recycling, products that can be reused, such as plastic, paper, glass, and metal, must be sorted. Because it is difficult to sort these materials at the landfill, the separation process is done at the MRFs. The floors at these facilities are also subject to deterioration from glass and metal particles.
Corrosive liquids are another threat to tipping floors and have become a critical point for waste station facilities. Government mandated clean-water regulations have changed the way garbage is transported from the local community to the waste stations. As garbage is collected, waste liquids can leak out of the backs of the trucks as they drive though a community.
Environmental directives demand that these waste liquids be processed within the waste stream and not leaked out into the community. To contain the liquids, garbage trucks installed large rubber gaskets along the truck’s container edges. With this improvement, all the waste liquid now ends up at the transfer station. While this is good for the environment, it is bad for the concrete tipping floor.
As the solid waste is dumped onto the tipping floor, so is this soup of acidic or caustic liquids. As it sits on the floor waiting to be processed and moved, these liquids chemically attack the floor and break down the cement. Along with the impact and abrasion damage that the tipping floors receive, corrosive liquids also aggressively attack the surface.
Tipping floor wear
Knowing that tipping floors will deteriorate at some point, facility operators must determine when the floors need to be repaired. Most tipping floors start out as a concrete slab that is 8 to 12 inches thick. The floors will degrade at different rates depending on how much use the floor receives and the character of the waste stream.
Monitoring floor wear is critical to budgeting and for scheduling repairs to avoid facility downtime and loss of income. With accurate floor monitoring, a facility manager will know several years in advance when a floor repair will be necessary, allowing time for budget considerations and downtime.
The process of evaluating, monitoring, and specifying repair work on a tipping floor can be complicated and daunting. However, through simple methodology and selective maintenance, the continued performance of a tipping floor can be ensured for the lifetime of a facility.
There are several methods available for determining floor wear. Of course, visual inspection is a good indicator, but not always technically reliable. Certain floor conditions such as cracks, gouges, ponding water, and holes indicate that a tipping floor is losing some of its original surface, but does not determine when the floor must be resurfaced.
A more scientific method for identifying floor deterioration is called “shooting the floor.” A laser device measures the floor elevation when the floor is new or still in good condition. Over a specified period of time, such as every six months, another electronic measurement is taken. After a year or two of measurements, the floor’s rate of deterioration can be determined and a tolerable level of deterioration can be established, allowing prediction of when a floor will need repairs and exactly where the repairs will be needed. This precise indication of floor wear helps facility managers plan for repairs, rather than being forced to shut down a facility for emergency repairs when the tipping floor becomes so compromised that it is unusable.
Another method for determining floor wear is a wear indicator, a triangular piece of aluminum. Wear indicators are embedded into the tipping floor at predetermined areas. As the concrete tipping floor begins to wear, so does the top of the aluminum triangle. By measuring the exposed surface of the triangle face, it is possible to determine how much floor wear has occurred and when a floor repair should be scheduled.
Usually a tipping floor must have an indication of at least one-half-inch of wear before the floor can be assessed for possible repair. The facility manager should also be aware of the original design and construction of the floor, since not all concrete is the same. Field analysis or floor sampling might be needed to determine wear characteristics.
It is also important to factor in how much use a facility receives and how much use is anticipated. Sometimes economic or environmental considerations enter into the equation, along with budget requirements when determining floor repair needs. Facility managers should know if the waste stream will continue to be consistent or if there are indications that it will be increasing, for instance, if more housing or commercial development is planned for the community.