A proactive approach to minimizing downtime and maximizing return-on-investment.
Extreme and harsh conditions in solid waste facilities and transfer stations create challenges for tipping floors. Every day, these floors are exposed some of aggressive environments including impact loads, abrasive elements, chemicals and damage from heavy processing equipment. The successful operation of transfer stations is keeping these tipping floors in the best condition possible while minimizing downtime and optimizing return-on-investment.
Most tipping floors are composed of poured concrete. However, concrete does not hold up well under the heavy abuse of a high-volume transfer station and is prone to cracking and fracturing. The surface of the tipping floor can lose a significant portion of the concrete every year in high-volume transfer stations. These tipping floors may require frequent repair or replacement. While this is a costly proposition, the 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
Tipping floors are typically an intermediate position between a garbage source, such as a dense suburban community and a landfill. Rather than have 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.”
Efficiently designed transfer stations have a tunnel or drive-through area below the tipping floor. Larger waste transfer trucks are situated in the tunnel under a large hole at the end of the tipping floor. Once 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. Instead of 15 or 20 trucks going to a landfill, only three or four of the larger trucks are needed. In addition to saving money on transportation costs, this also eliminates excessive truck traffic through a community.
With all of the constant pushing and scraping of the front-end loaders, tipping floors are exposed to continual stress. Some transfer stations might process only 500 to1,000 tons-per-day, and larger facilities might handle from 3,000 to 5,000 tons-per-day of garbage and refuse. This refuse contains glass and metal pieces that gouge the floor, and 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 back into the economy such as plastic, paper, glass, and metal must be sorted. Since 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.
Damage and Deterioration
Another threat to tipping floors are corrosive liquids. Regulations and government-mandated clean water regulations have changed the way garbage is transported from the local community to the waste stations. Waste liquids can leak out of the backs of the trucks as they drive though a community.
These environmental directives demand that waste liquids be processed within the waste stream and not leaked out into the community. Garbage trucks installed large rubber gaskets along the truck’s container edges to contain the liquids. As a result, waste liquid is now transferred to the transfer station. The new processes are good for the environment, it is bad for the concrete tipping floor.
As the solid garbage is dumped onto the tipping floor, so does this “soup” of acidic and caustic liquids. As it sits on the floor waiting to be processed and moved, these liquids chemically attack the floor and breakdown the cement. Along with the impact and abrasion damage that the tipping floors receive, corrosive liquids also aggressively weaken them.
Wear and Tear
It is not a question of if tipping floors will deteriorate, but when and how bad. All tipping floors will deteriorate at some point; we need to understand how to determine when the floors need to be repaired. Typically, tipping floors start out as a concrete slab that is 8-inches to 12-inches thick. Depending on conditions, tipping floors will degrade at different times and under different conditions.
By monitoring floor wear and budget planning for scheduling repairs, owners can avoid facility downtime and loss of revenue. With a proper floor monitoring approach, a facility manager can identify several years in advance when a floor repair is necessary. This allows time for prioritization, budgeting and planned downtime.
Evaluating, monitoring and specifying repair work on a tipping floor can be a complicated and daunting process. However, through careful planning, 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. Visual inspection is, of course, 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 needs to be resurfaced.
Better indications of floor deterioration can be achieved through more scientific methods. One of these methods is called “shooting the floor.” A laser device measures the floor elevation when the floor is new or “healthy.” Over a specified period of time, such as every six months, another electronic measurement is taken. After a year or two of measurements, an exact indication can be made of how much wear the floor is receiving.
With these scientific calculations, it can be predicted 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 cannot be used.
Another method for determining floor wear is a “Wear Indicator,” a triangular-shaped piece of aluminum. Wear Indicators are embedded into the tipping floor at predetermined locations. 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 and floor constitution.
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.
Once it has been determined that a tipping floor needs to be replaced, some facility managers might think it would be advantageous to “just pour more concrete on top of the damaged floor.” However, this approach is neither cost-efficient nor practical. Concrete floors have a short life span, between two-to-three years depending on usage and conditions. Continual repair and replacement of floors costly and can shut down a facility for up to two weeks while repairs are made.
Replacement of a concrete floor can be a time-consuming and labor-intensive process. Damaged floors must be broken up and removed, the surface must be prepared, and a bonding agent applied before the new concrete floor can be poured. Typically, tipping floor operations can be impacted for one-to-two weeks while the concrete work is being done and the concrete is fully cured. Due to the loss of revenue and the continual costs for new concrete tipping floors, replacing concrete floors with more concrete might not be a viable budget option.
Many tipping floor operators are turning to a more valuable, cost-effective alternative for repairing tipping floors. These alternatives are available in the form of high-performance, cement-based toppings. These engineered toppings consist of a combination of recycled iron shavings and concrete. They are made of a strong, chemical- and impact-resistant concrete materials specifically designed for tipping floors. The repair material is eight to 10 times better performing than the original concrete. Most importantly, iron aggregate flooring can be quickly installed over a weekend, eliminating the need for lengthy work interruption.
A key advantage of iron aggregate flooring is that it can last from six to eight years or more, making it much easier to fit tipping floor replacement into schedules and budgets. In addition, the low-porosity topping is also easier to keep clean than concrete flooring, since it does not absorb the fats and oils contained in the waste stream. Another advantage is that as the engineered topping wears it develops a “modeled” effect, which provides good traction for waste handling equipment, unlike concrete floors whose smooth surface provides no traction.
Tips for Floor Repairs
There are several important points to consider when choosing an engineered-topping floor repair system once a facility manager has determined that the tipping floor needs to be repaired. An important step in the process is to research the repair company to ensure that they will provide the best products for your investment. Seek recommendations from other tipping floor owners. Most importantly, make sure that the repair company employs well-trained, professional, repair technicians and uses the proper equipment.
Scheduling for downtime is one of the challenges of tipping floor repairs. Engineered toppings can be installed over a weekend, allowing a facility to be up-and-running on Monday morning. In most cases, the existing concrete floor does not have to be torn-up. Once the damaged floor surface is cleaned and prepared, the engineered topping is poured on top of the concrete floor.
The new slab should be about 1 1/2-inches to 2 1/2-inches thick.
Another advantage of engineered toppings is that only a portion of a floor can be repaired if necessary. For example, a facility might have a 50,000-square-foot tipping floor, but only a segment of the floor is damaged (5,000-square-feet to 10,000-square-feet). In this instance, a “postage-stamp repair” can be made—negating the need to restore the entire floor. This not only saves money, but also allows waste station operations to continue while the damaged floor section is repaired.
Monitoring and Maintenance Programs
Oftentimes it can be hard to know how your floor is performing and where you are in the life cycle of your current surface, until you are faced with serious concerns like exposed rebar, concrete spalling and cracking, or structural failures. These unanticipated concerns often get dealt with on a reactionary basis. This leads to increased cost, inopportune downtime, strained budgets and issues with general operation. Developing and establishing a monitoring program is a valuable tool in projecting for these concerns as well as protecting your investment.
Whether implemented on its own or in conjunction with a repair project, a monitoring program can provide valuable information. As described earlier, “shooting the floor” can determine how much wear a tipping floor has received. Initially a full site evaluation survey is done to provide a baseline for evaluating existing wear and develop a plan going forward. After the initial survey a plan should be put in place to monitor the floor on a regular basis approximately every six months to a year in order to evaluate the performance of different areas and materials. This report will help a facility manager to plan budget and downtime for the next repair process. Additionally, following a floor repair installation, “shooting the floor” will demonstrate how much material has been applied to the floor providing a new baseline for tracking the performance of your investment.
As an additional measure wear indicators can be installed in the floor surface to indicate when the floor is beginning to show wear on its surface. A reputable floor repair contractor should provide and set up a measurement system for monitoring floor wear. The contractor should continue to monitor floor wear with frequent visits to the facility or they can train facility personnel to perform and gauge the measurements.
It is important to keep in mind that to get the most value out of a monitoring and survey program more involved data evaluation techniques can be used. Topographic maps highlighting wear patterns can be generated to assist in load path planning, as well as developing and designing a repair solutions. Statistical modeling and wear rate graphing can generate timelines for repair of a variety of different areas. Surface modeling and volume loss calculations can help create cost per ton figures for your tipping floor which help you to better understand your return on investment for different repair solutions. The modern tipping floor monitoring program is well beyond the simple drawing showing a few elevation points without any real information.
Keeping Tipping Floors Healthy
In a solid waste facility, a transfer station or a material recovery facility, the tipping floors are where money is made or lost. If the floors are kept healthy and in good condition, the whole process will be working properly. Floors that are damaged with cracks, gouges and holes will put stress on waste transfer equipment and front-end loaders, and their tires. Uneven floor surfaces are unsafe for personnel, putting them at risk from slips and falls. Shutting down a facility for two weeks or more, especially for an unscheduled floor repair, can have a significant impact on business.
Long-lasting, impact- and chemical-resistant alternatives to plain concrete are possible. Engineered floor toppings can be quickly installed, providing a cost-efficient solution that will return a tipping floor to better-than-new condition. Along with a continual floor maintenance program, engineered floor toppings are a worthwhile investment in your business.
Jim Andrews is the CEO of American Restore (Huntington Beach, CA. In over 30 years of innovative specialty contracting that ranges from the basics of concrete construction and repair to highly specialized and exotic concrete materials methods, Jim has cultivated extensive experience with a wide variety of project types. Field investigations have featured bonded overlays, topping systems and heavy public and private sector industrial slabs. His specialized training, knowledge and hands-on experience have included projects in civil and industrial, public and private construction improvements. Jim is frequently called on by owners, engineers and operators to consult and evaluate premature failure of high wear floors and overlays. For more information, visit www.tippingfloors.net.