The idea that a steel-wheeled landfill compactor can help pack more trash into the limited space of a landfill is a simple one, mainly because it makes logical sense. The step between the tool and the result, however, is where many operators struggle.

Waste compaction might not be rocket science, but it is a science.

When Fred Caron, founder of Caron Compactor Co., unveiled the first landfill compactor, the Pactor, in the 1960s, he understood—long before anyone else—that waste compaction is a vital part of running a landfill.

Since releasing its first compactor, Caron Compactor Co., based in Escalon, California, has been a leader in innovation when it comes to landfill compaction. Yet more than half a century later, the industry is still trying to apply fundamental laws of physics to something as obscure as waste compaction. Let’s talk about how to put some science into the compaction process.

Manage the moisture

Much of the organic portion of trash consists of cellulose fibers, which include wood, green waste, paper, cardboard, and many other subtypes of materials.

Cellulose fibers are rigid and can hold their shape against strong forces. They can also resist bending, flexing, and compressing when dry. When wet, however, cellulose fibers lose much of their strength and become softer, making them more susceptible to the compressive force of a landfill compactor.

That’s why experienced operators are always looking for ways to get moisture into dry loads comprised of cellulose fibers. Residential trash, sludge, and food waste are familiar sources of moisture in the waste stream.

Some landfills will even spray liquid on the active face to minimize dust and litter and to increase compaction. As a general rule, applying 25-30 gallons of liquid per ton of waste is sufficient to improve compaction without generating excess liquid that could create other issues. Of course, many variables must be considered, and every landfill will have its unique recipe.

The point is, though, that moisture can be beneficial in providing higher rates of compaction in landfills.

Spread waste in thin layers

The downward force of a landfill compactor decreases with depth, resembling a subsurface pyramid. At some point, the weight of the compactor will not be felt. Even at depths of just 4-6 feet, the weight of the heaviest landfill compactor will not crush pallets or break bottles.

Have you ever seen a contractor dump a load of soil to build a ramp when crossing a concrete curb? That soil ramp acts like a bridge to help dissipate, or spread out, the force exerted by a heavy truck or tractor, thereby protecting the concrete curb from damage. That 4-6 feet of trash in a landfill creates the same type of “bridge” that inhibits the compressive force of the landfill compactor.

To achieve the optimum compaction, the compactor’s teeth should extend fully through each layer of trash. That way, every bit of trash that goes into your landfill is impacted by the teeth.

For that reason, trash should be spread in thin layers to maximize the force applied to all waste. Most operators probably have heard of the 2-foot rule. Even here, there is science.

When uncompacted trash is spread across the active face of a landfill, it has a density of approximately 400 pounds per cubic yard (pcy).

After the first pass with the compactor, the density increases 250 percent to around 1,000 pcy. Accordingly, that initial 24-inch layer is compressed to less than 10 inches, which is close to the tooth height on many compactors.

As compactor teeth wear, waste must be spread in thinner lifts to achieve that same full-length penetration. The solution is to continue reducing the layer thickness or replace the compactor teeth more frequently. Studies indicate that more frequent tooth replacement saves landfill space and makes financial sense.

Make long runs

Landfill compactors are at their peak productivity when traveling at full speed, even if it’s only 3 miles per hour. But at the end of every run, that machine must slow down, stop, reverse direction, and then accelerate back up to production mode. This is lost, nonproductive time.

From the perspective of maximizing the compactor’s productivity, long runs are better because the machine spends a greater percentage of its time at full speed, and less operating time is spent slowing, stopping, reversing, and accelerating.

If you are covering with soil, the concept of making long runs conflicts with the idea of maintaining a tiny active face to minimize the use of soil cover.

This was once standard practice, but conditions have changed. For landfills using alternative daily cover (ADC), the cost of covering more active faces is a small price to pay for the increased density achieved from more extended runs.

Use aggressive teeth

When it comes to teeth on landfill compactors, size matters.

Compactors with many large teeth will consistently yield the best results. You could save money by going with smaller teeth or by spacing them out on the wheel, but these savings only consider your upfront costs. In the long run, the cost of airspace trumps everything else.

Larger compactor teeth also have greater demolition ability. They can also reach further into every layer of waste to ensure thorough compaction.

Tooth spacing is an important consideration, as well. Have you ever seen a landfill compactor that was not achieving full depth penetration with the teeth? In other words, have you ever seen daylight between the drum and the trash? I have not. That indicates that a denser tooth pattern would more effectively get more teeth into the waste.

The one drawback is that a dense tooth pattern can exacerbate wheel packing, where mud or sticky waste gets stuck between the teeth, and the compactor works more like a smooth-drum roller rather than a toothed compactor.

This can be mitigated by installing cleaner bars on the machine. Some compactors are designed with cleaner bars on all wheels. The operator can also help prevent wheel packing by staying on the trash and not traveling across areas of wet soil.

Many factors should be considered when selecting the right tooth design, size, and placement pattern for your compactor. Please note that your decisions can impact the overall operation.

Prep for cover

Waste compaction ranks high among the most critical considerations for landfill managers. After all, it’s all about airspace. But when it comes to airspace, many don’t think about a hidden cost. It’s the cost associated with excavating, hauling, and placing cover soil. The secret part of that cost is related to the airspace consumed by the cover soil.

The single most considerable avoidable cost in the landfill industry is the excessive use of cover soil. So, in talking about compaction and airspace, the conversation isn’t over until the issue of cover soil is addressed.

Prepping the waste before cover soil is applied on the landfill face can help the compactor operator reduce the consumption of cover soil.

Whether it’s soil or some form of ADC, cover is placed most efficiently when the waste surface is finished correctly.

This process begins by placing homogeneous, non-bulky trash on the surface. Sometimes this requires the dozer to warehouse a few loads until the end of the day to ensure the compactor has good material to work with. Then it comes down to the compactor operator doing a good job of trimming and filling to create a surface with a smooth, uniform plane.

The process of compacting trash at a landfill truly is a science. Yes, a component of the process is art, but only where it lines up with the fundamental laws of physics.

Learn more:

• Bioenergie Schuby Biomethane Project
• Waste-to-Energy Projects Overview
• Plastic Waste Pyrolysis Insights
• Tire Pyrolysis Reference Plants

Smarter Landfills Begin with Smarter Technology

Understanding landfill compaction is essential for optimizing space, minimizing methane emissions, and improving environmental outcomes. Whether you’re upgrading your municipal landfill or planning a waste-to-energy transition:

Klean Industries offers the expertise, engineering, and technology to transform landfill operations from wasteful to resource-efficient.

Contact us to explore landfill-to-energy strategies, advanced compaction tools, or integrated recycling systems.