For over four decades, since Fred Caron developed the first self-propelled landfill compactor, the waste industry has equated increased waste density with more efficient use of airspace, a simple concept with simple benefits. But under closer inspection, the true benefits of waste compaction, though simple, are much more extensive.
From the first load of trash to the last, the steps of constructing a landfill, like the links in a chain, are tightly interconnected. When you tweak one part of the operation, it naturally pulls on everything else. So, by maximizing waste compaction, savvy managers have learned how to pull their operations to higher levels of efficiency, saving money today and extending those savings throughout the lifetimes of their facilities.
No other component of landfill activity provides more benefits than good waste compaction, which is why—at today’s modern landfill—having a compactor is not considered an option. Nearly all landfills that receive more than 100 tons of waste per day, and many smaller ones as well, have a compactor. Like peanut butter and jelly, landfills and compactors just naturally go together. Heck, having a compactor is so expected, it’s not even something we to stop and think about…and therein lies the problem.
Over the years, I’ve been able to speak with several hundred landfill managers and several thousand landfill workers, mostly equipment operators. Far above all other issues, the majority of them have ranked waste compaction as the most important operational goal. Again, the benefits of waste compaction are widely acknowledged—and, as we said, simple.
Let’s review why waste compaction ranks first in your landfill’s playbook.
First, landfill airspace is tremendously valuable, partly due to the cost of developing it, but also because of the revenue it can generate. These are both true, valid reasons—each of which is dependent on the time value of money (TVM).
The cost of development is usually a current cost—in terms of the TVM. If it costs $5 per cubic yard to create airspace for the next one to two years, then that is essentially today’s cost (i.e., the net present cost).
Revenue, on the other hand, is often discounted considerably in regard to the TVM. Here’s the scoop: Suppose your landfill charges $40 per ton and has 20 years of remaining life. You find that by increasing your compaction rate you could add another year of life. So the increased value is the revenue you’d receive in year 21. If we assume a 4% annual interest rate, then bringing the revenue back to a present value discounts it from $40 per ton…to less than $18 per ton.
These are the industry’s core reasons for compacting waste, and very good reasons they are. But if we stop here—thinking that these alone are enough justification—then, as noted earlier, we’ve stopped thinking.
When making operational decisions in this down economy, landfill managers should have as much information as possible. If your question has to do with finding the cost/benefit sweet spot of compaction, you must know how much it’s costing you to compact waste—and the value of the benefits it provides. Here are few more benefits to toss into the equation:
- Liner construction costs, as mentioned earlier, can be expressed as an airspace cost, such as $5 per cubic yard. In this context, a few dollars per cubic yard seems pretty palatable. But in the real world of cash flow, those liner costs come periodically as staggering capital outlays. Once you’ve filled the current phase of your landfill, and it’s time to build the next one, you’ll likely be cutting a check for a few million dollars. In this scenario, achieving better compaction can help defer those big capital projects. And sometimes a little bit is just enough.
- Construction projects must occur in certain windows, mostly dictated by weather conditions. Increasing your landfill’s compaction rate by just enough to stretch until the next season’s construction window can save you hundreds of thousands of dollars in simple interest just by deferring those big capital costs for another year.
- Your landfill, like virtually all others, is required to accumulate money for closure and post-closure. And while this closure/postclosure funding can take on many forms, the annual (or per-ton) rate is based on the ultimate cost of closure/postclosure, divided by the remaining life of your landfill, expressed in years (or tons). Thus, if you can increase the size of the denominator, by increasing your compaction rate, the annual or per-ton cost will decrease. This can help you cut your costs…which could open the door for your landfill to be more competitive…attract more waste…generate more revenue…and so on. Anyway, there are lots of potential results, most of them quite favorable.
- Even though the benefits of compaction all trickle down, eventually, to the bottom line, some of them are a bit more hands-on. Being able to pack a given mass of waste into a smaller volume will result in less surface area to cover each day. This, in turn, means less airspace consumed, reducing hauling costs. Cover soil is always a significant cost factor, and better waste compaction can help keep it down.
- By increasing the compaction rate at your landfill, your landfill structure will perform better. Sounds a bit vague, but what it really means is that your landfill’s vehicle access roads, scraper/truck, ditches, benches, downdrains, and other surface improvements will experience less settlement, require less maintenance, and, in general, cost less.
- Finally, as they age and settle, perimeter landfill slopes will flatten, making it necessary to rebuild those areas in order to recover all available airspace. While thin wedge fills may be cost-effective in the long run, they are nonetheless more difficult and more costly than normal operations. Achieving good compaction today can help minimize or eliminate the need for rebuilding slopes in the future.
As we run down the list of benefits that good compaction provides, it’s clear indeed that operational improvement in one area can leverage improvement in many other areas. When it comes to compaction, the better it gets…the better it gets. For landfill managers, waste compaction is so important, so vital to peak operations, that we should be thinking about it first…and we should continue thinking about it every day.