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Understanding Landfill Cover Materials

Understanding Landfill Cover Materials

Posted by Trashcans Unlimited on 23rd May 2018

Landfills are an unpleasant reality of modern life. Every American throws away about 4.6 pounds of solid trash per day, totaling about 230 million tons per year for the country as a whole. With less than a fourth of this waste being recycled, the remainder must be disposed of by either burning it or by burying it in landfills. With approximately 53 percent of the nation’s municipal solid waste being handled by 1,908 landfill facilities, the waste disposal situation in the United States is a delicate balancing act.

“Current production and consumption systems do not offer enough incentives for preventing and reducing waste. From product design and packaging to material choices, the entire chain is not designed with waste prevention in mind,” the American Society of Civil Engineers said in its 2017 infrastructure report card.

“Changing the way we think about waste requires effort by all the parties concerned: consumers, producers, policymakers, local authorities, and waste treatment facilities, among others. Increases in recycling can only occur where consumers are willing to sort their household waste, and the infrastructure and market is in place to collect and utilize the recycled materials.”

As more landfills are being dug nearer to densely populated areas, the need to properly manage exposure to solid waste becomes more acute. One method of landfill management operators use is the utilization of landfill cover material. Landfill cover is not only useful in controlling the emission of offensive smells; it also deters pests, limits rainwater runoff, prevents waste fires, and discourages scavenging. By federal regulation, landfill operators must lay a minimum of six inches of cover on their active landfills daily.

The Importance of Daily Cover

(Courtesy: Pixabay)

The Importance of Daily Cover

The idea of daily cover originated with the Fresno Municipal Sanitary Landfill, which was the first modern landfill in the United States. Many of the procedures innovated there have become standard practice across the country. A key element of Fresno-type landfill operations is the practice of regularly compacting the daily load, depositing it in a large trench, covering it with fill excavated from an adjacent trench, and then moving on to the new trench when the first trench is full.

The benefits of such a system are fairly self-evident. In areas adjacent to residential areas, immediately covering up fresh waste not only prevents the proliferation of rodents and other pests, but also reduces the diffusion of offensive odors. It only takes one bag of particularly redolent trash to produce an odor noticeable throughout an entire city block. Additionally, because the trash is immediately removed from contact with the open air, the possibility of fire and windborne pollution of the surrounding areas is greatly reduced.

This “trenching” method, however, is not a perfect solution. It greatly increases the size of the landfill space required and adds the need for compacting and excavation equipment, as well as workers, for daily landfill operation. Finally, the reduced air access caused by daily cover also impedes rainfall evaporation, creating a situation where contaminated runoff could potentially seep into the water table. This runoff, called leachate, presents a significant environmental problem. Additionally, sealed decomposition of garbage creates pockets of potentially dangerous gases that could also seep into the water table, burn underground, or create other unforeseen problems.

The benefits of daily cover, however, are generally believed to outweigh the drawbacks when compared with “open” landfills.

Alternative to Ground Soil in Daily Cover

(Courtesy: Pixabay)

Alternative to Ground Soil in Daily Cover

Even if there are currently no better alternatives to daily landfill cover, there are alternatives to the “trenching” of ground soil for the purpose of daily cover material.

For example, purpose-designed geotextile cloth can be used as an Alternative Daily Cover (ADC). These gas- and liquid-permeable cloths are typically used as base layers and retaining walls for newly dug landfill trenches, and for compliance with federal regulations for ADC. Other ADCs available to landfill operators include soap- or resin-based foams, and slurries made of cellulose. However, the daily use of such materials can be financially impractical, and preparation and application can be effort-intensive.

A better solution is to use waste itself to handle waste management. Waste-derived ADCs can be used on their own, or blended with ground soil at a 1:1 ratio.

Some of the most common waste-based ADCs are:

  • Ash. Landfills can use the ash from their incinerators, or from other combustion processes, as their daily cover. The ash can be applied directly, as a mix-in with soil, or as a sludge. Landfill operators can even sell disposal space for an ash producer’s waste products as an additional source of revenue.
  • Auto shredder fluff. When an automobile is shredded, the metal and plastic are sorted for separate disposal. The remainder — auto shredder fluff — is typically burned or sent to landfills. This fluff, instead, can be used as ADC when mixed with soil at a 1:1 ratio.
  • Construction and demolition waste (C&D waste) fines. Most construction and destruction waste can be reclaimed. That which cannot, including fines — the soil-like remains of C&D waste — usually ends up in a landfill. The fines can be filtered out and used as an ADC.
  • Compost. Green materials, bio-waste, and decomposing wood work well as a soil alternative for daily cover, and can also produce revenue from those seeking disposal for such materials. Wood mulch and developed compost can both be used as ADC, and green waste can be used either whole or ground. A proper community waste disposal plan is key to securing strong daily cover on a regular basis. An important part of this plan requires the availability of the appropriate containers and receptacles. Trashcans Unlimited offers the best prices on commercial and decorative trashcans as a trusted source for all your trash can needs.
  • Contaminated sediment. It can be difficult to get rid of biologically, chemically, or radioactively contaminated material. While the leachate from these materials can be an environmental concern, landfills that are willing to use such materials as ADCs can open themselves up to additional lines of revenue.
  • Waste tires. Vulcanized tires are difficult to dispose of; they cannot be recycled without costly de-vulcanization, and disposal of the tires can be space-consuming and potentially toxic. Shredded waste tires can be used as ADC, reducing the airspace that would otherwise be used in burying them.

The best landfills are supported by strong partnerships between the landfill owners and the host communities. For this partnership to exist, it’s important for the landfill to be a good neighbor, and properly applied daily cover is a crucial part of this effort. While it is not necessary to excavate new cover every day, and some cover choices may carry the added benefit of bolstering the landfill’s revenue, understanding both the pros and cons of each daily cover option is key to staying on good terms with the community.