Alternative daily covers that are effective, and easy to apply are an attractive option for landfill managers. If they can be retrieved and used multiple times, that’s even better! Reusable covers do exist, and all types are essentially some variations of tarp, typically a synthetic geomembrane. The covers are spread over an active face at the end of each work day, and function much like rain tarps placed over baseball diamonds during rain delays. The tarps are secured in place at the end of the day, then rolled up the next morning. Highly durable tarps may last through hundreds of reuses, so reusable ADCs can represent significant savings in materials, labor and equipment compared to traditional soil covers.
Re-usable alternative daily covers offer another important advantage over soil and some other single use covers. Since these tarps are removed each day before accepting more waste, the cover is not a permanent addition to the landfill mass. Avoiding wasted airspace is critical to efficiency and profitability of a landfill. The savings can be significant; in fact, some studies have found that using a reusable ADC can add one year of life to a landfill for every four years used, depending on the amount of tonnage taken in. That’s an impressive improvement!
Cost used to be an issue for tarp-based daily covers, but reusable tarps deployed and retrieved using an automated tarping machine are often the least expensive option, at under a penny per square foot. Being the safest and quickest way to cover a working face adds to their popularity.
Reusable tarps offer another important advantage, particularly for those landfills focused on generating energy through landscape gases. Since the covers are always removed, no seals or compressed materials remain to impede the free flow of produced gas or leachate to collection layers.
Deployment
In small landfill operations, tarps may be manually deployed without difficulty, especially if the tarp is constructed of a naturally lightweight material. In larger landfills, that method may not be efficient, so a host of Automatic Tarping Machines (ATMs) are now available. Some are designed for proprietary use on a specific company’s product, while others are more adaptable.
Some tarping mechanisms are designed to attach to commonly used equipment that’s probably already in the landfill’s inventory, such as blades for a dozer or trash compactor. The tarping mechanism, which may be operated by remote control, spools the tarp out over the working face as a single operator drives. The spooling action reduces the risk of damage to the tarp from stretching and dragging and extends the life of the cover. Some ATMs can even unload an empty spool and pick up a new one, eliminating the need for multiple machines when several spools are in place.
Reusable tarps deployed by a tarp deployment system improve safety since employees aren’t required to walk through trash daily to spread and retrieve cover. Reusable tarps deployed in this fashion are also effective, efficient, and affordable. In fact, a typical working face that would ordinarily require over three hours (and several crew) to cover with dirt requires a mere 20 minutes and a single operator to cover with tarps.
Materials
Daily covers in sanitary landfills aren’t typically exposed directly to leachate, so high levels of chemical resistance aren’t as important. However, they are repeatedly exposed to abrasion and the risk of tears and puncture as the tarps are dragged across the working face. Tarping machines reduce a lot of this abuse, but the material used for an ADC must be durable enough to last through multiple years of this treatment. AquaArmor products, from BTL Liners, feature a reinforcing layer of woven HDPE, sandwiched between layers of highly flexible LDPE coating. This construction produces an impermeable geotextile with maximum puncture and tear resistance and exceptional durability. The combination is exceptionally light, flexible, resistant to UV, and is easy to work with whether you’re using a tarping machine or installing it by hand in a small operation.
Ballasts
Since winds are often a concern in landfill operations, tarp producers have developed many options for keeping covers where they belong, including sophisticated attachments and ballast systems. Chains, or cables secured in pockets across the tarp can keep it in place in even the highest winds. These weighted tarps can also be deployed using compatible ATMs.
Custom fabricators like BTL Liners can offer a host of different attachments around the tarp’s perimeter, including grommets, D-lines, or reinforced triangles that can be used to attach tiedowns.
Benefits
Using reusable alternative daily covers offer many benefits.
- No loss of airspace
- No barriers to the free flow of landfill gas may produce more gas and increase revenue
- No barriers to the free flow of leachate to the collection layer, minimizing potential for leachate seeps.
- Controls odor and dust
- Minimizes windblown litter
- Discourages owls and birds
- Prevents pests and critters
- Improves fire safety by reducing fire risk
- Sheds surface water more quickly
- Improves the overall appearance of the landfill
