User talk:Kevin Carel

Alternative Daily Cover
Alternative Daily Cover Alternative daily cover also know as alternate daily cover (ADC) means cover material other than earthen material placed on the surface of the active working face of a municipal solid waste landfill at the end of each operating day to control vectors, fires, odors, blowing litter, and scavenging. Federal regulation 40 CFR 258.21 requires landfill operators to use six inches of earth material as daily cover unless other materials are allowed as alternatives.

There is a large number of ADC options for facilities to choose from. Generally, ADCs can be classified into two basic types: waste-derived materials and non-waste-derived materials. Waste-derived materials include ash, auto shredder fluff, construction and demolition (C&D) waste fines, compost, green waste such as vegetation and leaves, contaminated sediment and soil, sludge, and shredded tires. Non-waste-derived material can generally be classified into two groups: spray-on materials and geosynthetic materials or tarps. Depending on the state regulations, the following materials may be used as a substitute for soil daily cover, either on their own or after being blended with soil.

Waste Derived ADCs

Ash. This ADC typically comes from the incineration of materials, such as the combustion of coal in energy generation. Ash can be used as-is or blended with soil or sludge. Given the U.S. Environmental Protection Agency’s recent focus on coal combustion by-products, this material may become a growing revenue source for landfill managers in the future.

Auto shredder fluff. This material is the result of the process of shredding automobiles and recapturing the metals and plastics for reuse. Typically, the fluff is less dense than soil and is blended with soil prior to use.

C&D waste fines. Fines are a soil-like material that is left over after C&D waste is processed for recycling.

Composted materials. These ADCs can consist of decomposed wood, green waste or other solid waste. If this material is not of sufficient quality to produce revenue, then its use as an ADC could be attractive.

Green waste. This material is readily available at most landfills. Either ground or unground, this material can replace soil and also can be used as a substitute for gravel in maintaining roads and tipping pads.

Contaminated sediment and soil. Soils that have become contaminated with man-made chemicals such as petroleum or other alterations are a good option to replace clean soil.

Sludges. Sludges can be used as an ADC as there is often no other use for them. They can be attractive as a revenue source and because use of sludge can increase the overall waste density at a facility due to its high density and moisture content.

Shredded tires. Using shredded tires as an ADC is a great way to dispose of tires without additional use of airspace, as they would otherwise be landfilled like any other waste.

Non Waste ADCs

Spray Applied ADC. There are two categories of spray-on ADCs: foams and slurries. Soap, starches or resins are mixed with water to create foam. Slurry ADCs are made by mixing solids with water and spraying the mixture on the working face of the landfill. Solids commonly used to make slurries are wood fiber, newspaper, cement kiln dust and fly ash.

Specialized spray equipment is used to apply the spray-ons to the surface of the landfill. This forms a thin layer over the waste. Several additional applications from different directions may be needed to ensure even coverage of the waste.

The biggest advantage to spray applied ADC is that they do not need to be removed. Left in place, they are pulverized as the next lift of waste is applied on top of them, and therefore they use up none of the landfill’s valuable airspace. Spray-ons have the added benefit of being able to include odor control agents or colors to improve the aesthetics of a site. The major disadvantage of spray-on ADCs is the additional cost of the material and the specialized equipment required to apply it.

Geosynthetic covers (tarps). Geosynthetic covers or tarps are large pieces of plastic or fabric material that are deployed by equipment or hand akin to the rain tarp placed over a baseball diamond during rain delays. The advantages of tarps include using no airspace, minimal cost, speed of deployment and removal, and the fact that they are reusable. Some of the drawbacks include the difficulty of deploying tarps (especially in windy conditions), exposure of employees to the waste, and tearing that often occurs when the tarps are dragged across the waste.

Special equipment can be used to deploy tarps. Such equipment is not required, and can be expensive both in capital and maintenance costs. However, using specialized deployment equipment improves safety, reduces the number of workers needed, and can increase the speed of placing and removing the tarp. Tarps typically last from 60 to 180 days.

Benefits The biggest advantage of ADCs is the conservation of airspace. Landfills are in the business of selling and managing airspace. Any tool that can increase the amount of waste that can be placed in a landfill can greatly impact the bottom line of the facility.

One of the technical advantages of using ADCs relates to the management of landfill gas and leachate. Using non-waste derived ADCs means reducing the amount of soil in your landfill. This helps with landfill gas and leachate flow by removing potential barriers to their free movement within the waste. This can result in greater landfill gas generation, which in turn may also increase revenue from captured landfill gas. It can also facilitate the flow of leachate through the waste mass to the collection layer, minimizing the potential for leachate seeps that cause operational and regulatory headaches.

ADCs can serve as another source of revenue for a landfill, in addition to tipping fees and renewable energy from landfill gas. By getting paid to take a material instead of having to spend money on hauling on-site soil or procuring soil from off-site, landfill facilities can greatly reduce operating costs and improve their bottom line.