EACH NIGHT, BEFORE PUTTING a landfill to bed, operators must ensure their waste is snug and secure with a daily cover, so as not to offend the neighbors with unwanted smells or visitors. But how to choose that perfect nighttime landfill blanket?
Alternative daily covers (ADCs), such as foundry sand, tarps, foam and green waste, can be used to meet federal rules requiring landfill daily covers. Soil also is a common landfill daily cover choice, although operators say it can be costly and eat up airspace. According to Mike Crist, staff engineer for the Wayne Township, Pa., landfill “ADCs are the way to go [if] you want to minimize the amount of soil that you are putting [on a landfill] in order to save airspace.”
There are several factors a landfill owner or operator must examine when deciding which ADC to use, such as what type of landfill it will cover, what the weather conditions are like and, most importantly, what types of ADCs the facility is permitted to use. Frequently, sites choose one main ADC and a couple of backups because what works best for one site or in certain weather conditions does not mean it is foolproof in keeping trash secure in all situations.
Tarps sometimes are used because of their convenience. But foundry sand, contaminated soil, paper sludge, foams, wood chips, green waste and soil mixtures can work equally as well.
Tucked in with Tarps
According to the city of Lincoln, Neb.'s Landfill Site, it has several ADC options to choose from. The Nebraska Department of Environmental Quality has approved petroleum-contaminated soils, foundry sands, and a wood chips and soils mixture as acceptable ADCs. However, the facility does not use these options frequently because of the inconsistency of a guaranteed waste stream and the restrictions placed on them, says Karla Welding, superintendent of solid waste operations. Instead, the facility's primary ADC is a Tarpomatic tarp system, although it has some restrictions, too.
“The use of the tarps is intended to save the airspace typically consumed by soils,” Welding explains. The mechanically deployed polyethylene tarp is rolled over the landfill at night and rolled away in the morning. However, “we will not deploy the tarp when forecasted winds are for 45 miles per hour or greater, or when the snowfall forecast is for 6 inches or more, per our permit,” which would hinder deployment and performance, she adds.
Located in Lincoln, the city of Lincoln Landfill Site operates two landfills that serve Lancaster County. One facility is a permitted construction and demolition (C&D) landfill, and the other is a municipal solid waste (MSW) facility. With a disposal area of 171 acres, the MSW site has a capacity of up to 23.6 million cubic yards. The landfill currently is in phase nine of 15 and has filled about 93 acres. On average, the landfill receives 758 tons of waste per day, with highs averaging 2,000 tons per day and lows, which generally occur on the weekends, averaging 500 tons per day. Because of the facility's terrain and weather conditions, the landfill still keeps its cover options open to more than one backup type of ADC.
To choose the best ADC for a specific facility, operators should research the system's capabilities and limitations, and work through a benefit to cost analysis, Welding recommends. “It [also] is important to [ensure] the equipment operators thoroughly understand the intent of ADCs and understand the limitations of the system, if any, in their particular operation. An ADC system chosen for economic reasons may not produce the desired savings if it is difficult for equipment operators to employ, or cannot be used as frequently as anticipated because of other operational limitations,” she says.
Sand and Soil
The Wayne Township Landfill in Clinton County, Pa., chooses its ADC based on available materials and cost. The landfill, which serves the north central part of the state, is comprised of 33 acres and is permitted to receive up to 750 tons of waste per day, although the daily average is closer to 500 tons per day. The incoming waste can be divided into three major components: municipal, residential and C&D waste. Residential and commercial waste comprises 80 percent of the loads.
According to Staff Engineer Crist, the township first turned to the Pennsylvania Department of Environmental Protection for a list of approved ADCs when choosing its material. The facility gained approval for three types of tarps, which is its most frequent ADC choice. The facility uses a Cormier Textiles Inc. WP-1440FR, an Integra Plastics Inc. 12-FR and Airspace Saver Daily Cover's Airspace Saver TGNN-FR. The facility also is approved to use paper sludge and foam, but “since our source went away, we don't use paper sludge as much,” Crist adds. And in his case, foams were more expensive.
Consequently, tarps are used at the landfill most often. However, “there are issues with any ADC that is used,” Crist adds. His landfill's use of foundry sand is inconsistent because operators are dependent on when a hauler or customer brings it in. Alternate materials such as paper sludge can develop odors if the pile is not turned over. “Therefore, the operator needs to look at the issues and determine what's best for them,” Crist emphasizes.
Going with Green waste
Orange County, Calif., decided its best ADC option was green waste. The Integrated Waste Management Department of Orange County in Santa Ana, Calif., manages three sites totaling 2,800 acres: Olinda Alpha in North Orange County, Frank R. Bowerman in Central Orange County and Prima in South Orange County.
“Every landfill is different and every area is different,” says Dave Lowry of the Integrated Waste Management Department of Orange County, Calif. But the Olinda Alpha, which comprises 565 acres and can receive up to 8,000 tons of waste per day, is mandated to use processed green waste as its ADC. Tarps are used as a backup. The other two sites, Frank R. Bowerman and Prima, use heavy plastic tarps.
“I can't say which [ADC] is better, as [policy dictates] what I have to use,” Lowry says, “but every landfill operator should be actively involved in using [ADCs] as well as conscious of the airspace associated with using soil because it does not degrade over time.”
In Olinda Alpha's case, “using green waste is a benefit for everyone,” because cities can get credit for using the recyclable material, Lowry says. But landfill operators should thoroughly research all of the products and the regulations to find the best match for their facility's needs, he says.
Leslie Harrison is a Waste Age contributor.