Like lids for garbage cans, landfill alternative daily covers (ADCs) keep waste contained and under control during hours when humans aren't present. So when your eyes are making use of their lids, ADCs are doing the same to protect working faces and keep trash still, while saving precious disposal space.
However, no one-size-fits-all solution covers all landfill operations. The reasons one landfill gravitates toward a particular daily cover — either dirt, clay, foam, tarps, sand and sometimes finely crushed glass — will vary depending on site needs and challenges. In addition to helping landfills meet state and federal requirements, ADCs can control blowing litter, animals and insects, and prevent fires. Materials also can be developed to meet weather conditions.
Facing a Vertical Face
The Monmouth County Reclamation Center, Tinton Falls, N.J., resides on the shore, forcing the facility to brave storms. On average, the 900-acre site accepts 2,400 tons of waste per day from household and construction and demolition (C&D) sources in Monmouth County. The tipping fees are $53 per ton excluding taxes for household garbage and $86 per ton for C&D debris.
A private company processes waste through one of the center's four balers, compressing the waste into cubes. Waste then is transported to a 100-acre balefill, according to Christopher Murray, acting superintendent of the operation.
At the landfill, bales are stacked three-high per cell. To cover the tall vertical face with soil, let alone to remove soil cover at the start of a new operating day, would consume more time, money and manpower than Murray cares to imagine.
“You can't place soil across the vertical face,” he says. “The only soil used is for the 12-inch intermediate cover barrier between each lift, and we advance (dirt) daily to the very edge of the vertical wall.”
Instead, the county uses a Rusmar, West Chester, Pa., spray-on foam, which the county also used when the disposal site operated as a more conventional landfill that shredded its solid waste and dealt with traditional slopes. Murray says the county decided to stick with the familiar, using a foam that has a consistency of shaving cream, because it worked with the bales.
“It dries and adheres to the vertical face,” Murray says. The cover is spread on the landfill's working face in about half an hour using a sort of water cannon mounted on the back of the county's roll-off military trucks. The foam typically lasts four or five days, which is advantageous when storms and nor'easters come across the shoreline, he adds.
“You can orient your working face so that it points away from [inclement weather],” Murray explains. When storms are approaching, the staff only opens portions of the site that are more protected from the weather; they leave the ADC stuck fast to parts of the landfill that are directly in the storm's path.
Outlasting the Elements
The St. Lucie County Solid Waste Baling and Recycling Facility, Ft. Pierce, Fla., also uses a foam ADC from New Waste Concepts, Erie, Mich., to help its balefill withstand Mother Nature.
The 331-acre site takes in nearly 1,000 tons of waste per day from unincorporated St. Lucie County and the cities of Port St. Lucie, Ft. Pierce and St. Lucie Village. Tipping fees for the nearly 500 tons per day of garbage are $32 per ton. C&D debris costs $19 per ton, while yard waste tipping fees are $20 per ton.
Leo J. Cordeiro, facility solid waste manager, says once the landfill bales garbage into dense cubes and stacks them like building blocks, the operation needs a product that will withstand south Florida's frequent thunderstorms. The foam lasts from six months to a year, depending on weather conditions, Cordeiro says. “Some of the perimeter walls are sprayed and left exposed for a year or more.”
The ADC is mixed and applied with an all-purpose sprayer from Finn Corp., Fairfield, Ohio. “It takes approximately 30 minutes to apply a load,” Cordeiro says. And the ADC “has fire prevention and fire-fighting properties.”
Containment in the Wind
The Salina, Kan., Landfill receives waste from five counties and is used by public, independent and municipal trash haulers. The site receives approximately 300 tons per day for a tipping fee of $27 per ton. The 640-acre facility has 282 acres permitted to receive waste. To date, the operation has landfilled about 95 acres.
Robert Helm, landfill superintendent for the Salina Municipal Solid Waste Facility, says he chose a high-density, woven polyethylene tarp ADC manufactured by Airspace Saver Daily Cover, Baton Rouge, La. A machine by Tarpomatic Inc., Canton, Ohio, automatically rolls out the tarp.
Salina's tarp sheds water off the landfill's working face. High winds originally were a concern. However, Helm says he has not had problems with the tarp moving off of the trash in windy conditions.
With proper training, “operators have learned to place the tarps using the wind,” he says.
Snow can present challenges, however. “In our part of the country, heavy snows prevent us from removing the tarps,” Helm says. So when it snows, and on Saturdays when state regulatory agencies mandate, the landfill uses a 6-inch layer of soil.
But ADCs have a more important purpose than just withstanding the weather, Helm notes. “The tarps saved us airspace and reduced the amount of dirt needed to be hauled with scrapers,” he reports. Helm estimates the airspace savings equal nearly $1,300 per day over a 5,000-square-foot area.
“We experienced a payback of the cost of tarps and the application machine within approximately 48 days in just airspace savings alone,” Helm adds. Less time required for operating dirt-moving equipment is another benefit.
The Delaware Solid Waste Authority (DSWA), Dover, Del., operates three landfills — totaling approximately 1,856 acres — that service all waste types for the entire state. On average, the largest of the three facilities accepts nearly 1,700 tons per day, while the other two take in 400 and 500 tons daily. Statewide tipping fees for each facility are $58.50 per ton, and contract customers receive a $10 rebate.
According to N.C. Vasuki, CEO of the DSWA, the authority currently uses Airspace tarps that are deployed by Tarpomatic equipment. Nevertheless, the authority has experimented with several ADCs since about 1983.
“We test all kinds of materials,” Vasuki says, noting that the DSWA looks for effective and economically viable alternatives. “We do an economic evaluation and choose what suits us best at a given time,” he explains. “It depends on market conditions.”
For example, the authority has examined several waste materials that can be used as daily cover, including municipal sludge mixtures, carpet fibers and residues from C&D waste recycling.
The DSWA also has experimented with dirt from soil cleanup activities. Soil may come from areas where a buried gasoline tank was dug up, Vasuki notes. “The soil may have some gasoline,” he says, but it “is treated to remove the hydrocarbons and we take the material and use it. It's better than buying soil.”
Vasuki touts the authority's willingness to experiment with ADCs as good landfill management. “[Any well-managed landfill] will always be looking at three or four different options,” he says.
Fortunately, there are several ADC options to ensure your facility has a good night's sleep. Not only are manufacturers making products to meet a plethora of operational demands, but “if you use waste materials, [which should be] properly tested, you're actually recycling waste,” Vasuki says.
Carol Badaracco Padgett is a Waste Age contributing editor.