When A Landfill's Airspace Isn't Dirt Cheap

Cheryl L. Dunson

In Fauquier County, Vir-ginia, solid waste manager Ellis Bingham is pioneering a new path in landfill operations.

While most of his county peers are preoccupied with balancing residential growing pains with the community's traditional agricultural roots, Bingham is gearing up to operate a new landfill that will never see the first ton of dirt. As Bingham's efforts indicate, the increasing use of alternative daily covers (ADC) in the landfill industry is charting new waters for operators and is taking the landfill business into the 21st century with the same fervor as NASA's space program.

Economics coupled with better utilization and preservation of valuable airspace are motivating landfill operators to de-mand more from their cover systems than a daily sprinkling and compaction of six inches of dirt.

"Dirt is a scarce commodity for us," said Bingham, explaining why Fau-quier County initially entertained the use of ADC. "We're land-locked. But, even if we had to bring dirt from an adjacent area, the [ADC] is cheaper, easier on the equipment, and has saved us $400,000 in the first six months of our pilot program."

Bingham sprays a slurry mixture of kiln dust, cellulose and water onto his landfill's working face daily. The product, Posi Shell, is manufactured by Landfill Service Corporation, Apa-lachin, N.Y. Bingham says it's saving him about $2,500 daily in space, and will almost double the life of his new facility when he moves into its first cell this year.

Although the slurry hardens upon application, it "breaks right up" the next day, neutralizes odors, reduces methane gas migration and controls vectors, said Bingham.

He budgets approximately $125,000 a year for its use, which includes equipment rental, slurry materials, the storage facility and labor.

"It's less labor-intensive than if we use dirt. It saves times and equipment," Bingham added. "Now that we've trained all the landfill personnel to use the equipment, they consider themselves to be technicians and take more pride in their work."

Bingham isn't alone in his ardent belief and use of ADCs. As airspace becomes more valuable due to the increasing cost of new regulations, many landfill managers are turning to ADCs to extend their facility's life.

Distinctions arise when discussing which cover systems are the most efficient. Gayle Wilson, director of solid waste management for Chapel Hill, N.C., is in a position similar to Bing-ham: They both use ADCs, manage relatively low-volume landfills and are convinced they're saving valuable air space. While Bingham, who has researched ADC programs extensively, is basically satisfied, Wilson is more straightforward about the application process.

The system requires a dozer "to pull the hydroseeder to spray the slurry," he said. "We also have to clean the equipment after every use so material doesn't harden in the ap-plication lines overnight." Because of a patent on the application equipment, Wilson said, the city is "paying a royalty for a not-very-sophisticated technology."

Also, he said he is re-stricted on where and how the equipment can be used.

Nevertheless, Wilson plans on incorporating the ADC into his operations when he's gathered a full year of operational data.

Foam Covering After successfully perfecting the use of foam ADC over a six-year period, Logan Miller, Central Division Man-ager of the Delaware Solid Waste Authority, Dover, is trading the Central Landfill's Pneumatic Foam Unit (PFU) for tarps.

"We took a hard look at our budgets, and the bottom line was we were spending $100,000 per year in foaming," Miller said. "Although I believe it paid for itself in space savings, we've stopped using it."

Miller's experience with foam began during a lysimeter test of two one-acre cells in 1989. When his staff began using more soil than normal due to the small cells' size and number of slopes, they responded with foam to correct the problem.

"It's not that we weren't concerned with cost," Miller recalled, "but we wanted to get the cells mirroring the operation of our 20-acre cell as soon as possible."

The test results indicated the foam provided excellent waste-to-cover ratios. The authority eventually contracted with Rusmar Inc., West Chester, Penn., which manufacturers the soap-based product and sells the application equipment.

John Gray, superintendent of the Monmouth County (N.J.) Reclamation Center, has been using foam for almost a year. The facility averages 1,700 tons per day and serves 53 New Jersey municipalities. "Foam is equal in value to importing soils from outside," Gray said. "We've freed up manpower and machinery. Now, they can do other site maintenance. That's hard to quantify into dollars."

Because the foam cannot be ap-plied during rain since it dissolves, the county has linked up with a reliable weather service to alert them to inclement conditions. The foam unit also occasionally freezes during winter months, so Gray responded with a heat generator which is placed atop the unit at night.

Another reason for the use of foam is the county's decision to bale waste, Gray said. "Baling is high density and, therefore, foam compliments this process because its a low space-consuming technology."

The Wood County Landfill in Bowling Green, Ohio, uses a slurry-type cover system, Con-Cover, manufactured by New Waste Concepts Inc., Erie, Mich.

This cover is comprised of a slurry of recycled fibers and polymers that's mixed with water; unused slurry can remain in the spreader over-night for the next day's use.

At $300 a day, the cover product appears expensive, landfill superintendent Ken Vollmar admits, but said that cost must be weighed against savings. "When we figure how much airspace we're saving at $35.30 per ton, we realize we can pack a lot more into that space," he said.

The Wood County Landfill accepts roughly 150 tons per day, and had a life expectancy of 18 years in 1993. "We've stayed at 17 years of life for the past two years," Vollmar emphasized.

Aging Well With Tarps In the debate over which ADC programs are more effective, tarp users are convinced that they are perfecting the secret to landfill longevity. And, like their foam counterparts, the issue is what types of tarps are the most cost-effective and user-friendly.

For Brian Bowen, site manager of the Kirby Canyon Landfill in Morgan Hill, Calif., money was the catalyst for choosing tarps as an ADC. Bowen operates a 1,500-tons-per-day, "soil-rich" landfill for Waste Management, Inc., Oak Brook, Ill.

"Like any other landfill, empty airspace is our asset," Bowen said. "Subtitle D airspace is quite expensive, and if we can postpone the life of the landfill a year or two, it's worth it."

Regulatory and operational concerns convinced Bowen that tarps were the ADC of choice for his 311-acre facility. Although he researched other methods, he decided "strictly on tarps" because he believed that they would be more easily accepted by the California Integrated Waste Manage-ment Board.

The regulatory agency allowed Bowen to begin the project as a pilot program without amending the facility's operations permit. Kirby Canyon personnel use a series of woven, polypropelene tarps, manufactured by Airspace Saver Daily Cover, Prairie-ville, La., five days a week to cover waste. On the sixth day, they are required to cover the working face with cover soil.

"We work a very lean operation, with only 10 full-time employees," Bowen explained. "Plus, tarps are low-capital investments," added operations manager Joe Morse. "Our only concern with tarps is deployment."

Because Kirby Canyon is a canyon fill, and high winds can cause problems, chains are sewn to the edges of the tarp to prevent them from becoming airborne.

Santek Environmental, Inc., Cleve-land, Tenn., manages publicly-owned landfills in several states, and began experimenting with tarps more than three years ago.

They began with heavier tarps which "were heavy and hard to de-ploy, even with equipment," said Rob Burnette, vice president of engineering. The company converted to woven poly-propelene tarps, manufactured by AmCon Environ-mental, Sommerset, Ky. Burnette said, because they're lighter and more manufacturers sew straps to them for easier deployment.

Their lifespans are "anywhere from two to eight months," he said, but the company has invested in sewing machines to perform on-site maintenance and extend the tarps' life.

"Managing Subtitle D landfills with small-to-medium volumes, Santek is definitely in a cost-driven situation which is why we began looking at tarps," Burnette explained. "They range in price from 12 cents to 25 cents per square foot. The more expensive tarps perform better."

Working with different regulatory agencies has posed certain challenges for the company. In Tennessee, where it originally began using tarps, the company submitted a letter and manual to the Tennessee Department of Environment and Conservation, detailing the tarps' specifications, benefits and deployment practices.

In contrast, the North Carolina Department of Health, Environment and Natural Resources required them to perform a demonstration of the tarps and agreed only to a 90-day trial period before allowing the company to incorporate them into the Wake County landfills' operating permits.

"When you compare the cost of the tarps to cover soil, the savings are going to vary depending on what it costs you to haul dirt and the status of soil availability," Burnette said. "But, when you compare the cost of tarps to the cost of airspace, the tarps win hands down."