When it comes to using large numbers of shredded tires, few landfill operations can compare with Atlantic Waste Disposal Inc., in Sussex County, Va. In 1996, the 1,300-acre landfill, accounted for nearly 4 million tires—equivalent to almost two-thirds the number discarded last year by Virginia's motorists.
A subsidiary of Brambles Industry Inc., a $3 billion-a-year, Sydney, Australia-based company with similar operations in 76 countries, Atlantic Waste uses shredded tires for several civil engineering applications, including ``daily'' and ``alternate daily cover,'' according to Safety Compliance Co-ordinator David Bailey.
Periodically, the day's covering of tire shreds is not removed the following day, but left undisturbed. The result is a 6-inch layer of shreds at each 10-ft. level of the landfill, Mr. Bailey explained.
``We choose to leave it in place because it serves as a good filtration layer and encourages gas and leachate migration,'' he said.
The operation, located south of Richmond, Va., is a ``recirculating landfill,'' in which leachate or liquid runoff is captured by a plastic liner at the bottom of the fill, then piped back to the surface where it then is allowed to filter back down through the mass of debris.
The plastic liner at the bottom of the fill, he explained, prevents the leachate from escaping to contaminate the natural ground water. Meanwhile, the floor of this man-made basin is graded so as to direct the liquid to the center where it can be collected by pipes and returned to the surface. The plastic covered floor also is covered with a layer of permeable tire shreds, allowing the leachate to filter through to the collection pipes.
All this has the benefit of encouraging production of methane or landfill gas which Atlantic Waste hopes one day to harvest and use for fuel.
Being a relatively new landfill, only 2-1/2 years old, the Sussex County site has yet to produce enough gas to harvest. But that remains the company's goal.
In days to come when production of the gas picks up, the company expects to use it to fuel a generator for on-site power use, Mr. Bailey said. Then later, if production volume increases enough to permit, Atlantic Waste hopes to generate electrical power to sell commercially.
The company also uses tire shreds when constructing a new cell at its landfill, according to Mr. Bailey.
To do so, he explained, workers first put down an 18-inch layer of hard clay, then a water-proof plastic liner which then is covered with a layer of sand or rock whose net effect is to allow liquids to filter through at the bottom layer. In place of such natural aggregate, the company has been using tire shreds, according to Mr. Bailey.
He said the company has a good supply of shreds on hand, at least for the present. ``I've probably got a thousand tons—something in the neighborhood of 1 million tires. But we're going to use half of them next week,'' he added.
While the company operates a small collection system within the state and extending into parts of West Virginia, North Carolina, Maryland and Washington, D.C., most of its tires come from other collectors.
``We're predominantly a landfill that also processes tires. Right now we've got more needs than material,'' Mr. Bailey said. ``So from time to time—in order to get to 4 million tires in one year, for example—it's been necessary to buy from someone else. We've had to depend on our competition to supply us with material.''
While the Sussex County operation could use up as many as 9,000 shredded tires a day, ``we just don't get that many tires,'' he said.
In fact, that's more tires than the number scrapped each day in Virginia, said Mr. Bailey, who previously was with the state's Department of Environmental Quality and developed the commonwealth's scrap tire program before coming to work for Atlantic Waste about 30 months ago.
Actually, last year's 4-million-tire consumption was something of a record for the company, said Mr. Bailey. ``We won't be constructing at that level for another year and a half,'' he added.
He estimated this year's usage at between 750,000 and 1 million tires.