ABOUT 2 billion waste tires sit in several thousand dump sites across the United States, and the growing pile is prompting state governments to tackle the problem by stimulating the fledgling tire recycling industry.
There are now tire recovery programs in 47 states.
But while many tire dumps are being cleaned up, hundreds more remain breeding grounds for pests, especially mosquitoes.
``We find rattlesnakes, rats, mice, skunks, possums, feral cats, everything in these old tire dumps,'' says tire shredder Jerry Martinez, an employee of Tire Recycling of San Antonio. One of about 200 companies now shredding tires in the US, Tire Recycling has stockpiled about 1.3 million shredded tires because the company cannot find a buyer for its material.
Meanwhile, the supply of used tires continues to grow. The Environmental Protection Agency (EPA) estimates that Americans discard about 250 million tires each year.
The challenges to the nascent industry are formidable. Illegal dumping of tires continues because state law prevents many landfills from accepting them. One dump site in California contains more than 30 million tires.
``Tires were made to last a long time and they do. So they are hard to wear down, melt down, or reformulate into a different product,'' explains Hope Pillsbury, who works in the EPA's solid-waste division. ``Glass bottles can be turned into more glass bottles. But it's hard to take tire rubber and make it back into tires.''
Mary Sikora, publisher of the Connecticut-based Scrap Tire News, says tire recyclers are responding to the challenge. ``Tires may not be as far along as paper, but the market is coming along,'' she says. ``It's not any different from growth in other recycling markets. A certain amount of infrastructure has to come on line before viable markets are created.''
Burning tires for fuel is one solution. With a Btu content equal to coal, Ms. Sikora estimates that 58 million tires a year are burned by paper mills, electric utilities, cement producers, and other large energy consumers.
In addition to their value as a fuel source, tires can be used to make consumer products or durable asphalt pavement. New Mexico architect Michael Reynolds uses old tires to construct low-cost homes that only need tires and rammed earth for a foundation. But Mr. Reynolds's idea is highly labor-intensive. And the market for consumer goods and rubberized asphalt is growing only gradually.
Minnesota's waste tire program may be the most successful of the 47 states with programs. The state passed the first used tire legislation in 1985 and it will finish cleaning up all of its tire dumps by mid-1994. Funded by a $4 fee on vehicle title transfers, Minnesota pays companies to clean up waste tire dumps and funds a market development program to find uses for the 4.5 million old tires state residents generate each year. It recently began using shredded tires for lightweight fill in road building.
Used tires may also be used for road surfacing. The Intermodal Surface Transportation Efficiency Act, passed by Congress in 1991, requires states receiving federal highway funds to begin using rubberized asphalt by next year. By 1997, the law will require states to use rubberized asphalt in 20 percent of their road projects, which could consume nearly 70 million tires a year.
However, the biggest use for tires may be as fuel. John Serumgard, chairman of the Scrap Tire Management Council in Washington, predicts that by 1999, as many as 200 million tires a year could be used for fuel. ``At one plant owned by Illinois Power, the company will replace 2 to 3 percent of its coal load with shredded tires. That will consume 7 million tires a year,'' he says.
That is about 60 percent of all scrap tires generated in Illinois each year.
Over the past eight years, the percentage of tires being reused has increased five-fold, Mr. Serumgard says. Today, he estimates that 35 percent of all waste tires are being reused.
While dozens of companies are using shredded tires to produce trash cans, garden hoses, landscaping timbers, and other consumer products, industry officials say more outlets are needed.
Scott Hvidsten of the Minnesota Pollution Control Agency says it will take several more years to develop outlets for all of America's used tires.