Chips Beneath The Greens Solve Pollution Problems
Americans discarded an estimated 273 million scrap tires in 2001, with only 33 million being retread or recapped for additional use. Most of these old tires were stockpiled, as state regulations require, but in piles they collect rainwater, create breeding grounds for mosquitoes, and have a tendency to catch on fire.
Now, researchers at the University of Wisconsin–Madison have found an environmentally friendly use for these mountains of tires — they can grind them into bits for placement beneath golf course greens. These rubber bits can absorb excess chemicals from fertilizers and pesticides, preventing them from leaching into groundwater and contaminating the surrounding environment.
In a paper accepted for publication in the journal “Waste Management,” Jae (Jim) Park, a professor of civil and environmental engineering at UW-Madison and a golfer with a 6 handicap, has shown that used tires could provide a barrier to the the fertilizers and pesticides applied to the golf course greens that now pollute the environment.
Park says some 1,000 pounds of pesticides are applied yearly to a single golf course and there are more than 23,000 golf courses in the United States.
“Because many greens are built near groundwater levels or wetlands,” explains Park, “it is vital to consider the mitigation of environmental contamination caused by the pesticides and fertilizers applied to golf courses.”
“Tires are a waste material,” says Park, “and we need to have safe ways to dispose of them.”
In the latest study, Park and his team found that tire chips can absorb nitrate – one of the main chemicals in fertilizers. Park says studies show that infants who drink water containing excess amounts of nitrate can become seriously ill and, left untreated, could die.
For the study, the researchers inserted tire chips six to nine millimeters in diameter between layers of sand and peat root mix and gravel, both commonly found beneath golf green turf. The rubber layer was either five or 10 centimeters thick. While the field sites were seeded with a grass, the lab samples were left bare.
To test the ability of the tire chips to absorb chemicals, the Wisconsin scientists applied water spiked with different concentrations of nitrate to each sample. Then, they measured the concentration that seeped out of the bottom gravel layer. In all experiments, the researchers found that the rubber layers did absorb the compounds.
Some environmentalists have expressed concern that chemicals released from the tires will percolate into the environment, but Park says many scientific studies show that the amount released is minimal compared to the amount the tires can trap.
“We’ve proved that is not an issue,” he says. “Some contaminants have been reported, but the levels are so low.”
Greens with a tire chip underlay look just as good as traditional greens. Turfgrass quality, color, density or germination rate did not appear to be affected, Park says.
“Excess amounts of fertilizer will be absorbed by ground tires. They’ll be trapped right there instead of traveling.” Over time, he says, soil microbes will remove the nitrate from the rubber layer, which could remain intact and last for years.
Besides absorbing chemicals harmful to the environment, Park says tire chips are light weight, allowing for easy transportation and installation; they absorb shock, possibly alleviating foot pains of golfers; and they trap heat, promoting turf and root growth longer into autumn and earlier in spring.
But, above all, he says, “The technology reuses a waste material that’s hard to dispose while it protects the environment.” Park estimates that about 72,000 tires would be needed to include a 10 centimeter layer of tire chips for an 18 hole golf course.
Researchers throughout the world have been searching for ways to reuse tires that are accumulating in stockpiles.
Civil engineers have utilized tires, either in scrap or ground-up form, to develop fuel, artificial ocean reefs, bumpers, playground equipment, and asphalt additives that extend the life of roadways and shock absorbent playing fields.
Ground up rubber products, including the soles from sneakers, can be found beneath the turfgrass at many athletic stadiums, including Camp Randall Stadium at UW-Madison.
Provided by theEnvironmental News Service.