Firm Hopes to Store Ash in Salt Mine : Environment: Idea meets opposition from residents, who fear that chemicals from N.Y. incinerator waste will contaminate their rural Genesee River Valley.

The Retsof salt mine extends 1,063 feet beneath the Earth’s surface, as far below as the 77-story Chrysler Building rises above.

Tunnels carved out in more than a century of mining stretch for 20 square miles under the Genesee River Valley, about 30 miles south of Rochester.

Now Akzo Salt, owner of the mine, is proposing to fill the excavated tunnels with hardened ash from municipal waste incinerators.

The mine, the largest in the Western Hemisphere, will thereby be able to earn money from its vast, unused spaces.

The idea has met with vehement opposition from residents who fear that toxic chemicals from the ash will contaminate their rural valley, and from environmentalists who believe that opening a cheap, virtually inexhaustible storage space will encourage incineration instead of recycling.

“We’re a small, agricultural county,” said Glenda VanRy, a high school teacher who heads Protect a Clean Environment, a local group opposed to the project. “Why should one small community accept that risk?”

Salt is one of the most stable geological environments on earth, said Jeffrey Over, a geologist at the State University of New York in Geneseo. It is highly impermeable and under geologic pressures, it creeps, forming a seal around whatever is buried in it.

The federal government stores its strategic petroleum reserves in salt mines near the Gulf Coast, and is testing whether radioactive waste from nuclear-weapons plants can be stored 2,200 feet deep in a New Mexico salt bed.

The Retsof mine is a vast network of caverns and tunnels that disappear into darkness. The headlights of mine vehicles glint off crystals in the walls of solid salt. A chalky white salt dust coats the floor and settles on equipment and visitors. Even the air tastes salty.

Chunks of salt are carried by a rattling conveyor belt from the work areas more than five miles to the mine entrance. Huge drills and under cutters, machines that look like enormous chain saws, cut into the mine walls in preparation for the ammonium nitrate explosives that are detonated each night.

Two and a half million to 3 million tons of rock salt, most of it used for de-icing roads, are mined at Retsof each year. With the mine constantly growing, there is almost indefinite storage space, said Larry Milliken, Akzo’s director of storage.

Akzo wants to build a processing plant that would accept 4,000 tons of incinerator ash daily and could be expanded to double that capacity. The company hopes to bring in ash from New York, New Jersey, Connecticut and Massachusetts.

The ash would be brought to the plant by rail in specially designed, sealed containers, Milliken said. The containers would be opened only inside the plant; the ash would be kept wet to keep dust from forming.

At the plant, the ash would be ground to a uniform consistency and mixed with water to make slurry. The slurry would be pumped underground, where it would harden into a concrete-like substance.

Although incinerator ash is not considered hazardous by the New York or federal governments, it contains heavy metals, including lead, mercury, cadmium and chromium, that can be poisonous.

With so much ash being transported, opponents say even a tiny percentage of escaped dust could be a significant health threat.

“The problem is there’s no 100% containment system for this kind of operation,” said Richard Denison, a senior scientist at the Environmental Defense Fund. “There is always some percent that gets released, no matter how good a system you design.”

Local residents fear that contaminants could reach the nearby York Central School, or the dairy farms that line the train tracks through the valley.

“It’s still pretty pristine here,” said Barry Caplan, who worries about the effects of the ash project on his three children. “I don’t want to sell my valley for any amount of money.”

Akzo is working with a firm that has built uranium mills to design a virtually dust-free plant, Milliken said. The company hopes to begin a four- to six-month demonstration project by June. After that, it will be at least three years before the permit and construction process is complete and operations could begin.

Once underground, the ash will be far safer than it is in landfills, Milliken said. Both salt and the shale surrounding it are far less permeable than the requirements for landfill liners.

“Landfills will fail and be subject to erosion long before anything is even conceivably going to disrupt this mine,” Milliken said. “We far and away will exceed the requirements that any landfill has.”