AVELLA, Pennsylvania - A Pennsylvania landowner is suing an energy company for polluting his soil and water in an attempt to link a natural gas drilling technique with environmental contamination.

George Zimmermann, the owner of 480 acres in Washington County, southwest Pennsylvania, says Atlas Energy Inc. ruined his land with toxic chemicals used in or released there by hydraulic fracturing.

Water tests at three locations by gas wells on Zimmermann's property -- one is 1,500 feet from his home -- found seven potentially carcinogenic chemicals above screening levels set by the U.S. Environmental Protection Agency as warranting further investigation.

Jay Hammond, general counsel for Atlas, said Zimmermann's claims are completely erroneous and that the company is in compliance with Pennsylvania's gas-drilling regulations. Hammond said Atlas will vigorously defend itself in court and declined further comment.

But Zimmermann says he has evidence that chemicals used by Atlas contaminated his land.

There are substances that can't be made by nature and that's what's in the ground, he told Reuters during an interview in his 12,000-square-foot house on a remote hilltop.

Atlas is exploiting the Marcellus Shale, a vast gas reserve that underlies about two-thirds of Pennsylvania and parts of West Virginia, Ohio and New York State. Experts estimate it contains enough natural gas to meet total U.S. demand for at least a decade.

The gas is being extracted by hydraulic fracturing, or fracking, in which a mixture of water, sand and chemicals is forced a mile or more underground at high pressure, fracturing the shale and causing the release of natural gas.

Development of the Marcellus, together with other major shale fields in Texas, Louisiana and other states, is being aided by advances in fracking combined with horizontal drilling, which provides more exposure to a formation than a vertical well and leads to less surface disturbance.

If Zimmermann wins his case, it would be the first in America to prove that hydraulic fracturing causes water contamination. Such a finding could slow the development and use of cleaner-burning natural gas that would reduce American dependence on overseas energy.

PERFECT BASELINE TESTS

Baseline tests on Zimmermann's water a year before drilling began were perfect, he said. In June, water tests found arsenic at 2,600 times acceptable levels, benzene at 44 times above limits and naphthalene five times the federal standard.

Soil samples detected mercury and selenium above official limits, as well as ethylbenzene, a chemical used in drilling, and trichloroethene, a naturally occurring but toxic chemical that can be brought to the surface by gas drilling.

The chemicals can cause many serious illnesses including damage to the immune, nervous and respiratory systems, according to the Endocrine Disruption Exchange, a researcher of the health effects of chemicals used in drilling.

Zimmermann's suit, filed in September in the Washington County Court of Common Pleas and obtained by Reuters, follows claims by residents in many gas-drilling areas of the United States that fracking pollutes private water wells with toxic chemicals and threatens widespread contamination of aquifers from which many rural households draw drinking water.

Although communities as far apart as Pennsylvania and Wyoming complain that their water has become unusable, they have been unable to prove a link to gas drilling. Energy companies refuse to say what chemicals are used in so-called fracking fluid, saying the mixture is proprietary.

Companies are not required to disclose the composition of the fluid because of an exemption to a federal clean water law granted to the oil and gas industry in 2005.

Many local residents have been deterred from fighting the gas companies by the expense of legal action and water testing. Zimmermann says he has spent about $15,000 on water tests and will spend whatever it takes to prove his case.

Rural residents who live near gas drilling say their water has become discolored, foul-smelling, or even flammable because methane from disturbed gas deposits has migrated into water wells.

DEATHS, MUTATION OF LIVESTOCK

Farmers in southwest Pennsylvania blame cattle deaths and mutations on local fracking. Other complaints attributed to tainted water include children's sickness, skin rashes and neurological disorders.

The industry says the chemicals used in fracking are injected through layers of steel and concrete thousands of feet below aquifers, and so pose no threat to drinking water. Spokesman argue there has never been a documented case of water contamination as a result of fracking.

On Zimmermann's property, the presence of water and soil contaminants that exceed EPA screening levels risks wider pollution of drinking water supply, wrote Cleason Smith, a consultant with Hydrosystems Management, which tested the soil and water, in a letter explaining the test results.

Atlas rejected Smith's report, saying in court documents that the findings were inadmissible.

Smith said further tests are needed to confirm the source of contamination but that some chemicals seem to come from fracking or related activity. Benzene, for example, is unlikely to be found on land that was previously forested, he said.

Zimmermann's suit says his land has become virtually valueless because it is permanently contaminated with toxic chemicals as a result of the 10 wells that Atlas has drilled.

The suit accuses Atlas -- which is able to drill on the land because it acquired the mineral rights from a previous owner -- of negligence. It is seeking an injunction against further drilling, and unspecified financial damages.

With a wife, an eight-year-old son and eight-month-old twins, Zimmermann, 66, worries about air and water quality.

He said he has invested about $11 million in the estate, which includes a winery and an heirloom-tomato business, but he now just wants to walk away because he believes it has been ruined by gas drilling.

He rates his chances of selling the property as slim to none in light of the proven water contamination.

I don't want to live here any more, Zimmermann said. I'm afraid of the chemicals.

(Editing by Mark Egan and Philip Barbara)