But the legal fight is back on now - with a vengeance.

The magnesium company, for years the nation's worst toxic polluter, says Congress exempted its processing waste from the nation's cradle-to-grave hazardous waste law, even though it was contaminated with toxic chemicals. It has asked U.S. District Court Judge Dee Benson to throw out the case.

The U.S. Environmental Protection Agency wants Benson to allow the case to go forward to trial, complete with a look at efforts by U.S. Magnesium's parent company to dodge financial responsibility by declaring bankruptcy in 2002. No trial date has been set.

Neither side would discuss the litigation, saying they don't want the case tried in the press.

But both confirmed that last week they had representatives out at the plant, on the southwestern edge of the Great Salt Lake, as Benson toured the facility.

It was a blue jeans and hard-hat gathering that took place in spite of last Thursday's snowstorm.

"The judge requested the tour," said Tom Tripp, technical services manager for the company. "We showed him the process of making magnesium."

U.S. Mag collects magnesium chloride from Great Salt Lake waters to make pure magnesium and alloys for use as a steel strengthener. Its plant discharges thousands of gallons of liquid waste each day into ditches and a 400-acre pond.

The waste includes cancer-causing dioxins and hexochlorobenzene, a manufacturing byproduct that, until being banned in 1976, was produced as a pesticide.

The EPA insists the waste should be tracked under the Resource Conservation and Recovery Act, the federal law that requires close oversight of industrial waste from the time it is created until it is disposed of. After state environmental officials failed to get the company to comply, the EPA filed a $902 million lawsuit against the company, then called Magnesium Corp. of America, six years ago to force the company to stop the dumping toxic wastes that might harm workers and wash into the Great Salt Lake, and to clean up past contamination.

U.S. Mag insists that Congress built into Resource Conservation and Recovery Act an exemption for waste from the process used at its Utah plant.

In court papers, the company insists that the EPA is now reinterpreting the exemption.

Since the suit was filed, the company has faced two other related suits.

In 2003, the U.S. Bankruptcy Court sued Ira Rennert, owner of the parent company, the Rennert Group, and a trust, for selling bonds to investors without disclosing the dispute with EPA. The $1.5 billion suit against Rennert also names his legal advisers.

And, in 2005, the company faced another EPA environmental lawsuit for dumping cancer-causing polychlorinated biphenyls (PCBs) at the site.

fahys@sltrib.com