NASHVILLE - Chemical maker Olin Corp. said Friday that it was spending $160 million to change production techniques at a southeast Tennessee chlorine plant that has been targeted by environmentalists for emitting high levels of mercury - and was the focus of a 2008 Inquirer article about a pro-business agenda at the U.S. Environmental Protection Agency.

Olin, one of the few remaining U.S. companies that use mercury to produce chlorine, said it would convert its Charleston plant, eliminating the use of mercury in the manufacture of the chlorine and caustic soda it produces in 2012.

Mercury contamination in the nearby Hiwassee River has made the company a target for the environmental group Oceana since 2005. Olin also faced the possibility that a pending congressional bill would force it to upgrade within two years. The controversy was highlighted in a 2008 Inquirer series critical of the EPA's praise of the mercury-producing Olin factory, despite high levels of mercury in the area and environmental violations.

As recently as last winter, plant officials told the Chattanooga Times Free Press that two years was not enough time to redesign and reconstruct the plant to do away with the use of mercury.

But in a news release on the change, Olin chairman, president, and chief executive officer Joseph Rupp referred to another pressure.

"Over the past 18 months we have experienced a steady increase in the number of our customers unwilling to accept our products manufactured using mercury cell technology," he said.

Oceana's Jackie Savitz called the announcement of the elimination of mercury "huge news for Tennessee."

"When we first started working on this five years ago, the Olin plant was the biggest mercury emitter in all of Tennessee," she said.

Another Olin plant, in Augusta, Ga., also will stop using mercury for manufacturing in 2012. That plant will discontinue the manufacture of chlorine and caustic soda and be converted to produce bleach and distribute caustic soda.

German chemical company Wacker Chemie AG announced in February 2009 that it would build a hyperpure polycrystalline silicon plant nearby. At the time the investment was announced, the company said the site's proximity to chorine producer Olin was one of the deciding factors in building the plant in Tennessee.

Wacker Chemie announced on Thursday that site preparation was under way on the $1.5 billion plant.

Asked whether Wacker was influential in the decision to revamp the manufacturing process, Olin spokeswoman Elaine Patterson said she could not discuss specific relationships with clients but called Wacker a "valued customer."

Cleveland, Tenn., Mayor Tom Rowland told the Cleveland Daily Banner that health, safety, and environmental protection are fundamental to Wacker's decision making.

"Rebuilding the Olin plant is extremely important in view of Wacker being one of their major clients," he said.