GREEN RIVER - A federal judge has authorized a class-action lawsuit over alleged cuts in pension benefits brought against Solvay Chemicals Inc., one of southwest Wyoming's leading soda ash producers.

An attorney for the plaintiffs said employees of Solvay have been invited to join the national class-action lawsuit aimed at fighting changes in the soda ash giant's pension benefits.

U.S. District Judge Alan Johnson authorized the class action in the lawsuit filed against Solvay in a Feb. 8 order and ruled that the case could move forward under federal age discrimination laws.

Richard Honaker, co-counsel for the class-action members, said he hopes to include in the lawsuit all employees in Wyoming and elsewhere who were affected by the company's pension changes.

"We are pleased that Judge Johnson has given the green light for this case to proceed," Honaker said in statement.

"We now move on to the next challenge, which is to be sure that all the employees harmed by Solvay's pension policies are included in the class-action suit and receive increased retirement benefits," he said. "This is a very important matter."

The lawsuit's lead plaintiffs are Wade Jensen, a 15-year surface plant operator, and Donald Goff, who worked at the plant for 23 years before being discharged in 2005.

The two allege that their retirement benefits were cut because of their age, in violation of the federal Age Discrimination in Employment Act and the Employee Retirement Income Security Act.

The lawsuit alleges that for years, the company's pension plan offered benefits calculated on a formula based on an employee's pay and years of service.

The complaint says that when Solvay changed to a system based on credits assigned in a retirement balance account, known as a "cash balance" pension plan, the initial balances did not reflect the value of the plan under the previous system.

Solvay attorney Richard Hammett, with the Houston-based Baker and McKenzie LLP, said in a phone interview the company "understands that the pension plan change remains an important issue" for a number of employees.

"They very much respect the legal process and the right of employees to invoke the legal process, and that's what's going on here," he said.

Hammett noted that in past similar lawsuits, "the courts that dealt with this question have ruled in favor of the (pension) plan changes."

The class-action lawsuit seeks to recover the lost pension benefits and obtain damages for Solvay's "willful violation" of age discrimination laws.

Solvay's trona mine and soda ash plant is the fifth largest employer in Sweetwater County. The company employs 415 workers at its soda ash facility, located about 20 miles west of Green River.

The company recently expanded its production capacity to about 1.8 million tons of soda ash per year.

Solvay Chemicals is a member of the Solvay Group, a $9 billion, 144-year-old group of chemical companies headquartered in Brussels, Belgium. The group employs more than 30,000 people in 50 countries.

Honaker said Solvay employees at the Green River mine and plant are among the Solvay Group employees most affected by the pension changes.

Honaker said current or former Solvay employees - who were 40 years or older as of Feb. 8 - wishing to join the class-action suit have until June 9 to do so. Interested employees must return a "consent form" to join, he said.

Southwest Wyoming bureau reporter Jeff Gearino can be reached at 307-875-5359 or at gearino@tribcsp.com.