RAPID CITY, S.D. (AP) â¿¿ Natural gas and electric utility Black Hills Corp. said Tuesday that Tom Ohlmacher, president and chief operating officer of its non-regulated energy business, will retire early next year and it plans to rearrange its leadership as a result.

Ohlmacher, 58, has worked at Black Hills for 36 years.

With his departure, Linn Evans, president and COO of Black Hills' utility businesses, will take charge of its power generation and coal mining businesses, the company said. He will continue reporting to CEO David Emery.

The company said Evans reorganized the leadership structure for the businesses below him to improve efficiencies at its gas and electric utilities and between its utility and non-regulated energy units.

Among the changes, Stuart Wevik has become vice president of utility operations. He was vice president of electric utilities.

And Ivan Vancas has become vice president of utility services. He had been vice president of operations for Black Hills Energy â¿¿ Kansas and Colorado Gas.

Black Hills shares rose a penny to $30.44 in after-hours trading, after finishing regular trading up 21 cents at $30.43.

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