Coupled with earlier statements of proposed sales, the group's plan now calls for sales of all Gencorp units except its tires and plastics operations.
Tunnel D-24 was one of the more distant shafts, drilled as an oil exploration point for the plastics operation.
The company, spun off from Uniroyal Tire, sold a business that produces high-quality plastics in February and plans to divest its remaining small plastics operations.
Vestar, an investment firm, will own 51 percent of Suiza's plastics operations.
"The summer slowdown in automotive production seriously affected our automotive plastics operations," Mr. Allen said.
He also closed a money-losing plastics operation.
Both companies have strong plastics operations in Latin America, Western Europe and the Pacific, he said, and Borg-Warner has a strong position in eastern Asia.
He said that about 40 new jobs would be added, mostly for the plastics operation, in addition to the 750 people the company already employs in the region and around the country.
It added that GE Capital, NBC and its plastics operations all achieved double-digit increases.
He joined Celanese in 1946 and made his career in its chemical and plastics operations.