Hercules' $145 million missile-manufacturing project, rejected by Salt Lake County planners last month, was unanimously approved by the County Commission Monday morning.The commission's decision was the final defeat for Magna area residents who opposed the project, fearing an accidental explosion could destroy homes surrounding the plant. Surveyors were to begin preparing ground Monday afternoon for construction of the project, which will expand facilities already at the plant, Hercules officials said.

The company will manufacture Titan IV and Delta II rocket motors for the U.S. government.

Commissioners made no comment as they voted to overrule the Planning Commission, which rejected the project on a tie vote. The decision came after a two-hour hearing attended by several hundred people.

Hercules officials said the project will generate $2 billion over the next 10 years and add five times that to the local economy. But because of delays in approval from the county, the company may lose money by missing its first deadlines.

"We have a due-date to produce those first rocket motors," said Jack DeMann, Hercules public affairs director. "We've run out of wiggle-room. We need some breaks with the weather."

Construction is expected to take 20 months, he said.