Excavation and site preparation has started for construction of the $145 million expansion of the Hercules Aerospace Bacchus West automated rocket motor facility in west Salt Lake County.

Manager David E. Thompson said excavation has started on the casting pits for the new cast/cure facility, which will be one of five near major complexes. Road paving will start later this month.Gilbert Western Corp., Murray, was the excavation contractor and will do the road paving, Thompson said.

The expansion also will include new mixing, mix bowl cleaning, pre-bath storage and mix bowl transport service buildings in addition to seven new utility buildings and substantial modifications to four existing buildings at Bacchus West.

The case preparation facility will be doubled in size with a 175- by 190-foot addition for more floor space and installation of a second robot spray fixture.

Thompson said additions also will be constructed to the aluminum premix buildings, and modifications are planned for one of the two mix buildings and the mix bowl cleaning buildings. Two additional process control computers will be installed at the control center.

The additions, along with additions at Bacchus East and the Freeport Center in Clearfield, are necessary for increased production for upgraded solid rocket motors for Titan IV and graphite epoxy motors for Delta II space vehicles.