In 1983, after it stood vacant and incomplete for seven years, funding finally became available again to finish construction on a 5-story, southern California medical center. The foundation, walls and floors had already been completed, but the 7-year-old floors, made of lightweight concrete over metal decking, were badly out of tolerance. The original finish was bumpy and uneven. And the floors had sagged between the steel beams, creating high spots over the beams and low dished areas between the beams. The engineer decided that grinding the 300,000 square foot flooring would be the least expensive and most permanent repair measure. Two types of grinding machines were used on the floors: first a large floor grinder with a helical cutting head that could grind between 500 and 1000 square feet per hour, then two smaller, slower grinders that were used to produce the final floor finish.