Rockwell International's decision to seismically retrofit its eight-story Seal Beach, California, information systems center was a contractor's nightmare. The job was loaded with unusual specifications and performance requirements, as well as the mandate that only six 24-hour holidays could halt Rockwell's operations in the building. Many of the proposed construction techniques were untried and at the time of bidding some were not yet developed. Morley Construction was awarded the job, which was scheduled for completion in the first quarter of 1991.
Base isolating an existing building is like cutting it from its foundation and remounting it on a series of shock absorbers. Because they are flexible in the horizontal direction, isolators prevent most horizontal movement from being transmitted to the building during an earthquake. Because the equipment housed in the basement level is essential to continued operations in the building, the owner and designer decided to install the isolators between the first and second floor rather than below the first floor as is normally done. When workers began work on the exterior isolators, they discovered old dewatering holes that were right where the new cassions needed to be. Locations for drilling piles had to be adjusted slightly to accommodate the old wells.