It was interesting in that, unlike the World Trade Center, here no explosion by-products were generated. An explosion is similar to a fire in that soot composed of oxidized organics, chlorides, nitrates, sulfides, and carbon is generated and spread throughout the facility. In Oklahoma City, the blast was external to the buildings so that was not a problem. Construction material particulates such as pulverized concrete, mortar, gypsum, and cellulose were the major contaminants measured, and no long term corrosive mechanisms which would affect the equipment reliability were found within these buildings.
The Federal Courthouse, the "Old Post Office", Federal Office Building, the Metropolitan Library Building, and the C.R. Anthony Building all had similar damage from the blast. Windows were blown out with the glass shrapnel widely spread through various rooms. Ceiling fixtures and suspended ceilings collapsed, plaster ceilings crumbled onto the contents of the room. Computer equipment was propelled to the floor, and book shelves overturned. In one case, building structural damage dictated the removal of all office furniture and computer equipment and relocation to a temporary location. To make matters worse, rain was imminent. Senior project managers began the emergency mitigation procedures to stabilize the environment and to protect the contents of several major buildings which had been severely impacted by the blast. Windows were boarded, glass and other debris were removed, and controlled demolition was done as required to allow restoration to proceed. BMS CAT worked around the clock to finish the restoration work, with over 90 management/supervisory staff and over 400 persons on the labor staff. Good organization was necessary in order to carry out an efficient and orderly restoration with over 530,000 square feet of buildings restored and all four of the previously mentioned buildings ready for reoccupancy on schedule Monday April 24.
With the extremely tight FBI security measures in place, ingress and egress of this staff of workers was a challenge in itself. During the first few days, all personnel had to report to the command center at 8th and Harvey each morning and get in line to be issued a 24 hour pass. The FBI finally went to a permanent color coded photo badge. Red badges were allowed inside the outer perimeter which was maintained by FBI and ATF agents. Getting all individuals approved for entry to the work site and photo badged took several hours. Workers went on standby for several hours at the Federal Court Building to allow time for the FBI evidence team to clear the building.
Dave McDaniel is a Chief Scientist with BMS Catastrophe