the site, died of a heart attack suffered while fleeing the disaster area. 45 people were injured, with two injured critically. The most seriously injured victims were a 23-year-old tow truck driver from Brooklyn, who was scalded over 80 percent of his body by the steam and had to be put in a medically induced coma, and his passenger, a 30-year-old woman, who was being driven back to Brooklyn after her car broke down. A witness reported that the tow truck was lifted 12 feet (4 m) by the escaping steam, higher than a nearby city bus. Cause The investigation report was issued on December 18, 2007. Engineers were unable to access the crater to assess the damage until the tow truck was removed on July 22, and the on-site investigation was complicated by the asbestos contamination in the crater. The official report released by the utility company on December 27, 2007, cited a combination of factors, accepting responsibility for deficient repair work done by a contractor that ultimately led to the rupture. The report said that excess sealant, previously used to repair a leaking joint, migrated to two steam trap valves used to drain excess condensed water, clogging them. Then, when heavy rains on the day of the event cooled the pipe causing excess condensate to collect in the steam pipe, the valves could not remove it. As a precaution, the utility replaced more than 1600 similar valves throughout the system, but did not find any other clogs. States of water Steam hammer was suggested as a possible cause. It is a phenomenon that can occur when cold water comes in contact with a hot steam pipe, causing the steam inside to condense into liquid water, resulting in multi-phase flow which can damage piping. Runoff from the heavy rain that day, or possibly a water main break, have been suggested as possible triggers. There was a broken water main at the bottom of the crater, near the broken steam pipe, but it is not known if this was a cause, or an effect. The utility initially reported that instrument readings did not indicate any pressure buildup prior to the explosion. They subsequently revised this assessment saying the ruptured pipe "experienced a sudden internal over-pressurization, due to water hammer, at least five times greater than normal." Cold water impinging on the cast iron pipe may have also put excess stress