in the process. When the pipe had been installed, it was tightly bent, adding to its stress levels. The addition of the water main caused it to break. The explosive gas reached the shop basement by migrating around and over pipes, causing the foul odor. However, gas company technicians were unable to detect the gas before the blast. Investigators discovered that holes used to detect gas below ground were only deep when the gas was about down; therefore, there was no way that the gas could be detected in this manner. Perhaps the most crucial error in detection occurred when a technician turned on his equipment while in the building rather than in fresh air as required, causing a failure to detect gas. The ignition source was found to be an air-conditioning switch with heated wiring. The San Juan Gas Company vehemently denied responsibility and suggested that the blast could have been caused by sewer gas. However, the lighter-than-air sewer gas collects in the ceiling, while propane collects on the floor. The investigation showed that stored shoes were tossed up by the explosion, meaning that the fuel had to be at ground level. An upward-bent beam was also crucial to determining that the blast had come from below. Aftermath The San Juan Gas Company was sued by the victims' families and owners of the businesses affected. There were a total of 1,500 lawsuits presented. Through the process, the company admitted no wrongdoing. Of all the lawsuits, 725 were settled out of court, while 101 were ruled against the company. The remaining lawsuits were settled in 2002 for $28 million. There was also criticism of the company's training practices, which management promised to rectify. According to a city resolution, all underground gas lines in Río Piedras were removed to avoid further tragedies. The area of the explosion now has a mural in remembrance of those who died. Dramatization The disaster was examined in the "Puerto Rico Gas Explosion" episode of the documentary series Seconds From Disaster on the National Geographic Channel. See also List of explosions Dupont Plaza Hotel arson, a New Year's Eve fire in Puerto Rico 2009 Cataño oil refinery fire, an oil refinery explosion and fire in Puerto Rico Morris J. Berman oil spill, an oil spill on the north coast of Puerto Rico Notes References Seconds From Disaster: "Puerto Rico Gas Explosion" (December 13, 2005; Season 2,