Investigators have discovered a "break" in UGI Corp.'s underground natural gas pipeline that is the "likely source" of the gas involved in last Wednesday's explosion in Allentown, PA, which killed five people.

More information is trickling out as teams of UGI and Pennsylvania Public Utility Commission investigators have been working at the site of the Allen Street explosion. Over the weekend a videoscope was inserted into the gas main on Allen Street between 13th and Mercer streets.

"The main has been shut down since the Feb. 9 explosion and has been the focus of our investigation into the cause of the incident," said UGI Utilities CEO John Walsh. "The video inspection revealed a section of pipeline which appears to have been damaged."

Crews exposed the damaged section of the 12-inch gas distribution line and conducted a visual inspection, which revealed a break "that we believe to be the likely source of the gas involved in this incident," he said. "We have shared this information with the Pennsylvania Public Utility Commission as part of our investigation plan, as well as with the Allentown Fire Department and mayor's office."

The section of damaged pipe was to be shipped to an independent lab, Affiliated Engineering Laboratory in Edison, NJ, for forensic examination and testing. Soil tests will also be conducted on samples taken at the site to determine whether soil conditions played a role in the incident, UGI said.

"Our work on the site continues," Walsh said. "However, in the meantime, residents and businesses in the affected area can be confident that it is safe. Our technicians have surveyed every foot of pipeline in the neighborhood, and crews remain on-site 24/7 to continuously survey the six-block affected area every 45 minutes."

Five people were killed last Wednesday in the explosion of the underground gas line (see Daily GPI, Feb. 14; Feb. 11). Allentown Police Chief Roger MacLean said the epicenter of the explosion was at the home of Beatrice Hall, 74, and her husband, William, 79, who were killed. A four-month-old boy, a 16-year-old girl and a 69-year-old woman also were killed on the block where the explosion occurred.

A fire following the explosion affected 47 properties, including 10 businesses, and forced more than 750 people to evacuate over a three-block area.

The tragedy, coupled with the San Bruno, CA, pipe explosion last September, has moved Congress to take a look at new pipeline safety standards. A bill might get out of the Senate by this spring (see related story).

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