# NTSB Safety Recommendation Letter P-79-029

- **operation:** document
- **citation:** P-79-029
- **title:** NTSB Safety Recommendation Letter P-79-029
- **source type:** guidance
- **agency:** National Transportation Safety Board
- **status:** guidance
- **official:** true
- **published on:** 1979-10-04
- **effective on:** 1979-10-04
- **summary:** Official NTSB transmittal letter for safety recommendation P-79-029, issued 1979-10-04.
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- **source url:** https://www.ntsb.gov/safety/safety-recs/recletters/P79_29.pdf
**body:**

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L T WASHINGTON, D.C. ISSUED: October 4 , 1979 Mr. G.H. Lawrence President American Gas Association 1515 'Wilson Boulevard Arlington, Virginia 22209 I \ SAFETY RECOMMENDAT ION (SI At 3:05 p.m., e.s.t., on May 11, 1979, two almost simultaneous explosions and an ensuing fire destroyed three buildings near the intersection of Tacony and Margaret Streets in Philadelphia, Pennsylvania. Seven persons, including a Philadelphia Gas Works (PGW) employee, were killed, 19 persons were injured, and several adjacent rowhouses were damaged. The explosions also caused a section of Margaret Street to collapse, exposing a large cavern underneath the paved surface. I/ Natural gas which had leaked from a broken, &inch, cast-iron gas main under Margaret Street had migrated through a damaged 8-inch sewer lateral and into the basement of the building where it was ignited by an undetermined source. The soil which had supported the gas main had eroded over an extended period of time and contributed to the collapse of the pipe. The prompt arrival of the gas company and the fire department at the site after the explosion and fire, and their coordinated evacuation of adjacent residences together with the expeditious "greasing off" of the gas main probably prevented secondary explosions and additional fatalities and injuries. Therefore, the National Transportation Safety Board recommends that the American Gas Association: - 1/ For more detailed information read "Pipeline Accident Report-Philadelphia Gas Works Natural Gas Pipeline Rupture, Explosion and Fire, Philadelphia, Pennsylvania, May 11, 1979" (NTSB-PAR-79-3). 2753

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-2- Advise its member companies of the circumstances of this accident and of the prompt and effective coordination between the gas company and the fire department and urge them to review their emergency practices and procedures, particularly those concerning evacuation and liaison with fire and police departments to insure that coordina- tion is planned adequately for similar accidents. (Class 11, Priority Action) (P-79-29) KING, Chairman, DRIVER, Vice Chairman, McADAMS, GOLDMAN, and BURSLEY, hlembers, concurred in this recommendation.
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