NTSB Safety Recommendation P-70-029

NTSB safety recommendation P-70-029.

THE NTSB RECOMMENDS THAT THE OFFICE OF PIPELINE SAFETY OF THE DEPARTMENT OF TRANSPORTATION TAKE THE FOLLOWING ACTIONS: REQUIRE IN THE MINIMUM FEDERAL SAFETY STANDARDS THAT EACH GAS UTILITY ESTABLISH A PROGRAM FOR THE PREVENTION OF CONSTRUCTION-ORIGINATED DAMAGE TO ITS UNDERGROUND FACILITIES. THIS PROGRAM SHOULD CONTAIN PROVISIONS: (1) FOR EDUCATION AND GENERAL LIAISON WITH CONTRACTORS AND THEIR MACHINE OPERATORS; (2) FOR OBTAINING NOTICES OF CONSTRUCTION WORK IN CLOSE PROXIMITY TO UNDERGROUND GAS FACILITIES; (3) TO INSURE THAT GAS FACILITIES ARE MARKED OR OTHERWISE PROTECTED DURING SUCH CONSTRUCTION WORK; AND (4) TO FOLLOWUP AND INVESTIGATE ACCIDENTS WHICH DO OCCUR, TO DETERMINE WHERE THE PROGRAM FAILED AND HOW IT CAN BE STRENGTHENED.

Priority: CLASS II

Overall Status: Closed--No Longer Applicable

Issued Date: 1970-10-14

Adopted Date: 1970-10-14

Overall Date Closed: 1976-09-10

Synopsis: ON NOVEMBER 6, 1969, DURING A HIGHWAY CONSTRUCTION PROJECT IN BURLINGTON, IOWA, A BULLDOZER WEIGHING 70,000 POUNDS DROVE OVER AND PARTIALLY COLLAPSED THE STEEL COVERS OF A GAS REGULATOR PIT, DAMAGING THE REGULATOR. WHILE THE PRESSURE WAS PARTIALLY CONTROLLED BY A MONITORING OR SAFETY REGULATOR, GAS, REPORTEDLY AT FOUR TO FIVE TIMES THE NORMAL OPERATING PRESSURE, ENTERED THE DISTRIBUTION SYSTEM. GAS CUSTOMERS IN THE AFFECTED AREA STARTED REPORTING HIGH GAS PILOTS AND FIRES TO ISU AND THE FIRE DEPARTMENT. THE HIGH-PRESSURE GAS SOURCE WAS TURNED OFF BUT FIRES CONTINUED TO BE REPORTED, THE FIRES WROUGHT MAJOR DAMAGE TO THE INTERIORS OF 10 HOUSES AND MINOR DAMAGE TO KITCHENS AND APPLIANCES IN 42 OTHERS. PROPERTY DAMAGE WAS ESTIMATED AT $80,000.

Probable Cause: The probable cause of the fires in the houses was the continued overpressure condition of the low-pressure distributions system for an extended period of time, which allowed pressure to build up until high gas flames ignited nearby objects. The initiation of the overpressure was caused by a bulldozer which damaged the largest primary working regulator which, with other regulators, controlled the gas pressure entering the low-pressure systems; and by inadequate performance of the monitoring regulator which failed to operate to limit the gas pressure to a safe level.

Keywords: Excavation, Training and Education

Ntsbnumber: DCA70MP001

Report Number: PAR-70-01

Addressee Name: RSPA

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1976-09-10

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1971-07-17

Communication Type: Official Correspondence