Guidanceguidance
P-70-042
NTSB Safety Recommendation P-70-042
Current as of 1970-10-14 Government source
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NTSB safety recommendation P-70-042.
THE NTSB RECOMMENDS THAT THE IOWA STATE HIGHWAY COMMISSION TAKE THE FOLLOWING ACTION: PROVIDE COPIES OF THE FINAL CONSTRUCTION PLANS AND SPECIFICATIONS TO ALL PARTIES INVOLVED IN THE PROJECT, SUCH AS GAS AND OTHER UTILITIES, AND CITY OFFICIALS.
Priority: CLASS II
Overall Status: Closed - Acceptable Action
Issued Date: 1970-10-14
Adopted Date: 1970-10-14
Overall Date Closed: 1976-07-20
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.
Ntsbnumber: DCA70MP001
Report Number: PAR-70-01
Addressee Name: State of Iowa, Highway Commission
Addressee Status: Closed--No Longer Applicable
Addressee Date Closed: 1976-07-20
Addressee Organization Type: S-State Government
Communication Date: 1970-12-21
Communication Type: Official Correspondence
Communication Contents: LETTER FROM THE DIRECTOR OF THE IOWA STATE HIGHWAY COMMISSION: THE RECOMMENDATION HAD ALREADY BEEN IMPLEMENTED.
This material provides agency context. It does not replace binding regulatory text, and its legal effect depends on the underlying authority and facts.