# NTSB Safety Recommendation P-70-034 **Citation:** P-70-034 **Type / status:** guidance / guidance **Agency:** National Transportation Safety Board **Effective:** 1970-10-14 **Published:** 1970-10-14 THE NTSB RECOMMENDS THAT ALL STATES, THE DISTRICT OF COLUMBIA, AND PUERTO RICO TAKE THE FOLLOWING ACTION: ENCOURAGE UTILITIES HAVING UNDERGROUND FACILITIES IN THE SAME AREA SUCH AS GAS, ELECTRIC, AND TELEPHONE, ETC., TO ESTABLISH A COORDINATED NOTIFICATION FACILITY, WHERE PRACTICABLE, SO THAT A PERSON PLANNING TO EXCAVATE OR BLAST CAN INFORM ALL UTILITIES BY MAKING ONE TELEPHONE CALL. ## Document text NTSB safety recommendation P-70-034. THE NTSB RECOMMENDS THAT ALL STATES, THE DISTRICT OF COLUMBIA, AND PUERTO RICO TAKE THE FOLLOWING ACTION: ENCOURAGE UTILITIES HAVING UNDERGROUND FACILITIES IN THE SAME AREA SUCH AS GAS, ELECTRIC, AND TELEPHONE, ETC., TO ESTABLISH A COORDINATED NOTIFICATION FACILITY, WHERE PRACTICABLE, SO THAT A PERSON PLANNING TO EXCAVATE OR BLAST CAN INFORM ALL UTILITIES BY MAKING ONE TELEPHONE CALL. Priority: CLASS II Overall Status: Closed--No Longer Applicable Issued Date: 1970-10-14 Adopted Date: 1970-10-14 Overall Date Closed: 1976-07-20 Synopsis: ON NOVEMBER 6, 1969, DURING A HIGHWAY CONSTRUCTION PROJECT IN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 Wyoming Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of West Virginia Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Washington Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: Commonwealth of Virginia Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Vermont Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Utah Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Texas Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Tennessee Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of South Dakota Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of South Carolina Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Rhode Island Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: Commonwealth of Pennsylvania Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Oregon Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Oklahoma Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Ohio Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of North Dakota Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of North Carolina Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of New York Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of New Mexico Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of New Jersey Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of New Hampshire Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Nevada Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Nebraska Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Montana Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Missouri Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Mississippi Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Minnesota Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Michigan Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: Commonwealth of Massachusetts Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Maryland Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Maine Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Louisiana Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: Commonwealth of Kentucky Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Kansas Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Iowa Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Indiana Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Illinois Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Idaho Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Hawaii Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Georgia Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Florida Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Delaware Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Connecticut Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Colorado Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of California Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Arkansas Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Arizona Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Alaska Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: State of Alabama Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: Commonwealth of Puerto Rico Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 Addressee Name: District of Columbia Addressee Status: Closed--No Longer Applicable Addressee Date Closed: 1976-07-20 ## Provenance - Official: Yes - Source: - Source ID: `ntsb-pipeline` - SHA-256: `a12d4cfc1d47c3081218e0bc3bbf832001f1d058e12da9fdcf3f94262bc41e35` - Retrieved: 2026-08-20T04:57:24.741Z - Exported: 2026-08-22T21:30:14.041Z - Document slug: `ntsb-recommendation-p-70-034` ### Source metadata ```json { "recordKind": "ntsb_safety_recommendation", "safetyRecommendationNumber": "P-70-034", "recommendationMode": "Pipeline", "topicMode": "Pipeline", "ntsbNumber": "DCA70MP001", "priority": "CLASS II", "overallStatus": "Closed--No Longer Applicable", "overallStatusAcronym": "CNLA", "overallDateClosed": "1976-07-20", "lastModifiedDate": "2016-11-15", "reportNumber": "PAR-70-01", "reportUrl": "https://www.ntsb.gov/investigations/Pages/DCA70MP001.aspx", "transmittalLetterUrl": "http://www.ntsb.gov/safety/safety-recs/recletters/P70_29_42.pdf", "addressees": [ { "addresseeName": "State of Wyoming", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", "addresseeDateClosed": 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"Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] }, { "addresseeName": "State of New York", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] }, { "addresseeName": "State of New Mexico", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] }, { "addresseeName": "State of New Jersey", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] }, { "addresseeName": "State of New Hampshire", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] }, { "addresseeName": "State of Nevada", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", 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"Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] }, { "addresseeName": "State of Hawaii", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] }, { "addresseeName": "State of Georgia", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] }, { "addresseeName": "State of Florida", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] }, { "addresseeName": "State of Delaware", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] }, { "addresseeName": "State of Connecticut", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] }, { "addresseeName": "State of Colorado", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] }, { "addresseeName": "State of California", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] }, { "addresseeName": "State of Arkansas", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] }, { "addresseeName": "State of Arizona", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] }, { "addresseeName": "State of Alaska", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] }, { "addresseeName": "State of Alabama", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] }, { "addresseeName": "Commonwealth of Puerto Rico", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] }, { "addresseeName": "District of Columbia", "addresseeStatusAcronym": "CNLA", "addresseeStatus": "Closed--No Longer Applicable", "addresseeDateClosed": "1976-07-20", "addresseeDetails": [] } ], "jurisdiction": "US" } ```