# NTSB Safety Recommendation P-77-003

- **operation:** document
- **citation:** P-77-003
- **title:** NTSB Safety Recommendation P-77-003
- **source type:** guidance
- **agency:** National Transportation Safety Board
- **status:** guidance
- **official:** true
- **published on:** 1977-06-08
- **effective on:** 1977-06-08
- **summary:** EXPEDITE, IN CONJUNCTION WITH EQUIPMENT MANUFACTURERS, THE DEVELOPMENT OF A SURVEY UNIT THAT COULD BE USED TO DETECT THE LOCATION OF SINKHOLES IN THE VICINITY OF CAST-IRON GAS MAINS. "DOWNWARD-LOOKING" RADAR EQUIPMENT SHOULD BE INVESTIGATED AS ONE POSSIBLE MEANS OF SURVEYING FOR SINKHOLES.
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- **source url:** https://data.ntsb.gov/carol-main-public/sr-details/P-77-003
**body:**

NTSB safety recommendation P-77-003.

EXPEDITE, IN CONJUNCTION WITH EQUIPMENT MANUFACTURERS, THE DEVELOPMENT OF A SURVEY UNIT THAT COULD BE USED TO DETECT THE LOCATION OF SINKHOLES IN THE VICINITY OF CAST-IRON GAS MAINS. "DOWNWARD-LOOKING" RADAR EQUIPMENT SHOULD BE INVESTIGATED AS ONE POSSIBLE MEANS OF SURVEYING FOR SINKHOLES.

Priority: CLASS III

Overall Status: Closed - Reconsidered

Issued Date: 1977-06-08

Adopted Date: 1977-05-18

Overall Date Closed: 1985-07-01

Synopsis: ON AUGUST 8, 1976, A GAS EXPLOSION DESTROYED A HOUSE AT 1127 OAK STREET, ALLENTOWN, PENNSYLVANIA. THE GAS MIGRATED FROM A BREAK IN A 4-INCH CAST-IRON MAIN UNDER THE STREET, THROUGH LOOSE SOIL UNDER A CONCRETE SIDEWALK, AND INTO THE BUILDING THROUGH CRACKS AND OPENINGS IN ITS FOUNDATION.

Ntsbnumber: DCA76MP024

Report Number: PAR-77-02

Addressee Name: UGI Corporation

Addressee Status: Closed - Reconsidered

Addressee Date Closed: 1985-07-01

Addressee Organization Type: P-Private Industry

Communication Date: 1977-12-22

Communication Type: Official Correspondence

Communication Contents: UGI CORPORATION LTR: UGI STATES THAT THEY HAVE CONCLUDED: "DOWNWARD-LOOKING" RADAR IS TOO RESTRICTED AS TO DEPTH; GROUND PENETRATING RADAR IS ADVERSELY AFFECTED BY REINFORCED CONCRETE, WATER AND OTHER URBAN AREA PROBLEMS; OTHER METHODS CANNOT BE APPLIED TO URBAN AREA WORK; THE BUREAU OF MINES IS WORKING ON SEISMIC REFLECTION AND MICROWAVE DETECTION BUT ARE TOO EARLY IN DEVELOPMENT TO BE CONSIDERED. THE ONLY PROBABLE METHOD IS SEISMIC DETECTION AND THIS IS COSTLY AND MAY CAUSE MORE PROBLEMS THAN IT WILL SOLVE. UGI WOULD LIKE NTSB TO RECONSIDER THIS RECOMMENDATION.

Addressee Organization Type: P-Private Industry

Communication Date: 1985-07-01

Communication Type: Official Correspondence
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