# NTSB Safety Recommendation Letter P-80-012 through P-80-013

**Citation:** P-80-012 through P-80-013  
**Type / status:** guidance / guidance  
**Agency:** National Transportation Safety Board  
**Effective:** 1980-03-05  
**Published:** 1980-03-05

Official NTSB transmittal letter for safety recommendations P-80-012 through P-80-013, issued 1980-03-05.

## Document text

Page 1
President Northwestern Public Service Company Northwestern National Bank Building Huron. South Dakota 57350 SAFETY RECOMMENDAT I ON (5) P-80-12 and -13 A t 10:25 a.m., c.d.t., on August 28, 1978, natural gas, which had escaped from a circumferential fracture in a socket heat-fusion coupling on a 2-in. polyethylene (PE) main, operating at 40-psig pressure, migrated beneath a one-story house in Grand Island, Nebraska, exploded, and then burned. One person w a s injured; the house at 2517 Apache Road was destroyed; and three adjacent houses were damaged. The gas was ignited by an unknown sowce. The 2-in. PE main was installed by a contractor for the Northwestern Public Service Company at a depth of 30 in. in a northsouth utility easement along a lot line, terminating just south of 2517 Apache Road. The main was inspected and tested on November 12, 1971. On December 6, 1971, a 4-in. acrylonitrile butadiene styrene (ABS) sewer service was installed at a depth of 52 in. perpendicular to and just beyond t h e end of the gas main and was inspected. On August 22-24, 1972, the gas main was extended 495 ft., inspected, and tested. The failed coupling was 23 in. south of the coupling used to tie in the extension. When the flexible, 2-in. PE gas main was exposed after the accident, it w a s laying on the semirigid, 4411. ABS sewer pipe at a depth of 52 in. The coupling that failed was located at a depth of 48 in. A 64-in. section of pipe, from a point 27 in. north of the sewer line to a point 37 in. south of t h e sewer line, was displaced from its original depth of 30 in. This sharp displacement, caused by the settling of improperly compacted backfill material, initiated a stress in t h e coupling which, in time, resulted in the circumferential fracture on the bottom of the coupling. The downward force which caused the displacement might have been prevented if t h e company had followed the construction procedure outlined in the Northwestern Public Service Company specifications for plastic pipe installation. Section 18, BACKFILL, of these specifications contains the following instructions: The Contractor shall make sure the line is properly supported by undisturbed earth in the trench hottoin before the back-fill operation begins. Any voids under the h e shall be filled by hand. Special care shall be taken to assure proper support at transition points from steel to plastic. Where bell-holes have been dug for any reason, the back-fill shall be compacted below the line before mechanical back-fill operation begins. 2839

Page 2
-2- Other sections of the specifications make damage t o the pipe during the construction Services Company's construction procedures we G, apparently the procedures were not followed carefully during t h e construction of the main extension in August 1972. Therefore, the National Transportatio Northwestern Public Service Company: Emphasize the enforcement of company construction procedures b project engineers and inspectors through training programs an supervisory followup. (Class 11, Priority Action) (P-80-12) Examine sample locations of utility crossings and tie-ins, and take the necessary appropriate corrective measures to insure that mains are properly supported. (Class 11, Priority Action) (P-80-13) KING, Chairman, DRIVER, Vice Chairm concurred in these recommendations. GOLDM

## Provenance

- Official: Yes
- Source: <https://www.ntsb.gov/safety/safety-recs/recletters/P80_12_13.pdf>
- Source ID: `ntsb-transmittal-letters`
- SHA-256: `b58d5288cb99adc740424c3166e414599ecc069ec9bf7bd4645955285c806491`
- Retrieved: 2026-08-20T04:55:47.446Z
- Exported: 2026-08-27T18:49:32.345Z
- Document slug: `ntsb-transmittal-letter-p80-12-13`

### Source metadata

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  "caveat": "An NTSB safety recommendation is advisory and does not itself create a binding regulatory requirement.",
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}
```