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ABOUT 6:45 P.M. ON 6/9/94, A 2-INCH-DIAMETER STEEL GAS SERVICE LINE THAT HAD BEEN EXPOSED DURING EXCAVATION SEPARATED AT A COMPRESSION COUPLING ABOUT 5 FEET FROM THE NORTH WALL OF JOHN T. GROSS TOWERS, AN EIGHT-STORY RETIREMENT HOME OPERATED BY THE ALLENTOWN HOUSING AUTHORITY AT ALLENTOWN, PENNSYLVANIA. THE FAILED UGI UTILITIES, INC,. (UGI) SERVICE LINE RELEASED NATAURAL GAS AT 55 PSIG PRESSURE, & THE ESCAPING GAS FLOWED UNDERGROUND TO GROSS TOWERS. THE GAS PASSED THROUGH OPENINGS IN THE BUILDING FOUNDATION, ENTERED THE MECHANICAL ROOM THROUGH FLOOR VENTS, & MIGRATED TO OTHER BUILDING FLOORS.
THE NTSB RECOMMENDS THAT THE UGII UTILITIES, INC.: MODIFY ITS EXCAVATION-DAMAGE PREVENTION PROGRAM TO INCLUDE THE REVIEW & CLOSE MONITORING OF ANY PROPOSED EXCAVATION NEAR A GAS SERVICE LINE, INCLUDING ANY LINE WITH UNANCHORED COMPRESSION COUPLINGS, THAT IS INSTALLED NEAR A BUILDING & THAT, IF DAMAGED, MIGHT ENDANGER PUBLIC SAFETY SIGNIFICANTLY.
Original recommendation transmittal letter:
Closed - Acceptable Action
Allentown, PA, United States
UGI Utilities, Inc., Natural Gas Distribution Pipeline Explosion and Fire
Addressee(s) and Addressee Status:
UGI Corporation (Closed - Acceptable Action)
Safety Recommendation History
The Safety Board understands that UGI procedures include consideration for close monitoring of services as well as gas mains when excavation projects are in close proximity to the company's gas facilities. On large construction projects, or projects in close proximity to UGI gas facilities, a "locate person/inspector" may be assigned to that specific project for the duration of the construction. In addition, UGI has further modified its procedures to clarify the criteria used to determine the need to revisit or inspect. Because UGI has taken the requested action, Safety Recommendation P-96-5 is classified "Closed--Acceptable Action."
Letter Mail Controlled 06/06/2001 1:18:34 PM MC# 2010462 For quite some time UGI procedures have included consideration for close monitoring of services as well as mains when excavation projects are in close proximity to our gas "facilities." This was evident in our System Surveillance Plan procedures at the time of the Gross Towers incident as stated in Section 4.0, paragraph C.4.b: On large construction projects, or projects in close proximity to our gas facilities, a locateperson/inspector may be assigned to that specific project for the duration of the construction. We have since modified our procedures to provide more clarity in the criteria used to determine the need to revisit or inspect. Paragraph C.4.b & e. now provides as follows: b) Visiting Job Sites of Outside Contractors: The locateperson/inspector should randomly visit contractor crews working in the Area to review contractor work practices regarding proper care and concern for our gas facilities. The leadsperson/inspector will consider revisiting sites as long as any of the below criteria are ongoing. Note: These contractor revisits can be scheduled using our work order system. (1) Type and Duration. Major construction projects, i.e., shopping centers, industrial parks, large building construction in high-density areas, municipal water main and sewer replacement projects that are adjacent to our gas facilities. Job duration of greater than 3-5 days. (2) Proximity of Gas Facilities. If a gas main or service is located within 1:1 slope of the area known to be excavated. (3) Type of Equipment. Large excavation equipment (three foot bucket), directional boring equipment, hoe rams or hydra hammer types of equipment, utilized in the vicinity of piping known to be susceptible to damage. (ex.cast iron piping). (4) Importance of Our Facilities. Work being performed near any medium pressures main feed distribution piping, any medium pressure plastic mains, or major feed line in our system. Service lines entering facilities 2" in diameter or greater. (5) Areas of Work. Excavation work being done near schools, hopsitals, high rise apartment buildings, industrial sites, or where building density is a factor. (6) Past Experience "/Excavator. We should regularly visit with contractors who have frequently hit our facilities in the past. Each Area has a list of these "problem" excavators. This information can be obtained from the Substructure Damage Program coordinator via each Area Construction and Maintenance (C&M) Superintendent. Copies of One Call (Act 187) Books should be handed out to new and/or problem contractors. On large construction projects, or projects in close proximity to our gas facilities, a locateperson/inspector may be assigned to that specific project for the duration of the construction. While at the construction site, the Locateperson/Inspector shall: (1) Monitor the contractor's compliance with the following requirements regarding the proper support and protection of our gas facilities: (a) MSP Std.2.2.5 - Supports and Anchors, (b) MSP Std 4.2.3 - Supports of Small Diameter Gas Facilities Across Sewer Trenches, (c) MSP Std. 5.3.7 - Clearance from Underground Structures - Use of Lily Pads and (d) Title 25 - Department of Environmental Resources, paragraph 211.52 - Blasting in the Vicinity of Utility Lines. (2) Inspect any previous markings of gas facilities, making sure they are adequate, and locate any other facilities, which have not been marked. (3) Make sure a copy of the preconstruction handout is at the jobsite. (See Figure C.2-1) (4) Observe the general conduct and concern shown by the contractor's personnel working near lines which have been previously marked. (5) Watch for the use of hydrahammers near service lines, cast iron or screw-coupled mains. (6) Make note of all visits to job sites in his "Locate Log Book," as described in Part a) (3) of this section. (7) If a contractor is found to be operating in a manner inconsistent with UGI policies, the Locateperson/Inspector must follow the procedure described in Part B.8. - "Unsafe Practice Violations by Outside Contractors. UGI does not consider it appropriate to establish specific monitoring parameters for underground compression fittings. Such fittings, connecting metallic underground piping, are considered restrained and anchored. In any event, excavation sites where compression fittings could possibly fail are already included as sites that we would revisit to inspect in accordance with our current System Surveillance Plan.
The Safety Board has not received a response to any of these three recommendations, and we would appreciate learning what action has been taken, or is planned, to implement Safety Recommendations P?96-4 though -6. Please address your response to Ms. Carol J. Carmody, Acting Chairman, citing the recommendation numbers above. A copy of the recommendation letter is enclosed for your reference.
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