Johann F. Szautner, PE, Civil Engineering Consultant ::::
The Accident: A municipality in Pennsylvania hired a contractor to install a concrete sidewalk, a concrete curb, and to replace stormwater collection inlets in and along an existing paved municipal street. Prior to commencing construction, the contractor made the required PA-1 call to ascertain the location of underground utility lines within the excavation limits. A storm sewer pipe running along the edge of the pavement, and a gas service line crossing it were located and marked properly. As the backhoe operator peeled off a portion of the pavement, the spotter, who walked alongside the backhoe, saw the yellow gas line, and yelled a stop command to the operator. The explosion occurred immediately, where the gas line entered the building, destroying the building, which was unoccupied at the time. Thankfully, only property damages resulted from this accident.
The Regulations and Best Practices:
Code of Federal Regulations, 49CFR192.361 requires that a gas service provider install a service line with at least 18 inches of cover in a public right-of-way, and with at least 12 inches of cover on private property. However, where an underground structure prevents installation at those depths, the service line must be able to withstand any anticipated load.
PA Underground Utility Protection Act 121, P.L.852, No.287 requires that contractors use prudent techniques, including hand digging or vacuum extraction to determine the exact location of a marked facility within the tolerance zone.
CGA Common Ground Alliance Best Practices were issued by a USDOT task force to provide a construction guide for the prevention of underground utility damage. This guide stipulates that hand digging and non-evasive methods are not required for pavement removal.
The Investigation: During the investigation, it was found that the gas distribution line was at a depth of 6 feet, and the service line rose from this depth to within 7 inches of the pavement surface near the right-of way line. The top of it was partially encased by the pavement. The subject gas service line was installed in the early seventies, to replace the original but corroded service line. The replacement service line was raised to this height to cross over a 24-inch diameter storm sewer pipe, which was installed by the municipality over the original gas line. However, the replacement service line could have been easily installed by laying it under the storm water pipe, or alternatively by protecting it from displacement with a concrete encasement.
It is not uncommon that gas pipes are not in marked locations, and the contractor who contractually assumes the risks associated with excavating a gas line, must always proceed with due care assessing foreseeable risks. But what if a gas line is installed negligently, and in violation of pertinent regulations? Is this a situation a reasonable contractor can foresee and therefore should be held liable? Or is it a situation where the utility owner knew or should have known about the faulty installation and then be jointly liable for damages?
The Outcome: The litigation was resolved by a jury trial finding the contractor 100% liable.
Johann F. Szautner, PE is a Civil Engineering Consultant with DJS Associates and can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.