Excavation Safety First: Top 5 Digging Disasters
Most digging disasters are the result of inadequate assessment of existing underground utilities. It is, therefore, essential that contractors contact the relevant authorities before commencing digging operations.
According to a press release from the Common Ground Alliance (CGA), based on the findings of its Damage Information Reporting Tool (DIRT) Report, there were over 509,000 reported cases of excavated-related damages to underground utilities in 2018. This figure represents a 16% increase over the number of damaged utilities in 2017.
These staggering statistics highlight the need for proper safety measures during trenchless drilling and open-cut excavations. In this article, we will highlight some of the most catastrophic digging disasters to occur in the last two decades.
Kansas City, Kansas — February 19, 2013
On February 19, 2013, a gas pipeline explosion leveled a restaurant building at 910 W 48th St. on the western side of the Country Club Plaza. The incident resulted in the death of one of the restaurant’s employees and injured 15 other people.
An investigation into the explosion determined that it was the direct result of trenchless drilling and installation activities at a nearby construction site. At the time, a contractor for the Time Warner Cable Company was allegedly in the process of installing telecommunications fiber optic cables using horizontal directional drilling (HDD). (Read What is Horizontal Directional Drilling?)
During the installation, which took place across the street from the building, the drill struck a 2-inch diameter polyethylene (PE) gas main along the north side of W 48th St.. The natural gas escaped the main and migrated through the backfill beneath the asphalt roadway into nearby sanitary sewer piping. The escaped gas then accumulated in the restaurant where it ignited and exploded.
The restaurant and building owner successfully sued the Time Warner Company for negligence for a total of $5.9 million in damages.
Bergenfield, New Jersey — December 13, 2005
A gas explosion in an apartment in Bergenfield, New Jersey, occurred after natural gas migrated into the structure following damage to a nearby pipeline. The incident transpired on December 13, 2005, during the removal of an underground oil tank at a nearby parking lot located adjacent to the building.
During tank removal operations, a break in an underground 1¼-inch steel natural gas line was discovered. The break occurred at a threaded tee section, downstream from where excavators were in the process of removing the oil tank.
Natural gas migrated into the building and ignited, causing a devastating explosion, which resulted in the deaths of three apartment residents. Four residents and a tank removal worker were also injured during the incident. According to Bergen Country tax records, the total damage to the building was assessed to be $863,300 USD.
A post-incident analysis conducted by the National Transportation Safety Board determined that the main cause of the rupture of the gas pipeline was negligence by the American Tank Service Company. The company had failed to adequately support the natural gas line from soil movement (shifting) during excavation.
As a result, the pipeline experienced excessive deflection, causing it to burst and release gas into the apartment building.
Murrieta, California — July 15, 2019
Another gas pipeline explosion resulted in the death of one person and injured 15 more. This particular incident occurred at a house in Murrieta, California, on July 15, 2019. According to reports, a contractor conducting home improvement on the home struck the natural gas line and subsequently reported the incident to the Southern California Gas Company (SoCalGas).
Personnel from SoCalGas arrived on the scene shortly before 11am to repair the broken line. Just over an hour later (12:10am), the explosion occurred. An employee of the gas company perished, while the injured 15 were transported to hospital and treated for their injuries.
Investigations into the cause of the explosion determined that the contractor did not contact the designated authorities to determine the location of existing buried utilities in the area as required by law.
McKinney, Texas — May 16, 2008
On May 16, 2008, near Hwy. 5 in McKinney, Texas, two houses exploded when a construction crew accidentally struck a gas line in the neighborhood. According to McKinney Fire Chief Mark Wallace, a construction crew was working at a nearby street when they hit an underground gas line at approximately 5:30pm.
Six minutes later, the gas seeped into and ignited in nearby homes, causing two of them to explode. A third home also caught fire during the incident. Fortunately, no one was killed in the explosion; however, three people were critically injured and had to be airlifted to local hospitals for emergency treatment.
The injuries sustained during this incident were also attributed to the inadequate response of emergency personnel. According to reports, more than an hour after the gas leakage, none of the homeowners were informed of the leak, nor were any of them evacuated from their homes.
Portland, Oregon — October 19, 2016
On October 19, 2016, a large explosion occurred in the Northwest District neighborhood of Portland, Oregon, at NW 23rd Ave. and NW Glisan Street. During the installation of a junction box in a sidewalk for Comcast, an excavator made contact with a buried gas pipeline. While the pipe did not break, it was pulled out from a valve located downstream.
This resulted in a massive leak, which caused the gas to travel under the sidewalk, and into the basement of Alfred C. F. Burkhardt House located at 500 NW 23rd Ave.. The gas ignited, totally destroying the building and causing considerable damage to surrounding structures.
While there were no fatalities, the explosion injured eight people and damaged a total of 13 buildings. An investigation conducted by the Oregon Public Utility Commission concluded that the accident was due to insufficient notice to the Utility Notification Center by the contractor.
Up to 2019, lawsuits were still being filed against the contractor as a result of the incident.
While these disasters had different outcomes, they all have one element in common; in each case, the digging contractor failed to properly assess the presence of existing utilities in the area. In the United States, federal law requires that all organizations contact their local One-Call organization (811) before performing any excavations.
One-call will then confirm the presence of utilities in the area either by contacting the relevant utility companies or by going out into the field and physically determining the location of the buried infrastructure.