Fire Department releases final investigation report of American Fork home explosion

SALT LAKE CITY — The American Fork Fire Department released the final investigation report from a March 20 home explosion on Tuesday.

The explosion and ensuing fatality were classified as unintentional. But investigators noted that the explosion was preventable, according to the report.

Related: Video: Explosion at American Fork House

Service preceded the blast

Officials said an American Fork fire investigator was called to the scene and arrived at about 7:20 a.m. At that point, the occupant in the northern half of the duplex was found deceased. She was later identified as 78-year-old Kathy Harrison.

The investigation found that Dominion Energy workers were at the home a day before the explosion. They were conducting a “hot change” service on one of the home’s natural gas valves. The process allows uninterrupted natural gas service while workers change service valves.

A Dominion Energy employee said a fellow employee entered the home to use the restroom, the investigation found. During that time, the employee allegedly smelled natural gas and investigated with an explosive gas detector.

The final investigation report found that the detector did not sense any explosive gasses.

No pressurization check completed

A pressurization check was not completed on the service lines after the Dominion Energy workers finished their servicing. The report concluded that such a check could have detected a leak in the system.

Later on in the report, it was noted that a detective with American Fork police received information from a subpoena request filed against Dominion Energy. According to that information, an increase in natural gas usage was found at the explosion site.

This increase in usage occurred from the time Dominion Energy workers were at the house until the explosion the next morning, between 14 and 15 hours later.

Supply valve opened by a subcontractor

The investigation found that a supply valve at the home was opened by a subcontractor employed by Dominion Energy, who was servicing the line. After that line was opened, natural gas began to flow into the home, reaching an air concentration that could cause an explosion.

At roughly 6:00 a.m., on March 20, the home’s furnace switched on. This ignited the gas and caused an explosion that destroyed the building. It also killed Kathy Harrison, and injured one other person.

The report included recommendations to prevent further incidents, including alternative forms of leak testing. While Dominion Energy workers did walk through the area with a gas detector, other leak testing was not done on the system.

Finally, the report suggested capping outlets that aren’t connected to appliances using a threaded plug or cap. The report states that this type of leak prevention should have been done to comply with code requirements.