Berthoud, CO – Investigations into the cause of an explosion that occurred at a Berthoud business earlier in the month have been completed and initial suspicions that suggested a natural gas leak as the cause have been verified.

According to a press release from the Berthoud Fire Protection District, investigators determined that the explosion that occurred at the Rainbow Auto Sales car lot on December 3 was accidental in nature, caused by an unspecified gas leak in a service line that ran through the property.

At approximately 9:38 a.m., on Sunday, December 3, an explosion completely destroyed the modular home that served as the office of Rainbow Auto Sales. A neighboring house also sustained damage in the explosion, losing several windows.

Because of a Colorado State law that prohibits the sale of motor vehicles on a Sunday, no one was in the building or on the lot at the time of the explosion.

An initial investigation following the explosion suggested that the service line, which ran directly beneath the modular structure and served the residential home on the south side of the property, was the source of the leak. The modular building, which used electricity for heat, was not connected to the gas line.

Before investigators could locate the exact location of the leak, a concrete pad, which served as the foundation for the modular structure, needed to be removed. Upon removal of the pad, investigators from Excel Energy and an independent engineering firm were able to specifically locate the leak.

It is believed that the leak stems from damage to the line caused when an electrical contractor had dug a trench earlier in the year. The matter has been turned over to the contractor’s insurance carrier for resolution.

For 19 years, Rainbow Auto Sales was located out on the old Hwy. 287 north of Berthoud before re-opening at the new location just west of Kwik Korner at the intersection of the new highway and Hwy. 56 the Monday prior to the explosion.

With transactions still pending from the first week of sales, Rainbow Auto Sales was open for business the day following the explosion, with employees working out of a makeshift office in a camper trailer.

Although none of the vehicles on the lot were damaged in the explosion, records and office equipment were completely obliterated.

Among other things lost, owner Dennis Henneberg says he kept a lot of collectible items in his office—Denver Bronco memorabilia that had been autographed by John Elway, photographs of his son-in-law who races stock cars, and family photographs.