The cause of the explosion at the Voluntary Purchasing Group plant in Bonham was undetermined after a State Fire Marshal’s Office investigation into the Aug. 8 incident, however, a recently released report indicates possible contributing factors to the explosion.

The investigation report from the State Fire Marshal’s Office, which the Herald Democrat obtained Friday, states the point of origin of this explosion was inside a tank that was being filled with the liquid chemical Triclopyr 3. The ignition source, ignition sequence and first material ignited could not be determined, according to Investigator Chuck Allen in the report.

“The determination regarding causation is based on a methodical search of the area, observation of structural damage to building and tank, evidence observed at the scene, and statements of eyewitnesses,” Allen says in the report. “Based on this information, it is my opinion that this explosion shall be classified as undetermined.”

The report listed four factors that could have contributed the the explosion: The truck and trailer offloading the chemical was not grounded, which was required for the process; the intermodal tank was improperly vented during the unloading process; a centrifugal pump was used that was not made to handle flammable materials as per the manufacturer’s instructions; a sensor system was used, which its paperwork stated should not be used in hazardous environments.

VPG officials did not return a phone call seeking comment Friday afternoon.

At about 7:25 a.m. Aug. 8, the Fannin County Sheriff’s Office received multiple calls reporting an explosion at the plant located on FM 87 near State Highway 56, west of Bonham. The Bonham Fire Department responded and a large hole was found in the roof of a building at the VPG complex, which the report stated the commercial building is single story with a three-layer metal roof. In previous reports, VPG officials said it was a bulk tank storage facility.

Bonham firefighters entered the building and found no one inside and no signs of fire. The report noted that the structure had a fire alarm system, sprinkler system and heat detectors, and the sprinkler system activated from the explosion. Two minor injures were reported in connection to the incident; one person was transported to hospital and another visited a local doctor. The report stated the person transported said it was due to a blood pressure issue resulting from the traumatic experience.

VPG manufactures and processes chemicals used in herbicides and fertilizers. In the report, the investigator outlined the damage to the facility and identified the tank where the explosion occurred was being filled with Triclopyr 3 from the intermodal tank outside. The tank ruptured about half way up and it was opened outward. No evidence of fire was discovered in the area, the report stated.

In interviews with people at the scene, the report stated the driver of the tuck with the intermodal tank trailer arrived at the facility at about 7 a.m. to offload the the chemical. The investigator did not observe any visible grounding connections between the the trailer and facility. VPG policies and procedures indicated the truck must be grounded before offloading chemicals, according to the report. About 2,956 gallons of the chemical was offloaded into the tank inside the building before the explosion.

Several witness reported to the investigator of hearing two explosions, and a few employees reported they were knocked off their feet. From the employee interviews, the investigator found that the Triclopyr 3 pump used to offload the chemical was recently replaced. It was the second time that pump was used, according to the report. The manual and the pump itself had a warnings listed that it was not to be used with flammable liquids. The warning also stated that doing so could result in an explosion. The report noted that Triclopyr 3 is considered a flammable liquid.

The report also noted that the sensor, which measures the amount of liquid in the storage tank, should not be used in hazardous environments.

On Sept, 8, 2016, a month after the explosion, a second explosion occurred in a separate part of the VPG plant. Officials with the Texas Commission of Environmental Quality reported the incident was a flash fire that was sparked from mixing two dry chemicals in a hopper. The incident injured two employees who suffered burns to their hands, arms, chests and faces. VPG officials previously said the employees were cleaning the equipment when the incident occurred.

VPG President/CEO Steve Money previously said that after the first explosion, they hired a consulting firm to evaluate all of the company’s product lines involving liquids. The consults made recommendations on how the company can improve its operations, and Money said VPG would spend about $200,000 to $250,000 to implement the recommendations in order to make the plant safer. Money previously said the facility does not handle ammonium nitrate, the chemical involved in the West Fertilizer Plant explosion, nor anhydrous ammonia.