Among other tasks, one of the most common ones for a vacuum truck takes place in an oil field. This equipment is an indispensable tool for collecting the by-products of oil and gas exploration, such as basic sediment and water. Unlike other liquids, waste that is collected from oil and gas exploration is potentially flammable, so even though the equipment is designed to perform this job, there are necessary precautions that must be implemented in order to avoid this type of serious accident.

Risks Involved

While sediment and water collected from gas and oil production wells may seem like just another mix of waste water, they could contain flammable hydrocarbons that can combust at a high rate and therefore carry a great deal of risk and danger. An analysis conducted by the Chemical Safety and Hazard Investigation Board (CSB) on nine wells showed that eight out of the nine tested had flashpoints below 30º F. According to the Occupational Safety and Health Administration (OSHA), any liquids that have a flashpoint of 100º F are considered to be flammable.

The study regarding the potential risk of loading and unloading the sediments and water waste generated by gas and oil wells began when an accident occurred at an oilfield waste disposal complex on January 13, 2003, in Rosharon, Texas, just outside of Houston. A couple of vacuum trucks were in the process of unloading a mixture of sediment and water that had been collected from oil field production wells. The two trucks were parked 16 feet from each other and the drivers were given instructions to unload and rinse out the vehicles. After this was done, the two drivers proceeded to the driver’s shed for their papers to be processed. After a few minutes, a huge explosion occurred inside the waste disposal facility killing three people and causing severe burns to three others. The explosion also caused a great deal of damage to the facility.

An investigation conducted by the CSB and OSHA revealed that the condensation inside the tanks caused the explosion and the source of ignition was the truck engines, which were still running. These findings were backed by eye witnesses of the incident, as well as other evidence that was found at the scene.

What Went Wrong

Many factors contributed to this explosion occurring. The shipper failed to identify the flammability of the waste being disposed. The transportation company did not request the Material Safety Data Sheet (MSDS), which could have provided information about the hazards of the material being transported. The waste collection facility also did not have an effective system of determining the hazards of handling and unloading water and sediments from oil and gas wells.

How to Be Safe

Before handling flammable waste liquids including basic sediment and water, an operator must first undergo training for: hazard communication; flammable and combustible liquids; hazardous waste operations and emergency responses; air contaminants; and the proper classification and manifestation of flammable liquids. Below is a list of other precautions the drivers could have taken to save the lives of those affected by the blast.

• Request MSDS - Operators must always request an MSDS, and refer to it to determine the hazards associated with the material before transporting it.

• Be Aware of Hazards - Operators should be aware of any potential source of ignition, including the engine.

• Don’t Mix Liquids - Different types of liquids should not be mixed to avoid any possible reaction.

• Test Atmosphere - Atmospheric testing should be done on-site to determine if any hydrocarbon concentration has reached the flammable range.

• Spark Control - Bonding and grounding should be implemented to eliminate any potential source of sparks.

Every vacuum truck is designed to be a safe means of transporting various types of waste material, including those that are hazardous and flammable such as those found in oil field work. Incidents such as the one mentioned above may still occur when operators are negligent in handling their equipment. The information provided above fill hopefully furnish the necessary knowledge about the hazards of handling oil and gas well waste products and how to avoid them – be careful!