The sad event reported below did not happen in the environmental remediation field, but it demonstrates a liability with certain practices in that field.
A 38-year-old arc welder died as a result of an explosion. The victim was working to repair a large garbage truck by welding brackets on the back of the truck. He used a metal 55-gallon barrel as a worktable. Apparently the heat or sparks from the welding ignited residual vapors and/or material in the barrel, causing it to explode.
An employee found the victim lying on the ground, with exploded portions of the drum falling about him. There were secondary explosions and fires. The fire increased rapidly and involved propane and acetylene tanks in the establishment. When the fire department and county sheriff arrived on the scene, the entire building was in flames. The fire was extinguished, and the victim's body was found near the garbage truck.
In the cases of leaking petroleum underground storage tanks, we have instances where the petroleum reached groundwater. The illustration below depicts the leaking petroleum resting as a pancake on the water table.
(LNAPL = Light Non Aqueous Phase Liquid; a liquid that is not water, lighter than water, and therefore will float; for example, gasoline.)
Source: USGS Fact Sheet FS-084-98 http://toxics.usgs.gov/definitions/lnapls.html
We insert wells into the aquifer as a means to observe, inspect, and measure the groundwater conditions and thickness of the floating petroleum.
Where leaking petroleum products reach groundwater, California Regulations demand removal of the free product to the maximum extent practicable.
The Code warns that flammable products must be handled in a safe manner consistent with state and local requirements.
Where free petroleum is sitting on the water, regulators demand interim emergency actions for removal of the free product. These actions usually skim the petroleum that free-floats inside monitoring wells.
In many cases, the free petroleum is gasoline, and we observe instances where risky practices are employed. These practices skim the gasoline and dump it into temporary containers. The gasoline containers wait at times up to 90 days for collection. The containers are usually 55-gallon drums made of steel or high-density polyethylene like these:
The storage of gasoline in such drums may lead to an internal atmosphere that provides an explosive air/fuel mixture. Given an ignition source, this mixture could result in a drum explosion or fire.
The important point to know is that these drums ARE NOT DESIGNED to withstand the pressure when the mixture undergoes instantaneous combustion. As the drums cannot endure the high pressure, something must give; either the clamped top will blow away as a burning projectile or the drum will explode.
The photo below captures the effects of drums exploding inside a storage facility.
Associated Press / Alex Slitz
The story behind the photo: “A fire at a fuel storage facility… sent exploding oil barrels into the air… as residents were evacuated for several miles around the site…. Crews battling the blaze were forced to back away after a fuel barrel exploded…. About 15 explosions were heard in the next hour and more…. Blasting fuel barrels -- many 50-gallon drums filled with bulk oil -- flew about 50 feet into the air…. One burning barrel landed on and ignited an adjacent building.” (http://www.nola.com/news/index.ssf/2009/08/fuel_storage_facility_fire_for.html)
Implementing controls is a must to mitigate this risk of explosion. Unfortunately, there are cases where the needed controls are not implemented, because of either unawareness or reliance on “luck.”
Here are illustrations of what one might see in sites where storage of skimmed gasoline is practiced:
One may see drums staged in an orderly manner like this,
haphazardly like this,
Source: Illinois Environmental Protection Agency
or even abandoned like this.
Where such gasoline drums get together, we need just one to explode to start a chain reaction of a lightning-speed propagating blast.
There are strict fire and safety codes pertaining to the storage of flammable substances. If one should store gasoline in drums in a fashion resembling the examples above, they could be in violation of the codes and fire safety ordinances; but even more seriously, they might be putting fellow workers and innocent public in harm’s way.
Some of the needed safety features would likely involve
1.) Visual signage:
2.) Containment buildings:
3.) Installation of and proper training in the use of fire extinguishers:
4.) Fencing of the storage area: