The decontamination of drilling rigs and drilling equipment is required on most sites involving contamination assessment and remediation. Decontamination procedures may include cleaning at the shop and job site prior to drilling. Decontamination may involve using high-pressure steam and approved solvents to remove greases and oils. The decon water may need to be contained and treated or disposed of in accordance with regulations.
Why all the fuss? The procedures sometimes appear to be excessive, but if you understand the ramifications of carrying a few unwanted soil particles from one job site to the next or from place to place on the same job site, importance of decontamination would be more apparent.
Action levels for many compounds on contaminated sites are in the low parts per billion. A part per billion is 1/1000 of a part per million (a billion is 1000 times 1 million). A part per billion is equal to one second in 37 years. It doesn't take much to bring significant levels of contamination from one job site to another. A few drops of fluid or grains of sand could do it. For example, suppose you drilled at a dry cleaner site prior to moving to a gas station. Somehow the inside of the lead auger is not cleaned properly prior to drilling. Analyses of soil from the first split spoon sample shows tetrachloroethylene (PCE) above action levels. All of a sudden the gas station is now under a program to look for, and monitor for, dry cleaning compounds. An investigation shows your equipment came directly from a dry cleaner site. Your chances of winning "driller of the year" fall by the wayside and a lawsuit is pending. Although the previous account is fictional, it is plausible. Taking time to follow procedures and diligence in your responsibilities is time well spent.
Other potential sources of contamination related to drilling activities include drilling water (which should only be derived from known sources of potable supplies) and greases and oils used on and in the drilling rig. Leaky hydraulic pumps and hoses should be repaired and cleaned, lead in paint on older rigs is a potential problem, oil in manilla rope (used on the cat head), and solvents in duct tape can cause contamination.
If you're in the environmental drilling business, it takes a special commitment to cleanliness to meet the expectations of your client.