When Recognized Environmental Conditions (RECs) are found on a property, the next step of action is to conduct a Phase II Environmental Site Assessment (ESA). Part of the Phase II involves groundwater sampling, in which scientists drill into the potentially contaminated soil using a Geoprobe until water is reached. Samples of water are collected, logged and sent to a lab for further testing. They are then compared to the EPA regional screening levels, or state clean up criteria, to determine if contamination is present.
See how groundwater sampling is conducted: