An observation well is located in which location?

An observation well is located in which location?

• A. Outside The Tank Excavation Until Ground Water Is Reached
• B. Inside The Tank Excavation, Extending 1' Below The Bottom Of The Tanks
• C. Outside The Tank Excavation Within 25 Feet
• D. Inside The Tank Excavation, No Deeper Than 15 Feet

Answer: (B)

Observation wells used in tank tightness testing are placed in the tank excavation and extend just below the bottom of the tank. This setup keeps the monitoring point in the area where any leaked liquid from the tank would first accumulate, providing a direct and timely indication of tank integrity. If a well were located outside the excavation or at a greater distance, leaks could go undetected or be reflected only in distant groundwater, delaying detection. If the well were deeper than the specified shallow depth, it would not monitor the immediate leakage path under the tank. Extending about 1 foot below the tank bottom ensures the probe sits in the zone most likely to show contamination from a leak.

Observation wells used in tank tightness testing are placed in the tank excavation and extend just below the bottom of the tank. This setup keeps the monitoring point in the area where any leaked liquid from the tank would first accumulate, providing a direct and timely indication of tank integrity. If a well were located outside the excavation or at a greater distance, leaks could go undetected or be reflected only in distant groundwater, delaying detection. If the well were deeper than the specified shallow depth, it would not monitor the immediate leakage path under the tank. Extending about 1 foot below the tank bottom ensures the probe sits in the zone most likely to show contamination from a leak.