How far below the bottom of the tanks should observation wells extend to be effective?

For observation wells to be effective in monitoring groundwater and the potential presence of contaminants from underground storage tanks, the recommended depth is that they should extend at least 2 feet below the bottom of the tanks. Placing observation wells at this depth allows for adequate monitoring of the surrounding groundwater table and ensures that any possible leaks or releases from the UST can be detected promptly.

This depth helps to create a buffer zone, where the well can collect samples of groundwater that may be influenced by potential contamination. If the wells were to extend less than 2 feet below the tanks, they might not reach the necessary depth where any contaminants would travel, especially during changes in the water table or following heavy rainfall events.

Furthermore, this specific depth requirement aligns with best practices established in the industry for effective groundwater monitoring, making it a standard guideline for UST operators to follow to ensure environmental safety and compliance.