

Must be conducted monthly to detect a release
Tank liquid level measurements are taken at the beginning and ending of a period. A release is suspected if the variation between beginning and ending measurements exceeds the weekly or monthly standards.
Must be capable of detecting a 0.1 gallon per hour leak rate from any portion of the tank that routinely contains product.
Testing or monitoring for vapors within the soil gas of the excavation zone.
Testing or monitoring for liquids on the groundwater.
Interstitial monitoring between the UST system and a secondary barrier immediately around or beneath it may be used, but only if the system is designed, constructed, and installed to detect a leak from any portion of the tank that routinely contains product
Release detection methods based on the application of statistical principles to inventory data.