What are acceptable methods of release detection for underground storage tank systems?

Automatic Tank Gauge (ATG): An ATG keeps track of the inventory inside the fuel tanks and records the required inventory records for each day of operation. Many ATGs also have a tank test mode which will allow the operator of the fuel systems to test the tanks to see if they are leaking. Some ATGs will test at a .2 gph leak rate which meets the monthly tank monitoring requirements, and some ATGs will test at a .1 gph leak rate which counts as the annual tank tightness test. Additionally, some ATG tests also test the product lines as well as the tank. Interstitial or Annular Space Monitoring: To use this method of release detection, the operator must first install or already have installed double walled tanks. A double walled tank is a tank inside another one and has space between them in which an electronic probe can be placed to test for the presents of liquids. The monitoring of the “interstitial or annular” space between the inner and outer tank can be done manually or ...  more