33.1-13-01-03. General release detection requirements for aboveground storage tank systems.

An owner or operator of a new or upgraded aboveground storage tank that is secondarily contained shall provide release detection for tanks by interstitial monitoring or visual inspection as follows:

1. For double-walled or double-bottomed aboveground storage tank systems: a. The inspection or testing method must detect a release through the inner wall in any portion of the tank that routinely contains product. b. The interstitial space between the tank walls must be inspected and documented at least monthly or have a continuous sensor or gauge installed. c. If using a continuous sensor or gauge, it must be tested at least annually for functionality.

2. For aboveground storage tank systems with a secondary containment barrier: a. The inspection or testing method used must detect a release between the aboveground storage tank system and the secondary containment barrier. b. The secondary containment barrier around and beneath the aboveground storage tank system must meet the requirements of section 33.1-13-01-02. c. The secondary containment barrier must direct a release to a monitoring point that allows for detection. d. The monitoring point must be inspected and documented at least monthly. e. Precipitation must not be allowed to accumulate to render the monitoring point inoperative.