Owners and operators using interstitial monitoring must comply with the requirements of this section.

(1) Standards. The interstitial monitoring system must be able to detect a leak through the inner wall of any portion of the tank or underground piping that routinely contains a regulated substance. Methods that continuously monitor the interstitial space using a vacuum, pressure, or a liquid must be able to detect a breach in both the inner and outer walls.

(2) Performance. Interstitial monitoring must be performed in accordance with the manufacturer's instructions and any conditions or limitations specified in the certification of the equipment.