(a) All new aboveground tanks must have a system for monitoring leakage between the tank bottom and the secondary containment system. This may include perforated gravity collection piping or channels in a concrete foundation or other equivalent method acceptable to the department. Monitoring may be accomplished by visual, mechanical, electronic or other means acceptable to the department. Tanks which are entirely aboveground, such as tanks on racks, cradles or stilts, may be visually monitored for leakage to meet this requirement.

(b) Observation wells or other systems which monitor the soil or groundwater external to the secondary containment system do not satisfy the leak detection requirements of this section.