Our primary concern is with gas stations that are either abandoned, unregistered, or both. Abandoned tanks may still have product left in them that can leak out over time due to deterioration of the tanks. Unregistered gas stations are not being monitored and may not be in compliance with current regulations. They may also have undetected leaks in their tanks or pipelines. Our UST Division currently has approximately 25,000 USTs registered in their database and they estimated that there are at least one-third that number not registered.
Leaks can also develop in the piping between the tanks and the pumps.
Active stations that are monitoring according to the regulations should be able to detect a loss of product on their inventory. Abandoned stations are the worst threat of product is left in the tanks. There is no way to detect leaks because they are not monitored. In Gilbert, the abandoned gas station that contaminated the wells had been abandoned for about 10 years before the leak impacted the wells. The tanks were evidently leaking at the time of closure and migrated to the shallow wells over time.