In case there is a release from an underground storage tank (UST) the incident has to be reported to the local agency within 24 hours. The duration may differ according to different agencies. In case the leak is based in Indian Country, it should be reported to the Regional UST program that is under the jurisdiction of the EPA.
After a release is detected, steps should be taken immediately to stop it from contaminating soil. The first thing you need to do is ensure that there is no immediate threat to human life and health. Then, measures should be taken to stop it and prevent threats to the personnel or people near it.
In case the spill is less than 25 gallons or any other amount that the agency specifies, you may not need to report it. The same is the case if the spill can be cleaned up within 24 hours. In addition, it is also not necessary to let the agency known of a hazardous substance which releases in the environment in quantities that are less than reportable quantities under CERCLA.