When required by the Department, owners and operators of UST systems shall follow the procedures in R18-12-250 to determine if the UST system is the source of off-site impacts. These impacts include the discovery of regulated substances (such as the presence of free product or vapors in soils, basements, sewer and utility lines, and nearby surface and drinking waters) that has been observed by the Department or brought to its attention by another party.
Ariz. Admin. Code § R18-12-252