(1) When required by the department based upon a suspected release, an owner and operator must follow the procedures in ARM 17.56.504 to determine if the 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 have been observed by the department or the implementing agency or brought to its attention by another person.