(1) Any facility that detects Table 1 [ARM 17.50.708] constituents of a hazardous substance in ground water at concentrations above background at the facility will be required to conduct post-closure ground water monitoring.

(2) Any facility designated by 75-10-207, MCA, that closes on or after January 1, 1993, is required to monitor ground water for at least 30 years following closure.   The post-closure monitoring schedule will be determined by the department.