(1) The purpose of this subchapter is to provide uniform standards for ground water monitoring and corrective action at Class II disposal facilities and Class IV disposal units.   For purposes of this rule, "Class II disposal facility" and "Class IV disposal unit" have the meaning expressed in ARM 17.50.504.

(2) Compliance with the requirements of this subchapter must be implemented according to the following schedule:

(a) all new Class II units must be in compliance with this subchapter and initial sampling must be completed before waste can be placed in the unit;

(b) existing Class II units and lateral expansions that serve a geographic area with a population of 5,000 or more persons must be in compliance with all requirements of this subchapter and have commenced ground water monitoring by October 9, 1993; and

(c) existing Class II disposal units and lateral expansions that serve a geographic area with a population of 4,999 persons or less, except those meeting the requirements of ARM 17.50.506(16) , must comply with this subchapter according to the following schedule:

(i) existing Class II disposal units and lateral expansions less than 1 mile from a drinking water intake (surface or subsurface) must be in compliance and have commenced ground water monitoring by October 9, 1994;

(ii) existing Class II disposal units and lateral expansions greater than 1 mile but less than 2 miles from a drinking water intake (surface or subsurface) must be in compliance and have commenced ground water monitoring by October 9, 1995;

(iii) existing Class II disposal units and lateral expansions greater than 2 miles from a drinking water intake (surface or subsurface) must be in compliance and have commenced ground water monitoring by October 9, 1996.

(d) Owners and operators of all MSWLF units that serve a geographic area with a population of 4,999 persons or less and meet the conditions of ARM 17.50.506(16) must comply with the requirements of this subchapter according to the following schedule:

(i) all MSWLF units less than 2 miles from a drinking water intake (surface or subsurface) must be in compliance and have commenced ground water monitoring by October 9, 1995; and

(ii) all MSWLF units greater than 2 miles from a drinking water intake (surface or subsurface) must be in compliance and have commenced ground water monitoring by October 9, 1996.

(e) All Class IV units must be in compliance with this subchapter (except for the provisions of ARM 17.50.705) , and operated in compliance with this subchapter, and initial sampling must be completed before waste can be placed in the unit.