(a) Applicability. Unless provided otherwise, the requirements of this section as well as 8 CAR §§ 60-624, 60-625, and 60-626 shall apply only to:

1. (1) Newly permitted facilities;
2. (2) Increases in the permitted capacity or disposal area; or
3. (3) Permit renewals as specified in 8 CAR § 60-309.

(c) Minimum design criteria. At a minimum, the bottom and side slope liner systems of new Class 4 landfills and expansions of the permitted fill area shall be constructed:

1. (1) With a compacted clay liner consisting of at least an eighteen-inch thickness with a hydraulic conductivity of no more than 1 x 10^-5 cm/sec; or

2. (2)

   1. (A) In accordance with a design approved by the Director of the Division of Environmental Quality.
   2. (B) The design must ensure that the concentration values specified in Appendix 3 will not be exceeded in the uppermost aquifer at the relevant point of compliance, as specified by the director under 8 CAR § 60-620.
   3. (C) Landfills sited in favorable, uniform geologic settings exhibiting in-place permeability equal to or less than 1 x 10^-5 cm/sec may be constructed without compacted liners provided the standards of this section are met.

(d) Final cover system requirements. Each waste unit shall at a minimum provide a final cover system consisting of, from bottom to top:

1. (1) A compacted clay barrier layer of at least an eighteen-inch thickness with a hydraulic conductivity of no more than 1 x 10^-5 cm/sec; and
2. (2) An erosion layer of at least six inches (6”) thickness that is capable of supporting vegetation; or

3. (3)

   1. (A) In accordance with a design approved by the director.
   2. (B) The design must demonstrate equivalency to the prescriptive final cover requirements contained in subdivision (d)(1) of this section.