329 IAC 10-22-7 Final cover requirements for existing MSWLF units constructed without a composite bottom liner

Sec. 7. (a) The owner, operator, or permittee of an MSWLF containing existing MSWLF units constructed without a composite bottom liner shall install a final cover system as appropriate to subsection (b) or (c) within one hundred eighty (180) days on any area in the MSWLF units as approved in the closure plan that: (1) has received the final waste volume; or (2) is filled to the approved final waste elevation; or as approved under section 5(b) of this rule. (b) Unless otherwise approved by the commissioner based on a final cover system providing equivalent environmental protection, final cover systems for existing MSWLF units constructed with a soil bottom liner and a leachate collection system that were permitted under 329 IAC 2, which was repealed in 1996, and closing after January 1, 1998, must consist of the following: (1) On slopes equal to or less than fifteen percent (15%) or eight and fifty-three hundredths (8.53) degrees, the final cover must be constructed as follows: (A) A twenty-four (24) inch barrier layer of soil of the Unified Soil Classification ML, CL, MH, CH, or OH directly over the waste. Other suitable material approved by the commissioner may be used if it provides an adequate level of protection to human health and the environment. The soil must be compacted to achieve a hydraulic conductivity equal to 1 × 10-7 centimeters per second or less. Grain size, Atterberg limits, and hydraulic conductivity tests as approved by the commissioner or as required by this article must be performed to confirm the quality of the final cover. (B) A vegetative layer must overlay the top protective layer. This layer must consist of at least six (6) inches of earthen material capable of sustaining vegetation. (2) On slopes greater than fifteen percent (15%) or eight and fifty-three hundredths (8.53) degrees, the final cover must be constructed as follows: (A) A twenty-four (24) inch barrier layer of soil of the Unified Soil Classification ML, CL, MH, CH, or OH directly over the waste. Other suitable material approved by the commissioner may be used if it provides an adequate level of protection to human health and the environment. The soil must be compacted to achieve a hydraulic conductivity equal to 1 × 10-6 centimeters per second or less. Grain size, Atterberg limits, and hydraulic conductivity tests as approved by the commissioner or as required by this article must be performed to confirm the quality of the final cover. (B) A vegetative layer consisting of at least six (6) inches of earthen material capable of sustaining vegetation must overlay the barrier layer. (C) An increase in the thickness of the layers required in this subdivision may be required by the facility permit or the commissioner. (3) The maximum projected erosion rate of the final cover must be no more than five (5) tons per acre per year. (4) The final cover must have a slope: (A) no less than four percent (4%) or two and twenty-nine hundredths (2.29) degrees; and (B) no greater than thirty-three percent (33%) or eighteen and twenty-six hundredths (18.26) degrees. (c) Unless otherwise approved by the commissioner based on a final cover system providing equivalent environmental protection, final cover systems for existing MSWLF units constructed without a soil bottom liner or a leachate collection system that were permitted under 329 IAC 1.5, which was repealed in 1989, or 329 IAC 2, which was repealed in 1996, and closing after January 1, 1998, must consist of the following: (1) On slopes equal to or less than fifteen percent (15%) or eight and fifty-three hundredths (8.53) degrees, the final cover not including benches, swales, and drainage features, must be constructed as specified in section 6(b)(1) through 6(b)(7) of this rule. (2) On slopes greater than fifteen percent (15%) or eight and fifty-three hundredths (8.53) degrees, the final cover must be constructed as specified in subsection (b)(2). (3) The maximum projected erosion rate of the final cover must be no more than five (5) tons per acre per year. (4) The final cover must have a slope: (A) not less than four percent (4%) or two and twenty-nine hundredths (2.29) degrees; and (B) not greater than thirty-three percent (33%) or eighteen and twenty-six hundredths (18.26) degrees.