R 299.9620 Liner requirements for landfills, surface impoundments, and waste piles.

Rule 620. (1) A liner system must be located, designed, constructed, and operated so that there is no direct contact between the liners and groundwater in a saturated zone and moisture content would not adversely affect the structural and containment integrity of the liners. (2) The primary liner for a landfill must be a composite liner. The composite liner must be designed to have a flexible membrane liner meeting the requirements of 40 CFR 264, subpart N, directly over compacted clay which is a minimum of 150 centimeters thick and meets the requirements of subrule (3) of this rule. (3) A compacted clay liner that is designed to meet the requirements of 40 CFR 264.221, 264.251, and 264.301, which are adopted by reference in R 299.11003, or R 299.9619 must meet all the following requirements for that clay liner: (a) Comply with the criteria for a unified soil classification of CL or CH as determined by the provisions of ASTM standard D2487-11. (b) Have more than 25% of the soil particles be less than 5 microns in size. (c) Be placed in horizontal lifts of not more than 25 centimeters and be uniformly and thoroughly compacted to the standards approved in the design. The lift thickness must not be more than 25 centimeters, 6 inches after compaction. However, the material must not be compacted to less than 90% of the maximum dry density, as determined by the modified proctor test described in the provisions of ASTM standard D1557-12, or 95% of the maximum dry density, as determined by the standard proctor test described in the provisions of ASTM standard D698-12, which are adopted by reference in R 299.11001, and the moisture content must be within a range of -2% to +5% of the optimum moisture content. (d) Have a maximum permeability coefficient of 1.0 x 10-7 centimeters per second or less at all points. (4) The waste pile or landfill base floor must be graded to a minimum slope of 2% in directions perpendicular to the leachate collection pipes to promote drainage. The leachate pipes must be laid on a slope of 1% or more in a direction to intercept liquid flow. The director may approve an alternate design to those specified in this subrule if the owner or operator demonstrates to the director that the design, together with location characteristics, complies with both of the following requirements: (a) The alternate design will prevent the migration of any hazardous constituent into the groundwater or surface water not less than as effectively the design requirements specified in this subrule. (b) The alternate design will allow the detection of leaks of hazardous constituents through the top liner not less than as effectively as the design requirements specified in this rule. (5) Liner systems and leachate collection systems must be designed to prevent the damage of the materials of both systems in the event of differential settlement of the foundation under worst case conditions.