To help prevent groundwater contamination due to leaching from CCR units, the CCR Rule established design requirements for the liners of new landfills and surface impoundments. Existing CCR units are not subject to the same liner design requirements as new CCR units and can continue to receive CCR as designed, as long as the CCR units meet all applicable groundwater monitoring and corrective action criteria to address groundwater releases.
New CCR landfills, new CCR surface impoundments, and lateral expansions of all CCR units must contain a composite liner. This liner must consist of a geomembrane and a two-foot layer of compacted soil that are installed in direct contact with one another. Alternative liners may also be used, provided the liner performs at least as effectively as the composite liner. Additionally, new landfills are required to include a leachate collection and removal system to remove excess leachate that may accumulate on top of the liner (40 CFR 257.70 and 40 CFR 257.72).
Although existing CCR surface impoundments can continue to operate as designed without retrofitting, they are required to be documented and certified by a qualified professional engineer as lined or unlined within 18 months after the rule publication date in the Federal Register (by October 17, 2016). Additionally, if existing CCR surface impoundments were constructed without a liner or at least two feet of compacted soil with a specified hydraulic conductivity, the rule requires that the impoundment be retrofitted or closed if concentrations of one or more specific contaminant are detected in groundwater above specified levels (40 CFR 257.71).