Which of the following is an example of a liner system required by Subtitle D?

The correct answer is a single composite liner with compacted soil and a geomembrane. Subtitle D of the Resource Conservation and Recovery Act (RCRA) establishes standards for the disposal of nonhazardous solid waste, specifically addressing the design and operation of landfills. A single composite liner consists of a combination of a geomembrane, typically made of high-density polyethylene (HDPE), and a compacted soil barrier. This design effectively reduces the potential for leachate migration into the soil and groundwater.

The use of compacted soil in conjunction with the geomembrane provides two levels of protection, significantly improving the integrity and functionality of the liner system. This method is aligned with the Subtitle D requirements that emphasize environmental safeguards to prevent harmful substances from contaminating surrounding ecosystems.

A double composite liner with a leachate collection system, while effective, is not the minimal requirement under Subtitle D; it represents a more advanced system used in certain situations. A triple liner system is not standard as Subtitle D focuses on the primary function of leachate containment with cost-effective measures, which also makes a simpler and sufficiently effective single composite liner preferable. Lastly, a single liner without soil layers does not meet the criteria for enhancing containment and would not be sufficient for