How many inches of soil must be placed on a finished landfill?

The requirement for covering a finished landfill with a specific thickness of soil is typically informed by regulatory standards designed to minimize environmental impacts and enhance site stability. A coverage of 24 inches of soil is often mandated as it serves multiple purposes: it provides a barrier that prevents exposure to underlying waste, helps to control odors, and supports vegetation growth, thus promoting natural reclamation processes.

This thickness is also significant in the context of landfill management practices, as it aids in the reduction of potential leachate generation and creates an effective cap over the waste material. A cover that is too thin might not effectively shield the waste from the elements or limit the potential for future land use, while a layer that is excessively thick may not be practical from an engineering or economic standpoint.

The other options, although within a reasonable range, do not satisfy the typical regulatory requirements that often specify a 24-inch cover for final closure of landfills, which is why this particular answer is the most accurate and commonly adopted standard in landfill management.