Frequent Questions

Is the definition of "facility structures" in 40 CFR 258.23(a)(1) intended to include below grade gravity main manholes?

There is no Federal definition of facility structures or clarification of whether facility structures specifically includes below grade gravity main manholes. The regulations do indicate that the definition of facility structures excludes gas control or recovery system components.

Owners or operators of all MSWLF units must ensure that the concentration of methane generated by the MSWLF does not exceed twenty-five percent of the lower explosive limit (LEL) in on-site structures, such as scale houses, or the LEL itself at the property boundary (56 FR 50978, 51007; October 9, 1991).

This guidance represents clarification of the Federal regulations. If you have questions about municipal solid waste landfills, we recommend that you contact your state implementing agency. In the United States, regulations governing the management of nonhazardous solid waste are implemented by individual states. A list of solid waste contacts is available at the following URL:

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