A modification class that is used to modify an existing permit to incorporate groundwater monitoring wells is:

• A. Class I modification
• B. Class III modification
• C. Class IV modification
• D. Class II modification

Answer: (D)

Modifications to a permit are categorized by how much they change the permit and what review they require. Adding groundwater monitoring wells means you have to update the permit to specify the new monitoring locations, sampling frequency, parameters, QA/QC, reporting, and any related corrective actions. This changes the monitoring obligations and the permit text itself, and typically triggers regulatory review and public involvement, but it doesn’t entail a complete overhaul of the facility’s processes or emission limits. That middle level of change is why it fits a moderate modification category.

A purely administrative edit that doesn’t affect monitoring or limits would be a minor modification, while changes that alter emission limits or expand the facility’s scope would be major and require more extensive proceedings.