On July 13, 2020, EPA Region 1 issued a Clean Air Act Administrative Order (AO) to Middlesex Jail and House of Corrections (Middlesex Jail) of Billerica, Massachusetts. The AO addresses violations found at this medium security detention center operated by the Middlesex County Sheriff's Office located at 269 Treble Cove Road in Billerica, Massachusetts. Specifically, the AO requires Middlesex Jail to comply with various notification and reporting requirements and to prepare and submit to EPA a site-specific monitoring plan pertaining to the National Emission Standards for Hazardous Air Pollutants (NESHAP) for stationary reciprocating internal combustion engines, found at 40 CFR Part 63, Subpart ZZZZ.