The Pretreatment Regulations apply to publicly owned treatment works (POTWs) and to industrial users discharging pollutants to POTWs from non-domestic sources. The Pretreatment Regulations prohibit any discharge to a POTW that causes a violation of the POTW?s NPDES permit or disrupts the POTW?s treatment process. With limited exceptions, POTWs that receive industrial waste are required to develop pretreatment programs. These programs must include mechanisms to ensure that industrial users comply with pretreatment standards and requirements, which include enforcement if necessary. EPA has direct implementation authority for the pretreatment program in Montana, which means EPA directly oversees the implementation of pretreatment programs in Montana. The City of Billings (City) POTW has an EPA approved pretreatment program and is considered a control authority with regard to the Pretreatment Regulations in their service area. NPDES inspectors conducted a pretreatment compliance inspection (PCI) at the Billings Wastewater Treatment Plant on May 4-6, 2015. The following deficiencies were identified:
? Failure to update local limits .
? Failure to permit Categorical Industrial Users.
? The pretreatment ordinance does not accurately reflect the local limits as approved by EPA.
? Program modifications regarding grease trap and hauled waste legal authority were not submitted to the EPA.
? The City does not have a written Industrial Users identification and characterization proced