The definitions contained in ARM Title 17, chapter 30, subchapter 13 are hereby incorporated by reference in this subchapter.   The following definitions pertain to indirect dischargers and POTW's subject to pretreatment standards and the MPDES program:

(1) "Approved POTW pretreatment program" means a program administered by a POTW that meets the criteria established in (8) of this rule and which has been approved by the department in accordance with ARM 17.30.1413.

(2) "Indirect discharge" or "discharge" means the introduction of pollutants into a POTW from any non-domestic source regulated by the MPDES program.

(3) "Industrial user" or "user" means a source of indirect discharge.

(4) "Interference" means a discharge which, alone or in conjunction with a discharge or discharges from other sources, both:

(a) inhibits or disrupts the POTW, its treatment processes or operations, or its sludge processes, use or disposal; and

(b) therefore is a cause of a violation of any requirement of the POTW's MPDES permit (including an increase in the magnitude or duration of a violation) or of the prevention of sewage sludge use or disposal in compliance with the following statutory provisions and regulations or permits issued thereunder (or more stringent state or local regulations) :   section 405 of the Clean Water Act (CWA) , the Solid Waste Disposal Act (SWDA) (including Title II, more commonly referred to as the Resource Conservation and Recovery Act (RCRA) , and including state regulations contained in any state sludge management plan prepared pursuant to Subtitle D of the SWDA) ,

the Clean Air Act, the Toxic Substances Control Act, and the Marine Protection, Research and Sanctuaries Act.

(5) "National pretreatment standard" or "pretreatment standard" means any regulation containing pollutant discharge limits promulgated by the EPA in accordance with section 307(b) and (c) of the CWA, which applies to industrial users.   This includes prohibitive discharge limits established pursuant to ARM 17.30.1406(4) .

(6) "Pass through" means a discharge which exits the POTW into state waters in quantities or concentrations which, alone or in conjunction with a discharge or discharges from other sources, is a cause of a violation of any requirement of the POTW's MPDES permit (including an increase in the magnitude or duration of a violation) .

(7) "POTW treatment plant" means that portion of the POTW which is designed to provide treatment, including recycling and reclamation of municipal sewage and industrial waste.

(8) "Pretreatment" means the reduction of the amount of pollutants, the elimination of pollutants or the alteration of the nature of pollutant properties in wastewater prior to or in lieu of discharging or otherwise introducing such pollutants into a POTW.   The reduction or alteration may be obtained by physical, chemical, or biological processes, process changes, or by other means, except as prohibited by 40 CFR 403.6(d) .   Appropriate pretreatment technology includes control equipment, such as equalization tanks or facilities, for protection against surges or slug loading that might interfere with or otherwise be incompatible with the POTW.   However, where wastewater from a regulated process is mixed in an equalization facility with unregulated wastewater or with wastewater from another regulated process, the effluent from the equalization facility must meet an adjusted pretreatment limit calculated in accordance with 40 CFR 403.6(e) .

(9) "Pretreatment requirements" means any substantive or procedural requirements related to pretreatment, other than the national pretreatment standard, imposed on an industrial user.

(10) "Regional administrator" means the administrator of Region VIII of the EPA, which has jurisdiction over federal water pollution control activities in the state of Montana.

(11) (a) "Significant industrial user", except as provided in this section, means:

(i) all industrial users subject to categorical pretreatment standards under 40 CFR 403.6 and 40 CFR chapter I, subchapter N; and

(ii) any other industrial user that discharges an average of 25,000 gallons per day or more of process wastewater to the POTW (excluding sanitary noncontact cooling and boiler blowdown wastewater) ; contributes a process wastestream which makes up 5% or more of the average dry weather hydraulic or organic capacity of the POTW treatment plant; or is designated as such by the control authority as defined in ARM 17.30.1410(1) on the basis that the industrial user has a reasonable potential for adversely affecting the POTW's operation or for violating any pretreatment standard or requirement (in accordance with ARM 17.30.1411(7) ) .

(b) Upon finding that an industrial user meeting the criteria in (a) above has no reasonable potential for adversely affecting the POTW's operation or for violating any pretreatment standard or requirement, the control authority (as defined in ARM 17.30.1414(1) ) may on its own initiative or in response to a petition received from an industrial user or POTW, and in accordance with ARM 17.30.1411(7) , determine that the industrial user is not a significant industrial user.

(c) The board hereby adopts and incorporates by reference 40 CFR 403.5 (national pretreatment standards:   categorical standards) (July 1, 1991) , and 40 CFR chapter I, subchapter N (effluent guidelines and standards) (July 1, 1991) .   Copies of these materials are available from the Department of Environmental Quality, PO Box 200901, Helena, MT 59620-0901.

(12) "Submission" means either a request by a POTW for approval of a pretreatment program to the department, or a request by a POTW for authority to revise the discharge limits in categorical pretreatment standards to reflect POTW pollutant removals.