(A) Effluent limitations promulgated by the Federal Water Pollution Control Act, P192-500, shall apply in any instance where they are more stringent than those in this chapter. Under section 307 (b) of the Act, federal pretreatment standards are designed to achieve the following two purposes.
(1) To protect the operation of community- owned treatment works.
(2) To prevent the discharge of pollutants which pass through the works inadequately treated.
(B) Users in industrial categories subject to effluent guidelines issued under section 304 (b) of the Act, which are discharging incompatible pollutants to community-owned treatment works, are required to adopt the best practicable control technology currently available, as defined by the Administrator pursuant to section 304 (b) of the Act. Where the Board of Public Works and Safety's treatment works was designed to treat the four pollutants listed in the definition for compatible pollutants in § 50.002, which are BOD, suspended solids, pH, and fecal coliform bacteria, it is not appropriate to require the industrial user to achieve the best practicable control technology currently available, since this would lead to uneconomical duplication of treatment facilities.
(C) While the term “substantial removal” is not subject to precise definition, it generally contemplates removals in the order of 80% or greater. Minor incidental removals in the order of 10% to 30% are not considered “substantial”.
(D) For some industrial categories, it may be necessary to define pretreatment guidelines for problems that may arise as a result of any adjustments required for particular industrial categories, which should be considered in connection with the Board's requirements rather than the national pretreatment standard. Limitations on wastewater strength in § 51.069 may be supplemental, with more stringent limitations pursuant to § 51.082, if the following occur.
(1) The Board determines that the limitations in § 51.069 may not be sufficient to protect the operation of the Board's treatment works; or
(2) The Board determines that the limitations in § 51.069 may not be sufficient to enable the Board's treatment works to comply with water quality standards or effluent limitations specified in its National Pollutant Discharge Elimination System (NPDES) permit.
(Ord. 10-1978, passed 7-11-78)