(a) General. Either the Approval Authority or a POTW with an approved POTW Pretreatment Program may initiate program modification at any time to reflect changing conditions at the POTW. Program modification is necessary whenever there is a significant change in the operation of a POTW Pretreatment Program that differs from the information in the POTW's submission, as approved under §403.11.

(b) Substantial modifications defined. Substantial modifications include:

(1) Modifications that relax POTW legal authorities (as described in §403.8(f)(1)), except for modifications that directly reflect a revision to this part 403 or to 40 CFR chapter I, subchapter N, and are reported pursuant to paragraph (d) of this section;

(2) Modifications that relax local limits, except for the modifications to local limits for pH and reallocations of the Maximum Allowable Industrial Loading of a pollutant that do not increase the total industrial loadings for the pollutant, which are reported pursuant to paragraph (d) of this section. Maximum Allowable Industrial Loading means the total mass of a pollutant that all Industrial Users of a POTW (or a subgroup of Industrial Users identified by the POTW) may discharge pursuant to limits developed under §403.5(c);

(3) Changes to the POTW's control mechanism, as described in §403.8(f)(1)(iii);

(4) A decrease in the frequency of self-monitoring or reporting required of industrial users;

(5) A decrease in the frequency of industrial user inspections or sampling by the POTW;

(6) Changes to the POTW's confidentiality procedures; and

(7) Other modifications designated as substantial modifications by the Approval Authority on the basis that the modification could have a significant impact on the operation of the POTW's Pretreatment Program; could result in an increase in pollutant loadings at the POTW; or could result in less stringent requirements being imposed on Industrial Users of the POTW.

(c) Approval procedures for substantial modifications.

(1) The POTW shall submit to the Approval Authority a statement of the basis for the desired program modification, a modified program description (see §403.9(b)), or such other documents the Approval Authority determines to be necessary under the circumstances.

(2) The Approval Authority shall approve or disapprove the modification based on the requirements of §403.8(f) and using the procedures in §403.11(b) through (f), except as provided in paragraphs (c) (3) and (4) of this section. The modification shall become effective upon approval by the Approval Authority.

(3) The Approval Authority need not publish a notice of decision under §403.11(e) provided: The notice of request for approval under §403.11(b)(1) states that the request will be approved if no comments are received by a date specified in the notice; no substantive comments are received; and the request is approved without change.

(4) Notices required by §403.11 may be performed by the POTW provided that the Approval Authority finds that the POTW notice otherwise satisfies the requirements of §403.11.

(d) Approval procedures for non-substantial modifications.

(1) The POTW shall notify the Approval Authority of any non-substantial modification at least 45 days prior to implementation by the POTW, in a statement similar to that provided for in paragraph (c)(1) of this section.

(2) Within 45 days after the submission of the POTW's statement, the Approval Authority shall notify the POTW of its decision to approve or disapprove the non-substantial modification.

(3) If the Approval Authority does not notify the POTW within 45 days of its decision to approve or deny the modification, or to treat the modification as substantial under paragraph (b)(7) of this section, the POTW may implement the modification.

(e) Incorporation in permit. All modifications shall be incorporated into the POTW's NPDES permit upon approval. The permit will be modified to incorporate the approved modification in accordance with 40 CFR 122.63(g).

[62 FR 38414, July 17, 1997]