40 CFR § 35.2206 - Operation and maintenance.
(a) The grantee must assure economical and effective operation and maintenance (including replacement) of the treatment works.
(b) Except as provided in paragraphs (c) (1) and (2) of this section, the Regional Administrator shall not pay more than 50 percent of the Federal share of any project unless the grantee has furnished and the Regional Administrator has approved the final plan of operation required by § 35.2106, and shall not pay more than 90 percent of the Federal share of any project unless the grantee has furnished and the Regional Administrator has approved an operation and maintenance manual.
(c)
(1) In projects where segmenting of a proposed treatment works has occurred, the Regional Administrator shall not pay more than 90 percent of the Federal share of the total allowable costs of the proposed treatment works until the grantee has furnished and the Regional Administrator has approved an operation and maintenance manual.
(2) In projects where a component is placed in operation before completion of the entire project, the Regional Administrator shall not make any additional payment on that project until a final operation and maintenance manual for the operating component is furnished and approved.