Where an industry now or hereafter discharging any waste into a sewer connected to the public sewer system contemplates providing facilities for pretreatment of such wastes so as to reduce the strength of the waste, the industry may, by special agreement with the City of Cincinnati, entered into within 6 months after the effective date of ordinance No. 25-1953 of the City of Cincinnati, bind itself to construct such pretreatment facilities within 12 months after the effective date of the sewerage surcharge made pursuant to the ordinance. If any industry provides satisfactory pretreatment within the prescribed time, it shall be entitled to a refund in an amount equal to the difference between the surcharge actually paid and the surcharge that would have been paid had such pretreatment facilities been in operation on the date that the sewerage surcharge went into effect.
('73 Code, § 51.11)