Where an industry otherwise producing or now discharging any sewage or waste into a stream, or otherwise disposing of such sewage or waste contrary to law, contemplates providing its own proper facilities for the treatment of this sewage or waste instead of utilizing the metropolitan sewage disposal system, this industry or producer 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 its own proper facilities for the treatment of its sewage and wastes within 12 months after the effective date of the sewerage surcharge provided for in the ordinance. If any such industry or waste producer provides satisfactory treatment facilities within the prescribed time, it shall be entitled to a refund of any sewerage service charges or surcharges paid by it.
('73 Code, § 51.10)