IPR SWTPs shall be designed to provide a high level of nutrient removal, as outlined in Subchapter 3 of this Chapter. At a minimum, IPR SWTPs shall be designed to comply with the Biological Nutrient Removal requirements outlined in OAC 252:656-16-3. Other nutrient removal options will be evaluated on a case-by-case basis.
Okla. Admin. Code § 252:628-5-5