(1) Facilities subject to more than one subpart of this part must monitor for compliance for each subpart after treatment and before mixing of the waste with wastes of any other subpart. Alternatively, a multiple wastestream subcategory facility may certify that it provides equivalent treatment as defined in § 437.2(h) for the applicable waste and monitor for compliance with the applicable set of multiple wastestream subcategory limitations after mixing.

(2) Facilities subject to one or more subpart of this part must monitor for compliance with the applicable subpart after treatment and before mixing of the waste with wastes of any other subpart, uncontaminated storm water, or wastewater subject to another effluent limitation or standard in subchapter N. If, however, the facility can demonstrate to the receiving POTW or permitting authority the capability of achieving the effluent limitation or standard for each subpart after treatment and before mixing with other wastestreams, the facility may monitor for compliance after mixing. In the case of a facility which elects to comply with the applicable set of multiple wastestream subcategory limitations or standards, it is only subject to one subpart.

(3) When a CWT facility treats any waste receipt that contains cyanide at a concentration higher than 136 mg/L, the CWT facility must monitor for cyanide after cyanide treatment and before dilution with other wastestreams. If, however, the facility can demonstrate to the receiving POTW or permitting authority the capability of achieving the cyanide limitation or standard after cyanide treatment and before mixing with other wastestreams, the facility may monitor for compliance after mixing.