How is release notification handled for mixtures under EPCRA section 304?
Similar to the release notification requirements in CERCLA section 103, release notification of a mixture under EPCRA should be in accordance with the Clean Water Act (CWA) mixture rule. If the quantity of all the hazardous constituents of the mixture or solution is known, notification is required where an RQ or more of any hazardous constituent is released. If the quantity of one or more of the hazardous constituents of the mixture or solution is unknown, notification is required where the total amount of the mixture or solution released equals or exceeds the RQ for the hazardous constituent with the lowest RQ. (April 22, 1987, final rule (52 FR 13378, 13385, and 13392))
(See Zendesk 13350 for more information on the mixture rule.)