Artisan EHS found an error in the Code of Federal Regulations concerning Reportable Quantity calculations for K169, K170, K171, and K172. EPA corrected the error in a Direct Final Rule dated February 22, 2012, effective April 23, 2012. This correction provides specific constituent concentrations for use in calculating Reportable Quantities using the CWA Mixture Rule.

We submitted the Request for Correction on November 14, 2011. In addition to the request for reinstating constituent concentration data that were included in the Final Rule published on August 6, 1998, we also reiterated the use of the mixture rule developed in connection with the Clean Water Act section 311 regulations for calculating Reportable Quantities of mixtures.

EPA published the Direct Final Rule in the February 22, 2012 Federal Register. The preamble to the Direct Final Rule includes the definition of CWA mixture rule, ‘Discharges of mixtures and solutions are subject to these regulations only where a component hazardous substance of the mixture or solution is discharged in a quantity equal to or greater than its reportable quantity’.

Where you know the concentrations of constituents in a mixture, you can calculate the mixture-specific Reportable Quantity. As a special case, maximum constituent concentrations for calculating Reportable Quantities for K169, K170, K171, K172, K174, and K175 listed hazardous wastes are published in 40 CFR §302.6. Otherwise, a 'person in charge' must have specific knowledge of their mixture concentrations in order to apply the mixture rule. Artisan EHS has developed a template for calculating mixture Reportable Quantities, which is available for your use.

The most recent revision was October 2012. We check routinely for updates or additional information, and will publish updated links as available. These links are to http://www.epa.gov/emergencies/tools.htm#lol.