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Show The Agency plans to address th ese and other major comments by issuing a notice of supplemental information in the Federal Register in early 1988. The notice will discuss and request comment on alternate approaches suggested by commenters to deal with a number of issues in the proposed rule. Incinerator Amendments The Agency plans to propose amendments to the hazardous waste incinerator standards of Subpart 0, Part 264 in early 1988. The amendments would strengthen the incinerator standards to establish emissions limits for the 12 metals on Appendix VIII of Part 261 and to limit CO levels to help control PIC emissions. In addition, a number of minor revisions to the permitting procedures will be proposed to clarify ambiguity in the existing rules and to allow the permitting process to operate more efficiently (e.g., trial burn testing of POHCs other than those normally expected to be in the waste would be explicitly allowed). Th~ proposed metals controls for incinerators would establish risk-based emission limits for each metal using an approach similar to that proposed for boilers and industrial furnaces. Emission '&its would be established as a function of effective stack height, terrain (i.e., complex versus noncomplex) and land use (i.e., urban versus rural). (The notice of supplemental information for the boiler and furnace rule will request comment on using this same approach so that emission limits will be identical for incinerators, boilers, and industrial furn~ces.) Current thinking on the proposed PIC controls for incinerators would establish a three-tiered approach to establishing CO flue gas limits in the permit. Conformance with any tier is acceptable. Under Tier I, the permit would limit CO levels to 100 ppm over a 60 minute rolling average. An alternate standard requiring less sophisticated and expensive monitoring and recording equipment would also be provided -- CO levels could not exceed 100 ppm for more than 6 minutes in any clock hour and a CO limit of 1000 ppm could not be exceeded at any time. (The alternate, "time above the limit" approach ensures that mass CO emissions per hour are equivalent to CO emissions allowed under the 60 minute rolling average.) Tier II would allow CO levels to be established as those that occur during the trial burn provided that nonmethane hydrocarbon emissions do not exceed de minimis, risk-based levels. The de minimis levels for nonmethane hydrocarbons were developed assuming: (1) all nonmethane hydrocarbons as measured by a flame ionization detector (FID) with sampling lines heated to 250 to 350°F are carcinogenic compounds with a unit risk (i.e., increased cancer risk posed by 70 year exposure to 1 ug/m3) equivalent to the weighted average of all PIC emissions measured to date t~om incinerators, boilers and industrial furnaces burning ,J flBzardous waste (including chlorinated dioxin and furan emissions) ; and (2) the acceptable increased lifetime cancer risk to the most exposed individual is 1 in 100,000. The resulting acceptable ambier.t level of nonmethane hydrocarbons and the conservative -3- |