The various environmental statutes envision BAT determination as a fairly straightforward “engineering problem" of identifying readily available control technologies that every well-operated plant should have in place. In fact, it has become a much more complicated standard-setting processof identifying “feasible” control technologies, evatuating their effectiveness, and assessing the character of the burdens their required use places on society — that is, economic effects such as likely plant closures and price increases, energy consumption, or other adverse environmental effects. As part of this process, for example, EPA identifies for secondary emissions from converter operations, for ex- ample, EPA concluded that BAT required further contro] at the six copper smelters with a feed material arsenic content greater than 6.5 kilograms per hour. For the remaining eight smelters, EPA concluded that BAT does not require the control of these secondary emissions.’ Similarly, in setting BAT standards for secondary emissions from the matte and slag operations of these copper smelters and the furnace emissions from glass manufacturing plants, EPA concluded that the control cost for plants with a relatively low potential to emit was unreasonable in light of the small emission reduction achieved. As a result, EPA concluded that BAT required the control of secondary emissions from matte and slag operations at only four of the fourteen low arsenic feed copper smelters and the control of arsenic emissions from fourteen of nineteen glass furnances. In discussing these proposed regulatory cutoffs, EPA noted that its analysis did not provide a clear cutoff—a “knee” in the cost curve--at which the costs of control were clearly “unreasonable” in comparison with the likely emissiun reductions.* Indeed, EPA’s emissions and removal cost data for both the low arsenic feed copper smelters and glass manufacturing plants suggest a continuum with,increasing removal costs as the potential emissions of these plants decline. (See Tables II and III.) +48 FR 33143. *48 FR 33143 and 33157. © a ee -—— | source categories and subcategories as a way of differentiating the stringency of BAT contro! requirements across plants and obtaining more reasonable regulatory standards. Certainly, it would not be feasible (or sensibie) to establish a single standard for, say, both copper smelters and glass manufacturing plants. As a result, EPA establishes standards for specific industry source categories and often uses a further subcategorization within specific industries as a way of tailoring its standards. In its proposed rule limiting inorganic arsenic emissions from various industrial sources, for example, EPA proposed a regulatory strategy involving a further categorization {and subcategorization) within specific industrial categories based on the “potential” of these. facilities to emit inorganic arsenic. Thus, EPA proposed to establish separate categories for “high” and “low” arsenicfeed copper smelters. In addition, EPA discusses and requests comments on two alternative approaches that would establish subcategories based on population exposure or public health risk. We think EPA should instead establish a more explicit approach that considers the effectiveness of alternative control requirements in terms of the likely public health gains tn light of the costs of achieving further control. To illustrate this point, we first discuss EPA’s BAT approach in setting proposed standards for sources emitting inorganic arsenic, and then consider the alternative approaches discussed by EPA for subcategorization using information on population exposure or public health risk. 1. EPA’s BAT Determination in the Proposed Rule In making its BAT determination, EPA uses the categorization (and subcategorization) of sources to differentiate the stringency of BAT-level control requirements across plants. In the case of copper smelters, for example, EPA proposes to establish two distinct source categories—“high feed arsenic” and “low feed arsenic” copper smelters—and proceeds with a separate determination of BAT-level control requirements for each of these source categories. EPA is also proposing to establish what are in effect subcategories of plants within the low arsenic feed copper smelter and glass manufacturing source categories in order to differentiate the stringency of BAT-level controls within these source categories. In the case of control requirements ——_ os : , 1-13-84 Published by THE BUREAU OF NATIONAL AFFAIAS, INC., Washington, D.C. 20037