1 October 1997
pollution control technology. In the case of incinerator plants, the performance of a spray dry
scrubber followed by a bag house is considered the BACT by most states. Dry lime and wet
scrubber systems have been shown to provide performance comparable to a spray dry unit. The
manufacturers should be able to provide design and performance data to prove their claims in order
to get the design approved and obtain a construction permit. Use of a relatively new technology for
which there is little or no data to prove it can perform as well as a spray dry scrubber will probably
not be approved.
(3) LAER. If the plant is to be built in a non-attainment area (poor ambient air quality), it
may be required to comply with the LAER concept. The plant will be designed to achieve the
lowest emission rates technically possible, regardless of cost.
(4) MACT. An emission limitation for new sources which is not less stringent than the
emission limitation achieved in practice by the best controlled similar source. Reflects the maximum
degree of reduction in emissions of hazardous air pollutants that the administrator (taking into
consideration the cost of achieving such emission reduction, any non-air quality health and
environmental impacts and energy requirements), determines is achievable by sources in the
category or subcategory to which such emission standard applies.
(5) RACT. Devices, system process modifications or other apparatus of techniques that are
reasonably available taking the following into account:
- The necessity of imposing such controls in order to attain and maintain a national ambient air
- The social, environmental and economic impact of such controls.
- Alternative means of providing for attainment and maintenance of such standard.
e. Emission Trade-Offs. If the ambient air quality is extremely poor, it may be necessary to
eliminate or reduce emissions from existing sources before the incinerator plant can be built