Mo. Rev. Stat. § 260.243
The department of natural resources shall not issue a permit to an applicant for a commercial solid waste processing facility designed to incinerate solid waste in any county unless such facility meets the conditions established in this section. For the purposes of this section, a commercial solid waste processing facility is a facility designed to incinerate waste which accepts solid waste for a fee regardless of where such waste is generated. Any commercial solid waste processing facility which incinerates solid waste shall be located so as to provide a health and safety buffer zone to protect citizens living or working nearby. The size of the buffer zone shall be determined by the department but shall extend at least fifty feet from a facility located in a nonresidential area in a city not within a county or at least three hundred feet from a facility located elsewhere. The department shall consider the proximity of schools, businesses and houses, the prevailing winds and other factors which it deems relevant when establishing the buffer zone. Any facility located within a city not within a county shall be required to strictly adhere to the terms, conditions and provisions of its permit.
§ 260.243, RSMo