Oregon Revised Statutes Public Health and Safety § 459.057

(1) Before issuing a permit for a landfill to be established under ORS 459.047 or 459.049 or for a disposal site established as a conditional use in an area zoned for exclusive farm use within the boundaries of Clackamas, Marion, Multnomah, Polk or Washington County, the Department of Environmental Quality shall require that, to the extent legally, technically and economically feasible only solid waste from transfer stations or solid waste residues from material or energy recovery facilities will be deposited in the disposal site. As used in this section, “transfer station” means a site established for the collection and temporary storage of solid waste pending shipment in a compact and orderly manner to a disposal site.

(2) Nothing in this section shall be construed to prohibit the department from allowing other solid waste to be deposited in the disposal site in order to protect the public health and safety or the waters of this state during a temporary emergency condition.