WAC 246-250-300   Disposal site suitability requirements for land disposal.  (1) Disposal site suitability for near-surface disposal. The primary emphasis in disposal site suitability is given to isolation of wastes, and to disposal site features that ensure that the long-term performance objectives are met.

     (a) The disposal site shall be capable of being characterized, modeled, analyzed, and monitored.

     (b) Within the region where the facility is to be located, a disposal site should be selected so that projected population growth and future developments are not likely to affect the ability of the disposal facility to meet the performance objectives of this chapter.

     (c) Areas shall be avoided having known natural resources which, if exploited, would result in failure to meet the performance objectives of this chapter.

     (d) The disposal site shall be generally well drained and free of areas of flooding or frequent ponding. Waste disposal shall not take place in a one hundred-year flood plain, coastal high-hazard area or wetland, as defined in Executive Order 11988, "Flood Plain Management Guidelines."

     (e) Upstream drainage areas shall be minimized to decrease the amount of runoff which could erode or inundate waste disposal units.

     (f) The disposal site shall provide sufficient depth to the water table that groundwater intrusion, perennial or otherwise, into the waste will not occur. The department will consider an exception to this requirement to allow disposal below the water table if it can be conclusively shown that disposal site characteristics will result in molecular diffusion being the predominant means of radionuclide movement and the rate of movement will result in the performance objectives being met. In no case will waste disposal be permitted in the zone of fluctuation of the water table.

     (g) The hydrogeologic unit used for disposal shall not discharge groundwater to the surface, except for groundwater monitoring operations.

     (h) Areas shall be avoided where tectonic processes such as faulting, folding, seismic activity, or vulcanism may occur with such frequency and extent to significantly affect the ability of the disposal site to meet the performance objectives of this chapter or may preclude defensible modeling and prediction of long-term impacts.

     (i) Areas shall be avoided where surface geologic processes such as mass wasting, erosion, slumping, landsliding, or weathering occur with such frequency and extent to significantly affect the ability of the disposal site to meet the performance objectives of this chapter, or may preclude defensible modeling and prediction of long-term impacts.

     (j) An existing disposal site may be located where nearby facilities or activities could adversely impact the ability of the site to meet the performance objectives of this chapter or significantly mask the environmental monitoring program, provided an extensive environmental monitoring program exists which is designed to differentiate, to the maximum extent practicable, between contributions from the disposal site and other nearby facilities.

     (2) (Reserved.)



[Statutory Authority: RCW 43.70.040. 91-02-049 (Order 121), recodified as § 246-250-300, filed 12/27/90, effective 1/31/91. Statutory Authority: RCW 70.98.080. 87-01-031 (Order 2450), § 402-61-220, filed 12/11/86.]