Surface Geologic Processes

(1) Exclusion Criteria. (a) Surface Geologic Process. Exclude sites where the probable waste management area would be located in the vicinity of surface geologic processes such as mass wasting, erosion, slumping, landsliding, whichoccurwithsuchfrequency and extent that such events would be reasonably likely to adversely affect the ability of the site to meet any DPH performance objectives or preclude adequate modeling and prediction of long term impacts. (b) Slope. Exclude sites where the probable waste management area would have an average slope greater than 20%. (2) Conditional Consideration Criteria. (a) Contaminant Migration. Consider sites with surficial deposits unlikely to substantially retard groundwater flow and radionuclide migration beneath the facility on compliance with 310 CMR 43.40(3). (b) Seismic Impact Zone. Consider sites located in a seismic impact zone on the condition that it can be reasonably demonstrated that the engineered structures, systems and components important to waste isolation and release containment functions of suitable facilities are sufficiently capable of resisting the maximum horizontal acceleration in lithified earth material to prevent a release of radiation which results in a dose exposure in excess of DPH performance objectives. (3) Preference Criteria. (a) Liquefaction Performance Standard. Prefer sites with less potential to subject the probable waste management area to potential liquefaction, over sites withgreater potential for liquefaction. (b) Soil Stability. Prefer sites that provide a more stable foundation for engineered containment structures, over sites with a less stable foundation. (c) Subsurface Dissolution. Prefer sites that demonstrate less significant past or active dissolution, over sites which demonstrate more dissolution. (d) Overburden Deposition Process. Prefer sites where the overburden is composed of lesser amounts of varved clay or holocene lacustrine deposits, over sites with greater amounts of such materials. Prefer sites inwhichthe overburdenis composed of greater amounts of glacial till, over sites with lesser amounts of till. (e) Overburden Composition and Depth. Prefer sites with thicker unconsolidated units and with a higher clay or silt content, over sites with thinner units or lower clay/silt content for facilities located above the ground or near to the surface. (f) Seismic Impact Zone. Prefer sites that have a lower predicted maximum horizontal ground acceleration, expressed as a percentage of the earth gravitation pull (percent g), over sites with a higher percent g. (g) Complexity and Uniformity. Prefer sites that have a less complex tectonic history and geologic structure, over sites that have a more complex tectonic history and geologic structure. (h) Retarding Migration. Prefer sites where natural characteristics, including but not limited to the permeability and the sorptive potential of the subsurface materials, provide greater potential to retard the movement of radionuclides, over sites with less retardation capability. (i) Erosion. Prefer sites exhibiting less potential erosion characteristics, over sites exhibiting greater potential erosion characteristics.