Agenda - Council - 11/25/1980 - Laserfiche WebLink

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HYDROGEOLOGY -- The Minnesota G~ological Survey (MGS) has prepared a report to the ~,¥MB that recommends that hazardous waste disposal sites be located away from major groundwater systems, such as significant bedrock and surficial aquifers. This would insure that a disposal facility would be less likely to pollute these natural resources by accidental seepage. MGS recommends that the WMB divide the State into three categories: · Areas where there is a Iow probability of groundwater contamination because significant groundwater resources are probably absent. · Areas where productive groundwater systems may or may not exist, so that there is a reduced probability of finding naturally favorable sites. · Areas where significant groundwater systems exist, and where extensive engineering or natural protection (e.g., Iow permeability clay so~ls) would be necessary to safeguard these groundwater systems from any accldental seepage from a disposal facility. SOIL PERMEABILITY --The U. S. Environmental Protection Agency (EPA) has stated that thick tayers of iow permeable soils -- such as certain heavy clays -- will inhibit the flow of spiged wastes into groundwater systems below even if the wastes somehow penetrate the engineered safeguards of a facility (such as liners and collection devices). Therefore, thick, impermeable soils might compensate for inadequacies in the hydrogeology factor. EPA at one point used the figures of five feet of material with a permeability of less than two inches per year. Such exact data are not available on a statewide basis, so on-site investigations would be necessary to determine the permeabilities and soil thicknesses of specific tracts of land -- if the citizens of the State and the WMB finally decide that soil permeability is an important siting factor. SURFACE WATERS AND FLOODPLAINS -- The Pollution Control Agency and the U. S. Environmental Protection Agency regulate hazardous waste disposal. Though they offer few specific siting criteria, they do prohibit certain locations, including: within a 100-year flood plain; within 1,000 feet of shoreland; and within a wetland. These surface water factors must be observed by the WMB in the siting process, although they may become most relevant only after specific sites are being considered. This is because many of these prohibited areas are often less than a township in size. So although~ part of a township is excluded, there still may be enough land within it for an acceptable site. prepared by: Minnesota Waste Management Board 7323 58th Avenue North Crystal, MN 55428