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"The uppermost aquifer within the mining district is a water table aquifer present within <br />the gravel deposits. Several glacial aquifer sequences are present beneath the water table <br />aquifer and do not appear to be in complete hydraulic connection with the water table <br />aquifer. These confined aquifer units are important water supplies to residential housing <br />developments around the perimeter of the mining district. The glacial aquifer systems are <br />separated from deeper bedrock aquifer units by the confining properties of the Eau Claire <br />formation and till units overlying the Eau Claire Formation. The Eau Claire formation <br />overlies the Mount Simon-Hinckley aquifer which is the lowermost aquifer in the vicinity <br />of the mining district. Bedrock aquifers beneath the Eau Claire formation may be under <br />artisan pressure where confined by the Eau Claire formation and/or till units." <br /> <br />"Shallow groundwater in the mining district is present as an unconfined water table <br />aquifer. Water table conditions are manifested within the esker complex at elevations <br />ranging from 950 in the northern part of the district to 925 at the southern margin. The <br />thickness of unsaturated sand and gravel ranges between 40 and 70 feet. The water table <br />aquifer is approximately 30 feet thick throughout the mining district." <br /> <br />"Various other sand and gravel units are present beneath the water table aquifer. The first <br />confined glacial aquifer beneath the water table aquifer occurs at a general elevation of <br />860 NGVD with a variable thickness of between 20 and 80 feet. This unit is utilized as <br />the primary water supply for residential developments west of the district. Other deeper <br />glacial aquifers are also present but are limited in thickness. The Mt. Simon-Hinckley <br />formations combine to form one confined aquifer and together are generally 150 feet <br />thick. There are no significant aquifer units beneath the Mt. Simon-Hinckley aquifer." <br /> <br />"The esker complex contains numerous depressions both natural and man-made that <br />influence the shallow groundwater flow system. The sand and gravel surficial material is <br />conducive to the rapid infiltration of precipitation and surface water depression storage <br />into the water table. Accordingly, standing water in these areas frequently represents a <br />surface expression of the water table. The flow patterns of the water table aquifer are <br />primarily controlled by recharge and discharge, surface topography and the relative <br />permeability of the shallow geologic materials in the area. Shallow groundwater <br />discharge likely occurs at springs near the base of slopes or into topographically low <br />streams or wetlands." <br /> <br />Describe measures to avoid or minimize environmental problems due to any of these <br />hazards. <br /> <br />General measures for minimizing risk to groundwater are noted below. <br /> <br />Describe the soils on the site, giving NRCS (SCS) classifications, if known. Discuss <br />soil granularity and potential for groundwater contamination from wastes or <br />chemicals spread or spilled onto the soils. Discuss any mitigation measures to <br />prevent such contamination. <br /> <br />The following is a listing of the Site soils as identified in the Soil Survey of Sherburne <br />County, Minnesota, dated May 1998 (Soil Survey). A map depicting the numbered units <br />is included as Figure 8 in Appendix A. <br /> <br />14 <br /> <br /> <br />