Agenda - Council - 03/23/1982 - Laserfiche WebLink

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I I I I ! :1 I I I I - 5 - Existin~ and Future Development Patterns Oak Grove Township is located well beyond the regional Metropolitan Urban Ser- vice Area. Urban services such as sewer and water are not planned for the area in this century, if ever. The community is expected to continue to exhibit a mixed agricultural/rural residential character. Increased residential devel- opment near the site in the future could lead to conflict .with the proposed site. Nevertheless, it cannot be said at this time that the si, re is seriously in conflict with existing and future development patterns. Environmental Impacts A review of well logs near the site indicates that the surrounding area has a continuous layer of sandy soils, 10 to 50 feet thick, overlying a 40- to 120- foot layer of clayey glacial till. This in turn is underlain by the Franconia bedrock formation or by bedrock valleys (see Figure 3). Soil borings taken on-site all showed a surface sandy mantle over 40 feet deep. An underlying layer of silty clay was seen in the borings. Groundwater was found beneath the site at depths-ranging from 8 to 26 feet. The surficial groundwater flows beneath the site to the south and discharges to Cedar Creek. The proposed fill area abuts a DNR Type 7 (tamarack/hardwood) wetland which forms the floodplain for Cedar Creek. Information from the Minnesota Geological Survey indicates there is a buried bedrock valley immediately south of the site and existing landfill. The site may overlie a side wall of this bedrock valley. ~[i-.ii! . ~MPCA's certification of the site as intrinsically suitable required that the I I I I I I I site be lined and a'leachate collection system installed. The presence of ~- Cedar Creek as a nearby discharge zone in the event of'failure of'the leachate ........ Control system was believed to be a mitigating factor. The. MPCA review of the . ..~.. ] site noted that underlying sandy soil "allows very rapid percolation to the water table and provides little if any leachate attenuation."* These soils also do not satisfy Council criteria for soil type suitable for landfills. Anoka County's evaluation of the hydrogeology of the site noted that the under- lying bedrock aquifer rises toward the surface approximately one-half mile east- northeast of the site. If this aquifer is not protected by an overlying con- fining layer, there is a potential for residential development in this area to alter the surficial groundwater flow. In the course of further environmental studies for this site, the adequacy of the proposed single liner and leachate collection system should be further evaluated in light of possible risk to this area northeast of the site. MPCA's review'also specified that collection channels will be needed in order to prevent contaminated surface water from leaving the site. Surface drainage for the site is ~oward the tamarack wetland at the southern edge of the fill area and toward Cedar Creek which drains to the Rum River 1.25 miles to the west. * MPCA, Report on the Director's Proposed Recommendations, 1981.