5.1 PCSR 08-23-1994 - Laserfiche WebLink

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AUG 1 6 1994 ATTACHMENT 2 LIEXH • B.A.LIESCH ASSOCIATES, INC. 13400 15TH AVE. N. MINNEAPOLIS, MN 55441 612/559-1423 FAX:612/559-2202 GROUNDWATER MONITORING RECOMMENDATIONS FOR PROPOSED SHIELY COMPANY GRAVEL PROCESSING WELL (AUGUST 1994) INTRODUCTION Shiely Company (Shiely) proposes to expand their sand and gravel mining operation within the Elk River Sand and Gravel Mining District. The proposed expansion will include utilization of an existing Mt. Simon - Hinckley well to provide process water. The existing well (unique well #217977) is currently not in-use, but is permitted by the Minnesota Department of Natural Resources (DNR) as a well for withdrawal of up to 50 million gallons per year (DNR Permit #913086). It is understood that the well will provide a high capacity water supply (more than 10,000 gallons per day or 1 million gallons per year) for the mining operation. Recommendations for monitoring the effect of the high capacity well use on the groundwater resource are provided herein. The proposed monitoring is intended to provide data that can be used to further characterize aquifer response to pumping, provide baseline data and identify and minimize potential impact on residential • water supply wells located outside of the mining District. Development and implementation of a groundwater monitoring program was recommended in the Elk River Sand and Gravel Mining District EIS and further recommended by the DNR following their review of the EIS. The monitoring recommended in the following sections includes installation of monitoring wells in the mining district buffer zone, water level monitoring and background water quality monitoring. RECOMMENDED MONITORING WELLS Two monitoring wells are recommended for installation in the mining district buffer zone south and west of the Shiely high capacity well. The recommended wells should be targeted for completion at the approximate depth of the nearby residential wells and thereby monitor the primary groundwater zone used by the residential wells for possible impacts resulting from use of the Shiely well. According to the EIS (Table 3.3-1) most of the residential wells west of the District are completed in the first confined glacial unit which occurs at a general elevation of 860 feet NGVD. The well depths range from approximately 65 to 130 feet. Therefore, a monitoring well installed to approximately the same elevation as these residential wells is recommended for installation west of the pumping well. The attached figure provides a general location for the recommended well. IIA monitoring well is also recommended south of the Shiely well. The EIS indicates (Table 3.3-1) that the majority of the residential wells south of the mining district are completed in the Mt. Simon - Hinckley Aquifer at depths of 230 to 400 feet. As such a Mt. Simon - Hinckley monitoring well is recommended for installation near the general location