01-14-2014 PC MIN - Laserfiche WebLink

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Planning Commission Minutes Page 7 January 14,2014 Kirstin Pauly, Sunde Engineering—stated that these are minimum excavation grades and final reclamation grades will come up at least 5 feet and up to 20 feet, depending upon the actual end use grades and the realignment of 221St Avenue. She noted that there are other mining operations in the city that mine into the groundwater table and the concern is not the actual mining in the water table,it is how fuel is managed on site. Ms. Paul explained that protection measures include having the secondary containment, a groundwater protection plan and groundwater monitoring. Commissioner Chad Westberg asked how runoff or erosion might impact the groundwater. He stated that it is his understanding the water table in this area is fairly high. He also asked if the MPCA also reviews this. Ms. Pauly stated that an NPDES Permit is required which looks erosion, sedimentation and suspended solids and one of the best management practices the MPCA encourage is to infiltrate into the groundwater. The practices in place at this site are in alignment with the MPCA best management practices. She explained that the groundwater elevations to be used is really about 2 feet lower that the groundwater. This additional 2 feet would act as filter medium (sands,gravels and other fine materials) to clean the water. Commissioner Chad Westberg asked if the testing is done by random placed wells on site. Ms. Pauly explained there is a production well on site that is tested annually. She noted that that several wells were put down as part of Elk River Landfill's Hydrogeological study on the site and Elk River Landfill will continue to monitor some of those wells,but that Tiller's one 111 production well will be what they will continue to test annually. Commissioner Mark Konietzko asked if this groundwater system provides drinking water to any of the residents in this area. Ms. Pauly stated that the groundwater flows to the southwest and there are residential wells that are located further on down. She stated that there are several layers of aquifer in this area, so she did not know specifically if they are drawing from this upper aquifer or not. Commissioner Konietzko asked if there are any other situations where mining is done in the water table and residents are getting their water from this same water source. Ms. Pauly stated that Midwest Asphalt mines in the groundwater table and that water also flows to the southwest. She noted there are other operations where mining is done up to and into the water table. Commissioner Konietzko asked what impact the proposed use could have on groundwater. Mr.Leeseberg stated that he had no information on what impact,if any, mining down to groundwater level would have on surrounding residential wells. He noted that Elk River Municipal Utilities does not review these types of issues, since it does not impact the city water supply. He stated that he will check with the city's consultant and noted that the conditions address preventative measures. Mike Caron, 7200 Hemlock Lane,Maple Grove,representative of Tiller Corporation— stated that it is quite common to mine into the groundwater for sand and gravel. He stated that Tiller has mined into the groundwater in Elk River and Livonia Township; mines to the east in Livonia have mined into the groundwater;Knife River mines in the groundwater; and • also, the property owned by BWB and Plaisted which was platted tonight, has been mined into the groundwater. He stated it is very common practice and has been very thoroughly