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4.0 DATA ELEMENTS The State rules relating to wellhead protection require that wellhead protection plans include specific data elements. Each of these elements was discussed specifically in the second scoping meeting with the MDH and are presented briefly here. 4.1 Geology A complete description of geologic conditions in the wellhead protection area is provided in City of CentervilleWellhead Protection Plan, Part 1(Amendment), prepared by Stantec (December 2018), which was approved by the MDH in January 2019(4720.5400, subp. 1, item B). See Appendix H.In general, it was determined that the Prairie du Chien-Jordan aquifer is not hydraulically connected to nearby surface waters. Confining units are generally limited to areas where the basal layer of the St. Peter sandstone is presentand/or layers of clay are present. While protective layers of clay are believed to cover most of the DWSMA and offer some protection from contaminants at the land surface, a “moderate” vulnerability designation was assigned to the DWSMA to reflect elevated tritium levels detected in Well 2. 4.2 Groundwater Quality The quality of water from the City’s wells is generally good.The 2019 Consumer Confidence Report is provided in Appendix C. Nitrates levels in the primary municipal wellis typically very low, at or near the detection limit.No other human-sourced contaminants have beendetected in the City’s wells. Tritium testing at Well 2 has shown 2.6 tritium units, suggesting that some younger water is entering the aquifer that supplies this well. This tritium resultwas the reason for assigning a moderate vulnerability level to the DWSMA. 4.3 Groundwater Quantity There are a number of wells in surrounding areas which are covered by State groundwater appropriation permits. The Part1 report (Appendix H) shows nearby wells and their volume pumped between 2012and 2016. Data indicates there are no known well interference problems in or around the CentervilleDWSMA. Data showing all well appropriations permits and volumes pumped can be viewed at the Department of Natural Resources website at http://www.dnr.state.mn.us/waters/watermgmt_section/appropriations/wateruse.html. 5.0 CONTAMINANT SOURCE INVENTORY 10 193803358 Stantec Consulting Services, Inc.