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<br /> <br />Chapter 1 <br />Data Elements and Assessment <br /> <br /> <br />I. REQUIRED DATA ELEMENTS <br /> <br />In accordance with the Minnesota Department 9rHealth's second Scoping Decision Notice (May <br />15, 2002) the following data elements are presented and assessed as it relates to the City of <br />Centerville's municipal wells. The Wellhead Protection Area (\MiPA) and Drinking Water Supply <br />Management Area (DVVSMA) of Centerville's Well #2 are vulnerable to contamination from <br />ground surface and near surface sources. Well #1 is not vulnerable. The City's DWSMAs are <br />provided in Figure 1. <br /> <br />The City has evaluated the following data elements to determine their significance in the <br />preparation and implementation of this wellhead protection plan. <br /> <br />Physical Environment <br /> <br />Geology <br />The geologic environment, surrounding Centerville's municipal wells, influences the <br />delineation of the WH PAs and well vulnerability classification. The configuration and <br />characteristics of geologic strata directly affects the infiltration of water and aquifer <br />vulnerability to contamination. <br /> <br />A county geologic atlas does not exist and focused geologic studies in the metro region do not <br />provide relevant data for the City's wellhead protection plan. No surface geophysical <br />information was identified. The Minnesota Department of Health performed a geologic and <br />hydrologic assessment of the ,region surrounding the City wells to aid in determining the <br />wellhead protection area and vulnerability. Part 1 of this plan describes the geologic strata, <br />WHPA, DWSMA, and vulnerability of the City's well. <br /> <br />Review of representative borehole geophysical and well construction records in the DWSMA <br />indicates that the aquifer units used by the City's wells (Jordan and Prairie du Chien) are <br />under low-permeability protective materials typically described as sandy clay with a thickness <br />of greater than 50 feet. <br /> <br />The geologic review indicates that regional precipitation, soil characteristics, and surface water <br />resources influence the aquifer units used by City wells. The regional influence of these <br />environmental elements extends beyond the City's DWSMAs and exceeds the scope of this <br />plan. <br /> <br />Precipitation <br />Precipitation recharges all aquifers. Recharge of the confined aquifers, used by City wells, <br />takes place on a regional scale encompassing large areas outside the City's DWSMAs. The <br />Minnesota Department of Natural Resources has maintained a system for monitoring <br />hydrologic data that addresses precipitation within the metropolitan region. <br /> <br />The primary source of moisture for precipitation in Minnesota is the tropical maritime air that <br />moves into the State from the south and southeast. The spatial variation of average (normal) <br />annual precipitation across Minnesota is determined by proximity to these moist air masses <br />coming northward out of the Gulf of Mexico. Therefore, southeastern Minnesota, averaging <br />near 32 inches, receives more precipitation than northwestern Minnesota,less than 19 inches. <br /> <br />July 3, 2007 <br /> <br />DRAFT <br />Centerville Wellhead Protection Plan (Part 2) <br /> <br />Page 1 <br />