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Evaluation of the Groundwater Conditions <br />In The Vicinity of the Stegner Farm Gravel Mine <br />1 Introduction <br />This report presents the results of an evaluation of groundwater conditions at and adjacent to the <br />Stegner Farm gravel mine east of LaPorte, Colorado operated by Aggregate Industries-WCR, Inc <br />(Aggregate Industries). The location of the mine is shown on Figure 1. This evaluation was <br />performed at the request of Aggregate Industries in response to complaints from local residents, <br />Mr. Darwin Roe and Dr. Bill Martin, that groundwater levels beneath their properties have been <br />significantly lowered since a slurry wall was installed around the Stegner Farm property. Mr. <br />Roe's and Dr. Martin's properties are located approximately 700 and 1,200 feet downgradient of <br />the southeastern corner of the Stegner mine property, respectively. The location of their <br />properties, including Dr. Martin's pond, is also shown on Figure 1. <br />Subsequent to the initiation of this evaluation, the complaint of Mr. Roe and Dr. Martin was filed <br />on their behalf by Kathy Troudt Riley with the State Division of Minerals and Geology. The <br />Division responded to the complaint with an inspection of the Stegner Farm site on October 31, <br />2001. Based upon that inspection and the Division's review of a preliminary evaluation of <br />groundwater conditions in the azea, performed by SCIENTECH for Aggregate Industries in May <br />2001 (SCIENTECH, 2001), the Division confirmed that conditions specified in the permit <br />application with respect to triggering events necessary to install a french drain had not been met. <br />The Division's inspection report did, however, indicate the need for a more comprehensive <br />groundwater analysis to assist the Division in determining whether Aggregate Industries is <br />operating within the requirements specified in CRS 34-32.5-116(4)(h) and {i). In accordance <br />with the requirements of the Division's inspection report, the evaluation was expanded to also <br />address groundwater mounding effects upgradient of the slurry wall. <br />Following the preliminary evaluation conducted in May, 2001, Aggregate Industries established <br />in July 2001 six (6) additional groundwater monitoring locations adjacent to and southeast of the <br />gravel mine. These wells included five (5) new monitoring wells (S-9 through 5-13) and one <br />existing well (5-14). Aggregate Industries incorporated these new monitoring locations into <br />their ongoing monthly groundwater monitoring program for the Stegner Farm mine area. The <br />locations of the existing and new monitoring wells are shown on Figure 1. <br />1 <br />