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significant K variation over short distances (Freeze and Cherry 1979), as has been <br />observed in the Denver Basin (Nielson 2001). The Laramie-Fox Hills Aquifer was <br />deposited in a near shore beach environment as seas receded to the east. Though shale <br />beds are found within the Laramie-Fox Hills Aquifer, the materials composing the <br />aquifer are generally more uniformly distributed in massive beds of sandstone with less <br />spatial variation in K value than the overlying formations (Romero 1976). <br />To help facilitate analysis, a set of box plot figures were prepared for the K values for <br />each of the six Denver Basin Region bedrock aquifers. Figure 5a presents a statistical <br />summary of K values from the three major types of data. To allow separate evaluation <br />and comparison of each type of test used to determine K, the values are also presented <br />separately for aquifer pumping tests, specific capacity tests, and laboratory tests in <br />Figures 5b, 5c, and 5d, respectively. Evaluation of the box plots indicates a consistent K <br />trend among the values obtained from the three data sources. <br />During evaluation of the aquifer pumping test and specific capacity test K data, a <br />consistent trend can be observed between these two test types. The data obtained from <br />the Upper Dawson and from the Upper and Lower Arapahoe Aquifers have higher <br />median K values indicating these aquifers should be more productive than the Lower <br />Dawson, Denver and Laramie-Fox Hills Aquifers. The specific capacity derived data for <br />the Upper and Lower Arapahoe Aquifers are lower than values obtained from aquifer <br />pumping tests. One explanation for this is that a large number of the aquifer pumping <br />test data values obtained from the Arapahoe Aquifer are clustered in the region between <br />Denver and Castle Rock, where the Arapahoe is generally more productive. Most of the <br />specific capacity data are from a random geographic distribution of wells, many of <br />which are installed in regions of the Upper and Lower Arapahoe Aquifer generally with <br />lower K values, as confirmed by aquifer pumping test values. The Denver and Laramie- <br />Fox Hills median K values are generally the lowest among median values from both <br />types of data. <br />When box plots from aquifer pumping and specific capacity tests are compared to the <br />box plots from all data types or lab data, similar trends are apparent between the data <br />types. However the aquifer pumping and specific capacity test values exhibit less <br />spread between the minimum and maximum values, as well as generally between the <br />quartile values. The wide ranges can be seen to originate in the values obtained from lab <br />testing. The widest variations in K values are observed in the lab data. This is likely due <br />to the fact that core samples are derived from very small intervals of aquifer materials <br />not as likely to be representative of bulk aquifer conditions as the intervals measured by <br />aquifer pumping or specific capacity tests. Additionally, the exact type of materials <br />cored is not available from many of the lab sample data sources and lab samples can be <br />biased due to factors discussed in Section 1.1. <br />The aquifer K data are described in the following subsections for each aquifer. Maps of <br />the Denver Basin Region showing the geographic distribution of the bedrock aquifer K <br />data are presented in Figures 6-11. <br />SPDSS Phase 2 Task 43.2 TM -Final 19 <br />2/ 13/ 2006 <br />