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as a swamp. The relatively high values shown along the eastern margins of the aquifer <br />may reflect a bias in the specific capacity and laboratory test results, due to uncertainties <br />in aquifer saturated thickness and the collection of lab samples from outcrops, <br />respectively. The large range of values shown in Figures 5c and 5d are evidence of <br />potential bias in the results obtained from specific capacity and laboratory tests. <br />3.1.4 Upper Arapahoe Aquifer Hydraulic Conductivity Data <br />A total of 102 K values were obtained from the Upper Arapahoe Aquifer. The K values <br />range from 0.01 to 6.7 ft/day with a median value of 1.1 ft/day. The K data are <br />presented in Figure 9 and summarized statistically in Table 2. <br />As shown in Figure 9, the data indicate there is significant variability, which is typical of <br />fluvial deposits (Freeze and Cherry 1979). However, most of the data from aquifer <br />pumping tests are from Robson (1983), and, as indicated in Section 1.2, it is unknown <br />whether these test data are from the Upper or Lower Arapahoe Aquifer. Even so, there <br />does appear to be a zone of relatively higher K values along the southern edge of this <br />aquifer as shown by data from sources other than Robson (1983). This could indicate <br />proximity to a sediment source area to the south as described by Raynolds (2004) and a <br />more productive aquifer in the area of higher K values. <br />3.1.5 Lower and Undivided Arapahoe Aquifer Hydraulic Conductivity Data <br />A total of 426 K values were obtained from the Lower Arapahoe Aquifer, the second <br />largest number of data values available for any of the bedrock aquifers. The K values <br />range from 0.0003 to 42 ft/day with a median value of 1.2 ft/day. The K data are <br />presented in Figure 10 and summarized statistically in Table 2. <br />As shown in Figure 10, the data are highly concentrated in northern Douglas and <br />southwestern Arapahoe Counties, but there is a reasonable distribution of data in other <br />parts of the aquifer except for the area where Douglas, Elbert and El Paso Counties join. <br />The results from different types of tests (pumping, specific capacity, and laboratory) <br />show consistent results. The highest K values obtained from this aquifer are clustered in <br />an area in Northern Douglas County. <br />Lower K values are generally found in the northwest, southwest and eastern portions of <br />the aquifer. This spatial trend of high K values is consistent with a source for these <br />aquifer materials entering the current vicinity of the Denver Basin from a location in <br />western Douglas County. The region of high K values is also where the Arapahoe <br />Aquifer reaches its greatest thickness resulting in some of the greatest well yields from <br />the Denver Basin bedrock aquifers. This area is thought to be the location of a large <br />distributary fan deposit, the Wildcat Mountain Fan, resulting from the deposition of <br />sediments originating in mountains to the west (Raynolds 2004). <br />3.1.6 Laramie-Fox Hills Aquifer Hydraulic Conductivity Data <br />A total of 357 hydraulic conductivity values were obtained from the Laramie-Fox Hills <br />Aquifer. The K values range from 0.0004 to 262 ft/day with a median value of 0.5 <br />ft/day. The K data are presented in Figure 11 and summarized statistically in Table 2. <br />SPDSS Phase 2 Task 43.2 TM -Final 21 <br />2/ 13/ 2006 <br />