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Lower Dawson and Lower Arapahoe Aquifers would cover a larger physical area than <br />the data from their overlying counterparts and would be more consistent with the <br />overall shape of the Denver Basin bedrock aquifers. This physical definition is used in <br />the SPDSS study for presentation purposes only and in no way is meant to affect the <br />legal definition of these aquifers. A graphical representation of the designations is <br />provided in Figure 3. <br />The Denver Basin Rules (DWR, 1985b) also delineate "sand" thicknesses for the various <br />aquifers. It should be noted that the designation of sand thicknesses by the DWR in the <br />geophysical log database and other works includes both sandstone and siltstone <br />lithologies determined as being capable of yielding water to a well (DWR 1997). <br />Of note is an area in the northwest corner of the Denver Basin Region referred to by the <br />DWR as the Complex Area. This is a portion of the bedrock aquifer system with <br />extensive faulting and vertical displacement in which the aquifer data should be viewed <br />with some caution due to the geologic complexity. Information on the characteristics of <br />the Laramie-Fox Hills aquifer in this Complex Area can be found in Kittleson (2004). <br />1.2.2 Data Screening <br />During Phase 1 under Task 43.2 (CDM 2004a) and during Phase 2 under Task 37 (CDM <br />2005), data were screened for the following reasons: <br />• Data from wells that could not be assigned to a specific aquifer as defined by the <br />Denver Basin Rules (DWR 1985a) <br />• Specific capacity tests of less than two hours duration <br />• Tests that were reported by the published source with insufficient location or <br />aquifer assignment information needed for analysis <br />• Wells located outside of the Denver Basin Region or outside an aquifer subcrop <br />During Phase 1, data from aquifers defined using former aquifer nomenclature were <br />evaluated to determine whether they could be reassigned to the current SPDSS aquifer <br />designations. This was possible for wells where the screened interval of the well and the <br />well location were provided in the original data report. During Phase 1, an automated <br />aquifer configuration interpolation program informally referred to as the "SB-5 <br />program," and its associated aquifer configuration database, were provided to CDM by <br />the DWR. These were used to assign a well to an aquifer for the data that did not follow <br />the current aquifer designations. These data were provided to the State as part of Phase <br />1 TMs and are included in the HydroBase data received from the State for use in Phase 2 <br />of the SPDSS. <br />Data obtained during Phase 2 Task 43.2 were screened from the database for the <br />following additional reasons, as described below: <br />• Specific capacity tests performed at wells less than 100 ft deep <br />• Lab data obtained from confining units between aquifers or impermeable units <br />between an aquifer's productive sands. <br />SPDSS Phase 2 Task 43.2 TM -Final 9 <br />2/ 13/ 2006 <br />