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1.1 Autumn Water Level Measurements <br />The DWR measures water levels in a network of wells located throughout the Denver Basin <br />bedrock aquifers and the alluvial aquifers of the South Platte River Basin. The DWR measures <br />water levels in the spring and fall for the alluvial aquifer along the main stem of the South Platte <br />River. In contrast, the DWR measures water levels only in the spring for the alluvial aquifers of <br />some of the Designated Basins and in the bedrock aquifers of the Denver Basin. Therefore, the <br />focus for this task was to collect autumn water level measurements in wells of the Denver Basin <br />bedrock aquifers and the alluvial aquifers of some of the Designated Basins. <br />The first step during Phase 2 for Task 39 was to identify a set of candidate wells that had been <br />measured by the DWR since 2000. Using the Phase 1 Task 42.2 bedrock aquifer configuration <br />data and well completion information, 109 of these wells were determined to be completed in a <br />single bedrock aquifer. These 109 bedrock wells were supplemented with 11 alluvial wells from <br />Designated Basins to bring the total list of wells to be measured in the fall of 2004 to 120 wells. <br />These wells were selected to provide a good spatial distribution of measurements within each <br />aquifer. A total of 83 of the 120 wells were successfully measured in the fall of 2004 for Phase 2. <br />The same list of the 120 candidate wells was used in fall of 2005 for Phase 3. However, during <br />Phase 2 data collection, two wells were found to be capped, one well could not be found, one <br />solicited well did not exist and four wells were not visited due to budget constraints, decreasing <br />the total number of wells targeted for measurement in Phase 3 to 112. A total of 90 of the 112 <br />well measurements were obtained in Phase 3. <br />Although all of the candidate wells are part of the DWR water level measurement network, <br />many of these wells are not measured directly by the State. Water level measurements from <br />approximately 100 wells (of the 269 in the DWR bedrock network) are solicited from individual <br />municipalities, water conservancy districts or other entities. To keep consistent with the State's <br />water level data collection protocols, the wells typically measured by the State were measured <br />under this task, and wells typically solicited by the State were solicited by CDM under this task. <br />1.1.1 Water Level Measurement Methods <br />Water levels collected in this task were measured using equipment and procedures equal or <br />similar to those used by the State in their water level monitoring program. Water levels were <br />measured using several methods, including a steel tape, airline, water level conductivity meter <br />(or M-scope) and sonic water level meter. DWR equipment was used during the data collection <br />to maintain consistency with past measurements at a given well. The variety of methods used to <br />measure water levels in this task was necessary due to well access limitations, presence of in- <br />wellwiring and equipment, and depth to water. Explanations of each method with their pros <br />and cons are discussed below to assist others in deciding what equipment to use in the future. A <br />comparison of the sonic meter to other methods, made in Phase 2 Task 39 is presented in <br />Appendix A. <br />Steel Tape <br />To obtain a water level measurement using a steel tape, one needs to remove the <br />top cap of a well, disinfect the portion of the tape being lowered into the well, <br />chalk up the end portion of the tape expected to come in contact with the water <br />SPDSS Phase 3 Task 39 Technical Memarandum -Final <br />09/27/2006 <br />