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Mr. Tom Schreiner, Division of Minerals and Geology <br />March 23, 2005 <br />Page 6 <br />~~ <br />CIVIL RES'AURCES, LLC <br />above the groundwater level. This condition will require that reclamation closely follow the active mining <br />progress. <br />12. In conformance with Rule 3.1.6(1), please describe the recharge rate to the aquifer from pit de- <br />watering operations, if appropriate, and any other existing sources of aquifer recharge in the <br />surrounding area. Please respond. <br />Section 4.2.1 of the Groundwater Model Report discusses recharge and specifically states that each <br />recharge site will be constructed to handle at least 500 gallons per minute of dewatering water. Each <br />recharge site will be constructed as shown on attached Figure entitled 5, Typical Recharge Pipe Section. <br />The surrounding area will still be receiving recharge from precipitation, irrigation wells and ditches. <br />13. In conformance with Rule 3.1.6(1), please characterize the response of the aquifer during the <br />Time of "maximum de-watering disturbance" as noted above in Item 10 and also coincident during <br />the time of peak demand for groundwater resources by surrounding domestic waters and irrigation <br />water users. Also, please describe the length of time necessary to maintain pit de-watering <br />operations until such time that all three (3) water storage facilities are completed, inspected, and <br />approved for water storage use by the Office of the State Engineer. Included in this characterization <br />should be an assessment of the hydrologic impacts to nearby surface water features, such as <br />wetlands, and to domestic as well as irrigation water users. Such assessment should include a <br />description of the lateral and vertical extent of the pit "cone of depression" expected and does the <br />cone of depression extend into the water level left after use by surrounding domestic and/or <br />irrigation water users. <br />Dewatering disturbances will occur and the modeling performed in the groundwater model analyzed <br />practical mining operations and took into account the response this stress would have on the aquifer as <br />presented in Section 4.2 of the Groundwater Model Report and Figure 11a. <br />Any wetlands in the area (except along the South Platte River) are surface water fed. Therefore, effects to <br />the groundwater from dewatering would have no effect on those wetlands. <br />Dewatering operations may continue for 20 years. The cone of depression will not extend into neighboring <br />phases due to remedial measures discussed in Section 4.3. <br />14. In conformance with Rule 3.1.6(1), please describe in detail the mitigation measures to be <br />implemented by the operator to minimize the affects to surface water sources and groundwater <br />users as predicted in Item 12 above. <br />The mitigation measures to be implemented as discussed in Section 4.2.1 of the Groundwater Model Report <br />will be recharge sites that receive pit dewatering water at the discussed flow rates in the Groundwater <br />Model. These mitigation measures will be implemented as mining proceeds and will decrease the effective <br />radius of dewatering as shown in Figure 11a of the Groundwater Model. <br />15. In order to verify the hydrologic impacts predicted during the mining and reclamation phases of <br />the operation, the Division requests that the applicant provide a detailed "Groundwater Monitoring <br />Program" to be Implemented prior to mining (minimum of 12 months of baseline data collection <br />required prior to pit de•watering activities); and throughout the mining and reclamation phases of <br />the operation. The monitoring program will need to specify fhe details of frequency of monitoring, <br />