2013-04-16_HYDROLOGY - M1999006 - Laserfiche WebLink

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Cheryl Signs, P.E. Kurtz SWSP April 15, 2013 Page 2 obtained. A copy of the affidavit is attached to this letter. For the purposes of this SWSP, this affidavit will be accepted for the dedication of the shares; however, if the State Engineer determines that a different affidavit or dedication process is necessary to assure proper dedication of the shares, additional information may be required prior to future SWSP approvals. Depletions The anticipated net depletions for this SWSP are 44.03 acre -feet per year. The currently exposed groundwater at the site has been reduced down to 7.8 acres per your February 1, 2013 letter. You have provided a monthly breakdown of the annual depletions made up of 20.06 acre -feet of net evaporative loss, 20.60 acre -feet of water lost with the mined product (which represents 700,000 tons of mined product), and 3.36 acre -feet of water used for dust control (which represents 1 water truck per day). A phreathophyte credit for the native salt grass had previously been applied to this plan which reduced the net evaporation depletions. The credit given for the salt grass in this plan was based on the 3- feet depth to ground water, pending better site - specific information. The demand for the salt grass was calculated to be 22.79 inches using the modified Blaney - Criddle method with Longmont 2ESE weather station data. In the previous SWSP approval we indicated that no credit will be given for the phreathophyte in any subsequent renewals of this plan unless the Applicant provides site - specific information regarding the depth to the ground water table at this location and the information is accepted by this office. As this information has not been provided to this office, no credit for phreathophytes has been applied to this plan. Computation of evaporation under this plan was also reduced during the ice covered period. You have assumed the ice covered period to occur during the months of January, February and December, based on the average temperatures of 26.5 °F for January, 31.0 °F for February and 29.7 °F for December; taken from the Longmont weather station. However, for the purpose of this SWSP, the Applicant shall replace the net evaporation depletions from the exposed ground water surface area that may occur during the assumed ice covered period (the months of January, February and December) for any time that the pit is not completely covered by ice. You indicated that in addition to the dewatering pumps installed in the pit for dewatering, the Applicant intends to use well with permit no. 74389 -F, for dewatering purposes at the site. This well was decreed by the Division 1 Water Court as Kurtz Well No. 11 in Case no. W -3873, for 1.84 cfs and irrigation purposes of 50 acres in the NW1 /4 of Section 28, Township 3 North, Range 67 West of the 6 P.M. The well is located on the Kurtz site DRMS permitted boundary and the well has not been used for irrigation since mining started at the Kurtz site. The IDS AWAS stream depletion model was used to determine the lagged depletions to the Saint Vrain Creek. The aquifer characteristics used in the model are: transmissivity (T)= 100,000 gallons per day per foot and specific yield (SY)= 0.28 (based on the USGS Water Supply Paper 1662D). The nearest stream is a natural drainage ditch that originates uphill from the site and flows continuously through the west side of the property to Saint Vrain Creek. The distance of the exposed ground water to the stream =720 feet, and the location of the parallel impermeable boundary was estimated to be 4,000 feet from the stream. The analysis took the depletions to a steady state condition. Therefore the lagged depletions equal the consumptive use on an annual basis at a monthly rate as shown on Table 1. Replacement The proposed source of replacement for this pit is the junior water rights that were decreed in case no. 2001CW274. The water rights decreed in case no. 2001CW274 can be used directly at the points of diversion or retained in reservoirs for storage when the water rights are in priority or used by