2010-07-07_HYDROLOGY - M1999006 - Laserfiche WebLink

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Cheryl Signs, P.E. Page 2 Kurtz Pit, DRMS-1999-006 You have provided a monthly breakdown of the annual depletions made up of 235.42 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. A phreathophyte credit for the native salt grass has been applied to this plan which reduced the net evaporation depletions to 235.42 acre-feet. 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-Cuddle method with Longmont 2ESE weather station data. For the purpose of this SWSP, the phreathophyte credit is accepted, however no benefit 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. 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. 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=80 feet, and the location of the parallel impermeable boundary was estimated to be 4,000 feet from the stream. Replacement The proposed source of replacement for this pit is the junior water rights that were decreed in case no. 2001 CW274. The water rights decreed in case no. 2001 CW274 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 exchange for releases from any or all of the reservoirs or any or all of the direct flow sources. The decreed information for these junior water rights is shown in the following table: WDID Source Appropriation Date Decreed Amount 0600532 VCI Godding Ditch Diversion from Idaho Creek 08/10/2001 11 cfs 0600551 VCI Rural Ditch Diversion from Boulder Creek 08/10/2001 11 cfs 0600756 VCI Rural Ditch Diversion from Idaho Creek 08/10/2001 11 cfs 0500642 VCI Goddin Hollow Diversion 09/08/2000 11 cfs 0500589 VCI Last Chance Ditch Diversion 08/10/2001 11 cfs 0504001 112 Reservoir 08/10/2001 1,552 acre-feet 0504003 Dakolios Reservoir 08/10/2001 1,104 acre-feet 0504002 Von Ohlen Reservoir 08/10/2001 1,300 acre-feet 0504000 Kurtz Reservoir 08/10/2001 4,000 acre-feet it (vote: I otal direct aiversion from all sources not to exceed 11 cfs. Storage rates are 90 cfs for Rural Ditch and Godding Ditch, 10 cfs for Godding Hollow and 100 cfs for Last Chance Ditch.