2012-11-20_HYDROLOGY - M1982131 - Laserfiche WebLink

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Mr. Jared Dains Bucklen SWSP November 20, 2012 Page 3 with one pump usually running continuously, and two pumps running in high water events. The water is pumped into two settling ponds north of Amendment Area A and immediately adjacent to the Cache la Poudre River, where it is allowed to seep and discharge into the river. Historically, the volume of water pumped has not been accounted for or otherwise tracked. This SWSP approval requires monthly volumes of dewatering discharge into the settling ponds to be recorded. However, these volumes do not need to be analyzed for depletions to the river as long as pumping remains relatively constant month to month. Dewatering operations that are constant and continuous will eventually reach a steady state condition where the accretions to the river generated by dewatering are equal to the depletions to the river generated by dewatering. Given the long duration of historical dewatering operations, it is assumed the pit's dewatering operations are in a steady state condition. At least 3 years from the expected cessation of dewatering, a plan that addresses the replacement of long term lagged depletions, including depletions that occur with the "first fill" of the pit must be submitted to our office. Should dewatering at the pit cease during this SWSP approval period, this SWSP will automatically be void until an amendment is sought and approved. The monthly evaporative and operational depletions to the Cache la Poudre River were lagged from the pit using the Alluvial Water Accounting System (AWAS) program developed by the Integrated Decision Support (IDS) Group at Colorado State University with the following parameters: • Distance from the gravel pit centroid to the river (X) = 1,390 feet • Alluvial aquifer width (W) = 10,650 feet • Specific yield (S) = 0.2 • Transmissivity (T) = 120,000 gallons per day per foot The stream depletion model shows that the Bucklen Pit's stream depletions will total approximately 38.34 acre -feet during WY 2013, as shown on the attached Table 3. Depletions will also occur as a result of using Greeley Irrigation Company (GIC) shares. GIC shares include subsurface return flow obligations which this plan is responsible to cover. This is described in detail under the replacement section for the GIC shares and is shown in Table 4. Replacements The sources of replacement water to be used for this SWSP are: 1) consumptive use credits associated with the historical irrigation use of five shares of the Greeley Irrigation Company ( "GIC "), 2) a lease of 19.4 acre -feet of augmentation water provided by the City of Aurora ( "Aurora "), and 3) a lease of 1.1 acre -feet of augmentation water provided by the Graham Ditch Company ( "GDC "). See Table 5 for a monthly breakdown of replacement water for WY 2013. Greeley Irrigation Company ( "GIC') Shares The applicant owns six shares of GIC shares, of which five are dedicated to this plan. The applicant's GIC shares will be delivered to the Cache La Poudre River at the 23 Avenue and Fourth Street Return Station (WDID 0302318). Those replacements will be made directly adjacent to the Bucklen Pit. Due to close proximity of the return station to the Bucklen Pit, no transit losses will be assessed to the delivery of the GIC shares. A portion of the Greeley Canal No. 3 (WDID 0300934) was changed in Division 1 Water Court in case no. 96CW658 based on a ditch -wide analysis by the Poudre Prairie Mutual Reservoir and Irrigation Company. The use of the subject ditch shares in this plan shall be in accordance with the