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Mr. Dick Wolfe, P.E. <br />December 31, 2010 <br />Page 3 <br />STREAM DEPLETIONS <br />The Baxter Road Pit is located in the Arkansas River alluvial aquifer approximately 500 feet <br />north of the river (distance from the river to the center of the permit area). Water losses at the <br />Baxter Road Pit will cause lagged depletions to the Arkansas River the time of which has been <br />determined by using State's Stream Depletion model. <br />According to Colorado Groundwater Series Circular No. 11, (USGS and Colorado Water <br />Conservation Board, 1972) the transmissivity_in this part of the Arkansas River alluvium is <br />approximately 100,000 gallons per day per foot and the specific yield is about 0.20. With this <br />distance and aquifer properties the stream depletion factor (SDF) is approximately 3.74 days. <br />The input data and results of the modeling of lagged evaporative depletions for 4.0 acre-feet of <br />exposed surface area from April 2000 through March 2012 are shown in Table 2. According to <br />the analyses, 14.16 acre-feet of depletions will occur during the 2011 plan year. <br />REPLACEMENTS <br />As previously mentioned, RBK Construction has a five-year lease agreement with Lower <br />Arkansas Valley Water Conservancy District (LAVWCD) for 21.00 acre-feet annually of <br />replacement water commencing April 1, 2010. The LAVWCD will provide up to 21.00 acre-feet <br />of Larkspur Ditch water released from storage in Pueblo Reservoir. A monthly schedule of the <br />14.16 acre-feet of replacement provided by LAVWCD for evaporative depletions at the Baxter <br />Pit are shown in Column (8) of Table 1. The LAVWCD will provide and account for the <br />appropriate replacement made each month to the Arkansas River. <br />POST PLAN DEPLETIONS <br />The State requires a bond with the Division of Minerals and Geology (DMG) for backfilling the <br />pond in addition to a financial warranty for post plan depletions occurring after the expiration of <br />the replacement water lease with LAVWCD. Copies of documentation from the DMG providing <br />a bond in the amount of $14,530 through St. Paul Fire and Marine Insurance Company Corporate <br />Surety Bond No. 400JZ5368 were provided with the 2003 renewal request. <br />The post plan depletions occurring after March, 2012 are calculated in Table 2 and total 5.28 <br />acre-feet. According to State policy, because more than 95 percent of the total depletions <br />(167.56 of the total 172.84 acre-feet) return to the stream prior to April 1, 2012, no financial <br />warranty is required for the post plan depletions.