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1fydr ikeological and Environmental Consultant-, <br />groundwater levels due to LGE's pit expansion, there was no prediction of changes to <br />surface flows in the South Platte River. MODFLOW has the capability of simulating <br />surface flows by using the stream routing package. However, using this package was not <br />considered in the modeling scenarios and as a result the impact to surface flows was not <br />estimated. <br />In addition to failing to estimate stream flows, WWE wrongly concludes that their modeling <br />results are conservative because recharge to groundwater from Little Dry Creek and <br />irrigation ditches was not included in the model. While this statement is true for predicting <br />groundwater declines, it is an incorrect assumption for water level mounding. On the <br />contrary, the opposite is true in that the modeling results will underestimate the mounding <br />effect because there will be more water added to the system if recharge is included. <br />Response to WWE Comment #9 <br />WWE report shows a rise in groundwater levels of 3 feet on the west side of mining <br />operation due to the slurry wall construction. Although this value is similar to the one in <br />Arnold's report (2 to 4 feet), WWE appears to ignore the impact of these results on the <br />South Platte River system. In the report WWE says that the mounding effect will be <br />mitigated by Little Dry Creek, which will act like a drain allowing higher groundwater <br />levels to discharge into the creek. Thus, lining of the aggregate pits will indirectly allow for <br />greater discharge into the South Platte River because Little Dry Creek confluences with the <br />South Platte River north of CR 18. Furthermore, a more direct impact will occur to the east <br />of the LGE Pits. Groundwater mounding on the south side of these pits also causes flow <br />toward the northeast which discharges into the South Platte River adjacent to the Bachofer <br />property. This discharge will increase surface flows in the channel. <br />Deere and Ault, Letters from Mr. Ross Bachofer Re¢ardine Flooding of Property East <br />of South Platte River near the Everist Fort Lupton Mine; September 22, 2010 <br />This report is a response by Deere and Ault to letters by Mr. Bachofer to the Colorado <br />Division of Reclamation, Mining, and Safety (DBMS). The report states unequivocally that <br />flooding on the Bachofer property is not related to the L.G.E.'s miming operation and the <br />construction of slurry walls. <br />Response to Deere and Ault Comment #1 <br />There is ample evidence to show that mining activities have altered the floodplain and <br />channel morphology of the South Platte River. As stated previously, the 100 year flood <br />plain level was determined by Weld County for obtaining a Flood Hazard Permit to be <br />4874.0 feet amsl at Mr. Bachofer's location. Because the level of his basement floor was <br />survey to 4874.6 feet amsl, Mr. Bachofer was not required to have a permit because his land <br />was above the 100 year floodplain level. The fact that Deere and Ault prepared a Letter of <br />Map Revision (LOMR) on behalf of Weld County and Aurora is a strong indication that the <br />original 100 -year flood plain level has changed and no longer represents current flow <br />conditions in the river. The reason that the 100 -year level is no longer accurate is because <br />7 <br />