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Bernhardt Pit Groundwater Evaluation <br /> May 2023 Page 2 of 31 <br /> 6. Documented the data, our assumptions, results, a discussion of parameter uncertainty and <br /> model sensitivity and conclusions in Appendix A- Groundwater Evaluation and <br /> Modeling. <br /> Results Summary <br /> We used the USGS MODFLOW2000 (Harbaugh et al, 2000) modeling program to evaluate the <br /> existing and future groundwater conditions at the Bernhardt pit and the Groundwater Vistas <br /> (version 8) Groundwater Users Interface (GUI) to prepare model files and evaluate the results. <br /> Using reasonable boundary conditions and aquifer properties, the model predicts that water level <br /> changes of approximately +- 2.5 feet (Figure A10). Mounding greater than 0.5 feet extends <br /> approximately 1,500 feet up-gradient (south), and shadowing less than -0.5 feet can be expected <br /> approximately 2000 feet downgradient (north). There are five registered wells located within <br /> modeled change between+/- 0.5 to 1.0 ft as summarized in Table 1. Four of the wells are located <br /> in the mounding area on the up-gradient side of the pit and one well (13701-F) is located on the <br /> downgradient(shadow) side. Two of the four up-gradient wells belong to the Bernhardt's which <br /> are now owned by the applicant. <br /> Table 1 —Water Level Changes>0.5 ft in Re istered Wells <br /> Permit No. Well Owner Twn I Rng Sec Qtr�Qtr Modeled Change(ft) SEO Link <br /> 14477-F I KASTEN CHERYL L&CARLENE M KASTEN 4N 67W 24 SWNW +0.5to 1.0ft httos://dwr.state.co.us/Tc)ols/WellPermits/0228691 <br /> 42519-F BERNHARDT,DAIRY 4N 67W 24 SWNE +0.5to 1.0ft httns://dwr.state.co.us/Tools/WellPermits/0353174A <br /> S-WCB MONGOMERY,VIOLET 4N 67W 24 SENW +0.5to 1.0ft https://dwr.state.co.us/Tools/WellPermits/C620005 <br /> 85-RF BERNHARDT,BEN 4N 67W 24 SWNE +1.0to 1.5ft https:/Idwr.state.co.us/Tools/WellPermits/9058262 <br /> 13701-F BERNHARDT,HERBERT B 4N 67W 1 12 1 SWSW -0.5to4.0ft https:fldwr.state.co.us/Tools/WellPermits/90617l6 <br /> We identified 29 registered wells that have reported water level depths (when drilled) less than 10 <br /> feet deep. However,none of these wells none are located with the modeled mounding area. <br /> Conclusions and Recommendations <br /> We do not believe the Bernhardt Pit slurry wall will have any adverse effect on the wells identified <br /> in Table 1 because the modeled impacts are less than 1 foot, which is less than the seasonal <br /> groundwater change. Therefore, we do not expect any of the well owners within the area of <br /> change will notice any impacts. If they do, we recommend that ongoing monitoring occur to <br /> quantify those impacts. <br /> If you have any questions,please give me a call. <br /> Sincerely, <br /> McGrane Water Engineers,Inc. <br /> Dennis McGrane, P.E., C.P.G <br /> McGrane Water Engineering,LLC <br /> 1669 Apple Valley Rd. •Lyons,CO 80540 0 Phone:(303)917-1247;email:dennis@mcgranewater.com <br />