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It is unclear if the model was calibrated using heads that were observed at SLM-1, SLM-2, and SLM-3, <br />that were also used to set the general head boundaries. Depending on the temporal nature of the water <br />table fluctuations, there could be a problem with transient predictions. <br />Appendix F reports that model parameters (K, T, etc.) were taken from the RGDSS. Please provide the <br />basis for these numbers, i.e., whether they were from actual aquifer tests, taken from site specific <br />literature, or taken as average values for typical strata from published literature. <br />I recommend applicant submit a ground water elevation contour map so that depicts the direction of <br />ground water flow, the hydraulic gradient, and the depth to. ground water. <br />Water levels in the pit, subsequent pumping, and pond design appear to be heavily based on conditions <br />that existed during the drought. Has the applicant considered this possibility and is inclusion of more <br />representative long-term data a concern? <br />There is a considerable body of research available on evaporation losses for center pivots. Has the <br />applicant included these relevant data in their calculations? <br />3) TDS. The alluvial aquifer is a classified area per Colorado WQCD Regulation 42. The background <br />Total Dissolved Solids concentration is in the range of 80 - 200 mg/L, but the West Pit ground water that <br />will be applied had 426 mg/L TDS when sampled July 24, 2004. This represents a significant degradation <br />in the water quality of the aquifer, and, according to CDPHE WQCD Regulation 41. and Table 4, will <br />cause a local violation of the ground water quality standard for TDS. <br />TABLE 4 <br />TDS Water Quality Standards <br />Background TDS Value (mg/1) Maximum Allowable TDS Concentrations <br />0 - 500 400 mg/1 or 1.25 times the background level, <br />whichever is least restrictive ' <br />501 -10,000 1.25 times the background value <br />10,001 or greater No limit <br />If the background TDS concentration in the aquifer is 200 mg/L, then the regulatory limit appears to be <br />400 mg/L. If the background TDS is 400 or more, then the regulatory limit appears to be 1.25 times that. <br />The West Pit water, if applied at a concentration of 426 mg/L, will be a violation of the water quality <br />criterion for TDS, which appears to be 400 mg/L. <br />4) It is unclear from the report whether BMRI is proposing more monitoring wells in addition to the <br />existing SLM series of wells. For the intensity of monitoring we should be requiring at this site, I <br />recommend more monitoring wells between pivot & compliance well to observe the fate of F and Mn <br />between the pivots and the town. This will provide better control on the concentration gradient should <br />elevated concentrations start to appear. The analytes selected for monitoring should include the full suite <br />of regulated parameters in the CDPHE Basic Standards for Ground Water, listed in Tables 1 through 4 in <br />the CDPHE Regulations. The pre-operational baseline monitoring should be conducted for 5 quarters. <br />