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2021 Groundwater Monitoring Report <br />www.arcadis.com <br />2021 Holcim FINAL GWMR 8 <br />4 Conclusions and Recommendations <br />Arcadis presents the following conclusions based on the information presented in this report: <br /> For the March 2021 groundwater sampling event, concentrations of all analytes measured in the two <br />downgradient wells, MW-7 and MW-13, were below the NPLs except for the total iron result for MW-7. The <br />concentration of total iron in monitoring well MW-7 was more than 10% over the NPL. However, because no <br />other exceedances were observed, per the revised GMP MW-7 can continue to be sampled annually. <br /> Concentrations of TDS and sulfate are generally decreasing in MW-7 and generally stable in MW-13. <br /> Generally stable or decreasing concentration trends for manganese, dissolved iron, and potassium to sodium <br />ratios continue to be observed in wells MW-7 and MW-13. <br /> Groundwater flow is to the south and velocity is 0.3 foot to 2 feet per year, which is consistent with historical <br />data. In addition, groundwater elevations and interpreted flow direction are similar to previous sample rounds. <br />Based on March 2021 sampling results that indicate there is no discernible impact from the CKD disposal area <br />and that only one parameter (total iron) exceeded its NPL, Arcadis recommends that groundwater monitoring <br />continue on an annual basis. <br /> <br />