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2022 Groundwater Monitoring Report <br />www.arcadis.com <br />2022 Holcim FINAL GWMR 05132022 8 <br />4 Conclusions and Recommendations <br />Arcadis presents the following conclusions based on the information presented in this report: <br /> For the March 2022 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 have been generally stable for several years at MW-7 and MW-13 and remain below <br />the NPL. <br /> Concentrations of sulfate at MW-7 have remained stable for several years. Concentrations have been <br />generally stable at MW-12 and MW-13, and though the MW-13 result exceeded the NPL, it was not by more <br />than 10 percent. <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 0.36 foot to 2.19 feet per year, which is consistent with <br />historical data. In addition, groundwater elevations and interpreted flow direction are similar to previous <br />sample rounds. <br />Based on March 2022 sampling results that indicate there is no discernible impact from the CKD disposal area <br />and that only one parameter exceeded its NPL at both MW-7 (total iron) and MW-13 (sulfate), Arcadis <br />recommends that groundwater monitoring continue on an annual basis. <br /> <br />