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Stiles Mining Resource <br /> Groundwater Monitoring and Mitigation Plan <br /> December 2022 <br /> Page 5 <br /> 3.6 GROUNDWATER QUALITY DATA EVALUATION AND REPORTING <br /> ASCI will compare post-operational groundwater sampling event results against the site-specific <br /> groundwater quality benchmarks within two(2)weeks of receipt from the laboratory to determine <br /> if any adverse impacts to groundwater quality may have occurred. The primary trigger for <br /> determining potential adverse off-site impacts to groundwater quality in nearby wells due to the <br /> mining operation will be parameter concentration(s) reported which exceed their site-specific <br /> groundwater quality benchmark(s)in the POC wells only(MW-4 through MW-6).Any parameter <br /> exceedance(s) reported in up-gradient monitoring wells (MW-1 through MW-3) would indicate <br /> the impact to groundwater quality is potentially from an off-site source. Should parameter <br /> exceedance(s) occur in up-gradient wells only, ASCI will monitor results from subsequent <br /> groundwater monitoring sampling events to determine if elevated concentration(s) of the <br /> parameter(s) persist and/or if migration to down-gradient POC wells (MW-4 through MW-6) <br /> occurs. ASCI's reporting of groundwater sampling event results to DRMS will be dependent upon <br /> the fmdings from data evaluations as detailed in Section 3.6.1 or Section 3.6.2. <br /> 3.6.1 No Exceedances in Points of Compliance Wells <br /> If groundwater sampling event results do not indicate potential adverse impacts to off-site <br /> groundwater quality (i.e., no exceedances above site-specific groundwater quality benchmarks in <br /> POC wells),results will be compiled in a groundwater monitoring report that will be submitted to <br /> DRMS as supplemental information with the annual report for the mine each year. <br /> 3.6.2 Exceedances in Points of Compliance Wells <br /> If groundwater sampling event results do indicate evidence of potential adverse impacts to off-site <br /> groundwater quality (i.e., exceedances of site-specific groundwater quality benchmarks in POC <br /> wells), ASCI will provide notice to DRMS within five (5) working days of discovery and will <br /> begin conducting mitigation measures, as detailed in Section 3.7. <br /> 3.7 MITIGATION MEASURES FOR GROUNDWATER QUALITY IMPACTS <br /> 3.7.1 Confirmation Sampling <br /> Should detection(s) above the site-specific groundwater comparison benchmark value(s) occur in <br /> a POC well (MW-4 through MW-6), ASCI will re-sample the POC well within two (2) weeks of <br /> discovery for the parameter(s) exceeding benchmark values to verify results. <br /> ■ If confirmation sample result(s) are at or below the site-specific groundwater benchmark <br /> value(s), ASCI will report confirmation sampling results to DRMS within five(5) <br /> working days of receiving results and continue with the current groundwater quality <br /> monitoring program schedule. <br /> ■ If confirmation sample results confirm exceedance(s) of site-specific groundwater quality <br /> benchmark value(s),ASCI will report confirmation sampling results to DRMS within <br /> five(5)working days of receiving results and begin review of the existing data set as <br /> detailed in Section 3.7.2. <br />