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Hydrologic Monitoring Plan <br />Northfield Mine <br />3. Filled sample bottles will be chilled as soon as possible <br />after filling, then kept cold until packed with ice for <br />shipment to the laboratory. . <br />4. Water quality samples for the NF monitoring wells and <br />SBWMW will be analyzed for the specific parameters listed <br />in Table 2 -Ground Water, Suggested Water Quality <br />Parameters. <br />5. Water quality samples for the Chandler Creek alluvium <br />well will be analyzed for the specific parameters listed in <br />Table 4. <br />D. Data Processing and Reporting <br />1. Copies of the field and laboratory data will be sent <br />quarterly to the Division. <br />2. Data will be summarized in the Annual Hydrology Report <br />submitted to the Division, as described below. <br />3. Permit holders will be notified by certified mail of well <br />data collected from a permit holder's well. <br />E. Data Based Plan Modifications <br />• 1. In the event water level in the Chandler Creek alluvium <br />well reduces by five (5) feet, water level monitoring <br />frequency will increase to monthly. <br />2. In the event two consecutive monthly water level <br />readings indicate a water level reduction of more than <br />five (5) feet or three consecutive monthly water levels <br />indicate a total water level reduction of eight (8) feet or <br />more, down gradient well permit holders will be notified <br />of the condition via certified mail along with a request to <br />monitor potentially impacted wells on a month to month <br />basis. <br />3. Monthly water level monitoring will continue until six (6) <br />consecutive water level measurements show no <br />substantial declines or changes in water level, at which <br />time quarterly frequency will resume. <br />F. Retreat Mining Plan Modifications <br />1. Prior to retreat mining anywhere in the N1/2 of Section 23, NW1/4 <br />of Section 24, or the SW1/4 of Section 13, the SBWMW will begin <br />monitoring on a monthly basis for water level. <br />2. Water level monitoring will continue at the monthly frequency until <br />retreat mining is <br />3 <br />Revised 12/19/2007 <br />