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0 Step 2 - Monitoring <br />Following slurry wall and drain installation and through mining, piezometers will continue to be <br />measured quarterly with measurements provided to the DRMS as part of the annual report. <br />Step 3 - Mitigation Triggers <br />A ground water modeling study was prepared for the proposed operation to include estimated effects <br />as a result of slurry wall and drain installation. The anticipated effects modeled at the locations of the <br />proposed piezometers are as follow: <br />Predicted Change in <br />Piezometer Water Elevation (Feet) <br />1 0 <br />2 -0.5 <br />3 0 <br />4 0 <br />5 0 <br />6 3.0 <br />7 0 <br />As can be seen the highest anticipated change occurs in piezometer 6 in the south east corner of the <br />• proposed mining operation and most near the Swartz residence. Despite this change, the ground water <br />surface is anticipated to stay well below (approximately 11 feet) the basement floor elevation of the <br />home following drain and slurry wall construction. <br />If a change in groundwater elevation greater than two feet beyond the seasonal baseline plus the <br />anticipated (modeled) change in ground water elevations occurs then an intermediate second <br />measurement will be taken 45 days after the initial reading. If the reading is still outside the mitigation <br />trigger and an impact is imminent (i.e. a flooded basement or field), mitigation will be performed. <br />Step 4 - Mitigation Alternatives <br />Mitigations to a raised or lowered water table will be completed by the City under the following <br />conditions. <br />1. Monitoring data demonstrates that a change in ground water surface elevation has occurred <br />beyond that anticipated through slurry wall and drain installation and as a result of seasonal <br />variation. <br />2. The change in ground water elevation has caused an impact to adjacent water supply, an impact <br />is imminent, or has caused an impact to basement or field as a result of high groundwater <br />elevation. <br />Lowering of water table <br />• If mitigation from a lowered water table is required, one of the two following actions will be completed <br />by the City.