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constructed underdrains, the ditch that extends the entire length of the toe of ECOSA, <br /> and stormwater controls (e.g., BMPs and EMPs). There have been two occasions where <br /> seepage was observed from the toe of ECOSA. The first occurred in 201 S following a <br /> very wet time period. The second more recently when a freshwater pipe beneath ECOSA <br /> broke. Both incidents resulted in seeps presenting in the ditch along the toe of ECOSA, <br /> which were captured and contained within the sediment control ponds preventing an <br /> impact to Grassy Valley. Newmont personnel inspect the area on a weekly basis to <br /> ensure controls remain effective. Additional controls will be evaluated on an as needed <br /> basis. <br /> 4.6.4.1 Monitoring Program <br /> • Page 31: The text states that there are 4 groundwater monitoring wells in Grassy Valley. <br /> However,the wells are not named in this section. Please list the names of the wells here <br /> as you have in this section for previous drainages. There appears to be only two <br /> groundwater monitoring sites labeled on Figure 2-1, GVMW-8A and GVMW-813. Please <br /> revise Figure 2-1 to show locations of all monitoring wells discussed in this section. <br /> RESPONSE. The 4 compliance groundwater wells monitored in Grassy Valley are listed <br /> on page 32 of the text. They are GVMW-8A, GVMW-8B, GVMW-22A and GVMW-22B. <br /> Figure 2-1 and Figure 2-1a has been revised to include the other 2 wells that were missing <br /> from the figure (See Attachment 2). <br /> • Page 31: The text states"the monitor program for Grassy Valley since 2012 has focused <br /> on water level measurements in 9 monitor wells and compliance monitoring (water quality <br /> parameters)in 4 wells."Please list the names of all of the wells mentioned in this <br /> section. Please show locations of all monitoring wells discussed in this section on <br /> Figure 2-1. <br /> RESPONSE. The 4 compliance monitoring wells located in Grassy Valley are GVMW- <br /> 8A, GVMW-8B, GVMW-22A, and GVMW-22B. These compliance wells and their <br /> locations are provided in Table 2, which is included in Attachment 2. There are 13 other <br /> wells in Grassy Valley that are considered active wells, and upon further investigation, it <br /> appears these other 13 wells are not part of CC&Vs active monitoring program. Rather <br /> these wells are maintained as active for future monitoring, if needed. These wells and their <br /> locations are listed on Table 4, which is included in Attachment 4, but are not shown on <br /> Figure 2-1 and 2-]a as they are not currently part of CC&V's regular monitoring <br /> program. <br /> 4.6.4.4 AM-I I Impacts to Ground Waters <br /> • Page 33: The text states"any infiltration from the ECOSA will be captured by the <br /> Diatreme drainage system." However,the northern portion of the ECOSA is located <br /> outside of the diatreme,and the underdrain system does not appear to be functioning <br /> properly. Therefore, how will you work to minimize impact to Grassy Valley from <br /> any ECOSA infiltrated water that does not drain to the diatreme? <br /> RESPONSE: Impacts to Grassy Valley are currently minimized by the designed and <br /> constructed underdrains and stormwater controls (e.g., BMPs and EMPs) and they have <br /> been functioning properly. There have been two observations of water near the toe of <br /> ECOSA. The first occurred in 201 S following a very wet time period post precipitation <br /> events. The second more recently when a freshwater pipe beneath ECOSA broke. Both <br /> resulted in seeps presenting in the ditch along the toe of ECOSA, which were captured <br /> and contained within the sediment control ponds preventing an impact to Grassy Valley. <br /> Newmont personnel inspect the area on a weekly basis to ensure controls remain <br /> effective. Additional controls will evaluated on an as needed basis. <br /> Page 22 of 28 <br />