2016-07-28_REVISION - M1980244 (2)

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RESPONSE. That is correct. EMP-008b was constructed as part of an earlier amendment. EMP-008c was permitted and constructed as part ofAmendment 10. The stormwater runoff pond system that is comprised of EMP 008b and 008c collects runoff from the upper elevation North Cresson Mine Area roads, soil stockpiles, and associated disturbance as well as a portion of the Squaw Gulch overburden storage area, interceptor canals above the Squaw Gulch Valley Leach Facility(VLF), and portions of mine haul roads. In addition to the EMPs in Squaw Gulch, there are several BMPs that were constructed as part ofAmendment 10 to trap sediment beneath the toe berm in Squaw Gulch. No changes to Squaw Gulch were proposed as part ofAmendment IL The stormwater controls in place were approved as part ofAmendment 10/MLE2 or previous amendments. Details of the stormwater controls in Squaw Gulch may be found in the Storm Water Management Plan, Storm Water Pollution Prevention Plan and Best Management Practices for Cresson Project, Carlton Tunnel, and Chicago Tunnel Mine Sites in Teller County(January 2015). 4.2.3.1 Monitoring Pro rg_m • Page 16: The text lists one surface water monitoring station, SG-10. However,this station is not shown on Figure 2-1. Please revise Figure 2-1 to show the location of this monitoring station. RESPONSE. SG-10 is not a compliance monitoring point and therefore was not included on Figure 2-1 or listed in Table 11-1 of the Project Description. A revised Figure 2-1 and Figure 2-la is provided with updated surface water and groundwater monitoring locations, including sample locations that are monitored for purposes other than compliance. Table 3 provides the locations of surface water monitoring locations for both compliance and other monitoring purposes. See Attachment 2. 4.2.4.1 Monitoring Program • Page 17: The text lists a total of 5 groundwater monitoring wells in Squaw Gulch. However, only 3 of these wells are shown on Figure 2-1 (SGMW-5, SGMW-6A, and SGMW-6B). Please revise Figure 2-1 to show locations of all monitoring sites discussed in this section. RESPONSE. Figure 2-1, 2-1 a and 2-lb have been updated to show the 5 active groundwater compliance monitoring points in Squaw Gulch. See Attachment 2. • Page 17: There appears to be a typo for the names of three of the groundwater monitoring wells. The text lists"GVMW-6B, GVMW-7A, and GVMW-7B"which is the naming system used for Grassy Valley. The Division believes this was a typo, and that these three wells should begin with SGMW rather than GVMW. If this is the case, please correct these typos in order to reduce any confusion they may cause. RESPONSE. The Division is correct in that the wells listed on Page 17 should be SGMW not GVMW. A revised Section 4.2.4.1 of the Hydrology Evaluation is provided below. 4.2.4.1 Monitoring Program Groundwater conditions in Squaw Gulch are assessed by one existing monitor well (SGMW-5) and four recently installed monitoring wells (Figure 2-1). The new monitoring wells are designated SGMW-6A (bedrock), SGMW-6B(alluvium), SGMW- 7A (bedrock), and SGMW-7B(alluvium). SGMW-6 AIB and SGMW 7AIB are co- located to allow assessment of vertical conditions of water levels and water quality in the adjacent granites. Page 18 of 28