2017-05-10_REVISION - M2002004 - Laserfiche WebLink

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If the field parameters do not stabilize,a minimum of five casing volumes shall be removed from the well prior to taking a groundwater sample'. If the well is bailed dry (evacuated) before purging three wetted casing volumes, the sample could be collected as soon as a sufficient volume of water is recovered in the well. 6. Within Section D - Revised Groundwater Monitoring and Sampling Plan, please define the "broad suite"analyte list which will be used to characterize groundwater samples.Please note, this should be a list of appropriate analytes from Tables 1-4 of Colorado Department of Public Health and Environment, Water Quality Control Commission 5 CCR 1002-41, Regulation 41 - The Basic Standards for Groundwater. GCC proposes to analyze all parameters in Table 3 (Agricultural Standards) of 5 C.C.R 1002-41, Regulation 41 -The Basic Standards for Groundwater. 7. TR-06 states GCC will amend its closure bond and mine closure plan to reflect the cost and method used to abandon and plug MW-006. Please provide details on the abandonment and associated costs of abandonment of MW-006. Please also provide the maximum anticipated depth and borehole diameter of MW-006. GCC intends to follow the standards set forth in Colorado Division of Water Resources Well Construction Rule 16,"Standards for plugging,sealing, and abandoning wells and boreholes" (2 CCR 402-2), to plug and abandon MW-006. Associated costs of abandonment are estimated to be $8.50 per foot given a borehole size of 8 inch diameter. At an estimated maximum depth of 100 ft., this would result in a total investment of about $1,000. GCC will proceed to amend its closure bond to reflect this amount. 8. Within Section E-Proposed Numeric Protection Limits (NPL), GCC proposes to use the NPLs established in 2009. However, these NPLs were developed from samples obtained from MW- 002, MW-003, and MW-004 (all have been abandoned) which were completed in saturated alluvium of Saint Charles River with no direct hydrologic connection to the dry colluvium underlying the operation. The NPLs established in 2009 appear no longer applicable. Should a sufficient number of monitoring events encounter groundwater as a part of TR-06, new NPLs will be established in accordance with the Colorado Department of Public Health and Environment, Water Quality Control Commission 5 CCR 1002-41, Regulation 41 - The Basic Standards for Groundwater. GCC commits to establish new NPLs in accordance with the Colorado Department of Public Health and Environment, Water Quality Control Commission 5 CCR 1002-41, Regulation 41 - The Basic Standards for Groundwater,should a sufficient number of monitor events encounter groundwater. 1 Colorado Department of Public Health and Environment.Water Quality Control Division."Suggested Sampling Protocol for Ground Water Monitoring Wells".