Laserfiche WebLink
c. For post closure, CC &V must provide a worst case scenario of the quantity and quality of release from <br />the overburden pile based on the results of these tests. Long term worst case scenario with ranges <br />between maximum and minimum releases must be submitted to the Division. <br />5) Sulfate was selected as a possible indicator for Acid Mine Drainage (AMD) in all the compliance <br />wells. For the past five years, the Division has observed an increase in sulfate concentration in the <br />Arequa Gulch ground water monitoring and compliance points. The current upward trend observed for <br />the past five years in the monitoring wells in Arequa Gulch, has not been associated with lowering of <br />the pH. At present, CC &V is pumping back the water from compliance well CRMW -3A and -3B as <br />make up water for the pad. <br />a. The operator must discuss the potential for sulfate dissolution and its potential to exceed existing GW <br />compliance standards in all the compliance wells. The discussion must include possible remedial <br />action(s) and recommendations. <br />b. Additionally, if sulfate is not a good indicator for AMD in the district because of its abundant <br />presence in the host rock of the ore body, what other metal(s) would CC &V suggest to monitor in the <br />compliance wells? The selected metal has to be good indicator for a potential AMD. Please provide a <br />detailed discussion and possible recommendations. <br />Ground Water Information- Rules 3.1.5(6), 3.104), 3.1.7, 6.4.7 (1) and (2), 6.4.21 (8), (9) & (12) <br />The ground water quality and depth to ground water are monitored and will continue to be monitored <br />in Arequa Gulch, Squaw Gulch, Wilson Creek, Vindicator Valley, Grassy Valley and Poverty Gulch. <br />Because the ground water is not classified, the Division set numeric protection levels in accordance <br />with the provisions of the Rules and the Act. All the compliance wells are nested and developed in <br />both the shallow and deep perched water bearing zones. These wells cover each of the drainage areas <br />in the district that have the potential to be impacted by the operation. CC &V monitors many more <br />wells within the drainage areas in addition to the compliance wells for their own record and to monitor <br />trends. At present, CRMW- 3A, (Arequa Gulch), SGMW- 4A (Squaw Gulch), VIN -lA (Vindicator <br />Valley), GVMW- 8A (Grassy Valley), MCMW- 6 (Wilson Creek), PGMW- I (Poverty Gulch) and <br />ESPMW -1 (external storage pond sampled only for pH and wad CN), are compliance wells with <br />numeric protection levels. The data collected are submitted to the Division each quarter. The post <br />closure monitoring of the ground water is as approved in previous amendments. Based on the <br />information submitted the Division has the following request. <br />6) Grassy Valley: The Division proposes that CC &V choose different well sites than the ones selected <br />(GVMW -16 and GVMW -24 A and B) and listed in table 11 -2. The new wells must have continuous <br />data for at least three years, with all the usual parameters analyzed. The two wells proposed by CC &V <br />do not meet this standard. Once the new compliance wells are agreed upon, the Division will set <br />numeric protection levels in compliance with Rule 3.1.7(iv) and Rule 6.4.24 as applicable. Please <br />provide your selection for the other two compliance wells that will meet the Division's minimum <br />requirements. <br />7) Arequa Gulch: As stated above, the compliance well in Arequa Gulch (CRMW- 3A) is being pumped <br />back to the pad (as is monitoring well CRMW -3B) as make up water because the sulfate standard has <br />been exceeded on a couple of occasions and is expected to exceed the set numeric standards on a <br />continuous basis once the foot print of the pad is expanded. The current yield of the well is <br />approximately 2 to 3 gallons per minute (gpm). The operator, at the request of the Division, completed <br />a deeper well in the bed rock at a depth of approximately 100 feet for additional monitoring. This well <br />is in addition to CRMW- 3B, which is also completed in the bedrock at a depth of 63 feet. The wells <br />are still being monitored for all the other parameters including sulfate, as they are compliance well <br />locations. With the exception of the sulfate, all other parameters are within or below the set numeric <br />protection levels. The detailed geochemistry evaluation conducted by CC &V for Arequa Gulch <br />indicates that as the foot print of the pad increases, the sulfate concentrations is also expected to <br />increase. What is the post closure plan to remediate sulfate, once the water is no longer used as make <br />up water for ore processing? What remedial action(s) is planned post closure if the upward trend <br />