Laserfiche WebLink
<br /> <br />1313 Sherman Street, Room 215, Denver, CO 80203 P 303.866.3567 F 303.832.8106 http://mining.state.co.us <br />John W. Hickenlooper, Governor | Mike King, Executive Director | Virginia Brannon, Director <br />1313 Sherman Street, Room 215 <br />Denver, CO 80203 <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />Re: McClane Canyon Mine, LLC (Permit No. C-1980-004) <br /> Technical Revision No. 18 (TR-18) <br /> Adequacy Review <br /> <br /> <br />As requested I have reviewed the above referenced revision relevant to the proposed changes to the <br />groundwater monitoring plan. <br /> <br />The revision proposes to remove from the monitoring plan and reclaim GW-3, an alluvial monitoring well to <br />monitor future disturbances in Munger Canyon Mine. This well is also listed in the Munger Canyon Mine <br />permit. Groundwater in the alluvium flows to the southwest. GW-9 is the downgradient monitoring well for the <br />McClane Mine disturbed area and is located up gradient from GW-3. McClane Mine has not produced coal <br />since 2010. Munger Canyon Mine (C-1981-020) is in the process of Phase III release. Munger Canyon Mine <br />was sealed and seeded in 2007. No water was encountered in the Munger Canyon Mine. <br /> <br />The groundwater resource monitored by GW-3 is the East Salt Creek alluvium, within a recognized alluvial <br />valley floor, which had high conductivity pre-mining. During the 2016 and 2017 water years, the average <br />conductivity was 5,000 umhos/cm. The average baseline conductivity at GW-3 in 1981 and 1986 was 7,256 <br />umhos/cm (PAP Table 4.2ii Groundwater Baseline Data). Data from GW-3 was used in the probable hydrologic <br />consequences for East Salt Creek Groundwater (Appendix N) to show that the addition of mine water did not <br />increase the salinity or productivity of water going to downstream farmers. The data showed a decrease in <br />salinity due to mine water addition. No elevated values of metals were noted in GW-3 in the baseline or recent <br />sampling. <br /> <br />The continued sampling of GW-3 is unlikely to provide additional useful information. I have no adequacy items <br />with respect to removing this well from the monitoring program at this time. <br />June 19, 2018 <br /> <br />Internal Memo <br /> <br />To: Clayton Wein, DRMS <br />From: Tabetha Lynch, DRMS <br />