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<br /> <br />STATE OF -iiiiiuiiiiiiiiiiii <br />COLORAUU <br />DIVISION OF MINERALS AND GEOLOGY <br />Department o(Nalural Resources <br />131 1 tihermun Si., Room 215 <br /> <br />Denver, ColoraAo AO203 <br />y <br />~lij~ <br />Phone: (3031 A66-3567 Il <br />FAX: (3071 A32~A106 <br /> DEPARTMENT' OF <br /> NATURAL <br /> RESOURCES <br />INTEROFFICE MEMORANDUM Roy Romer <br />DIVISION OF MINERALS AND GEOLOG Y e°`-e`nn, <br /> dames 5. Lochhead <br /> E+ecunve Duec~or <br />' Michael B Long <br />TO: Joe Dudash Division Di~eclu~ <br />FROM: Mike Boulay <br />DATE: June 27, 1997 <br />SUBJECT: Trapper Mine Inc. Permit No. C-81-O10, Technical Revision TR-75 <br />As requested, I have reviewed Trapper's responses to your adequacy questions concerning their <br />groundwater monitoring program reduction. My comments are provided below. <br />1. Response is acceptable. I agree with Trapper's conclusion that they have adequate <br />coverage of monitoring wells completed in both the "KI.M" and "QR" aquifers on a site <br />wide basis. At this time, I believe that sufficient monitoring data will be obtained for <br />these aquifers without requiring replacement wells for GA-1 and GA-2. As the Derringer <br />pit is advance, however, an assessment should be made as to whether or not shallow <br />groundwater is impacted. What is the depth of the Derringer pit and will the "KLM and <br />"QR" aquifers be intercepted. There are currently no monitoring wells immediately <br />downgradient of the proposed pit location. Therefore, once the Derringer pit is <br />established, the Division may request additional monitoring in the "KLM" and "QR" <br />aquifers downgradient from the pit. [,v~..o-~~... ~4c ti.,:.P.~`~ ~~^r=-~4O ~* <br />,r.r~ G~ -~ ,...~,~~..._~ aar.,.,., ~ _ ay <br />2. Water level measurements will not be accurate or useful with a downhole pump installed <br />in GD-l(2). Water quality data from this well will still be useful even with the automatic <br />chlorinator installed. The Twentymile Sandstone is a useable sandstone aquifer within <br />the mine area and GD-1(2) is one of only two wells completed within this important <br />aquifer throughout the mine site. The addition of chlorine should not effect most of the <br />B List parameters. List C and List B pazameters that may be effected include: <br />conductivity, TDS and pH. With the exception of water level data, I believe that Trapper <br />should continue monitoring well GD-1(2) as outlined in their approved sampling plan <br />(Table 4.8-13a). <br />3. Response is acceptable. Trapper has committed to continuing with quarterly water level <br />measurements on all wells. Trapper has also committed to purging each well with a <br />