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°•EP tb 'r-~F. rt4~12Pt1 r~I1'."I9~NEF.iiL=•2~E~ <br />INTEROFFICE MEMORANDUM <br />DMSlON OF MINERALS AA'D GEOLOGY <br />TO: Steve Shuey <br />FROM: Harry Posey <br />DAT13: September lEi, 1996 <br />SUBJEC?: Neglected Mine, cyanide testing <br />pENVER <br />OFFICE <br />Recetvad <br />SEP 1 61996 <br />Dur2r.~o F!a!d O}ftCs <br />L~-v;e~~n ti t.fi~erris 8 Geptp9Jr <br />Geochemical Review <br />The September 12, 1996 letter to Mined Development Corp from Dr. Joe Bowden, CDS <br />Laboratories, regarding samples from the Neglected Mine provides an explanation of water quality ' <br />parameters which indicates that the discharge from the mine is in compliance with water quality <br />standards. This memo accepts the inferences made by Dr. Bowden, and explains the data briefly <br />with respect to water qualify standards. <br />Water quality standards are established for Free Cyanide, only. By CDH conventions, cyanide <br />that is measured by either the Free cyanide method or the WAD cyanide method is considered free <br />cyanide. Cyanide that is evolved orily by strong acid dissociable methods - i.e., the measurements <br />report to a Total cyanide analysis, but not to a WAD or Free cyanide analysis - is not considered <br />to be frte cyanidc. <br />The concenn•ations of total cyanide and total iron in the most recent samples fiom the Neglected <br />Mine area, both in the mine outlet and in the tnixed water below the mine, indicate that the <br />majority of the cyanide is locked up as an Fe-cyanide complex. As such, this is a strong acid <br />dissociable complex. <br />Unless you have reason to suspect that concentrations of cyanide will increase either seasonally or <br />due to other factors, I would say that based on the information at hand, it is reasonable to conclude <br />that the tailings have been adequtitely detoxified, and the company should be perniittsd to proceed <br />with the next stages of the project. <br />cc: Bruce Humphries <br />Tom Gillis <br />