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N III IIIIIIIIIIIIIIII ~ <br />lNTEROFF/CE MEMORANDUM <br />DMSION OF M/NERALS AND GEOLOGY <br />TO: Steve Shuey <br />DENVER <br />FROM: Harry Pose OFFICE <br />DATE: September 16, 1996 <br />SUBJECT: Neglected Mule, cyanide testing. <br />Geochemical Review <br />The September 12, 1996 letter to Mined Development Corp from Dr. Joe Bowden, CDS <br />Laboratories, regarding sample<.; 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 quality 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 only 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 free cyanide. <br />The concentrations of total cyanide and total iron in the most recent samples from the Neglected <br />Mine area, both in the mine outlet and in the mixed water below the mine, indicate that the <br />majority of the cyanide is locket! 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 adequately detoxified, and the company should be permitted to proceed <br />with the next stages of the project. <br />cc: Bruce Humphries <br />Tom Gillis <br />