Laserfiche WebLink
~; ~ ~ ~ ~~I ~I~~I~~~~~~~~ ~~~ <br />sss <br />~" STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Dep. rlmenl of N. lu ral Resources <br />1313 Sherman SL, Room _'15 I{y~~ <br />' Denver, Colorado 81R(I7 II <br />Phone: 130 {) 866-3567 <br />fAh: 1}03783?-81 U6 <br />DEPARTMENT OF <br />NATURAL <br />RESOURCES <br />Roy Romer <br />Governor <br />DATE: November 6, 1996 E>teculsve Dnec or <br />Michael B. Lang <br />TO: Berhan Keffelew Division Director <br />FROM: Harry Pose~Y~2 <br />RE: Review: CC&V Response About Total Sulfur Analyses," Cresson Project, Permit <br />M-80-244. <br />This memo addresses C&V's response letter of October 26, 1996 with regard to the permit conditions <br />and discussions at our recent site meeting. <br />In the permit and in previous correspondence, the Division requested infra-mining rock <br />characterization studies. The purpose of these studies is to determine whether the Cresson waste rock <br />has sufficient concentrations of sulfides and metals to indicate a reasonable need to protect the rock <br />from weathering and generation of acid or metalliferous drainage. CC&V have provided a synopsis <br />of sulfur data to cover the Division's request. ' <br />Original sulfur data were not included in the letter, so there is no way to evaluate the Operator's <br />synthesis of the information. According to this unverified summary, measured sulfur analyses range <br />up to 4.6 weight percent, and sulfur estimates range up to 10 percent. Average sulfur analyses for <br />two sets of samples are reportedly 0.80 and 0.15 weight percent sulfur.Based on previous <br />mineralogical assessments, the ore and waste contain insignificant concentrations of sulfate and organic <br />sulfur; thus, virtually all of the measured sulfur can be reasonably assumed to represent sulfide sulfur. <br />The upper range values represent very high concentrations of potentially acid-generating material. <br />A proper assessment of the acid-generating and metals-release potential of these stored waste rocks <br />cannot be made without ancillary acid-neutralization tests and metals-mobility tests. Tests from this <br />site, which were reviewed previously, indicated a significant net acid-generating potential for some <br />of the waste rock. Verbal indications from CC&V appear to reflect an opinion that there is sufficient <br />carbonate in the host rocks to preclude the development of acidic conditions. To date, however, <br />CC&V has not presented a verifiable case to back up this opinion. <br />Previously-reviewed tests also indicated a potential for mobilizing several metals from local rock. The <br />presence of acidic, aluminum-bearing water in the springs beneath the Arequa Gulch waste storage <br />