Laserfiche WebLink
A- ~ iiiii iiiiiii <br />INTEROFFICE MEMORANDUM <br />DNISION OF MINERALS AND GEOLOGY <br />TO: <br />FROM: <br />DATE: <br />SUBJECT: <br />Allen Sorenson <br />Harry Posey ~~~~~- 4 <br />August 20, 1996 <br />Comments -Henderson Mine & Mill Groundwater Monitoring Plan Technical <br />Revision: M-77-342 <br />Ceochemical Review <br />This memo discusses sections of Climax Molybdenum Company's July 23, 1996, letter and recalls <br />our conversations on the subject of groundwater monitoring at the Henderson facility. <br />As background, it is my understanding that the rocks with which we are concerned include not <br />only the unaltered Pre-Cambrian, as mentioned by the operator, but also altered Pre-Cambrian <br />bedrock, and mineralized mine tailings. I have assumed further that the alteration zone and the <br />spent ore contains elevated concentrations of pyrite or other iron sulfides, and that the ore contains <br />elevated concentrations of other potential contaminants, which is consistent with general models of <br />molybdenum porphyries. <br />CMC asserts that the Division's proposed list of analyzes for groundwater monitoring is <br />"unreasonable." Presumably, their support for this assertion is (1) that some of the parameters are <br />not regulated water quality parameters, (2) that their current discharge permits from the CDPHE <br />do not require monitoring of some of these parameters, and/or (3) their belief that these pollutants <br />are not present in significant amounts in the waste rock. It should be noted that the Division's list <br />of proposed monitoring parameters will apply to a few wells from which water samples are to be <br />collected for five quarters in order to establish baseline groundwater conditions. Long term <br />monitoring requirements would be established from the list of baseline parameters. <br />The list of proposed monitoring parameters includes the regulated metals plus Na, which in high <br />concentrations may cause soil damage, and Mo, which in high concentrations can upset the Cu:Mo <br />ratio and induce molybdenosis in livestock and wildlife, particularly sheep. The Operator should <br />understand that the Division is not bound to follow the monitoring requirements of other agencies, <br />although the Division does serve as the implementing agency for the Water Quality Control Act on <br />matters dealing with groundwater. Rather, the Division's obligations are general, and require <br />i <br />