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£X�rz,Ay SfcvER rti'KEs <br /> 7. The response to item 31 of adequacy review#1,is insufficient. Under this revision,TR-15,part of the <br /> commissioning and testing phase required to obtain mill certification, a full chemistry evaluation of <br /> the process water will be required. In order to perform an accurate Reclamation Cost Estimate, the <br /> Division needs to understand the chemistry of the process water in order to determine the proper <br /> disposal method. <br /> Response: While OSMI uppr•ec•iates and Shares the desire to understand process water chemistry and <br /> duality. the use of TCLP results for bonding calculations of Bevill exempt vi,asle is a substantial change in <br /> regulatory practice. OS,1I1 is not aivare of any jurisdiction. neither domestic nor foreign, in ivhiclr TCLP <br /> is considered an appropriate standardfor evaluating mine waste or setting mine bonds. TCLP is not the <br /> preferred method because of strong organic acidification of the samples that is),rot expected in rock <br /> clumps with low organic content, and how that acidification c ffects,'suppresses oxidation reactions that <br /> are the driving.force ofmass loaditrg,froin mining ivastes. OSA11 has been unable to locate arry DR-M <br /> guidance or policy document in which TCLP is the basis for bonding Bevill Exempt waste. If this is <br /> DP-VS polies', OSMI requests access to the policy, cis well as the documents related to the process under <br /> which the policy was established. <br /> OSAll proposes that the disposal of'Process iTI'ater•at the end o_f inine life, or an unexpected long-term <br /> mill shut down, vi-ould proceed as folloNs: <br /> 1. Evaporation:: liquid would be allo►vedl'encour•aged to evaporate in existing secondary <br /> containment Enviromnental Protection Facility certified structures to.forin a relatively <br /> small volume and mass of solid waste. <br /> 2. Solid u aste Analysis: Solids resulting from the evaporation of wastewater would be <br /> analyzed to determine: <br /> a. trretallurgiecil i eilrte—waste with vcilite would be sold to smelter. <br /> b. leaching characteristics —Synlhelic Prec•ipitalion Leachate Procedure and Acid <br /> Base Accounting would be performed to evuluale appropriate onsile disposal, <br /> most like!•in a tailings facility, as the non-ec•onomie solids are likehv tailings. <br /> 3. Fillration: Solids would be further dewatered, if needed, through the filter presses <br /> The TCLP procedure for•liquids (0.5%solids) is filtration through glass filter to 0.6 - 0.8 microns with <br /> a total analysis of the filtrant. Given the stated pun pose of the TCLP is process water disposal bonding, <br /> OSA7I proposes that process water simply be analyzed for-the constituents ciir•r•ently monitored in <br /> groundwater our site during mill commissioning OSMI proposes to collect samples from each of tlic two <br /> circuits and the process water tank twice daring mill commissioning. once early in the introduction of <br /> ore, and once late in the commissioning process to evaluate mill water qualitp. Note that these two <br /> sampling events are expected to yield different results with the later being more representative of long- <br /> term ivater quality None-the-less, process water A'ould not be disposed of cis a liquid because of <br /> transportation costs and the safe!•factor involved in transporting solids over liquids. <br /> 8. The response to item 32 of adequacy review #1, was only partially addressed. It is noted that there <br /> is an 18,000-g a I i o n process water tank. Please provide an anticipated total volume of process <br /> water contained within the system at any given time. It is understood that the mill runs at a deficit of <br /> water and always requires additions, however the Division needs to understand an estimated total <br /> 3 � f> <br />