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~II II~'I~II~~I~~ ~I~ <br />999 <br />August, 18, 1992 <br />H `i'L~F.'6 k'I IJETIC'=;, INC <br />• <br />12975 W. 24th kl. <br />Golden, (Applewood) Colorado, 80401 <br />(303) 237-SSfiS <br />Dr. James A. PendletOri <br />Technical and Scientific Coordinator <br />Colorado Mined Land Reclamation Division <br />1313 Sherman Street, Room 215 <br />Denver, Colorado 89203 <br />.13_=Tc:3 E9 <br />• <br />RE: Review of "Modifications to Existing Ground Water <br />Monitoring System, Battle Mountain Gold Mine, August, 1992." <br />Dear Mr. Pendleton: <br />As we discussed by phone, we have some concerns with the <br />recently released study concerning "Modifications to the Existing <br />Ground Water Monitoring System" at Battle Mountains San Luis Mine. <br />The drilling and well testing achieved a number of the goals <br />initially established, but some unanswered questions remain. <br />Additional information on the geology of the site was collected, <br />the direction of ground water flow was established as the gradient <br />was defined, and information on the hydraulic conductivity of the <br />material in the upper portion of the aquifer was developed. This <br />has all been accomplished in a professional and well documented <br />manner. However, specific information on the porosity, or more <br />importantly the effective porosity, of the aquifer maternal was not <br />collected. Additionally, the aquifer tests were not coruducted for <br />a long enough duration to allow drawdown to occur in the other test <br />wells, and no monitor wells were installed. Consequently, no <br />values for the storage coefficient of the aquifer can be <br />calculated. The report suggests this deficiency was caused by the <br />time restraints imposed by MLRB, though we anticipate such <br />restraints could have been resolved if needed to collect accurate <br />data. <br />The report utilizes the data collected to project ground water <br />flow velocities. The assumption is made that the effective <br />porosity is 25~. Since porosity is inversely proportional to <br />groundwater flow velocity, an accurate value for this parameter is <br />important. The 25$ value may be appropriate, but there is no <br />supporting data to confirm this to be true. <br />P.R~ <br />~:vu::d l\`a~ei Ncdr; ilnr.c EnrinC2nRe ~=eoloet GrnF)hctiCS l: axechnie al C~.~~•~nlrn N:: <br />