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9/30/93 <br />Responses to Comments <br />San Luis Reclamation Evaluation Report <br />Page 3 <br />As can be shown for the data collected in conjunction with the <br />geotechnical investigation for the embankment raise and <br />included in the Phase II, Raise 1 Design Report, the tailings <br />are a dewatered, compacted system exhibiting characteristics <br />which are similar to engineered earthen liner/barrier systems. <br />The tailings deposition, in short, is functioning as designed <br />and permeabilities will continue to decrease throuq~out the <br />life of the operation. It is important to unders and the <br />functioning of the tailings system in order to realilstically <br />evaluate both BMRI's approved reclamation plan and the <br />Reclamation Evaluation Report. <br />2.0 Tailings Sampling <br />Tailings sampling was conducted using the hand augering <br />equipment in order to expedite the sampling program and <br />minimize the pre-sampling construction required to complete <br />ramps for heavier sampling equipment. BMRI decided tg try the <br />hand auger sampling technique initially in an attempt to avoid <br />potential damage to the liner system, minimize the loss of <br />impoundment capacity and to avoid hinderance to the functioning <br />of the thin layer deposition by construction of ramps for <br />mobile drilling equipment. it should be noted that although <br />ramps were constructed for the goetechnical drilling program, <br />they were constructed within the footprint of the embankment <br />raise, would ultimately become part of the raise and, as a <br />result, did not create impoundment capacity losses. The <br />geotechnical drilling ramps were also located close to the main <br />embankment and well away from active deposition, therefore <br />there was no concern with the potential to hinder the <br />functioning of the deposition. <br />In addition, BMRI sought to expedite sampling by elifiinating <br />delays associated with ramp construction, particularly in view <br />of the onset of winter and potential sampling difficulties as <br />a result. Finally, this decision was made based on the <br />operational constraints of the tailings facility (i.e. the need <br />to periodically move deposition between the impoundments) and <br />the lead times required to complete the laboratory testwork in <br />time for the report submittal deadline. Once BMRI evaluated <br />the samples obtained, it was believed that the various <br />detoxification procedures used at the facility were adequately <br />represented in the tailings samples obtained. Table 1 has been <br />developed to show the sample holes and various detoxification <br />treatment used with depth of sampling. <br />