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<br /> <br /> <br />1 <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />fJ <br /> <br />Larry Oehler <br />November 22, 1993 <br />Page 3 <br />QUALITY ASSURANCE TESTING AND PROCEDURES <br />Current field testing on the embankment fill has included approximately 16 density tests. <br />Tests have been taken at various depths ranging from 1 to 2 feet below the current lift <br />elevation Ito verify compaction at the lower levels of the filll. Currently thi:t quantity of <br />testing is working out to five tests per shift. There are two shifts in a 24 hour period. <br />A review of previous quality assurance field and laboratory testing is in progress. <br />DRAINAGE BLANKET BENEATH SOUTH END OF EMBANKMENT <br />As you mentioned on November 19, and as observed on site, BMRI has requested to proceed <br />with construction of the embahkment raise on the south end of the embankment. Drainage <br />blanket material testing in this area has shown percentage fines values above the specification <br />of 35 percent. From observation of the drainage blanket materials in this area and review of <br />the test results, WWL believes that the drainage blanket materials in this area anP acceptable. <br />This is because the materials in question will be covered with embankment raise fill of similar <br />drainage characteristics land not tailingsl. Therefore the gradient for flow and permeability <br />across the drainage blanket in this area would not be as critical as the gradient for flow and <br />permeability where the drainage blanket is directly beneath tailings. <br />If you have any questions concerning the information contained in this letter, please contact <br />Clint Strachan or me. <br />Yours sincerely, <br />WATER, WASTE & LAND, INC. <br />~. ~~ 45 <br />Dou las O. Gibbs, P.E. <br />Project Engineer, Geotechnical/Mining Division <br />DOG:sea <br />1 <br />