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HDR TECHNOLOGIES INC. TEL~303-'9~-563 Jun << 9~ 13~'tl Pdn.00~ P.0~ <br />Looking over the data we have on the decay of WAD cyanide in the pond sincae June ] S, <br />1992, and based on the experience 1 have with past tailings pond chemistry, I share your <br />opinion that the levels of cyanide in the pond will probably undergo some equ[libration <br />with the cyanide and other constituents in the deposited solids as the level of soluble <br />cyanide is reduced with CYTOX and peroxide. This equilibration has the potential to hold <br />soluble cyanide levels above even the projected exponential decay rate and it will be most <br />interesting to see if this in fact occurs over the next few days to two weeks. The whole <br />effort to detoxify this pond may have gotten past the "picking of the low hangigg fruit" as <br />the EPA might refer to the reduction of the extremely high cyanide levels at the start of the <br />program, and now be moving to the demanding area of getting to the mandated level of 4.4 <br />pprn fatal cyanide. I will still be very surprised to see this proceed at a linear rate! <br />Again, thanks in advance for forwarding the accumulating data on cyanide analyses at the <br />San Luis facility in as timely a manner as is practical and I will look forward to the <br />continuing chance to review this data and to contribute to the goal of getting this tailings <br />pond to the permitted 4 ppm cyanide level as quickly as is possible. <br />Sincerely, <br />David E. Hyatt, Ph.D. <br />Senior Research Chemist <br />L062592DEH 2 <br />