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The pH of well M-13 has been decreasing over the past year. BMRI has stated that this <br />is due to well installation issues (grouting setting up over time). Calcium concentrations <br />have been consistently increasing over time, which would be expected as the pH falls <br />below the calcite precipitation fence. Calcium concentrations were 25.6 mg/I in <br />November, 1992 (pH=9.08); ~" 45 mg/I in April and May, 1993 (pH=8.21 'in May); and <br />"52 mg/I in October 1993 (pH=7.12). In contrast, sodium concentrations have remained <br />nearly constant at "' 9-10 mg/I over the sampling project. The consistent tenoporal trends <br />in pH and calcium concentrations suggest that the water chemistry changes are not <br />seasonal and may instead be related to well installation. <br />I have changed the wording on (previous) page 9 about the dilution of the sample prior <br />to adding the spike to be more consistent the with conclusion section. <br />I have asked Core Laboratories to submit a letter to me regarding the discrepancy <br />between total cyanide values for the collection impoundment and lower tailings <br />impoundment samples in the Quality Control Report and the Analytical Report. The <br />differences are due to a 1:4 dilution for color in the samples, but I agree that it is not <br />clear from looking at the information I received from Core Labs. I will forward the letter <br />to you as soon as I receive it (early next week), although I believe it will say nearly <br />exactly what I have stated on pages 9-10 of the amended report. I have changed the <br />table of contents to include an Appendix F for the letter and have included .a cover sheet <br />for Appendix F so that you can include the Core Labs letter in the amended report as <br />soon as you receive it. <br />As I have stated in the past, I believe that Core Laboratories is asub-standard analytical <br />lab. Their internal QC appears to be lacking, as witnessed by the number .of times they <br />have exceeded recommended holding times for cyanide analyses or reanalyses. I do <br />recommend using another laboratory for any future work. We have had success with <br />ACZ Laboratories in Steamboat Springs, Colorado, and I can recommend them highly. <br />Please call if you have any questions regarding the amended report, or if there are <br />additional issues you would like me to address. <br />Sincerely, <br />v\ <br />Ann Maest, Ph.D. <br />Senior Associate <br />2 <br />