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Third Perty Oversight 19 Wetar, Waste & Lend, Inc. <br />' Sen Luis Mine June 9, 1994 <br />' Figure 3 also demonstrates that although laboratory permeability values btained from <br />tests conducted at relatively low (< 100 pcf) dry densities ISRK, 1994) are vali~, they do not <br />accurately reflect the quantity of compactive effort which was applied in the fiel as observed <br />' by WWL. <br />According to BMRI's Technical Revision No. 16 (BMRI, 1993s1, permeability tests <br />' indicated tailings values ranging from 1.9 x 10e to 5 x 10'' cmisec. However, results from <br />WWL's review of available permeability data (included on Figure 3 and Table 5.11 show CPT <br />values for the tailings ranged from 1.9 x 10'8 to 5.9 x 10~e cmisec and piezocone values <br />ranged from 7.2 x 10-e to 4.2 x 10-' cm/sec. The arithmetic and geometric means for the CPT <br />' data are shown on Figure 3. Based on this data, a reasonable permeability coefficient for the <br />tailings would be between 2 x 10-8 and 4 x 10-e cm/sec. <br />' 5.5 DRAINAGE PIPE SPACING <br />' In addition to the permeability of the drainage layer, drain spacing pis critical to <br />controlling the height of head and minimizing the rate of seepage through the VLDPE liner. <br />DMG had expressed concerns after their initial site inspection that drains were being spaced <br />' greater than the design value of 40 feet. Adequate spacing was verified during construction <br />oversight. <br /> <br /> <br />1 <br />1 <br /> <br />1 <br /> <br />1 <br />1 <br />1 <br />1 <br />