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Mr. Timm Comer <br />Manager, Environmental Resources <br />Proposed SLF Specification Changes <br />July 20, 2010 <br />s0 <br />45 <br />40 <br />35 <br />30 <br />25 <br />g 20 <br />15 <br />10 <br />S <br />0 <br />Phase 5 SLF <br />ameO <br /> <br />0 10 20 30 40 s0 60 70 <br />Fines Content (%) <br />Figure 1 PI vs Fines SLF Plot <br />AMEC is proposing increasing the maximum fines limit to 65 percent so that SLF with higher <br />fines can be blended in the stockpile and used for the VLF construction. Increasing the <br />maximum limit on fines will not physically change the performance of the SLF in the VLF as the <br />increased fines are silt not clay particles (e.g. not fat clays). <br />The increased fines content will affect the Maximum Dry Density (MDD) and Optimum Moisture <br />Content (OMC) of the SLF. However, per the current specifications, a Proctor Compaction test <br />is required every 5,000 cubic yards, so any changes in the MDD and OMC will be automatically <br />updated and implemented in the field. Figures 2 through 5 present plots of the MDD versus <br />fines content and Pi; and OMC versus fines content and PI. As shown in Figures 2 and 3, there <br />is a trend of decreasing MDD with increasing soil fines content; while there is a trend of <br />increasing OMC with increasing fines content. These trends are commonly observed in soils, <br />whereby an increase in the fines content, tends to increase the soil moisture content (due to <br />capillary action). Increasing the soil moisture content tends to decrease the MDD as more pore <br />space is occupied by water. <br />Figures 4 and 5 present the plots of MDD and OMC versus PI, respectively. Note that there are <br />no definite trends observed in these plots. Soil plasticity generally does not have a significant <br />effect on the MDD and OMC unless there are mineralogical changes in the soil. The SLF at <br />CC&V is relatively consistent from a mineralogical perspective (e.g. same parent rock source). <br />MACINTOSH HD:USERS:JLUPO:D000MENTS CCBV:SLF LETTER:SLF apes Werdoc 2