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Ralston Quarry Slope Stability <br /> PROJECT EARTHWORK <br /> Use of On-Slope Tailings The existing tailings on the subject slope are anticipated to <br /> comprise a significant proportion of the materials placed as compacted fill either in the <br /> stability embankments or stockpiles. We anticipate that the majority of the on-slope <br /> tailings will be suitable for re-use as compacted fill. Fragments of rock and cobbles up to <br /> 12 inches in maximum dimension may be included in the stability embankment fills, as <br /> long as the coarse clasts are not nested with resultant voids, and the surrounding soils <br /> can be compacted effectively. <br /> However, deleterious materials such as trash, organic material, and boulders, or <br /> construction debris likely will be encountered in the on-slope tailings and should not be <br /> included in stability embankment fills. <br /> Excess tailings from the slope should be placed in the stockpile (Zone 1) moisture- <br /> conditioned and compacted. <br /> Use of Existing Native Colluvial Soils Based on the samples retrieved from the test <br /> holes, we anticipate that the existing native soils consist largely of clays that should not <br /> be used to construct the embankment fills. (We anticipate that scattered pockets of <br /> clayey soil may become incorporated into the stability embankments, but this should be <br /> avoided to the extent possible.) The clay soils may be placed as fill in other locations. <br /> Imported Fill Materials We understand that most or all of the fill soils imported to the <br /> slope will be granular materials mined elsewhere on the Asphalt Paving Company <br /> property. Materials brought to the slope for use to construct the stability embankments. <br /> Imported material should exhibit 15 percent or less passing the No. 200 Sieve and a <br /> plasticity index of 5 or less. Materials proposed for import should be approved prior to <br /> transport to the slope. <br /> Fill Platform Preparation Prior to filling, the top 12 inches of in-place materials on <br /> which fill soils will be placed (except for utility trench bottoms where bedding will be <br /> placed) should be scarified, moisture conditioned and properly compacted in accordance <br /> with the criteria below to provide a uniform base for fill placement. <br /> Job No 18-3046 GROUND Engineering Consultants, Inc. Page 25 <br />