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• Because the native clays contain so many cobbles and boulders, the use of a "grizzly" to scalp <br />oversized materials will help to keep the fill soils with a proper gradation of materials to prevent <br />voids in embankments. Many of the sandstone boulders would be expected to break up and nest <br />together, if segregated and worked as a rock fill by bulldozers, separate from general fills. <br />Select Fill: We recommend that a select, non-expansive fill be placed within the upper 3 feet <br />below foundations and any interior concrete floor slabs. This material exists in some locations <br />on the site, but will require selective excavation and stockpiling. Soils meeting the following <br />specification will generally perform as anon-expansive material: <br />Liquid Limit - % % Passing No. 200 Sieve <br />Greater than 40 5 - 30 <br />• Between 30 and 40 5 - 45 <br />Less than 30 5 - 100 <br />A granular material is recommended for backfill around the reclaim tunnel. A material <br />similar to Class 6, 3!4-inch aggregate road base should be specified within the backfill zone. <br />Embanlanent Shrink-Swell: The site clay soils, when excavated, moisture conditioned and <br />placed as fill, will bulk an average of 0 to 5 percent. <br />Drainaee: Good surface drainage should be provided around all cut and fill slopes to direct <br />surface runoff away from these areas. Slopes and other stripped areas should be protected <br />against erosion by re-vegetation or other means. <br />17 <br />