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1 <br /> Jackson's aka PacWest Energy LLC JN 13465 <br /> ' December 9, 2013 Page 9 <br /> GENERAL EARTHWORK AND STRUCTURAL FILL <br /> All building and pavement areas should be stripped of surface vegetation, topsoil, organic soil, and <br /> other deleterious material. It is important that existing foundation(s) be removed before site <br /> development. The stripped or removed materials should not be mixed with any materials to be <br /> used as structural fill, but they could be used in non-structural areas, such as landscape beds. <br /> ' Structural fill is defined as anyfill, includingutilitybackfill, placed under, or close to, a building, <br /> 9 <br /> behind permanent retaining or foundation walls, or in other areas where the underlying soil needs <br /> to support loads. All structural fill should be placed In horizontal lifts with a moisture content at, or <br /> near, the optimum moisture content. The optimum moisture content is that moisture content that <br /> results in the greatest compacted dry density. The moisture content of fill is very important and <br /> must be closely controlled during the filling and compaction process. <br /> The allowable thickness of the fill lift will depend on the material type selected, the compaction <br /> equipment used, and the number of passes made to compact the lift. The loose lift thickness <br /> should not exceed 12 inches. We recommend testing the fill as it Is placed. If the fill is not <br /> sufficiently compacted, it can be recompacted before another lift is placed. This eliminates the <br /> need to remove the fill to achieve the required compaction. The following table presents <br /> recommended relative compactions for structural fill: <br /> LOCATION OF BILL MINIMUM RELATIVE{: <br /> PLACEMENT COMPACTION <br /> Beneath footings, slabs 95% <br /> ' or walkways <br /> Filled slopes and behind 90% <br /> retaining walls <br /> 95%for upper 12 inches of <br /> ' Beneath pavements subgrade; 90% below that <br /> level <br /> Where: Minimum Relative Compaction is the ratio,expressed in <br /> percentages,of the compacted dry density to the maximum dry <br /> density, as determined in accordance with ASTM Test <br /> Designation D 1557-91(Modified Proctor). <br /> Use of On-Site Soit <br /> if grading activities take place during wet weather, or when the silty, on-site soil is wet, site <br /> preparation costs may be higher because of delays due to rain and the potential need to <br /> import granular fill. The on-site soil is generally silty and therefore moisture sensitive. <br /> Grading operations will be difficult during wet weather, or when the moisture content of this <br /> rsoil exceeds the optimum moisture content. <br /> The moisture content of the silty, on-site soil must be at, or near, the optimum moisture <br /> ' content, as the soil cannot be consistently compacted to the required density when the <br /> moisture content is significantly greater than optimum. The moisture content of the on-site <br /> soil was generally above the estimated optimum moisture content at the time of our <br /> ' explorations. The on-site silty sand with gravel could be used as structural fill, if grading <br /> operations are conducted during hot, dry weather, when drying the wetter soil by aeration is <br /> 1 <br />