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• the following page shows that these soils are either poorly graded gravel-sand-silt or poorly <br />graded gravel-sand clay. <br />2) Those soils without coarse fragments (soil unified classification types SM-SC or SC). These <br />are soils 98D, 98E and 98F as shown on the soil inventory map of the permit. Table 1 on the <br />following page shows that these soils are either poorly graded sand-clay mixture or sand-silt- <br />clay with slightly plastic fines. <br />The material for the foundation will consist of the natural subsoils which are currently being <br />stripped by scrapers and replaced in the backfill. This material is also poorly graded, will have <br />coarse fragments and is classified as a GC soil -poorly graded sand-gravel-clay or GM -poorly <br />graded gravel, sand & silt. <br />The chart on the following page shows the range in strength parameters for each of these soils. <br />For this analysis, a full range of cases will be analyzed, to account for any possible <br />embankment soil and foundation soil which could occur on the site. <br />Samples of the embankment for Pond 008 were taken in January of 2000 and found to <br />correspond to the descriptions given above for SM-SC or SC soil. In place density tests of <br />embankment material were made by extracting a certain volume, replacing the void with a <br />known volume of sand and later weighing the material extracted. The average wet density of <br />the in-place material was found to be 137.3 Ibs/cu.ft. The material was then dried and re- <br />weighed to give an in-place compacted dry density of 118.6 Ibs/cu.ft. The moisture content of <br />the original material was approximately 12%. This material will'be representative of the material <br />used for all other dams on the site. The SM-SC or SC soils are preferred for the embankment <br />• since the clay content results in better cohesion for dam construction. The lower foundation <br />material was also sampled and found to also correspond to the descriptions given above for <br />SM-SC or SC soil. The material was much sandier and had less clay. The same density test <br />was performed on this material which resulted in an in place wet density of 112.3 Ibs/cu ft. The <br />dry density was much lighter -84.8 Ibs/cu. ft. The high water content of this material (24%), is <br />due to natural water present in the sandy subsoil. <br />The GC or GM soils have little clay to bind the material which results in a high angle of friction <br />but virtually no cohesion, while the SM-SC or SC soils have cohesive clay and a lower internal <br />angle of friction. <br />• <br />REVISED M11RCH zoos Attachment 2.05.3(3)-15-2 <br />