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<br />Geotechniwl Engineering Exploration <br />Hall-Irwin Construction Company <br />Project No. 2'1975089 <br />Soil and Bedrock Conditions <br />The following describes the characteristics of the primary soil strata encountered at the site <br />in order of increasing depths, along with cement groundwater conditions: <br />. • To soil - An approximate six (6) inch layer of silty topsoil was encountered at the <br />surface of each test boring. The topsail has been penetrated by root growth and <br />organic matter. <br />• Overburden Material -The overburden material consisted of a slightly cohesive to <br />cohesive sandy lean Gay (CL), sandy silt (ML), lean Gay with sand (CL), and/or fat Gay <br />(CN). 'these materials were encountered beneath the topsoil and extended to depths <br />of approximately three and one-half (3-~/2) to eight (8) feet below the surface. The silt <br />and Gay layers are relatively fine in nature, soft to medium stiff, and moist in-situ. <br />• Silty Sand (SM) and Poorly Graded Sand with Silt {SP-SM) -This poorly graded sand <br />stratum was encountered beneath the overburden materials at approximate depths of <br />three and one-half (3-1l2) to eight (8) feet below the surface, and extends to <br />approximate depths of five (5) to nine and one-half (9-1/2) feet below the surface. This <br />material is relatively non-plastic, is generally fine in nature, is loose to medium dense, <br />and moist to saturated with depth. <br />• Poorly Graded to Well-Graded Sand with Silt and Gravel (SP, SW-SM), Poorly Graded <br />to Well Graded Gravel with Silt and Sand (GW-GM) -This stratum was encountered in <br />all borings at approximate depths of five (5) to nine and one-half (9-1/2) to thirty-seven <br />and one-half (37-112) feet below the surface, and extends to approximate depths of <br />seventeen and one-half (17-1/2) feet below the surface. The sand and gravel stratum <br />is poorly graded to well-graded, is medium dense to very dense, contains moderate <br />amounts of silt, and is saturated in-situ. It is estimated that the maximum size of gravel <br />encountered with depth is approximately two (2) to six (6) inches in diameter. <br />• Weathered Sandstone/Clavstone/Siltstone Bedrock - The bedrock stratum was <br />encountered below the sand and gravel layer, and extends beyond the depths <br />explored. This stratum was encountered at approximate depths of seventeen and one- <br />half (17-1/2) to thirty-seven (37) feet below the surface. The upper one (1) to two (2) <br />feet of the bedrock is highly weathered, however, the underlying sandstone/siltstone is <br />relatively hard and/or well cemented with depth. <br />a <br />