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<br />(( <br /> <br />r. <br />~( <br /> <br />Cc <br /> <br />co <br />C"j <br />r~ <br />" ') <br /> <br />10 <br /> <br /><.J ,5. <br /> <br />MATERIAL PROPERTIES <br /> <br />-" <br />'-J <br /> <br />The materials on-site can generally be divided into two main <br />groups; residual soils derived from the Mancos shale and <br />pediment soils consisting of in-place pediment materials and <br />pediment derived soils. The residual soils consist of Quaternary <br />residuum (Qr), a11uvium-colluivum mixed (Qac) soils located <br />adjacent to residuum and weathered Mancos shale (Km). The <br />pediment soils consist of Quaternary pediment materials (Qp) and <br />alluvium-colluvium mixed (Qac) soils located adjacent to deposits <br />of pediment materials. <br /> <br />The residual soils are characteristically lean clayey fine <br />grained soils with plasticity indices greater than 7 and liquid <br />limits of 30 or more. <br /> <br />The pediment soils can be broken up into two groups; <br /> <br />o Fine-grained wind blown derived silty and clayey soils <br />which have plasticity indices of 9 or less and liquid <br />limits less than 30. <br /> <br />o Coarse-grained silty and clayey sands and gravels with <br />less than 30% to 40% fines and plasticity indices less <br />than 5. <br /> <br />A summary of the physical properties for each soil type is <br />provided in Appendix B on the Soil Data Summary Sheets. The <br />following sections present a summary of some of the in situ <br />properties and recompacted properties of the materials <br />encountered in the field investigation. <br /> <br />5.1 In Situ Properties <br /> <br />Of primary concern to site development are the hydraulic <br />properties of the in situ surficial soils and bedrock. To <br />determine these parameters, falling and constant head <br />permeability tests were performed in boreholes drilled in the <br />surficial soils and packer permeability tests were performed in <br />coreholes within the Mancos shale formation. <br /> <br />In general, all the surficial soils were fairly pervious at the <br />surface (0 to 1 foot depth) having permeabilities ranging from 1 <br />to 4 x 10-3 cm/sec (1.4 to 5.7 in/hr). Below a depth of <br />approximately 3 feet, the permeability varied from 1.4 x 10-3 to <br />2.5 x 10-5 cm/sec (2 in/hr to 3.5 10-2 in/hr) and averaged <br />approximately 3.5 x 10-4 cm/sec (0.5 in/hr). <br />