Laserfiche WebLink
• exploration borings will be discussed in the following sections. <br />The soils encountered in this exploration program have been divided into three types. All of these soils are <br />alluvial and appear to be quite similaz, with varying amounts of coarse gravels and boulders and varying amounts <br />of the clay fraction. Soil Type I comprises the matrix material for the coarser grained, gravelly and bouldery <br />debris fan deposits and has been most susceptible to piping. Soil Types II & III are alluvial sandy silts and silty <br />ciays and clayey sifts which appear ven• similar to one another and have similar engincering characteristics. It <br />is anticipated that Soil Tvpe Q & III, which are present on the ground surface and in much of the existing <br />embankment, will be mixed and utilized for reconstruction of the embanlmtent and the pond floor surface. <br />Virtually all of the coarse sand, gravel and larger sizes encountered in these three soil types are composed of <br />fragments of sandstone, siltstone, mudstone and shale which are derived from the Mount Garfield members of <br />the Mesa Verde Formation which outcrops on the upper slopes of Coal Canyon. <br />Soil Type 1, wfiile not encountered at c- . gar the existing ground surface, comprised the majority of soils on this <br />site. These soils are generally the matrix material for the debris flow deposits which exhibit significant gap <br />grading bchvicen the approximate %: inch size and the coarse gravels and boulder sized fragments of the deposits. <br />• These soils underlie the enfvety of Pond 12 and the embankments. In addition, these soils are exposed in the <br />lower slopes of the existing Coal Canyon Channel. These soils have been designated Soil Type I for this report. <br />This soil type was classified as a silty sand, as the matrix between coarse gravel and boulder sized rock <br />fragments. This material is generally nonelastic although, some strata may exhibit very low plasticity. These <br />soils were found to have moderate to moderately high permeability and were encountered in a low density, <br />slightly moist condition. This soil kill settle after being loaded and the maximum allowable bearing capacity <br />for this soil was Cound to be approximately 1500 psf. This maximum allowable bearing capacity assumes the <br />matrix soils will scltle or in some cases collapse but the gravel and boulder fraction will tend to support applied <br />loads. These soils were found to contain sulfates in detrimental quantities. <br />Soil Typc II was encountered neaz the ground surface and as thin strata throughout the lower debris fan deposits <br />of Soil Type I. <br />Soil Type II was classified as a ven• sandy silty (ML) under the Unified Classification System. This material <br />• is of very low plasticity, of low to moderate permeability and vvas encountered in a low to occasionally medium <br />