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Nn <br /> MI <br /> The scope of this investigation includes only the uppermost <br /> deposits within the Central valley. Continental rocks and <br /> deposits of Tertiary and Quaternary age compose a number of <br /> formations; in total they constitute the major aquifer of the <br /> Central valley and yield large quantities of water to wells. <br /> Lithologically these deposits are heterogenous mixtures of <br /> poorly sorted clay, silt, sand, and gravel and in places some <br /> beds of claystone, siltsone, sandstone, and conglomerate. <br /> The maximum thickness reported in these formations are <br /> 3,000 feet. <br /> Continental deposits of Quaternary age crop out primarily <br /> along the major rivers and streams of the valley as well as <br /> other low-lying areas; the deposits include river deposits, <br /> flood-basin deposits, and sand dunes. River deposits, <br /> including channel and flood-plain deposits, are considered to <br /> be the most permeable deposits in the valley; however, they <br /> are generally not tapped by. wells. Flood-basin deposits <br /> consist largely of fine-grained beds that restrict the <br /> vertical movement of water. <br /> .J <br /> 2.0 SOIL CHARACTERIZATION AND EXCAVATION <br /> The protocol implemented for soil characterization and <br /> profiling, in terms of numbers of samples and chemical <br /> analyses performed, were based on the requirements of the <br /> potential disposal facilities. The excavation planwas <br /> ' designed based ; n the results of the soil sampling and <br /> analysis and .disposal facility requirements. <br /> 2.1lures <br /> The soil sampling at the site was conducted using the grid <br /> pattern shown in Figure 4. The area proposed for excavation <br /> was. divided into five sampling sections designated A <br /> through F, each containing nine grid areas, except in <br /> sec..ion .F which has three grid areas. Each grid area .w-th <br /> dimensions of approximately 15 feet by 16 feet repres4nts two <br /> 5-food-thick portions of soil (approximately 50 cubic yards <br /> each) ,; One discrete sample was collected for every 50 cubic <br /> yards of soil with up to nine discrete samples_,composited- at _ __- <br /> -- the- laboratory for chemical analysis. Sampling points were <br /> lo-ated at the center of the grid areas. <br /> The sampl ng program was designed to characterize the soil at <br /> s' two depth intervals; from ground surface tc: 5 feet below <br /> grade and front 5 to 10 feet below. grade. Two discrete <br /> samples were collected from each depth interval at each <br /> borehole as follows: <br /> 3 <br />