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streams from about 35 million years ago to the present. In the vicinity of the <br /> Forward Landfill the marine sediments are generally overlain by approximately <br /> 2,500 feet of unconsolidated Tertiary and Quaternary sediments of(from oldest to <br /> youngest) the Valley springs, Mehtren, Laguna, and Victor Formations. Sediments <br /> of these formations were deposited by the activity of the major streams in this area <br /> that meandered across the valley floor. <br /> The most recent deposit, the Victor Formation, is typically heterogeneous and <br /> laterally and vertically discontinuous, indicative of a fluvial depositional- <br /> environment. The Victor Formation is generally coarse-grained, but is slightly <br /> clayey in the interfan sediment areas near the Forward Landfill. In this area, the <br /> Victor Formation is approximately 100 feet thick. <br /> 3.3.2 SITE GEOLOGY <br /> The geology and hydrogeology (discussed further in Section 3.7) of the existing <br /> Forward Landfill and Austin Road Landfill havebeen"detailed in severai-reports <br /> including Kleinfelder & Associates (1991, 1997, 1999), CH2MHill (1992) Beta <br /> Associates (1988), and EMCON Associates (1972). These studies confirm that the <br /> 0 geology as well as the hydrogeology....of the..Fww.ard.Landfill area are,aconsistent <br /> with regional conditions. <br /> As determined in exploratory boring and well installation programs performed at <br /> the site, geologic materials beneath the site occur as lenticular units composed of <br /> clay, silt, and sand with minor amounts of gravel. Bedding is typically <br /> discontinuous over distance and ranges in thickness from a few inches to <br /> approximately 20 feet. This variab iity'is consisterlWth deposition in a fluvial <br /> environment where the course of rivers or streams meanders and is subject to <br /> frequent flooding. The sediments observed in borings at the site appear to <br /> correspond with the Pleistocene Victor Formation and can be divided into three <br /> large groups based on gross lithology and pervasive distinctions in color. <br /> Group A. Surface to approximately 28 to 40 feet below ground - Highly <br /> interbedded sandy silt, clayey silt, silt, and clay. A few layers of sand. <br /> Generally sands are fine grained. Most of the sediments have an <br /> oxidized appearance as an orange brown color. <br /> Forward Landfill JTD 3-4 <br /> L:\AI lied\2000.193\Reports\finaljtd:Sec-3.0:08/20/01 <br /> BRYAN A.STIRRAT S ASSOCIATES <br />