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Bedding absent or nondistinct but appears to be essential) <br /> �. g is ab n d pp Y <br />' horizontal . Owing to a moderate to high silt and/or fine- <br /> grained sand content, the clays are not highly plastic. <br /> Permeability of the clays and silts is low whereas the sands <br /> exhibit somewhat higher permeability. <br /> The Modesto Formation is known to be underlain by older <br /> Pleistocene and Tertiary strata which in turn rest on <br />' crystalline basement. However, these formations are of no <br /> significance to this present study because of their depth. <br />' No faulting or fracturing is evident on or near this site. <br />' Vadose Zone <br />' The logs of the eleven wells indicate the unsaturated zone <br /> consists predominatly of silts and clays. A zone of sand is <br /> located between 20 and 30 feet below the surface. Another <br /> thicker sand layer begins at about 45 to 50 feet below the <br />' surface. This lower sand unit does not exist in wells MW-9 and <br /> MW-10 . The water table is presently located at 48 feet below <br />' grade. <br /> There is good correlation between the basic soil units except for <br />' the zone between 20 and 35 feet below the surface. This zone <br /> consists of lenses of sand and clay. The two units are not well <br />' <br /> defined across the site , however, because of the clay units this <br /> zone will have some effect on the vertical migration of the fuel. <br />' There are no clay units found in this zone in wells BM-6 and BM- <br /> 8 . Enclosed are two cross-sections, one between BM-9 and BM-11, <br /> Fig. 3 and the other between BM-4 and BM-10 , Figure 4 . <br /> Contamination has been found in wells BM-1, BM-4, BM-5, BM-7 , BM- <br /> C, and BM-9 along with boring B-1 . The benzene contamination <br /> found in well BM-9 in much higher at the 50 foot level than the <br /> Page 5 <br />