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I <br /> LOWRY &. ASSOCIATES <br /> Page 3 <br /> August 17, 19% <br /> L & a No. 90-190 <br /> River at the southern bridge abutment site penetrated soils that consist of medium dense <br /> brown slightly clayey fine sandy silts (ML) extending to a depth of 4-112 feet below <br /> existing site grade, underlain by stiff brown fine sandy clays (CL) and interlayered dense <br /> gray-brown fine to coarse sands (SW), gray-brown silty fine to medium sands (SM) and <br /> brown clayey fine to medium sands (SC). These soils were dense to cemented and <br /> extend to a depth of approximately 38 feet below existing site grade where they are <br /> underlain by stiff tan silty clays (CL) to a depth of at least 40 feet below grade. <br /> Test borings drilled within the lake beds penetrated soils consisting of soft light brown <br /> clayey silts (ML) and organic silts (OH) that contained lenses of brown slightly clayey <br /> silty fine to medium sands (SM) and gray silty clays (CL) to depths on the order of 20 to <br /> 25 feet below existing site grades. <br /> Boring No. B6, drilled within a proposed borrow pit location penetrated soils consisting <br /> of brown clayey fine sandy silts (ML) to a depth of approximately 3-1/2 feet below <br /> existing site grade. These surface soils were underlain by cemented "hardpan" consisting <br /> of light brown fine sandy silts (ML) and light brown silty fine sands (SM) that extended <br /> to at least 20 feet below existing site grade, the maximum depth explored at this location. <br /> t Ground Water <br /> Each test boring was checked for ground water during and after drilling. No free ground <br /> water was encountered within borings drilled along the ridge lines or at the proposed <br /> borrow pit location. In Boring No. T10, we observed ground water at a depth of <br /> approximately 22 feet (elevation +6 feet) below existing site grade and within Boring No <br /> B4 we observed ground water at a level of 14 feet (elevation -4 feet). Boring No. T11 <br /> encountered ground water at a depth of approximately 25 feet (elevation +5 feet) below <br /> grade. <br /> The difference in ground water depth appears to be the result of the distance the borings <br /> i were located away from the Mokelumne River. Borings No. T10 and Tll were drilled <br /> adjacent to the river and Boring No. B4 is approximately 1700 feet away from the river <br /> J <br /> 1 <br />