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t <br /> of the Pacific is a short distance to the northwest Refer to <br />' PLATE I for more details . <br /> GEOLOGIC & GEOMORPHIC PROVINCE - <br /> The site is located near the southern end of the Sacramento <br /> Valley, a sub-province of what is known as the Great Valley of <br /> California The Sacramento Valley is composed of in excess of <br /> 25, 000 feet of sediments derived from erosion and uplift of the <br /> Sierra Nevada Batholith to the east The sediments range in age <br /> from Recent to Cretaceous & possibly older, and consist of sands, <br /> gravels, silts, & clays produced by repeated reworking of the <br />' outwash from the Sierras <br /> Relief is very flat, less than 5 ' /mile, with drainage to the <br /> southeast towards the Sacramento-Stockton Delta area The <br /> Calaveras River is about one mile to the north-northeast, and <br /> Mormon Slough is roughly 2 miles to the south. PLATE II, from a <br /> USGS topographic sheet, shows the location of the site in <br /> relation to other nearby features <br /> SOIL CLASSIFICATION: <br /> According to the 1952 publication issued by the University of <br /> California, Berkley, the somal is this area is known as Stockton <br />' Adobe Clay It is a dark grey to brown alluvial soil derived as <br /> outwash from basic igneous sources, (le, the Sierra Nevada Bath- <br /> olith ) It is considered to have imperfect drainage, having <br /> hardpan subsoil layers generally underlain with unconsolidated <br />' material The Storie Index, 28, gives it a classification as <br /> poor. <br /> DEPTH TO GROUNDWATER: <br /> Based upon published data, the highest water level in the last 10 <br /> years was measured at about 27 ' bgl Groundwater was located at <br />' about 53 ' below grade during purging & sampling operations <br /> conducted in October, 1994 . Sampling operations conducted in <br /> March, 1995, revealed that the water table had risen 4 681 , to <br />' 48 .41 ' bgl . The June, 1995 sampling found water at 45 28 ' bgl , a <br /> rise of about 3 feet In October, the water table had dropped <br /> about 1 .5 ' (to an average of 46 . 931 , ) but had risen over 3 1/2 <br />' feet in February, 1996 to 43 191 . During the latest sampling <br /> event in July, 1996, the depth to water averaged 37 58 ' bgl in <br /> the 6 wells, the highest level since monitoring began in October, <br /> 1994 . <br /> PRIOR USE OF REMOVED UST' S : <br />' 2 <br /> 1 <br />