ARCHIVED REPORTS_XR0010333 - Laserfiche WebLink

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REGIONAL GEOGRAPHIC SETTING The property is located just east of Highway 99, between Waterloo Road, (Highway 88, ) and Fremont Street, (Highway 26, ) about 2-3 miles east of City Hall. The area is zoned for manufacturing and light industrial use; there are no residences in the immediate area. The Stockton Diverting Canal is a short distance to the east, and a spur of the Stockton Terminal Eastern RR is just to the south. PLATE I gives more details of the immediate area. GEOLOGIC & GEOMORPHIC_ PROVINCE The site is located near the southern end of the Sacramento Valley about 1 1/2 miles south of the Calaveras River and 3 miles northeast of the Stockton Deepwater Channel. Sediments in this area have been derived primarily from reworked maternal from meandering streams and flood plain deposits. The original source is outwash and erosion of the volcanic and metamorphic rocks formed during the uplifting of the Sierra Nevada Batholith to the east. The topography is one of very low relief, with drainiage towards the west-southwest at about 5 feet per mile. PLATE II is • a portion of a USGS quadrangle sheet showing the location of the property is relation to surrounding geologic features. SOIL TYPES According to the 1952 publication issued by the University of California, Berkeley, surface soils in this area are classified as Stockon Adobe clay, which is derived from reworked basin sediments. It is generally dark gray, fine textured, with a Storie Index of 24. It is typically underlain by calcareous subsoils containing hardpan or hardpan-like substratum The sediments encountered at this location generally conformed to that description, except at the southern end of the excavation, where a lease or pod of sandy clay was encountered. PLATE III, showing general soil types in the area, is from that 1952 publication. Detailed description of the sediments penetrated by the soil borings and monitoring wells are given later in this report. DEPTH TO GROUNDWATER A review of San Joaquin Co. Flood Control Maps indicates that the highest water level in this area occurred in the spring of 1986 - approximately 45' bgl at this location. Refer to PLATEN for a portion of that map. Groundwater was measured at approxi- mately 66 feet bgl, (39' MSL, ) during the latest quarterly moni- 0 toring done on August 1, 1994, the highest levels since measure- ments began in June, 1993. This is some 8' higher than the 2