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hKLEINFELDER Map of the San Francisco — San Jose Quadrangle," indicates that the site is underlain by Pleistocene alluvium (plant area) and Miocene fanglomerate. The northwest trending Midway Fault is located adjacent off site to the west. According to the U.S. Department of Agriculture, Soil Conservation Service, "Soil Survey of San Joaquin County, California" dated October 1992, soils at the site consist of Calla Clay Loam and Carbona Clay. These soils generally correlate to a CL or CH in the Unified Soil Classification System. Permeability is described as slow with rapid runoff in areas of significant slope. Kleinfelder is currently conducting a geotechnical assessment in the vicinity of the proposed 72 million-gallon pond(s). Several test pits and borings were advanced at depths ranging from 10 to 30 feet. No free groundwater was encountered. Soils encountered consisted predominantly of clays (CL) and silts (ML). Copies of the draft logs are included in Appendix C. Kleinfelder has previously conducted one field assessment at the site. In 1985, Kleinfelder attempted to install three groundwater monitoring wells adjacent to the evaporation ponds on site (Appendix C). The borings were advanced to depths of 50 to 90 feet below grade. In general, the soils encountered consisted of alternating clays and silts with minor sand and gravel lenses. No free groundwater was encountered in borings 1 and 3 to a depth of 90 feet. What was described as a perched groundwater condition was encountered in boring 2 at a depth of approximately 29 feet. According to the 1985 report, during installation of the production well for the Musco Olive facility, groundwater was encountered at a depth greater than 250 feet, rising to within approximately 50 to 60 feet of the surface. A copy of the DWR well log for the production well on site is included in Appendix C. Kleinfelder also requested available water well logs for the vicinity of the site from DWR (Copies included in Appendix C). Several references to a thick clay layer, in some logs described as being 100 feet thick, are included on well logs within one to two miles of the site. Additionally, several references were made to a "blue clay" or blue shale at various depths in several borings. With one exception, the wells appear to be screened at depths greater than 250 feet. A single well located at "Patterson Pass Road and Highway 580" is screened in a black sand from 153 to 193 feet. 20-2594-03.WP2/201IR002 Page 3 of 12 Copyright 2000 Kleinfelder,Inc. December 29,2000