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• Mr Ron Rowe February 24, 1999 Page 3 of 6 collect a groundwater sample from the well due to insufficient access for a bailer In order to determine the casing size, depth, and screened interval(s) of the onsite well, Ground Zero contacted the Department of Water Resources (DWR) and PHS/EHD to obtain information on any wells within 2,000 feet of the subject site -Wformation was available regarding the construction details of the water supply well on site A number of private domestic wells are located within 2,000 feet of the site, primarily to the southwest on Moreland Street and to the northeast on Gnekow Drive and Shippee Lane (see Surface Street Map, Figure 2) Groundwater beneath the site is expected to flow northeast, based on information obtained from the San Joaquin County Flood Control and Water Conservation District The nearest downgradicnt domestic well appears to be located approximately 600 feet northeast of the site on Gnekow Drive SUBSURFACE INVESTIGATION On November 9 and 10, 1998 Virgil Baker, Inc (VBI, C57-466270 as contracted to advance two pilot borings (CPT1 And C 2) using a CPT rig to identify subsurface stratigraphy, and to advance additional soil borings as necessary to collect soil and groundwater samples Borings iSB1 and SB2 were advanced to collect soil and groundwater samples in the vicinity of the former USTs and boring SB3 was advanced to collect soil and, if possible, groundwater samples in the vicinity of the former dispenser island Soil boring locations are shown on Figure 3 CPT Pilot Bonn s Pilot boring CPT1 was advanced in the location of the former USTs and CPT2 was advanced in the vicinity of the former dispenser island to determine subsurface conditions beneath the site and to identify specific target intervals for collection of soil samples CPT1 encountered refusal at a depth of approximately 75 5 feet bgs, preventing further penetration of the subsurface CPT2 was advanced to a depth of approximately 73 5 feet bgs, prior to encountering refusal Electric CPT data transmitted from the cone tip provided information on soil behavior by measuring penetration resistance, friction ratio, and pore pressure Correlation of soil behavior to soil type was made electronically, based on a soil classification chart interpreted by Robertson & Campanella (1983) Copies of CPT data tables and graphs are included in Attachment A Based upon the CPT sounding data and resultant graphical data (Attachment A) soil encou=ltered beneath the site consisted primarily ofLclaa with some silt to approximately 26 feet below ground surface (bgs), very csuff-fine_gratneed sca,11 from approximately 26 to 31133 feet bgs, interbedded c 9y and-silt with minor lenses of silty sand from approximately 31133 to 51152 feet bgs, very sh -fine-grained soil from approximately 51152 to 55 feet bgs, sand to silty sand from approximately 55 to 60162 feet bgs,5 ,and verb ff`fine g nia ed soil from approximately 60162 to 64 feet bgs, sand and silty__san from approximately 64 to 66 feet bgs, and very_ ttff�firie 9roundzcltu1eburg4nrirpt doe