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SECTION 4 FIELD ACTIVITIES AND RESULTS Borings for collection of groundwater samples were installed after the lithologic CPT borings.Sampling depths were agreed upon with Ron Rowe/PHS/EHD in the field after evaluating the lithologic logs. Exact sampling depths for each CPT boring can be found in Table 4-2. • Seven borings (CPT-9,10,-11,-12,43,-14,and-15)were installed between March 13 and March 17,2000, to assess the downgradient and cross-gradient lateral and vertical extent of petroleum constituents in groundwater(Figure 4-1). CPT-9 was installed approximately 120 feet northeast of CPT-8 on the.northern shoulder of Highway 4 to identify the eastern lateral extent of petroleum constituents in groundwater. CPT-14 was installed approximately 100 feet east of the source area in an effort to delineate the j eastern boundary of groundwater impacted by petroleum constituents.These boring locations were determined after the results of the groundwater samples from borings CPT-1 through CPT-8 were evaluated. Borings for lithologic description were installed to the following depths: • CPT-9,-11,-12,-13,and-14 were all pushed to a total depth of 150 feet bgs. • CPT-10 was pushed to a total depth of 148 feet bgs. Borings for collection of groundwater samples were installed after the lithologic CPT borings. Sampling depths were agreed upon with Ron Rowe/PHS/EHD in the field after evaluating the lithologic logs.Exact sampling depths for each CPT boring can be found in Tables 4-1 and 4-2.Due to time constraints a lithologic log was not obtained for CPT-15. The CPT-15 sampling depth(106 feet bgs)was estimated from lithologic logs of CPT-10 and CPT-11- 4.2 Results ' 4.2.1 Hydrogeology This section presents a description of the hydrogeology of the Del Monte site. The description is based largely on compilation of information available from CPT borings CPT-1 through CPT-15,and recent groundwater monitoring events. A Groundwater for Windows (GWW) database was developed to compile lithologic information from the CPT borings. GWW is a groundwater systems information software package developed by the United Nations Department for Economic and Social Development;Science Technology, Energy,Environment and Natural Resources Division;Water Resources Branch,New York. Computerized well logs created in GWW were used to construct geologic cross-sections A-A' through E-E' (Figures 4-3 through 4-7). The cross-sections help identify the lateral and vertical extent of water-bearing units that may act as preferential groundwater flowpaths. t The cross-section locations are shown on Figure 4-2. The CPT borings indicate alluvium as much as 150 feet thick in the vicinity of the study area. The alluvium consists of unconsolidated deposits of clay,silt,and sand. A 5-to-10 foot thick sand unit is located approximately 90 to 110 feet bgs directly beneath the site. The unit consists of sand and silty sand with some clay lenses. The overlying alluvium is comprised i primarily of clay,silts and inter-bedded lenses of sand. The sand unit appears to be as 4-z SFOICP7 REPORT_1.DOC/003670036 1