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' ARCO Products Company 4 ARCO 4932 16E Harding Way Stockton CA November 9 2001 Soil analytical result - - - -- Table-3 a - - e -- — - -- • yt s are summarized in Table 3 and shown on generalized geologic ' cross sections (Figures 3 and 4) MtBE and 1,2-DCA were reported in SB-1 at a depth of 48 feet bgs The water sample collected at 68 feet bgs from SB-1 reported nondetect for all constituents TPHg, benzene and MtBE were reported in water samples collected ' at 33 and 50 feet bgs from SB-2 MtBE was present in groundwater samples from SB-2 at depths of 65 and 77 feet bgs Groundwater"grab" sample analytical data is included in Table 3 ' Groundwater Monitoring Well Development, Sampling,and Surveying ' After installation, the groundwater monitoring wells were developed by rigorously surging over the length of the screen interval and by purging approximately ten casing volumes of water ' Groundwater samples were collected from the newly installed groundwater monitoring wells on July 20, 2001 Groundwater samples were analyzed for TPHg and BTEX by ' EPA Method 8015/8020 and fuel oxygenates (MtBE, DIPS, TAME, EtBE, TBA, and 1,2-DCA) by EPA Method 8260 Groundwater analytical data is summarized in Tables 4 and 5, and shown on Figure 5 ' TPHg and benzene were reported in well MW-9 at concentrations of 200 ug/1 and 12 ug/l, respectively MtBE was reported in wells MW-6, MW-7, and MW-8 at a maximum concentration of 67,000 ug/1 (MW-6) 1,2-DCA was reported in wells MW-5 and MW-9 at concentrations of 3 8 ug/l and 8 4 ug/l, respectively Fuel oxygenates TBA,EtBE, DIPE, EDB and TAME were not detected above the laboratory detection limit Separate phase hydrocarbons were present in wells MW-4 and SVE-1 on July 19, 2001 Groundwater analytical data is presented in Tables 4 and 5, and is shown on Figure 5 Field and laboratory procedures are presented as Attachment C Groundwater ' sampling parameters are included on the field sheets in Attachment E A land survey was performed following drilling and each wells longitude and latitude, California state plane coordinates, and elevation relative to mean sea level and were established by Morrow Surveying, a California licensed surveyor Attachment F contains the surveyor's site plan showing the locations and elevations of the wells 1 Groundwater Flow Direction ' Depth to groundwater at the site ranged from 26 49 feet bgs to 28 44 feet bgs Based on monitoring data collected on July 19, 2001, groundwater flow was to the northeast with a gradient of 0 002 (Figure 6) ' Well Survey SECOR personnel performed a door-to-door survey of businesses and residences in the ' area to identify any water supply wells within a 500-foot radius of the site Where no • response was observed, a questionnaire and stamped envelope addressed to SECOR was placed in a conspicuous place Verbal and written survey results suggest that no water 077 43826 330/AddAssess doc