ARCHIVED REPORTS XR0002758 - Laserfiche WebLink

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' ARCO Products Company 3 ARCO 4932, 16 E Harding Way Stockton CA November 6 2000 . Certified analytical reports and chain-of-custody documentation are presented as ' Attachment D 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 September 5, 2000 Groundwater samples were analyzed for TPHg and BTEX ' by EPA Method 8015/8020 and fuel oxygenates (MtBE, DIPE,TAME, EtBE, TBA, and 1,2-DCA) by EPA Method 8260 TPHg, benzene, and MtBE were reported in groundwater samples from all wells at maximum concentrations of 166,000 ppb, 10,500 ppb, and 708,000 ppb, respectively (MW-4) Fuel oxygenates TAME and 1,2-DCA were reported in all wells except MW- ' 3 at maximum concentrations of 427 ppb (MW-4) and 23 8 ppb (MW-1), respectively TBA was reported in wells MW-2 (215 ppb) and MW-4 (26,100 ppb) EtBE was ' reported in well MW-4 at a concentration of 2 22 ppb Groundwater analytical data is presented in Table 2 and is shown on Figure 2 Field and laboratory procedures are presented as Attachment C Groundwater sampling parameters are included on the field lie sheets in Attachment E The wells were surveyed relative to mean sea level by Tom Morrow Surveying, a California licensed surveyor Attachment F contains the surveyor's site plan showing the locations and elevations of the wells Groundwater Flow Direction ' Depth to groundwater at the site ranged from 26 45 feet bgs to 27 60 feet bgs Based on monitoring data collected on September 5, 2000, groundwater flow was to the northeast ' with a gradient of 0 005 (Figure 3) Well Survey ' SECOR performed a water well survey to identify the location of permitted water supply wells within a 1/2-mile radius of the site The water well survey consisted of ' review of California Department of Water Resources (DWR) files for the area Additionally, SECOR contacted the City of Stockton and California Water Company, which are the local water purveyors Ed Simonis, field station manager with City of ' Stockton-Water Department, and Enc Mar, facilities manager with California Water Company, both indicated that no municipal wells were operated within 1/2 mile of the site The closest wells identified from DWR file review are wells located approximately ' 1/2 mile east of the site at the Stockton State Hospital Well search data is presented in Table 3, and well locations are shown on Figure 4 ' 077 41983 330/well install