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tr: Former 76 Station 4409 S E C ® tR January 27, 2006 Page 3 details and usage of the well was not documented on the DWR well log The SJCEHD attempted to locate the well, however, the well was not found # y Additional well searches conducted in the area (adjacent LOFT site ARCO 4932, 16 East b Harding Way) indicated that 4 wells are located approximately 2,000 feet east (crossldowngradient) of the site at the Stockton State Hospital, one well is located 2,000 feet northeast (downgradient) of the site (near Cemetery Lane and Harding Way), and one well is located approximately 2,000 feet northwest (cross-gradient) at the intersection of f, Wyandotte and Commerce (as indicated by SJCEHD in their letter dated November 21, 2000) The use of the 4 wells at the Stockton State Hospital was not indicated on the well logs The well at Cemetery Lane and Harding Way was indicated as industrial use, and the r well at Wyandotte and Commerce is owned by California Water Service but is not active , The sensitive receptor survey is presented in SECOR's report Additional Site Assessment ; Report dated November 9, 2001 for ARCO 4932 MONITORING AND SAMPLING Current and historical monitoring and analytical data are included in Tables 1 and 2, respectively TRC's Data Transmittal, Groundwater Monitoring Field Notes and Laboratory Report dated • October 27, 2005 is included in Attachment B The report includes TRC's field and laboratory procedures, field data sheets, and certified laboratory analytical reports The site + has been monitored and sampled since the first quarter 2000 The field and laboratory a procedures, field data sheets, and certified laboratory analytical reports for the monitoring R< and sampling of MW-1 through MW-17 on October 6, 2005 are included in Attachment C ' Samples are analyzed for gasoline range organics (GRO) by Environmental Protection Agency (EPA) Method 8015M and benzene, toluene, ethylbenzene, total xylenes (BTEX), �s fuel oxygenates (MtBE, tertiary amyl methyl ether [TAME], di-isopropyl ether [DIPE], ethyl tertiary butyl ether [EtBE], tertiary butyl alcohol [TBA], and ethanol), and lead scavengers (1,2-DCA and ethylene dibromide [EDB]) by EPA Method 8260B Groundwater samples collected from MW-11 through MW-14 are also analyzed for dissolved lead by EPA Method 60106 DISCUSSION Groundwater monitoring wells (MW-1 through MW-17) were gauged and sampled by TRC on October 6, 2005 Water levels within groundwater monitoring wells that are part of the monitoring and sampling program at the ARCO Service Station (16 East Harding Way) were cooperatively measured by SECOR on October 5, 2005 through October 7, 2005 Regional groundwater flow direction within the A monitoring zone was to the northeast at approximately 0 004 foot per foot (ft/ft) beneath the ConocoPhillips site and radially outward beneath the ARCO site Regional groundwater flow direction within the B monitoring zone was to the northeast at an approximate gradient of 0 004 ft/ft The groundwater flow in the C monitoring zone was to the southeast at an approximate gradient of 0 005 ft/ft Shallow, intermediate, and deep monitoring zone groundwater contour maps (A, B, and C monitoring • zones respectively) are included as Figures 1, 2, and 3 ` "xt 4409 402005 QSR(CR)doc SFCORlntemational Incorporated ��sj