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SECOR tr data, except for a decrease in concentrations in EW -2 and an increase in concentrations in MW -3 Wells MW -1, MW -2, and DMW-1 were not accessible this quarter due to construction Wells MW -4 and MW -11 were not sampled this quarter because they are hooked up to a remedial system Well MW -8 was not sampled due to a car broken down on top of the well, the car's owner was not in the vicinity Groundwater elevations across the site increased by an average of 0 91 ft Groundwater flow for the shallow water - bearing zone was to the northeast at an approximate gradient of 0 008 ft/ft, and for the deep water bearing zone was to the northeast at an approximate gradient of 0 005 ft/ft, consistent with historical data Sampling dates were coordinated with the Tosco station 4409 located across the street from Arco 4932 Attachment C contains the groundwater elevations and analytical data for Tosco Station 4409 (Gettler- Ryan) This report presents our understanding of existing conditions at the subject site The conclusions contained herein are based on the analytical results, and professional judgment in accordance with current standards of professional practice, no other warranty is expressed or implied SECOR assumes no responsibility for exploratory borings or data reported by other consultants or contractors ATTACHMENTS: • Table 1 - Groundwater Elevation and Analytical Data • Table 2 - Fuel Oxygenates Analytical Data • Table 3 - Groundwater Gradient Data • Figure 1 - Groundwater Elevation Contour Map - Shallow Water Bearing Zone • Figure 2 - Groundwater Elevation Contour Map - Deep Water Bearing Zone • Figure 3 - Groundwater Chemical Concentration Map • Figure 4 - MtBE Isoconcentration Contour Map - Shallow Water Bearing Zone \� • Figure 5 - MtBE Isoconcentration Contour Map -Deep Water Bearing Zone • Attachment A - Field and Laboratory Procedures • Attachment B - Certified Laboratory Analytical Reports, Chain -of -Custody Documentation, and • Field Data Sheets • Attachment C - Former Tosco (Unocal) Service Station #4409 Groundwater Monitoring and Sampling Report (Gettler-Ryan) cc Mr Marty Hartzell, Regional Water Quality Control Board - Central Valley Region (RWQCB-CVR) Ms Lori Duncan, SJCPHS Vern Elrath, URS Corporation I V1RC0449321QMRS1200311 QMR03 doc .3-