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QUARTERLY MONITORING REPORT FOURTH QUARTER OF 1991 <br /> Tracy Boulevard Sheaf <br /> 3725 Tracy Boulevard,Tracy, California <br /> Shell WIC No 204-78844M I <br /> Delta Project No 40-89-012 <br /> Page 2 <br /> 2.1 Previous Work <br />' Background information and work conducted to date at the project site are discussed In the following reports <br /> • Proposed Work Plan for Pretank Closure Sue Assessment, Delta, June 19, 1989 <br />' • Pretank Closure Sue Assessment, Delta, November 22, 1989 <br /> • Preliminary Report and Tank Closure Report, Delta, November 28, 1990 <br />' • Quarterly Monuoring Report, Fourth Quarter of 1990, Delta, February 7, 1991 <br /> 0 Quarterly Monitoring Report, First Quarter of 1991, Delta, April 17, 1991 <br /> • Quarterly Monuoring Report, Second Quarter of 1991, Delta, July 25, 1991 <br /> 0 Quarterly Monitoring Report, Third Quarter of 1991, Delta, October 18, 1991 <br /> 2.2 Monitoring Wells <br /> ' Monitoring wells MW-1, MW-2, and MW-3 were drilled and installed around the perimeter of the site to <br /> a depth of 22 feet These wells were abandoned and replaced with monitoring wells MW-1A, MW-2A, and <br /> MW-3A on August 16, 1990 The new wells were installed adjacent to the abandoned well locations <br /> (Figure 2) <br /> ' 3.0 RESULTS OF INVESTIGATION ACTIVITIES <br /> ' 3.1 Ground Water Elevation Data <br /> Depths to ground water were measured at monitoring wells MW-IA, MW-2A, and MW-3A on <br /> November 21, 1991 Ground water elevations are summarized in Table 1 Using ground water elevation <br /> ' data collected during the November 21, 1991, sampling event, a ground water contour map was prepared <br /> and is presented in Figure 3 The ground water flow direction was toward the north-northeast at a hydraulic <br /> ' gradient of approximately 0 002 <br /> ' 3.2 Ground Water Analytical Results <br /> Ground water samples were collected on November 21, 1991, from monitoring wells MW-IA, MW-2A, <br /> ' and MW-3A and were submitted to a California-certified laboratory for analysis of benzene, toluene, <br /> ethylbenzene, and xylenes (BTEX), and total petroleum hydrocarbons(TPH)as gasoline Chemical analysis <br /> results were all below laboratory method detection Itrruts for BTEX and TPH as gasoline <br /> QMR013 BP <br />