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HARGIS+ASSOCIATES, INC. • <br /> Comparison of water level elevation data obtained since July 1989 indicates <br /> that groundwater flow direction and horizontal hydraulic gradients in the <br /> intermediate and deep zones have varied seasonally (H+A, 1989c) . The direction <br /> of groundwater flow in the intermediate and deep zones in July 1989 and July 1990 <br /> was to the southeast. The direction of groundwater flow in the intermediate and <br /> deep zones in January 1990 and January 1991 was to the east (H+A, 1990a) . The <br /> horizontal hydraulic gradient in the intermediate and deep zones in July 1989 and <br /> July 1990 ranged from approximately 0.0015 to 0.0039 (H+A, 1989c) . The <br /> horizontal hydraulic gradient in the intermediate and deep zones south of <br /> Washington Street in January 1990 and January 1991 ranged from approximately <br /> 0.0003 to 0.0009 (H+A, 1990a) . These seasonal variations may be due to <br /> agricultural and municipal pumping influences in the vicinity of the MCTC <br /> facility, and the Stockton Diverting Canal . <br /> Groundwater quality data obtained in the vicinity of the MCTC facility <br /> indicate a change in the direction of chromium migration since January 1989. <br /> Concentrations of total dissolved chromium detected in groundwater samples <br /> collected from intermediate zone monitor wells MW-421 and MW-430 have decreased <br /> since January 1989 (H+A, 1990a) (Figure 9) . Monitor wells MW-421 and MW-430 are <br /> located west of Sinclair Avenue between Horner Avenue and Main Street (Figure 8.) <br /> Concentrations of total dissolved chromium detected in groundwater samples <br /> collected from intermediate zone monitor wells MW-426 and MW-439 have increased <br /> since January 1989 (H+A, 1990a) (Figure 10) . Monitor wells MW-426 and MW-439 are <br /> located east of Sinclair Avenue between Horner Avenue and Main Street (Figure 8) . <br /> The decrease in concentrations of total dissolved chromium detected in <br /> groundwater samples collected from monitor wells located west of Sinclair Avenue, <br /> and the increase in concentrations of total dissolved chromium detected in <br /> groundwater samples collected from monitor wells located east of Sinclair Avenue <br /> indicate that dissolved chromium is migrating eastward in response to the current <br /> groundwater gradient in the vicinity of East Main Street. <br /> Concentrations of total dissolved chromium detected in groundwater samples <br /> collected from deep zone monitor wells MW-363 and MW-461 have increased since <br /> 100.514LF <br /> 13 March 15, 1991 <br />