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L & M OPERABLE UNIT-THIRD QUARTER 2014 SITE STATUS, REMEDIAL SUMMARY, <br /> AND GROUNDWATER MONITORING REPORT <br /> Groundwater Monitoring and Sampling <br /> October 31, 2014 <br /> • Dissolved phase TPHg and benzene, in B-Zone wells were generally delineated to <br /> the north, west, and south. Dissolved TPHo was generally delineated except to <br /> the north-northwest. Dissolved TPHd was not delineated except to the north. <br /> Dissolved MTBE was delineated except to the southwest and east. Wells located <br /> to the east (UOU and MOU wells) were not sampled, and therefore, data is not <br /> available to contour. TBA was reported as non-detect or below the laboratory <br /> method reporting limit during 3Q14. <br /> • Dissolved phase MTBE and TBA concentrations in C-Zone wells were generally <br /> delineated except to the east, during 3Q14. Dissolved phase TPHg was <br /> generally delineated to the southwest and northwest only. Dissolved phase TPHd <br /> and TPHo were not delineated during 3Q14. Dissolved benzene was delineated <br /> except to the south and east during 3Q14. <br /> • In the D-Zone wells, dissolved phase TPHg and TBA are delineated except to the <br /> north-north east and east. Dissolved phase MTBE is delineated. Dissolved phase <br /> TPHd and TPHo are not delineated. Dissolved phase benzene is delineated <br /> except to the north. <br /> • The extent of petroleum-affected deeper (B-, C-, and D-Zones) groundwater was <br /> not investigated by the City of Stockton at the UOU and MOU to the east. <br /> However, using historical data the deeper groundwater plumes appear to be <br /> stable. <br /> 2.8 ARSENIC <br /> Arsenic concentrations in selected shallow (A-Zone) wells within the hydrocarbon plume <br /> and within perimeter wells are evaluated for historical trends on an annual basis during <br /> the third quarter. Graphs depicting arsenic trends in selected A-Zone wells (MW-9, <br /> MW-32, 2AMW-12, MW-18, MW-20, MW-21, MW-22, MW-23, MW-25, MW-28, MW-31, <br /> MW-34, and MW-45) are included in Appendix H. <br /> 2.9 PURGE WATER STORAGE AND DISPOSAL <br /> Between July 7 and 10, 2014, approximately 1,010 gallons of purge water was <br /> transferred to the on-Site remediation system to be treated and discharged under the <br /> waste water discharge permit for West Weber Avenue and North Lincoln Street, <br /> Stockton, CA. Field data sheets are included in Appendix E. <br /> 5ta ntec 2.19 <br />