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TABLE 4 <br /> ANALYTICAL RESULTS OF GROUNDWATER SAMPLES <br /> ' Hess-Dubois Cleaners <br /> 348 West Harding Way, Stockton, California <br /> ' TPH as Ethyl- <br /> Sample I.D./ Stoddard Benzene Toluene Xylenes . <br /> Date benzene <br /> t Solvent <br /> 3.9 <br /> MW-1/11-493 660 3.4 ND 4.3 ND <br /> ' MW-1/6-22-94 190 ND ND ND <br /> MW-2/11-4-93 880 ND ND 4.3 6.2 <br /> MW-2/6-22-94 670 ND ND ND ND <br /> ' MW-3/11-4-93 41,000 29 ND 120 610 <br /> MW-3/6-22-94 2,800 ND ND 17 1.5 <br /> ' per as <br /> 5.2 Petroleum Hydrocarbon Impacted Soil <br /> ' <br /> Petroleum hydrocarbon impacted soil remains in the vicinity of MW-3. The lateral extent <br /> of the impacted soil has not been determined. Additional assessment will be necessary to <br /> determine the extent of impacted soil and to design an appropriate remediation system. <br /> 5.3 Petroleum Hydrocarbon Impacted Groundwater <br /> 1 <br /> Concentrations of TPH and BTE&X decreased in all three monitoring wells between <br /> November 1993 and June 1994. However, the down-gradient extent of the hydrocarbon / <br /> ' plume has not been determined.Additional monitoring wells will be necessary to determine✓ <br /> the lateral extent of the plume. Because of structures currently at the site, at least one <br /> monitoring well will need to be installed in the City of Stockton right-of-way along Harding <br /> Way, north or northwest of the site. <br /> A consistent northwest groundwater flow direction has been determined at the site. <br /> Therefore, we recommend that the requirement for monthly groundwater depth <br /> measurements be discontinued. Groundwater depths data should be collected on a quarterly <br /> basis. <br /> The next quarterly monitoring and sampling should be scheduled for September 1994. <br /> GeoAudit also recommends the preparation of a work plan for the installation of additional <br /> ' monitoring wells at the site. If wells are to be installed in the City of Stockton right-of--way, <br /> encroachment permits will have to be obtained. <br /> 0-6 j h A.&U�1- 10 <br /> S�.wn pnceQR1H-91iK615 i <br />