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PUBEC HEALTH SEI VICES qU N, <br /> SAN JOAQUIN COUNTY v <br /> JOGI KHANNA M.D., M.P.H. w . <br /> Health Officer <br /> P.O. Box 2009 ( 1601 East Hazelton Avenue) Stockton, Caltfotma 95201 <br /> ( 209) 468.3400 <br /> CHUCK CARMEL <br /> ENVIRONMENTAL ENGINEER <br /> ARCO PRODUCTS COMPANY 1 <br /> PO BOX 5811 <br /> SAN MATEO CA 94402 JUL 2 71993 <br /> RE: ARCO Station #548 SITE CODE: 1121 <br /> 1612 Hammer Lane <br /> Stockton CA 95207 <br /> San Joaquin County, Public Health Services Environmental Health Division (PHS/EHD) has <br /> completed review of the "Status Report First Quarter 1993" dated June 21, 1993 and <br /> prepared by RESNA. PHS/EHD has the following comments for your consideration. <br /> First quarter groundwater monitoring occurred on March 4, 1993. Unfortunately, due to <br /> recent asphalting of the site, monitoring well, MWl could not be located for sampling. <br /> Contamination was detected in groundwater samples collected from MW2 and MW3. The <br /> laboratory report indicated that detection limits were raised due to matrix interference and <br /> that lower boiling point contaminants were detected and quantitated as gasoline. In order <br /> to provide further information regarding these results, please consider utilizing additional <br /> analytical methods for analysis of future groundwater samples. <br /> Additional soil and groundwater investigation commenced on March 8, 1993 and consisted <br /> of five soil borings, B15 - B19. Soil boring, B19, was converted into MW5. <br /> Soil borings, B16 and B17 were drilled to investigate contamination associated with the waste <br /> oil tank; analysis of samples collected at 21.5 and 46.5 feet did not detect petroleum <br /> hydrocarbon contamination. The sample results of B16 and B17 provide the southern <br /> boundary of contamination associated with the waste oil tank. Additional investigation of <br /> the oil-water separator will still be necessary. <br /> Soil contamination was detected in B15 at 41.5 feet of up to 24 ppb benzene and 18 ppb <br /> xylene. The contamination detected was concluded to have been transported by the <br /> groundwater. Similarly, soil contamination was evidenced in the sample collected at 45 feet <br /> from B13, which was located 30 feet to the south of B15. Currently, groundwater is at <br /> approximately 45 feet below ground surface. An additional monitoring well or vapor <br /> extraction well may be necessary in the area west of the dispenser island, in order to <br /> investigate and remediate the contamination evidenced. <br /> A DtvWnn of San Joaquin Cowry Health tare Se cm �� <br />