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yrs <br />�A <br /> n <br /> e <br /> t <br /> q�p��rp�p �j��p p+ <br /> 4 1T l'9 1 ER 17 Sf®RK <br /> GEOCHEMICAL•GEOTECHNICAL•ENVIRONMENTAL <br /> A <br /> FEB f ►�^� <br /> January 15, 1990 <br /> E <br /> S <br /> ' <br /> ��RJiCL <br /> Ms. Darlene Reuss <br /> San Joaquin County Public Health Services <br /> Enviromenta7 Health Division <br /> P.O. Bos: 2009 <br /> Stockton, CA 95201 <br /> Re: Fourth Quarter Report-Tri Valley Growers,2_6200 Nowell <br /> Road, Thornton, CA <br /> Dear Darlene: <br /> This letter report updates the activities at Tri-Valley Grower's, <br /> Thornton plant during the fourth quarter of 1989. Activities <br /> during the quarter have included sampling for dissolved <br /> hydrocarbons and monitoring of groundwater. The two former tank <br /> pits were backfilled with clean fill in December 2989. <br /> Groundwater monitoring conducted- in November and December showed <br /> the water table rose approximately 0.5 feet during the quarter <br /> (Table 1). The groundwater contour maps (Figures l and 2) <br /> illustrate a westerly gradient at an approximate magnitude of <br /> 0.005 ft/ft. This is a decrease in magnitude and a change from <br /> the southerly direction observed in September. There are a <br /> number of possible reasons for these observed changes, however <br /> they must be evaluated over a series of monitoring events. <br /> Groundwater samples were collected from the six wells on December <br /> 7, 1989 for analysis of benzene, toluene, ethyl benzene, xylenes <br /> (BTEX) and total petroleum hydrocarbons (TPH) as gasoline, by EPA <br /> methods 8015/8020. In addition, MWl was sampled for oil and <br /> grease by EPA method 503E. Low levels of TPH as gasoline were <br /> reported in !.dl, MW3 and MW5 for the first time. The hydrocarbon <br /> levels in MW4 increased over the quarter. The oil and grease <br /> concentration in MW1 increased slightly. The blind replicate <br /> (MW7) for MW-6 reported non-detectable levels of hydrocarbon as <br /> did the original sample. The results are summarized in Table 2, <br /> and the laboratory reports and chain-of-.custody .are _presented.. as ------- ....__. <br /> -Attachment-l-.... <br /> 1710 MAIN STREET • ESCALON.CA 95320 • (209)838-3507 <br /> FRESNO.CA(209)222-3495 • RENO,W(702)788.6830 <br />