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F <br /> � f <br /> 4MSNA WATERWORK CORP. <br /> INDUSTRIES <br /> January 21, 1991 -' <br /> J A!1 2 5 'r <br /> Ms. Diane Hinson moi, rii if <br /> San Joaquin County Public Health Services <br /> Environmental Health Division <br /> P.O. Box 2009 <br /> Stockton, CA 95201 <br /> Re: '^° �� Quarter Report-Tri Valley Growers, 26200 <br /> r Nowell Road, Thornton, CA. a <br /> Dear Diane: s <br /> This letter report updates the activities at Tri-Valley Grower's <br /> Thornton plant during the first quarter of 1991. Activities <br /> during the quarter have included sampling for dissolved <br /> hydrocarbons and monitoring of groundwater. <br /> Groundwater monitoring conducted in October, November and <br /> December showed the water table ascended approximately 1/2 foot <br /> during the quarter (Table 1). The groundwater contour maps <br /> (Figures 1-4) show a consistent direction and magnitude of the <br /> o gradient (Table 1) during the quarter. This westerly direction <br /> varies significantly compared to previous quarters (Table 2). <br /> No discernible relationship between the gradient magnitude, <br /> gradient direction or water table elevation is apparent. N <br /> However, the shallow groundwater system clearly is responding to t <br /> 4 influences other than natural seasonal recharge. Recharge from <br /> irrigation or the effects of pumping in the area are probable <br /> 1 � <br /> factors. a <br /> Groundwater samples were collected from the six wells on December <br /> 20, 1990, for analysis of benzene, toluene, ethylbenzene, xylenes <br /> (BTEX) and total petroleum hydrocarbons as gasoline (TPHG), by 4 <br /> EPA methods 8015/8020. In addition, monitoring well, MW1 was <br /> sampled for oil and grease by EPA method 5520 C & F. [Sampling <br /> = was done using dedicated pumps in each well] . Applied Analytical <br /> (DOHS Cert. # 1211) performed the analyses. Laboratory results <br /> continue to show MW4 with moderate concentrations of gasoline <br /> hydrocarbons. Low concentrations of gasoline hydrocarbons were <br /> recorded in MW MW5, and MW6 -Oil and grease cancentrations---- -. .... <br /> were below <br /> r 1710 MAIN STREET :ESCALON,CA 95320 • (209)836-3507 - <br /> 23%A WALSH AVENUE • SANTA CLARA,CA 95051 • (408)496-1249 <br /> i'" <br /> now i <br />