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prf.• trwst5 „,., ,K�.iws;.- '� r`."r r' q qs... W, ¢fi.. :we :§ a^Y <br /> a <br /> r <br /> BROWN AND+CALDItJELL <br /> N--- <br /> CONSULTING ENGINEERS <br /> February 23, 1989 <br /> -' Mr. Kyle Christie <br /> ARCO Products Company <br /> 2000 Alameda de las Pulgas <br /> l + Post Office Box 5811 <br /> 6 <br /> San Mateo, California 94403 017-3214-15/1 <br /> R <br /> Subject: Report on January 1989 Quarterly <br /> Groundwater Sampling at ARCO Station 434, <br /> z 501 Kettleman Lane, Lodi, California <br /> f Dear Mr. Christie: <br /> 1 <br /> f This letter report describes the January groundwater sampling at ARCO Products Company <br /> y (ARCO) Station 434 in Lodi. A total of ten on- and off-site groundwater monitoring wells <br /> were installed between April 1987 and June 1988. The purpose of the monitoring wells is to <br /> characterize hydrocarbon occurrence in groundwater beneath the site resulting from a December <br /> 1986 gasoline leak at Station 434. An estimated 800 gallons of unleaded gasoline were lost <br /> as a result of the leak. <br /> i <br /> Figure 1 shows the location of monitoring wells, benzene concentrations in groundwater <br /> samples collected from these wells during January 1989, and the direction of groundwater <br /> l i flow.. Figure 2 shows the design of each monitoring well and the installation dates, and the <br /> : groundwater level beneath the site in April 1987, September 1988, and January 1989. <br /> `j Between July and November 1987, and again between May and July 1988, free product <br /> accumulated in monitoring wells W-2 and W-3. The maximum product thickness measured <br /> during these time periods was 3.18 feet of free product in monitoring well W-2. A total of <br /> 52 gallons of gasoline were recovered from these wells during these two time periods. No <br /> product has been detected in monitoring well W-2 or W-3 since the last groundwater sampling <br /> in September/October 1988. <br /> To track the dis8oivcd hydrocarbon trends systematically, ARCO authorized quarterly <br /> groundwater sa;npling and analysis for benzene, ethylbenzene, toluene, and xylene (BETX). <br /> _Groundwater s3mples_w_ere collected-for analysis on January_4,_5_,_and_6._1989. _Monitoring <br /> Y well W-8 was not sampled :as dissolved hydrocarbons have never been identified in <br /> groundwater from W-8, and it is located some distance from any identified dissolved <br /> hydrocarbon occurrence: <br /> rM- <br /> -723 6 STREET SAC0.4FAENTO.CALWORN:A 9351-?M•f9 W,N4•Ot23 <br /> c .. <br />