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i <br /> Brown and Caldwell <br /> Consultants <br /> URN5 <br /> 723 Street <br /> 723 S duke ham`" " <br /> { no <br /> Calrfornia 95814 7092 <br /> (916)444 0123 <br /> FAX(9161 444 8437 A UQ 7 1992 <br /> August 11 1992 ENVIR NMZNTA�, HEALTH <br /> EMIT/S ?VICES <br /> Mr Chuck Carmel <br /> ARCO Products Company <br /> Post Office Box 5811 <br /> San Mateo, California 94402 017-6731-03/1 <br /> Subject Second Quarterly Report for ARCO Station 434, 541 Kettleman Lane, <br /> Lodi, California: Site Code 1341 <br /> Dear Mr Carmel <br /> This report presents water levels and analytical results of groundwater sampling performed <br /> on May 11 and 12, 1992, at ARCO Products Company (ARCO) Station 434, located at 501 <br /> Kettleman Lane in Lodi, California. There are six on-site monitoring wells (W-IA, W-2, W- <br /> 2A, W-2B, W-3, and W-9) and eight off-site monitoring wells (W-4, W-5, W-6, W-7, W-8, <br /> W-10, W-11,and W-12) (Figure 1) All monitoring wells were sampled except W-2 and W-4, <br /> due to an obstruction in W-2 and lack of water in W-4 W-2 appears to be bio-fouled and <br /> attempts to mechanically unplug it have not been successful <br /> Field and Analytical Methods <br /> Emcon Associates (Emcon) personnel measured depth-to-water levels, supervised purging of <br /> each well, and collected groundwater samples at the site Static water levels were measured <br /> prior to purging A summary of the groundwater measurements is presented in Table 1 <br /> Prior to sampling, the wells were purged of a minimum of three well volumes, or until <br /> evacuated, using a submersible pump or bailer After purging, each well was sampled using <br /> a teflon bailer All groundwater samples were analyzed for total petroleum hydrocarbons as <br /> gasoline (TPH-G) and benzene, ethylbenzene, toluene, and xylenes (BETX) by U S <br /> Environmental Protection Agency (EPA) Methods 5030/8020/DHS LUFT <br /> Results <br /> The general groundwater flow across the site is to the south-southwest with an average <br /> hydraulic gradient of 0 002 Figure 1 illustrates groundwater contours and the groundwater <br /> flow direction Wells W-2A and W-2B are not used on contouring, as these wells are <br /> completed in shallower and deeper zones, respectively, than the other wells Table 2 shows <br /> past and present hydraulic gradients and groundwater flow directions <br /> Current and historical analytical results are summarized in Table 3 Emcon's May 1992 <br /> sampling data and the laboratory report are presented as Exhibit A Figure 2 shows BETX <br /> and TPH-G concentrations Figure 3 illustrates benzene logarithmic contours for the May <br /> 673 INR EPORTS\MAY92QTR R7r <br />