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'{ Ms. Mary MeaYs Page 2 <br /> January 9, 1998 <br /> t <br /> presented in Attachment A. The sample containers were labeled appropriately and <br /> Pmaintained in chilled coolers until they could be transported to the laboratory. <br /> 4 <br /> As you recall, oxygen-regenerating compound (ORC) socks were previously installed <br /> Ft within eight wells to enhance biodegradation of TPH and associated compounds (BTEX). <br /> These ORC socks were removed from each well on September 15, 1997, and water levels <br /> were allowed to recover prior to measuring water levels or collecting samples. <br /> F <br /> FGROUND WATER FLOW PATTERNS <br /> Ground water elevation data for the September 1997 monitoring event are presented in <br /> FAttachment A and contoured on Figure 2. As observed on this figure,the ground water <br /> flow direction is generally to the south, with a slight mounding in the immediate vicinity <br /> of Former Tank#2. The ground-water flow direction observed during this event is <br /> 1 # consistent with observations made during previous sampling events. <br /> .F I <br /> ANALYTICAL RESULTS <br /> Samples from all ten wells were analyzed for TPH(g) and TPH(d)by.USEPA Method <br /> 8015 modified and for BTEX compounds using USEPA method 8260. Samples from all <br /> ten wells were also analyzed for general water quality parameters to evaluate the <br /> Feffectiveness of the ORC process. Samples from four wells (MW-4, MW-5, MW-IA, <br /> and MW-2A) were also analyzed for heterotrophic plate counts. The water quality and <br /> plate count results were analyzed for comparison to the baseline conditions established <br /> during the third quarter 1996 monitoring event; they will not be included during every <br /> future monitoring event. <br /> FAll analyses were performed by Quanterra, Inc., (Sacramento, California), with the <br /> exception of the plate counts,which were sent to Aquatic Biological.Sciences (South <br /> Burlington, Vermont), and dissolved methane and dissolved CO2, which were sent to <br /> Fj Quanterra (City of Industry, California). Laboratory data sheets and chain-of-custody <br /> forms for this sampling event are included in Attachment B. <br /> FjTPH as gasoline and BTEX detections in ground water samples collected from Former <br /> Tank Sites#1 and 92 are provided in Tables I and 2, respectively. General water quality <br /> F1 <br /> Fi <br /> ' These water quality parameter(hereinafter,"general water quality parameters")include: nitrate,chloride, <br /> 1i pH,conductivity,manganese,carbon dioxide,methane,ferrous iron,and ferric iron. <br /> 1,3,5-Trim ethylbenzene and 1,2,4-Trimethylbenzene results are also provided on Tables 3 and 4. <br /> F_f <br /> `f <br />