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Mr. Steve Manildi <br /> October 12, 1.989 R <br /> Page 2 <br /> reflects amendments made to Table 5 of the June 28, 1989 Site Assessment <br /> Report including presenting the total petroleum hydrocarbon (TPH) results <br /> _ of the water sample taken from the primary supply well on June 19, 1989. <br /> The results for the ethylene dihromide and organic lead analyses are <br /> presented in Table 2. <br /> The analytical laboratory report containing data sheets, quality control <br /> data and chain-of-custody farms for the most recFnt samples collected is <br /> included as Attachment 1. The revised estimate of the lataral extent of <br /> soil and groundwater contamination (originally presented as Figure 8 of <br /> the .lune 28, 1937 Site Assessment Report) is presented on Figure 1. <br /> Benzene is still present in the groundwater at locations of MW-1, MW-3, <br /> and MW-6 although the concentrations are lower than what was observed <br /> during the first round of samples. However, these concentrations remain <br /> above the California Department of Health Services (DHS) maximum <br /> contaminant levels (MCLS) established in April 1989. Benzene was detected <br /> for the first time on September 20, 1989 in MW-8 at a concentration of 47 <br /> tig/L, which may indicate that. the lateral extent of the contamination is <br /> further south than what was previously estimated. <br /> Total petroleum hydrocarbon concentrations -.were detected in MW-1, MW-3, <br /> MW-6, and MW-8 from the most recent sampling occasion. These compounds <br /> had riot been previously detected at MW-1 and MW-8. At MW-3 and W-6, the <br /> TPH concentrations were lower than what was observed during the first <br /> xound of sampling. <br /> Ethylere dibromide and organic lead were. not detected in any of the <br /> samples collected at the detection limits of the instrumentation used to <br /> perform the analysis, <br /> -N Although in ;general the concentrations of chemical detected in the <br /> groundwater appear to have decreased, it is evident that the chemicals are <br /> still present and the apparent distribution of these chemicals in the <br /> groundwater has not significantly changed. Variations in chemical <br /> concentrations from one sampling occasion to another is a common <br /> occurrence. <br /> if you have any questions or comments, please do not hesitate to contact <br /> US. <br /> Very truly yours, <br /> +Gary B. aggaTt, 6.E.G. <br /> Principal Hydrogeo g°st <br /> kai <br /> Attachments <br /> i . <br /> r <br />