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Mr Terry Tarditi <br /> May 19,2000 <br /> Page 2 <br /> quarter (February, May,August, and November) Samples are required to be analyzed for the <br /> following constituents total petroleum hydrocarbons as gasoline "H-G), by EPA method 8015 <br /> Modified,benzene, toluene, ethylbenzene,and xylene (BTEC, and oxygenates by EPA method <br /> 8260B <br /> Groundwater Disposal <br /> Purge waxer from this sampling event was placed into drums and disposed of properly <br /> Quarterly Results Summary. <br /> Analytical laboratory Kiff Analytical,Inc,Davis, California <br /> (California Department of Health Services <br /> Certification No 2336) <br /> Sample exceptions None <br /> Shallow groundwater gradient 0 005 <br /> Shallow groundwater flow direction South southwest <br /> Average depth-to-water 62 47 feet <br /> Average change in shallow groundwater elevation <br /> from previous quarter 2 04 feet increase <br /> • Field data sheets frorn the April 2000 quarterly groundwater sampling event are included as <br /> Attachment A Historical groundwater elevation data is summarized in Table 1 Table 2 <br /> sutmmanzes groundwater flow direction and gradient Table 3 summarizes the historical analytical <br /> results for petroleum,hydrocarbon constituents Laboratory reports for the groundwater samples <br /> collected for this sampling event are included as Attachment B A comparison of last quarter's <br /> groundwater analytical results with this quarter's sampling results is summarized below in Table 4 <br /> Table 4. Comparison of Groundwater Analytical Results with Previous Sampling Event <br /> TPH-G Benzene MTBE(8260 B) <br /> 1st qtr,00 2nd qtr,00 1st qtr,00 2nd qtr,00 1st qtr,00 2nd qtr,00 <br /> Highest concentration,(µg/L) 2,600 2,100 620 940 2,300 3,400 <br /> Well with highest concentration MW-3 MW-3 MW-3 MW-3 1 MW-1 <br /> Number of wells with detection 2/4 2/4 3/4 3/4 3/4 3/4 <br /> Discussion <br /> Based on this quarter's data, groundwater flows south to southwest under a hydraulic gradient of <br /> approximately 0 005 Benzene concentrations increased slightly in well MW-3 from the previous <br /> quarter, decreased slightly in wells MW-1 and MW-4, and were not detected in the sample from <br /> MW-2 Tolulene, ethylebenzene, total xylene, and TPH-G concentrations remained consistent <br /> • Uje or duelowr of dala eamirnued on This.ihrel a -n Jeet to the nrtmaon.ipeafied at the hegrnneng of this dmument <br /> 05/19/00P\16000\16271\Rcports\2ndOOgtrdo� <br />