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4 <br /> Mr. Kyle Christie <br /> 1 February 26, 1990 <br /> 1 <br /> Page 4 • <br /> a closed ice chest from the time of collection through delivery to the laboratory. All purging and <br /> sampling equipment was washed with laboratory-grade detergent and tap water then rinsed with <br /> deionized water.before each use. All groundwater generated during the purging and sampling <br /> process was removed from the site by Armour Petroleum Service. <br /> September 1989 Analytical Results <br /> 4 All of the samples were analyzed for BETX and TPH by U.S. Environmental Protection Agency <br /> (EPA) Method .8015 using Method 5030 as the sample introduction method, and purgeable <br /> halocarbons by EPA Method 8010. The analytical results of the groundwater samples collected <br /> in the previous quarters and September 1989 are summarized in Table 2. Complete laboratory <br /> results for the September groundwater sample analyses are included in this report as Appendix A. <br /> BETX Results.t In well ATR-1, the benzene concentration has decreased approximately 30 <br /> percent over the June 1989 sampling interval. However, the benzene concentration remains <br /> above the action. level for drinking water as established by the California Department of Health ' <br /> } Services (DHS).; Ethylbenzene, toluene, and xylene have all increased in well ATR-1 and xylene <br /> exceeds the DHS action level. BETX concentrations in well ATR-2 have remained relatively <br /> constant for the past three quarters. In well ATR-3, BETX concentrations have increased since <br /> t June 1989. Benzene and xylene concentrations are above action levels in well ATR-3. The <br /> BETX concentrations have significantly decreased in well ATR-4 since June 1989. However, <br /> benzene remains above the DHS action level. The benzene concentration in well ATR-5 has <br /> ' been decreasing since March 1989 but remains above the DHS action level. Ethylbenzene, <br /> toluene, and xylene concentrations remain well below DHS action levels in well ATR-5. BETX } <br /> have been detected in trace amounts in ATR-6 but remain well below action levels. Only trace <br /> concentrations of benzene and xylene have been identified in well ATR-7. Ethylbenzene and <br /> toluene were not detected in the September 1989 samples. <br /> TPH Results. Groundwater samples from the seven wells were analyzed for low boiling point <br /> hydrocarbons (C4-C12) and were not characterized as gas, diesel, or motor oil in the laboratory <br /> report. Petroleum hydrocarbon concentrations were below the laboratory detection limit in ATR- <br /> 6, and ATR-7. Only trace amounts of petroleum hydrocarbons were identified in well ATR-2, <br /> ATR-4; and ATR-5. ATR-1 and ATR-3 contained 27 parts per million (ppm) and 7.4 ppm <br /> petroleum hydrocarbons, respectively. This is a slight increase for well ATR-3 over the June <br /> 1989 sampling event. Until September 1989 the petroleum hydrocarbon concentration has been . <br /> below laboratory detection limits or has been detected in very small amounts in well ATR-1. <br /> The September "sample, while still low, shows an increase in the petroleum hydrocarbon <br /> concentration in;ATR-1. The reason for this increase is unknown at this time. <br /> { <br /> Brown and Caldwell <br /> Consultants <br /> J _ <br />