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hl <br /> Mr Kyle Christie Project 0805-144 02 <br /> April 27, 1995 <br /> Page 2 <br /> data to evaluate dissolved gasoline hydrocarbon concentrations and the flow direction and <br /> groundwater gradient <br /> On February 14, 1995, a technician from EMCON took water level measurements and <br /> collected groundwater samples from monitoring wells MW-1 through MW-4 for <br /> subjective and laboratory analyses The technician did not observe floating product or <br /> product sheen on samples collected from the wells (see Table 1) <br /> The surveyed elevations of the top of casing and the depth-to-groundwater measurements <br /> (see Table 1) were used to evaluate the potentiometnc surface beneath the site On <br /> February 14, 1994, the direction of groundwater flow was toward the northwest with a <br /> gradient of approximately 0 01 (see Figure 3) The direction of groundwater flow is <br /> consistent with previous sampling events. Groundwater elevation decreased approximately <br /> 0 71 foot from the previous sampling event(December 1994) <br /> Groundwater samples from each well were analyzed for total petroleum hydrocarbons as <br /> gasoline (TPHG), and benzene, toluene, ethylbenzene, and total xylene isomers (BTEX) <br /> using Environmental Protection Agency (EPA) Methods Modified 8015 and 5030/8020 <br /> The samples were analyzed at National Environmental Testing, Inc , in Santa Rosa, <br /> California The results of analyses are summarized in Table 1 Copies of the laboratory <br /> analysis reports are presented in Attachment A Results of analyses indicated TPHG and <br /> BTEX concentrations were below laboratory detection limits In groundwater samples <br /> collected from wells MW-1 through MW-4 <br /> ACTIVITIES PERFORMED DURING THE FIRST QUARTER <br /> • Performed quarterly groundwater sampling <br /> ANTICIPATED WORK <br /> • ARCO will continue to perform quarterly groundwater monitoring The next <br /> sampling event is tentatively scheduled for May 1995 <br /> CONCLUSIONS <br /> The groundwater flow direction was to the northwest, which is consistent with previous <br /> sampling event (December 1994) Gasoline hydrocarbons were not detected in <br /> groundwater samples collected from monitoring wells MW-1 through MW-4 Gasoline <br /> hydrocarbons have not been detected in the monitoring wells since the monitoring <br /> program began, with the exception of MW-3, which contained total xylenes at a <br /> concentration of 0 7 ppb during fourth quarter 1993 <br /> SAMN 1PJ010805108051440 2ALr94111b 1 <br />