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1995 to confirm the detections The resulting analysts of the submitted samples was no detections <br /> of TPH-d, or BTEX, indicating possible field or laboratory contamination of the May 2, 1995 <br /> sample <br /> Monitoring well DMW-5 was sampled on May 26, 1995 for TPH-d and BTEX and was also <br /> tested for TPH-g and for volatile halogenated hydrocarbons (EPA 8010A), as requested by PHS- <br /> EHD The results for MW-5 reported no detections for TPH-g, TPH-d, or for BTXE Analysis for <br /> volatile halogenated hydrocarbons reported carbon tetrachloride, chloroform and 1,2-dichloroethane <br /> at concentration of 0 65 ug/L, 3 8 ug/L and 40 ug/L, respectively Soil samples taken from DMW-5 <br /> did not report detections of volatile halogenated hydrocarbons (Table 1) <br /> 4 5 GROUNDWATER LEVELS <br /> Nine rounds of groundwater level measurements have been conducted between July 1987 and <br /> May 1995 These data are shown on Figures 3, 4, and 5 From July 1987 to June 1988 water <br /> levels were measured in three monitoring wells (MW-1, MW-2 and MW-3) installed by J H <br /> Kleinfelder and Associates These wells were abandoned in July 1990 as a result of dropping water <br /> levels and replaced by four new monitoring wells (DMW-1 through DMW-4) Between July 1987 <br />• and May 1994 groundwater levels decreased by a net amount of about 26 feet This decline has been <br /> attributed to a combination of a series of years of less than normal recharge to the groundwater <br /> system and a general regional downward trend in groundwater levels as a result of groundwater <br /> overdraft (Dames & Moore, 1994a) <br /> Figure 5 shows the current groundwater levels and groundwater gradient, which currently <br /> flows from west to east across the site This gradient is similar to the groundwater gradient <br /> measured in May 1994 Groundwater levels rose about five feet from May 1994 to May 1995 <br /> Currently, groundwater level is slightly more than 56 feet below ground surface Despite two recent <br /> rainy seasons of significantly greater than normal precipitation in 1992/1993 and 1994/1995, current <br /> groundwater levels remain more than 20 feet lower than 1987 Existing groundwater levels of 56 <br /> bgs are substantially deeper than the levels assumed by the PHS-EHD in their assessment of the <br /> potential threat to groundwater <br /> SAC156 14 12 <br /> DAMES & MOORE <br />