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• <br /> sm FN <br /> liquid storage, and is currently stored on site The well development log is included in <br /> Attachment 2 <br /> GROUNDWATER MONITORING <br /> The delayed second quarter groundwater monitoring and sampling of monitoring wells MW-4 <br /> and MW-6 was conducted by Smith Environmental personnel on August 11, 1995 In addition, <br /> newly installed groundwater monitoring well MW-4R was sampled on August 22, 1995 Water <br /> level measurements were collected from all monitoring wells prior to purging and sampling <br /> during both events <br /> Subsequent to monitoring, each well was purged by extracting approximately 3 well casing <br /> volumes While purging, the groundwater parameters (temperature, conductivity, and pH) were <br /> monitored and allowed to stabilize before water samples were collected Samples were collected <br /> using dedicated, disposable bailers with bottom emptying devices to reduce volatilization The <br /> samples were transported to and analyzed by Argon Mobile Labs All purged groundwater was <br /> contained in a 55 gallon drum approved for hazardous liquid storage on-site pending appropriate <br /> disposal The well purge logs are included in Attachment 2 <br /> Groundwater samples were analyzed for BTEX using EPA Method 8020, and for TPHg and <br /> TPHd using modified EPA Method 8015 <br /> RESULTS <br /> Water levels generally decreased in all the wells since the last monitoring event in March 1995 <br /> (Table 1) Groundwater gradient maps were created using the data collected on August 11 and <br /> August 22, 1995 (Figures 2 and 3) Groundwater flows northeast, away from the slough, with <br /> a gradient of approximately 0 076 feet/foot or 401 feet per mile on August 11, 1995, and 0 077 <br /> feet/foot or 407 feet per mile on August 22, 1995 <br /> Analytical results for the three soil samples collected from the boring for monitoring well MW- <br /> 4R indicated that petroleum hydrocarbons were detected only in the sample collected from 6 5 <br /> feet bgs In that sample (MW4R-6 5) benzene was detected at a concentration of 0 19 parts per <br /> million (ppm), ethylbenzene at 0 012 ppm and total xylenes at 0 036 ppm <br /> Petroleum hydrocarbons were detected in the groundwater samples collected from monitoring <br /> wells MW-4 and MW-6 Benzene and TPHg were detected at concentrations of 22 parts per <br /> billion (ppb) and 160 ppb, respectively, in well MW-4 Toluene was detected at a concentration <br /> of 33 ppb in well MW-6 <br /> No petroleum hydrocarbons were detected in the groundwater samples collected from the newly <br /> installed well MW4R <br /> N\15OU7512QR-1995 WP5 3 <br />