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<br /> A S S O C I A T E S I N C
<br /> groundwater elevation contour map (Figure 3) Shallow groundwater beneath the site generally
<br /> flowed towards the east-northeast The average hydraulic gradient on January 12, 2005, was
<br /> calculated to be approximately 0 0005 ft/ft or approximately 2 6 ft/mile A summary of groundwater
<br /> monitoring data is presented to Table I
<br /> SAMPLING ACTIVITIES
<br /> On January 12, 2005, ATC personnel collected groundwater samples from monitoring wells MW
<br /> through MW7 The locations of the monitoring wells are shown on Figure 2 Prior to collection of
<br /> groundwater samples, the depth to water was measured in each well and the pH, electrical
<br /> conductivity, and temperature were measured in groundwater purged from the monitoring wells and
<br /> recorded A minimum volume of three well casings was purged from each well prior to sampling
<br /> The wells were allowed to recover and samples were collected from each well using a disposable
<br /> bailer
<br /> The groundwater matrix samples collected from each well were submitted to State-certified Argon
<br /> Laboratories (Environmental Laboratory Accreditation Program Certificate No 2359) for chemical
<br /> analyses of TPHg utilizing EPA Method 8015B, BTEX utilizing EPA Method 8021B, and gasoline
<br /> oxygenates/addrttves including MTBE, ETBE, DIPE, TBA, TAME, 1,2-DCA, and EDB utilizing
<br /> EPA Method 8260B Groundwater well purge and sample logs are contained in Attachment 1
<br /> ANALYTICAL RESULTS
<br /> The laboratory analytical results indicate petroleum hydrocarbons were detected to the groundwater
<br /> samples collected from all of the monitoring wells
<br /> TPHg was detected in the groundwater samples collected from MWI, MW2, MW5, MW6, and
<br /> MW7 at concentrations of 180 micrograms per liter (pg/L), 1,200 pg/L, 540 µg/L, 960 µg/L, and 90
<br /> pg/L, respectively Benzene was detected in the groundwater samples collected from MWI, MW2,
<br /> and MW6 at concentrations of 1 I pg/L, 1 5 pg/L, and 0 7 µg/L, respectively Toluene was detected
<br /> in the groundwater samples collected from MW2, MW5, MW6, and MW7 at concentrations of 3 7
<br /> pg/L, 4 0 pg/L, 4 8 µg/L, and 1 0 µg/L, respectively Ethylbenzene was detected in the groundwater
<br /> samples collected from MWI, MW2, MW5, MW6, and MW7 at concentrations of 12 gg/L, 8 6
<br /> pg/L, 73 µg/L, 19 pg/L, and 1 I pg/L, respectively Xylenes were detected in the groundwater
<br /> samples collected from MWI, MW2, MW5, MW6, and MW7 at concentrations of 2 5 µg/L, 26
<br /> pg/L, 87 gg/L, 30 µg/L, and 1 4 µg/L, respectively
<br /> MTBE was detected in the groundwater samples collected from MWI, MW2, MW3, MW4, and
<br /> MW7 at concentrations of 24 pg/L, 44 µg/L, 25 pg/L, 19 gg/L, and 43 gg/L, respectively TBA was
<br /> detected in the groundwater samples collected from MWI, MW2, MW3, and MW7 at concentrations
<br /> of 33 pg/L, 26 pg/L, 25 µg/L, and 23 pg/L, respectively 1,2-DCA was detected in the groundwater
<br /> samples collected from MW1 through MW7 at concentrations ranging from 4 0 µg/1- to 66 pg/L
<br /> The Maximum Contaminant Level (MCL) for benzene, 1 µg/L, was exceeded in the groundwater
<br /> i. samples collected from MWI and MW2 The MCL for MTBE, 13 pg/L, was exceeded in the
<br /> groundwater samples collected from MWI, MW2, MW3, MW4, and MW7 The MCL for 1,2-DCA,
<br /> 0 5 pg/L, was exceeded in the groundwater samples collected from all of the monitoring wells The
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