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elevation contour map (Figure 3) Shallow groundwater beneath the site generally flowed towards
<br /> the north, northeast The average hydraulic gradient on October 7, 2004, was calculated to be
<br /> approximately 0 0024 ft/ft or approximately 12 7 ft/mile A summary of groundwater monitoring
<br /> data is presented in Table 1
<br /> SAMPLING ACTIVITIES
<br /> On October 7, 2004 ATC personnel collected groundwater samples from monitoring wells MWI
<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/additives Including MTBE, ETBE, D1PE, 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 in the groundwater
<br /> samples collected from all of the monitoring wells
<br /> TPHg was detected In the groundwater samples collected from MW1, MW2, MW3, MW5, MW6,
<br /> and MW7 at concentrations of 230 micrograms per liter (gg/L), 600 gg/L, 82 µg/L, 680 gg/L, 510
<br /> pg/L, and 180 gg/L, respectively Benzene was detected in the groundwater samples collected from
<br /> MW2, MW6, and MW7 at concentrations of 3 1 gg/L, 0 6 gg/L, and 0 6 gg/L, respectively Toluene
<br /> was detected in the groundwater samples collected from MWI, MW2, MW5, MW6, and MW7 at
<br /> concentrations of 0 7 pg/L, 2 7 gg/L, 3 7 gg/L, 3 0 gg/L, and 0 7 gg/L, respectively Ethylbenzene
<br /> was detected in the groundwater samples collected from MWI, MW2, MW3, MW5, MW6, and
<br /> MW7 at concentrations of 1 0 gg/L, 6 7 gg/L, 0 8 gg/L, 37 gg/L, 8 0 gg/L, and 1 0 gg/L,
<br /> respectively Xylenes were detected in the groundwater samples collected from MW 1, MW2, MW5,
<br /> MW6, and MW7 at concentrations of 3 8 gg/L, 2 7 gg/L, 110 gg/L, 23 gg/L, and 2 6 gg/L,
<br /> respectively
<br /> MTBE was detected in the groundwater samples collected from MWI MW2, MW3, MW4, and
<br /> MW7 at concentrations of 7 8 gg/L, 51 gg/L, 23 pg/L, 28 gg/L, and 100 gg/L, respectively TBA
<br /> was detected in the groundwater samples collected from MWI, MW2, MW6, and MW7 at
<br /> concentrations of 24 gg/L, 27 pg/L, 13 gg/L, and 57 pg/L, respectively 1,2-DCA was detected in the
<br /> groundwater samples collected trom MWI through MW7 at concentrations ranging from 7 0 gg/L to
<br /> 66 gg/L TPHg was detected in the groundwater samples collected from MWI, MW2, MW3, MW5,
<br /> . MW6, and MW7 at concentrations of 230 gg/L, 600 gg/L, 82 gg/L, 680 gg/L, 510 gg/L, and 180
<br /> gg/L, respectively
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