|
(VYATC
<br /> A S S O C I A T E S I N C
<br /> north-northeast The average hydraulic gradient on July 7, 2004 was calculated to be 0 0011 ft/ft or
<br /> approximately 5 8 ft/mile A summary of groundwater monitoring data Is pâșesented in Table 1
<br /> SAMPLING ACTIVITIES
<br /> On July 7, 2004, ATC personnel collected groundwater samples from monitoring wells MW1
<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 MW1 through MW5 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 (ELAP Cert No 2359) for chemical analyses of TPHg utilizing EPA Method 8015B,
<br /> BTEX utilizing EPA Method 8021B, and gasoline oxygenates/additives including MTBE, ETRE,
<br /> DIPE, TBA, TAME, 1,2-DCA, and EDB utilizing EPA Method 8260B Groundwater well purge and
<br /> 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 /> Benzene was detected In the groundwater samples collected from MW2, MW3, MW5, MW6, and
<br /> MW7 at concentrations of 2 5 micrograms per liter pg/L, 1 0 pg/L, 0 8 pg/L, 0 8 pg/L and 0 6 pg/L,
<br /> respectively Toluene was detected in the groundwater samples collected from MW2, MW3, MW5,
<br /> MW6 and MW7 at concentrations of 1 8 pg/L, 1 8 pg/L, 5 2 pg/L, 2 3 pg/L, and 0 8 pg/L,
<br /> respectively Ethylbenzene was detected In the groundwater samples collected from MW2, MW3,
<br /> MW5, MW6, and MW7 at concentrations of 10 pg/L, 3 5 pg/L, 72 pg/L, 8 7 pg/L, and 1 2 pg/L,
<br /> respectively Xylenes were detected in the groundwater samples collected from MW2, MW3, MW5,
<br /> MW6, and MW7 at concentrations of 16 pg/L, 4 8 pg/L, 260 pg/L, 17 pg/L, and 19 gg/L,
<br /> respectively MTBE was detected in the groundwater samples collected from MW1, MW2, MW3,
<br /> MW4, and MW7 at concentrations of 19 pg/L, 42 gg/L, 64 pg/L, 20 pg/L, and 45 pg/L, respectively
<br /> TBA was detected in the groundwater samples collected from MW1, MW2, MW3, MW6, and MW7
<br /> at concentrations of 31 pg/L, 45 pg/L, 24 pg/L, 16 pg/L, and 48 pg/L, respectively 1,2-DCA was
<br /> detected in the groundwater samples collected from MW 1 through MW7 at concentrations ranging
<br /> from 3 3 pg/L to 47 pg/L TPHg was detected in the groundwater samples collected from MW1,
<br /> MW2, MW3, MW5, MW6, and MW7 at concentrations of 240 pg/L, 600 pg/L, 260 pg/L, 1,200
<br /> pg/L, 410 pg/L, and 140 pg/L, respectively
<br /> The Maximum Contaminant Level (MCL) for benzene, 1 pg/L, was equaled or exceeded in the
<br /> groundwater samples collected from MW2 and MW3 The MCL for MTBE, 13 pg/L, was exceeded
<br /> in the groundwater samples collected from MW I, MW2, MW3, MW4, and MW7 The MCL for 1,2-
<br /> DCA, 0 5 pg/L, was exceeded in the groundwater samples collected from all of the monitoring wells
<br /> The California Drinking Water Action Level for TBA, 12 pg/L, was exceeded in the groundwater
<br /> samples collected from MW1, MW2, MW3, MW6, and MW7 A summary of the laboratory
<br /> S lenvgronmentai1224931ReportsOQR-04 doe 3
<br />
|