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ANALYTICAL METHODS AND RESULT'S
<br /> Laboratory Analyses
<br /> Groundwater samples were delivered to CRL Environmental Corporation (CRL), a Caltrans-
<br /> approved and California-certified analytical laboratory, for the analyses of TPHg and TPHd
<br /> following EPA Test Method 8015, BTEX following EPA Test Method 8020 and fuel oxygenate
<br />' compounds (FOCs) including MTBE, tent-amyl methyl ether (TAME), ethyl tert-butyl ether(ETBE),
<br /> di-isopropyl ether (DIPE) and tert-butanol (TBA) following EPA Test Method 8260 Groundwater
<br /> analytical results are summarized on Table 1 Laboratory reports and chain-of-custody
<br /> documentation are presented in Appendix C
<br /> Groundwater Analytical Results
<br />' TPHg was detected in samples collected from wells MW-1 through MW-4, MW-6, MW-7, MW-10,
<br /> VW-1 and VW-2 at concentrations ranging from 51 (MW-7) to 5,700 (VW-2) µg/1 TPHd was
<br />' detected 1n the groundwater samples collected from wells MW-2, MW-3, MW-6, MW-9, MW-10,
<br /> VW-1 and VW-2 at concentrations of 410, 260, 71, 57, 54, 64 and 810 µg/l, respectively A case
<br /> narrative from CRL states that Analytical comments for METHOD 8015_W_DSL LL, SAMPLE
<br /> 510738-002A (MW-10), 510738-014A (MW-9), 510738-020A (MW-6), 510738-022A (MW-2),
<br />' 510738-024A (MW-3), 510738-026A (VW-1), and 510738-028A (VW-2) Sample contains
<br /> hydrocarbons that do not match the diesel pattern However, quantification is based on a diesel
<br /> standard " Benzene was detected in groundwater samples collected from wells MW-2, MM-3, MW-
<br /> 10, VW-1, and VW-2 at respective concentrations of 930, 1 2, 2 0, 0 56, and 1,600 µg/l Toluene,
<br /> ethylbenzene and total xylenes were also detected at concentrations ranging from 0 51 (MW-12 -
<br /> toluene) to 1,060 (MW-2 - total xylenes) µg/l MTBE was reported to one sample, VW-2, at a
<br /> concentration of 89 µg/1 TAME, DIPE, TBA and ETRE were not detected above laboratory method
<br /> detection limits in each of the groundwater samples collected TPHg, TPHd, benzene, and MTBE
<br /> concentrations for the Second Quarter - 2002 monitoring event are depicted on Figure 3, Petroleum
<br />' Hydrocarbons in Groundwater-July 2002
<br /> CONCLUSIONS AND RECOMMENDATIONS
<br />' The lateral limits of dissolved phase petroleum hydrocarbons in groundwater are not defined to the
<br /> west of wells MW-3 and VW-1 and may extend beneath B Street Geocon recommends that quarterly
<br />' groundwater monitoring continue at the Site to evaluate seasonal trends in groundwater elevation and
<br /> contaminant concentrations in the vicinity of the former UST locations at the Site The next
<br /> groundwater monitoring event is scheduled for September 2002
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<br /> Project No S8475-06-24A -3- September 11,2002
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