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1FIELD AC'I'MTIES
<br /> Depth to Groundwater Measurements
<br /> ' On July 8, 2002, a representative of Geocon measured the depth to groundwater in monitoring wells
<br /> MW-9, MW-II through MW-14, MW-16, MW-19, MW-20, MW-24, MW-25, VM-1 and VM-2
<br /> using a battery operated water level meter The measurements were obtained from surveyed
<br /> ' reference points at the top of the well casing(TOC) The approximate well locations and site features
<br /> are depicted on Figure 2, Groundwater Elevation Map-July 2002
<br /> ' During the Second Quarter - 2002, the depth to groundwater in the twelve existing wells was
<br /> recorded between 49 88 (MW-11) and 50 72 (MW-13) feet below TOC Based on the July 2002
<br /> groundwater elevation data, the groundwater beneath the Site appears to be directed toward the
<br /> northeast at an approximate gradient of 0 001 which is consistent with historical groundwater flow
<br /> ' A summary of the TQC elevations, depth to groundwater measurements and Mean Sea Level
<br /> groundwater elevations is presented on Table I
<br /> ' Well Purging and Sampling
<br /> Approximately three well volumes of water (5 to 79 gallons) were extracted from each well utilizing
<br /> ' a 2-inch diameter submersible pump During the well purging activities, the groundwater was
<br /> monitored for pH, electrical conductivity, temperature, and turbidity This information is included on
<br /> the Monitoring Well Sampling Data Sheets presented in Appendix B
<br /> Following the purging activities, groundwater samples were collected from the wells and decanted
<br /> into five 40-milliliter volatile organic analysis vials and one one-liter amber glass bottle The samples
<br /> were sealed, labeled, placed in an ice chest containing ice, and subsequently transported to the
<br /> laboratory using standard chain-of-custody protocol
<br /> The extracted groundwater was placed into 12 Department of Transportation-approved, 17-H, 55-
<br /> gallon drums and temporarily stored onsite pending receipt of laboratory analysis The drums were
<br /> transported by ABCO Environmental Services to Instrat, Inc located in Rio Vista, California
<br /> ' ANALYTICAL METHODS AND RESULTS
<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, benzene, toluene, ethylbenzene and total xylenes (BTEX)
<br /> following EPA Test Method 8020 and fuel oxygenate compounds (FOCs) including MTBE, tert-
<br /> amyl methyl ether(TAME), ethyl tert-butyl ether (ETBE), di-isopropyl ether(DIPS) and tert-butanol
<br /> (TBA) following EPA Test Method 8260 Groundwater analytical results are summarized on Table
<br /> 1 Laboratory reports and chain-of-custody documentation are presented in Appendix C
<br /> ' Groundwater Analytical Results
<br /> TPHg was detected in samples collected from wells MW-11, MW-13, MW-14, VM-1, and VM-2 at
<br /> concentrations ranging from 53 (MW-11) to 25,000 (VM-2) gg/l TPHd was detected in the
<br /> groundwater samples collected from wells MW-9, MW-11, MW-14, VM-1 and VM-2 at
<br /> concentrations of 55, 52, 70, 670 and 3,800 gg/l, respectively A case narrative from CRL states that
<br /> Project No S8475-06-24A -2- September 11,2002
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