ARCHIVED REPORTS XR0000231 - Laserfiche WebLink

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FIIELD ACTIVITIIES Death to Groundwater Measurements On December 10, 2002, representatives of Geocon measured the depth to groundwater in monitoring wells MW-9, MW-11 through MW-14, MW-16, MW-19, MW-20, MW-24, MW-25, VM-1 and VM- 2 using a battery operated water level meter The measurements were obtained from surveyed reference points at the top of the well casing(TOC) The approximate well locations and site features are depicted on Figure 2, Groundwater Elevation Map -December 2002 ' During the Fourth Quarter-2002, the depth to groundwater in the twelve existing wells was recorded between 51 61 and 52 51 feet below TOC Based on the December 2002 groundwater elevation data, the groundwater beneath the Site appears to be directed toward the northeast at an average gradient of 0 002, which is consistent with historical groundwater flow A review of the last reported ' groundwater level measurements for the Site indicates that from September to December 2002 the groundwater levels in each of the wells increased an average of 0 08 foot A summary of the TOC elevations, depth to groundwater measurements and Mean Sea Level groundwater elevations is presented on Table 1 Well Purging and Sampling On December 10 and 11, 2002, approximately three well volumes of water (4 5 to 76 gallons) were extracted from each well utilizing a 2-inch diameter submersible pump During the well purging activities, the groundwater was monitored for pH, electrical conductivity, temperature, and turbidity This information is included on the Monitoring Well Sampling Data Sheets presented in Appendix B Following the purging activities, groundwater samples were collected from the wells and decanted into four 40-milliliter volatile organic analysis vials and one one-liter amber glass bottle The ' samples were sealed, labeled, placed in an ice chest containing ice, and subsequently transported to the laboratory using standard chain-of-custody protocol ' The extracted groundwater was placed into eleven Department of Transportation-approved, 17-14, 55-gallon drums and temporarily stored onsite pending receipt of laboratory analysis The drums will be transported by ABCO Environmental Services to an appropriate disposal facility in January 2003 ANALYTICAL METHODS AND RESULTS Laboratory Analyses Groundwater samples were delivered to Creek Environmental Laboratories, Inc , a Caltrans-approved and California-certified analytical laboratory, for the analyses of TPHg and TPHd following EPA Test Method 8015, benzene, toluene, ethylbenzene and total xylenes (BTEX) following EPA Test Method 8020 and fuel oxygenate compounds (FOCs) including MTBE, tert-amyl methyl ether (TAME), ethyl tert-butyl ether (ETBE), di-isopropyl ether (DIPE) and tert-butanol (TBA) following EPA Test Method 8260 Groundwater analytical results are summarized on Table 1 Laboratory reports and chain-of-custody documentation are presented in Appendix C • Project No 58475-06-24C -2- January 23,2003