ARCHIVED REPORTS XR0009934 - Laserfiche WebLink

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Extended Investigation of Groundwater Quality - 152 East 11th Street, Tracy Page 7 beneath the ground surface On further investigation it was found that the soil in the well at a depth of 8 3 ft was of limited volume and was apparently a plug of earth that had become lodged in the casing - presumably after falling into it from the surface When the well casing was cleared tt was found that this well could be easily purged and it produced clear water when bailed It is now fully rehabilitated After all wells had been purged, the depth to groundwater in each was measured again prior to sampling to ensure that a representative sample was obtained In all cases the water levels in the well fully recovered between the tune of purging and the time of sampling Each well, that was not previously so equipped and that will be sampled in future sampling rounds called for by the approved sampling plan, was provided with a new dedicated, PVC bailer which has been hung in the well below the watertight, Iockmg well cap Water samples from the wells were recovered using the PVC bailers Water was decanted from the bailers using a valved decanting-spigot so as to completely fill clean, laboratory- supplied glassware The sample vials were then tightly closed, labeled for identification, entered into chain-of-custody control and packed on chemical ice for transport, within 24 hours, to Onsite Environmental Laboratories, Inc in Fremont, California for analysis Each groundwater water sample was analyzed for the following suite of analytes Analyte Method of Analysis Total Petroleum Hydrocarbons EPA Method 5030/8015 (as Gasoline) Benzene EPA Method 8020 Toluene EPA Method 8020 Ethylbenzene EPA Method 8020 Total Xylenes EPA Method 8020 The results of the analyses of the groundwater samples are mnnmanzed in Table 4 Copies of the certificates of analysis are included in Appendix B (Note For convenience of reference, the results of analyses of all groundwater samples that have been recovered during successive sampling rounds from all of the wells installed for both the 152 and 153 East 11th Street properties are compiled in Table 6 ) . INTERPRETATION OF RESULTS The geotechnical and geochenucal data from the investigations reported herein and data from available records of previous immestigations conducted on the 152 and 153 East 11th