ARCHIVED REPORTS_XR0007098 - Laserfiche WebLink

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I Site History 14000 Highway 88, Lockeford, CA ff + Time Oil Properly No.04-049 ppb xylenes), and MW-9 (1.4 ppb benzene). Hydrocarbons were not present at detectable concentrations ins the samples collected from MW-2, MW-7, and MW-10. Based on the results of the site investigation it appears as though soil impacts remain limited to the immediate vicinity of the former tank system. Although low concentrations of hydrocarbons appear to be migrating offsite to the east (MW-8, sidegradient) and west (MW-5, sidegradient), groundwater impacts appear to be fairly well defined in except to the northwest (MW-6, upgradient). Since the May 1996 quarterly sampling event hydrocarbon concentrations decreased in MW-2 and MW-4 and increased in MW-1 and MW-3; however, the changes were not very great in any of the wells. The observed fluctuations in hydrocarbon concentrations may be a result of a changes in groundwater elevation; however, not enough data has been collected to evaluate their significance. Additional groundwater data will be collected to further evaluate the extent of the dissolved hydrocarbon plume. The results of the most recent site investigation suggest that the extent of impacted soil has been defined in all directions, and that the extent of groundwater impacts is fairly well defined except to the northeast (upgradient) of the former lank system. Because the extent of impacts is nearly defined, and it may be difficult to obtain access to install additional upgradient monitoring wells, Time proposed that efforts be focused on interim remediation rather than further investigation, Time believes that the installation and operation of an interim remediation system, such as a vapor extraction system, may mitigate the need for additional investigation in the upgradient direction, as well as prevent additional groundwater impacts. During the operation of the interim remediation system, groundwater monitoring would be continued to confirm that additional contaminant migration is not occurring, to monitor remediation efforts, and to assist in identifying source areas which may require the = implementation of additional remediation technologies. Time requested the PHSIEHD's concurrence that additional investigative efforts will not be required at this time and that interim remediation efforts would be appropriate. A copy of SECOR's "Environmental Investigation and Quarterly Summary Report" dated October 9, 1996 was forwarded to the approporate agencies on October 21, 1996. 10