ARCHIVED REPORTS XR0003329 - Laserfiche WebLink

Home Browse Search

Third Quarter 19%Monitoring and Sampling Report/Request for Closure 2 The Southland Corporation-Store#20632,4627 Davina Drive Stockton CA October 2 1998 the south at a gradient of 0 003 Vft The groundwater mondonng results from the August 25, 1998 monitoring and sampling event and historical monitoring results are presented in Table 1 (Attachment 2) Field data sheets are included in Attachment 3 Monitoring Well Sampling and Analytical Results On August 25, 1998,groundwater samples were collected from three wells(MW-1 through MW-3 Before sampling, at least 4 well casing volumes of groundwater was removed from each monitoring well ' unless the well was purged dry The groundwater samples were collected using disposable bailers Groundwater samples were placed in analysis-specific containers with analysis- ' specific preservative The samples were then sealed using Teflon septum caps, labeled with the job identification nurnbcr,arc =o!o number,date,time, and type of laboratory analysis required The samples were stored on ice and transported under a chain-of-custody record to state-certified Core analytical Laboratory, in Anaheim, California Groundwater samples were analyzed for BTEX and TPH-G using Environmental Protection Agency(EPA) methods 8020/modified 8015, and for oxygenates MTBE, TBA, DIPE, ETBE, and TAME using EPA method 8260 ' Historical and current laboratory analytical results for groundwater samples collected on August 25, 1998 are presented in Table 1 Dissolved benzene was detected in two wells, MW-2 and MW-3, at levels of up to 0 648 micrograms per Ider(ug/L) Highest dissolved TPH-G and MTBE concentrations were reported in well MW-2 at 1,550 ug/L and 1,61 0ug/L, respectively Since October of 1997, BTEX concentrations in the downgradient well (MW-2) have typically remained below detection limits while BTEX in the k upgradient well (MW-1) have dropped to non-detectable levels In crossgradient well MW-3, benzene, TPH-G and MTBE concentrations have largely declined below method detection limits Overall, reduced hydrocarbon concentrations found in monitoring wells at the plume periphery indicates that the ' hydrocarbon plume is stable and in a general state of attenuation Underground storage tank upgrades will occur later during the year Well MW-4 has been abandoned (as approved by the San Joaquin County Public Health Services(SJCPHS) in anticipation of station rebuilding Replacement well installation will be addressed with the SJCPHS after completion of station upgrades Dissolved oxygen levels in the affected areas indicate localized depletion,which venfies that intrinsic biodegradation is ongoing, and likely to continue The laboratory analytical reports for the groundwater samples are included in Attachment 4 Purge Water Transportation and Disposal All purge water generated during this quarterly monitoring and sampling event was stored in 55-gallon Department of Transportation (DOT)-approved drums pending characterization and proper disposal FLUOR DANIEL GTI L«1