ARCHIVED REPORTS_XR0002408 - Laserfiche WebLink

Home Browse Search

i First Quarter 1997 Monitoring and Sampling Report — 2 The Southlaa¢Corporation,455 Grant Line Rd ,Tracy,CA June 9,9997 Monitoring Well Sampling and Analytical Results Groundwater samples were collected from wells MW-4,MW-5, MW-8, MW-9,and MW-10 Before sampling, at least four well-casing volumes of groundwater was removed from each monitoring well, unless the well was purged dry Field measurements of temperature, conductivity, and pH were recorded during well purging The groundwater samples were collected using disposable bailers and placed in analysis-specific sample containers wlth analysis-specific preservatives The samples were then sealed and labeled with the fob identification number,the sample number,date,time, and type of laboratory analysis required The samples were stored on ice in an insulated container and transported under chain-of-custody manifest to NEI/GTEL Environmental Laboratories, Inc in Wichita, Kansas The groundwater samples were analyzed for BTEX,MTBE and TPH-G using Environmental Protection Agency (EPA) methods 8020/modified 8015 Groundwater purged during the first quarter monitoring and sampling event was pumped through the groundwater extraction system Dissolved benzene and TPH-G were detected in groundwater samples from monitoring wells MW-8 through MW-10 with highest concentrations reported in MWA 0 at 6,100 micrograms per liter(pg/L)and 41,000 pg/L, respectively(Figure 3) MTBE was not reported in any of the samples collected, however,the reporting limit was raised in samples MW-9 and MWA 0 due to elevated hydrocarbon concentrations Analytical results from the groundwater samples collected on March 25, 1997 are presented in Table 1, and historical analytical results are summarized in Table 1A The laboratory analytical reports and the chain-of-custody records for the March 25, 1997 sampling event are included in Attachment 4 Remediation Progress Summary The groundwater extraction system was shut off in February 1997 because monitoring indicated that the system would not lower the groundwater table an acceptable level for sod vapor extraction Yield from the subsurface was significantly greater than expected, and groundwater extraction at rates of 6 to 7 gallons per minute (GPM)from GWE-2 produced less than a foot of drawdown in sod vapor extraction wells MW-8, MW-9, and MW-10 Alternative remediation methods, including aggressive in-situ bloremediation through nutrient and/or oxygen introduction,are currently being evaluated 0456QWRPT(STHL51) FLUOR DANIEL G71