ARCHIVED REPORTS_XR0008347 - Laserfiche WebLink

Home Browse Search

Quarterly Monitoring and Sampling Report(Q4 2001) 5 Ranch Market 23569 Santa Fe Road Riverbank,Cahfornia January 3,2002 Domestic Well Groundwater Sampling Procedures Domestic wells were purged by turning on the water at the well, thus draining the well's holding tank and filling the tank with fresh water from the aquifer Once the tank has been recharged, water samples were collected directly from a spigot at the holding tank DW-2R, DW-3, and DW-4 are sampled quarterly, and DW-1 is sampled monthly DW-3 was inaccessible and was not sampled this quarter Groundwater Sampling Procedures The groundwater monitoring wells were re-monitored to verify at least 80% recovery prior to sampling Adequate recovery was observed in the purged wells prior to sampling A disposable bailer was used to collect the groundwater samples All samples were collected in appropriate containers, preserved on ice, and transported under chain--of-custody manifest to KJff Analytical LLC located in Davis, California The water samples were analyzed for TPHg, BTEX, 1,2-DCA, EDB, and five oxygenates using EPA method 8260B Groundwater Analytical Results • Historical and recent groundwater laboratory analytical results are summarized in Table 3 The highest benzene and TPHg concentrations were detected in monitoring wells MW-1 at 4,500 parts per billion (ppb) and in MW-3 at 25,000 ppb, respectively (Figure 5) The highest MtBE concentration was detected in monitoring well MW-1 at 570 ppb No EDB, 1,2-DCA, or other oxygenates, including TBA, were reported above the laboratory detection limits in samples collected from the monitoring wells Domestic Well Analytical Results The water samples collected from domestic wells DW-2R and DW-3, sampled quarterly, did not contain detectable concentrations of TPHg, BTEX, oxygenates, 1,2-DCA, or EDB SECOR field personnel collected monthly water samples from DW-1 on October 1, November 2, and December 5, 2001 The DW-1 water samples did not contain detectable concentrations of TPHg, BTEX, 1,2-DCA,EDB, or oxygenates Copies of the laboratory analytical reports and chain-of- custody manifests are included in Attachment 4 Conclusion Nine groundwater monitoring wells and three domestic water wells were sampled this quarter Groundwater elevation declined an average 0 34 feet since July 2001 Refemng to Table 3, a decrease in the concentration of benzene, TPHg, and MtBE was observed in wells MW-1,NM- 2, and MW-4 A slight increase in benzene and TPHg concentrations and a decrease in the MtBE concentration were observed in MW-3 MW-6, located upgradient of the former USTs, File Ranch MarketlReportlRtverbank-0l-4Q