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u TPHG detection this quarter, it could be related to the IR" excavation activities near MW-9 that may have freed M contaminants from that location that then migrated downgradient Well MW-4 historically has not shown contaminant presence Previous site study, including geophysical study for additional potential product sources did not reveal any subsurface structures as possible tanks for product sources Residual sources in aquifer sediment probably cause some of the fluctuations observed The interpreted location of the dissolved plume based on the historic groundwater flow and interpreted contour information continues to show generally no net plume movement beyond the area in1meduitely around Wells MW-3 and MW-9 Conclusions and Recommendations Groundwater flow direction was northerly under a low calculated gradient and water levels in monitoring wells had risen about 0 50 feet since the previous quarter In our opinion, the mapped contaminant dissolved plume continues to occur near the center of the site, similar to historic site observations and previous investigation reports submitted to SJC/EHD The TPHG levels fluctuated in the wells,with a decrease in MW-3 and MW-9 Wright has completed and submitted an interim remedial action plan a" (targeted in the vicinity of MW-3 and MW-9) The excavation work began in mid-February and will continue to remove contaminated soil and a limited amount of groundwater in the area of the historic plume location (that is in the area around MW-3 and MW-9 Wells MW-3 and MW-9 were abandoned under approved SJC/EHD permits for this HUP work Once the IRAP is completed a report of the results will be prepared and submitted to SJC/EHD The site is scheduled for continued quarterly monitoring at this time Limitations This report has been prepared specifically for the Mr Ed's Muffler (Cox and Cox) Site at 595 E l lth Street in Tracy, and was done according to the current State and local agency suggested guidance documents for these investigations The interpretations, conclusions and recommendations made herein are based on the data and analysis for the soil and water samples collected on-site and should be reviewed in the context of this report and other site reports Please note that reports of contamination must be submitted to the agencies in a timely manner Wright Environmental. Services, Inc is not responsible for errors in laboratory analysis and reporting, or for information not available during the course of the study, and no warranty or guarantee is expressed or implied therein If you have any questions concerning this report,please call sincerely, Wnght Environmental Services,Inc. @ n�] CC NO 126z CERTIFIED tJohnjLynch EN,6 NHRIHO ph Christopher M Palmer Principal C E G 1262, HG 246 nf� s •,sa y� //�y, �G iE' Attachments: Table 1 Historic Groundwater Levels and Contaminants Figure 1 Groundwater Contour Map, January 12, 2004 Figure 2 Groundwater TPHG Plume Map, January 12, 2004 Figure 3 Groundwater Benzene Plume Map,January 12, 2004 Figure 4 Groundwater MTBE Plume Map, January 12,2004 Selected Tune vs Contaminant Graphs,MW-3,MW-9,MW-2 Groundwater Sampling Information Sheets Page 3