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Tahl,�d <br /> Groundwater Monitoring�t`� and Analytical Results <br /> Tosco(Former BP Oil)Service Station#11195 <br /> 16500 South 1-5 <br /> Lathrop,California <br /> EXPLANATIONS: <br /> Groundwater monitoring data and laboratory.analytical results prior to May 20, 1999,(with the exception of September 3, 1998),were compiled from reports <br /> prepared by Blaine Tech,Inc. <br /> TOC=Top of Casing TP14-D=Total Petroleum Hydrocarbons as Diesel (ppb)=Parts per billion <br /> TPH-G=Total Petroleum Hydrocarbons as Gasoline ND=Not Detected <br /> (ft.)=Feet B=Benzene —=Not Measured/Not Analyzed <br /> DTW=Depth to Water CC=Conductor Casing <br /> S.I.=Screen Interval T=Toluene NP=No Purge <br /> (ft.bgs)=Feet Below Grou n d Surface E=Ethylbenzene QA=Quality Assurance/Trip Blank <br /> GWE Groundwater Elevation X=Xylenes <br /> (msl)=Mean sea level MTBE=Methyl tertiary butyl ether <br /> On July 5,2002,the following wells were surveyed(MW-13,MW-14,MW-15,MW-16,and MW-17)by Virgil Chavez Land Surveying. The benchmark for this survey <br /> was a brass disk,stamped"City of Lathrop Bench Mark No.5,"at the southeast curb return of L.ouise Avenue and Harlan Road,(Benchmark Elevation=14.77 feet,NGVD 29). <br /> TOC elevations referenced to cross in sidewalk,run from City of Lathrop Benchmark No.5(Elevafion=9.22 feet,ms]). Prior to May 20, 1999,TOC elevations <br /> were referenced to San Joaquin datum,brass cap UV-34 at Mathey Road,45 feet north and 52 feet west of centerline(Elevation=12.50 feet.above rnsl). <br /> MTBE by EPA Method 9260. <br /> 2 <br /> Laboratory report indicates discrete peak C6. <br /> 3 Detection limit raised. Refer to analytical reports. <br /> 4 MTBE by EPA Method 8260 analyzed dilution past recommended holding time. Initial analysis was within hold time. <br /> 5 Total Oil and Grease(TOG)was ND. <br /> 6 Halogenated Volatile Organic Compounds(HVOCs)were ND. <br /> 7 TOG was detected at I 10 ppb. <br /> 8 Laboratory report indicates gasoline C6-C12. <br /> 9 Laboratory report indicates unidentified hydrocarbons C&C 12. <br /> 10 MTBE reported from dilution run. <br /> 11 This sample was analyzed outside of the EPA recommended holding time. <br /> 12 Laboratory report indicates weathered gasoline Cb-C12. <br /> 13 TPH-G and BTEX by EPA Method 8260. <br /> 14 Laboratory report indicates a hydrocarbon pattern is present in the requested fuel quantitation range but does not resemble the pattern of the requested fuel, <br /> 15 Well development performed. <br /> 16 TPH-G,BTEX and MTBE by EPA Method 8260. <br /> 17 Field Technician inadvertently missed well MW-8 for this event date. <br /> 19 TOC elevations were resurveyed in July 2002;data was provided on April 15,2003. GWE data for the following events 08/15/02, 11/18-19/02,02/13-14/03,and 02/21/03 <br /> have been changed to reflect the new elevations. <br /> 19 TOC was altered,do not use in contouring. <br /> 11 195.xls/#[80175 17 As of 08129/03 <br />