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Table l <br /> Groundwater Monitoring Data and Analytical Results <br /> Former Tosco(Unocal)Service Station#6981 <br /> 4707 Pacific Avenue <br /> Stockton,California <br /> EXPLANATIONS <br /> Groundwater monitoring data and laboratory analytical results prior to March 5, 1998,were compiled from reports prepared by MPDS Services,Inc <br /> TOC=Top of Casing TPH-G=Total Petroleum Hydrocarbons as Gasoline (ppb)=Parts per billion <br /> (ft)=Feet B=Benzene <br /> ND-Not Detected <br /> DTW=Depth to Water T=Toluene =Not Measured/Not Analyzed <br /> S I =Screen Interval E=Ethylbenzene NA = Not Available <br /> (ft bgs)=Feet Below Ground Surface X=Xylenes <br /> QA=Quality Assurance � <br /> GWE=Groundwater Elevation MTBE=Methyl tertiary butyl ether <br /> TOC elevations have been surveyed relative to the City of Stockton Datum On September 9, 1999 and on September 30,2000,TQC elevations were <br /> re-surveyed based on City of Stockton Benchmark,a brass cap in monument well on the east side of Pacific Avenue approximately fifty feet south <br /> of March Lane,(Elevation= 11 56)City of Stockton datum <br /> i <br /> i Laboratory report indicates the hydrocarbons detected did not appear to be gasoline <br /> z The analytical results of the groundwater samples collected from monitoring wells MW-8 through MW-13 on January 17 and 18, 1994,were <br /> inconsistent with the previous analytical results for these wells Therefore,MPDS Services,Inc resampled these wells on February 28, 1994 <br /> Laboratory has identified the presence of MTBE at a level above or equal to the taste and odor threshold of 40 ppb in the sample collected from this well <br /> 4 Covered by a new sidewalk <br /> 5 The positive result for gasoline does not appear to have a typical gasoline pattern <br /> b MTBE by EPA Method 8260 <br /> 7 Field Blank <br /> S Well was obstructed <br /> I 9 <br /> Laboratory report indicates gasoline and unidentified hydrocarbons>C8 <br /> 10 Laboratory report indicates gasoline and unidentified hydrocarbons C6-C8 <br /> 1 I Laboratory report indicates gasoline and unidentified hydrocarbons<C7 <br /> 12 Laboratory report indicates unidentified hydrocarbons>C7 <br /> it Laboratory report indicates gasoline C6-C12 <br /> 14 Laboratory report indicates weathered gasoline C6-C12 <br /> 15 Laboratory report indicates discrete peaks <br /> 16 Laboratory report indicates unidentified hydrocarbons C6-Cl2 <br /> 17 TPH-G and BTEX by EPA Method 8260 <br /> i <br /> I <br /> 6981 x1138 ! 16/07/03 <br />