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' Stockton Taxi Cah/Sunland Gasoline September 16, 2003 2085 Fremont Street,Stockton, California Page 6 I Report of Findings: Lateral and Vertical Extent of Soil and Groundwater Contamination 4.6 Monitoring Well MW-3 I The soil analytical results for MW-3 are summarized in the table below. ' Sample ID Gas Benzene Toluene E-Benzene Xylene MTBE 1,2-DCA MW-3 20.0' ND ND ND ND ND ND ND ' MW-3 30.0' ND 7.7 ." ND ND .18 ND ND MW-3 40.0' ND ND ND ND ND ND 18 MW-3 @ 50.0' ND ND ND ND ND ND 52 MW-3 P,55.0' ND ND ND ND ND ND 66 IMW-3 65.0' ND ND ND ND ND ND 11. MW-3 is relatively free from contamination at all depths sampled. The only analytes present are benzene at 7.7 ug/Mg, xylene at 18 ug/Mg and 1,2-DCA at I i to 66 ug/Mg. All other analytes are ND. See Table 1 and 2 for a complete tabular Isummary of the soil analytical data for MW-3. 1 4.7 Monitoring Well MW-4 The soil analytical results for MW-4 are presented in a tabular summary below. ,• Sample ID Gas Benzene Toluene E-Benzene Xylene MTBE 1,2-DCA Lead MW-4 80.0' 207 ' t... 266 -'.2;480 -I:'972:-- :.`5 200 ND 5:7 MW-4 90.0' `-•" 536 ND 862._;.'. ND ND NIA I MW-4 95.0' ':u:'1.3 ..':, 45 . ; ,:=141 ri ; ND ',,;,`797. :�� ND' ND NIA MW-4 100.0' .43 .. -'.231 803-' . , .' -311 1 690 �, 172. '',. ND NIA The laboratory analysis of the soil samples from MW-4, located at the southeast corner of the former UST location, shows the presence of significant levels of contamination from eighty to 100 feet below ground level. See Table 1 and 2 for a complete tabular summary of the soil analytical data for MW-4. 1 5.0 Geology ' The subject property is located on the western side of California's Central Valley. The Central Valley is approximately 400 miles long and averages 50 miles wide encompassing approximately 20,000 square miles. The valley is a large asymmetric ' trough that is bounded by granitic, metamorphic and marine sedimentary rocks of pre- tertiary age. This trough has been filled with as much as 30,000 feet of sediment in the San Joaquin Valley portion to the south, and as much as 60,000 feet of sediment in the Sacramento Valley portion to the north. The age of the sediments range from Jurassic to Holocene and include both marine and continental rocks and sedimentary deposits (Olmstead and Davis, 1961).