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i Mr.James Barton,RWQCB May 14,2008 Work Plan for Additional Site Assessment Former Dolly Madison Bakery,Stockton,California Page 5 behalf of these properties appears useful, and may be more representative of long-term trends in groundwater flow direction that may be expected at the site, than the results of the single monitoring event completed during the first quarter 2008. Groundwater monitoring on behalf of Texaco, at 441 West Charter Way (including wells owned by Texaco that are located on the Colombo Bakery property),has consistently shown a predominant east-southeast groundwater flow direction in the shallow subsurface, with components of radial groundwater flow away from the Texaco site. Groundwater monitoring at the Chevron facility (508 West Charter Way) between 1995 and 2007 has shown that shallow groundwater flow has predominantly been towards the east. Components of groundwater flow in the northeast, southeast, south, southwest, and west directions have also been reported for the former Texaco facility. Groundwater gradients in the site vicinity appear to be generally low. These data appear generally consistent with the fundings of groundwater flow direction for the former Dolly Madison site. A monitoring well network has also been completed to the "deeper water bearing strata" on behalf of the Texaco facility (approximately 75 to 90 feet bgs). Using the data measured from these more deeply screened wells, between November 2002 and May 2007, deeper groundwater flow was predominately calculated to be towards the southeast and south at low groundwater gradients (generally less than 0.01 ft/ft). Components of east, west, and southwest groundwater flow were also locally noted during select well gauging events. The northeast groundwater flow direction calculated for the former Dolly Madison facility well network constructed to this depth are generally inconsistent with the historical flow directions noted at the Texaco well network. Petroleum Hydrocarbon Impact to Soil Relatively high concentrations of petroleum hydrocarbons have been detected in shallow portions of the subsurface near the former UST location. Gasoline range organics (GRO) was reported at concentrations of 230 milligrams per kilogram (mg/Kg) (10 feet bgs), 1,700 mg/Kg (15 feet bgs), and 650 mg/Kg (20 feet bgs) in samples collected from recently advanced boring VW-3. Toluene (1.6 and 2.3 mg/Kg), ethylbenzene (16 and 28 mg/Kg), and xylenes (71 and 163 mg/Kg) were also noted in the VW-3 samples collected from 15 and 20 feet bgs. GRO (74 mg/Kg) and benzene, toluene, ethylbenzene, and xylenes (BTEX; benzene at 0.32 mg/Kg) were also detected in the sample collected from boring AS-1 at 30 feet bgs. Petroleum hydrocarbon concentrations appear to decrease significantly below approximately 30 feet bgs in the vicinity of the UST, based on soil analytical results for samples collected from borings MW-9 and MW-13 in January 2008. Benzene (0.29 mg/Kg), ethylbenzene (0.0082 mg/Kg), and xylenes (0.007 mg/Kg) were detected in the KATimothy Kong Property\Work Plans\Kon?may08workplan.doc