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�N . monitoring well PT-MW-1, Applied GeoSystems reportedly observed a petroleum sheen on water that was removed from the well The sheen was later reportedly observed prior to pre-sampling purging of PT-MW-1 Upon attempting to sample PT-MW-I, Applied GeoSystems reportedly measured an immiscible product layer of approximately 1/2 inch (0 05 foot) thickness A sample of this immiscible layer was not submitted for analysis by a state certified analytical laboratory In April 1991, Mr Ganzer (Ganzer and Williams) reportedly retained Falcon Energy and Geological Audit Services Inc to further define the extent of groundwater impact by petroleum hydrocarbons at the site In May 1991, Geological Audit Services (GAS) supervised the installation of two additional 4-inch diameter monitor wells (PT-MW-2 and PT-MW-3, Figure 3) Soil samples were reportedly collected at five foot intervals from each of the soil borings from 10 to 45 feet bgs Field observations during the drilling of PT-MW-2 indicated the potential presence of petroleum hydrocarbons from approximately 45 feet bgs to the total depth of 60 feet bgs Field observations while drilling PT-MW-3 indicated the potential presence of petroleum hydrocarbons from approximately 20 feet to the total depth of 60 feet bgs The 30, 35, 40, and 45 foot soil samples from each of the wells was submitted for quantitative analysis of TPH-g and benzene, toluene, ethylbenzene, and xylene (BTEX) by USEPA Methods 8015M and 8020, respectively Each of the samples reportedly contained detectable concentrations of the requested analytes The 40 foot bgs soil sample from PT-MW -2 was the most impacted with laboratory reported concentrations of TPH-g (880 mg/kg), and BTEX (9 2, 45, 14, and 77 mg/kg, respectively) In June 1991 , GAS surveyed the wells relative to a temporary benchmark and measured the depth to groundwater GAS reported measured product layers of 6 125 and 7 25 inches in monitoring wells PT-MW-1 and PT-MW-2, respectively GAS did not report observing an immiscible layer on PT-MW-3 but groundwater samples were not collected for analysis GAS reported that groundwater surface elevations had dropped approximately five feet since 1988 (Geological Audit Services, 1991) and that the groundwater surface elevation map had a relatively flat gradient with a slight slope to the south Geological Audit Services (1991) made the following conclusions (1) that offsite migration of petroleum hydrocarbons released from the site was a possibility, (2) the lateral extent of soil and/or groundwater petroleum hydrocarbon contamination was not yet determined, (3) the water bearing unit at 40 feet bgs should allow recovery of the free product and/or dissolved contamination from the first water-bearing zone, (4) that a more northerly source may be contributing to the identified petroleum hydrocarbon groundwater contamination, and (5) that 3,000 to 4,000 gallons of gasoline were potentially present in the groundwater beneath the site • Mam\DNEnvironmentalWarmarTexaco\Workplan\042003 wpd 7