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IT Corporation February 25, 2000 A Alember of The 1T Group Page 2 Additional excavation and sampling was completed on April 1.5, 1999 to remove the unidentified piping discovered on April 8, 1999. Over-excavation in the southern portion of the site was terminated to protect the structural integrity of the station canopy supports. Following removal of the former station canopy, canopy footings and kiosk, additional over- excavation was completed on June 1 and 2, 1999. An additional 960 tons of soil were removed to a maximum depth of 31 feet bgs. Over-excavation was terminated when, the structural integrity of the sidewalk was endangered and groundwater was encountered. Groundwater was encountered during additional over-excavation activities at a depth of approximately 31 feet bgs. One water grab sample was collected from the excavation. The grab water sample contained elevated total petroleum hydrocarbons quantified as gasoline (TPH-g), benzene, toluene, ethylbenzene, and total xylenes (BTEX) concentrations. SCOPE OF WORK As stated previously, this investigation was being performed in response to the August 23, 1999 SJCPHD/EHD letter requesting further site characterization at the subject site. The scope of work completed for this investigation included the installation of four monitoring wells to delineate the lateral and vertical extent of hydrocarbons in the soil and groundwater. Monitoring well locations are shown in Figure 2. As required by the Occupational Health and Safety Administration (OSHA) Standard • "Hazardous Waste Operations and Emergency Response" guidelines (29 CFR 1910.120), and by California Occupational Health and Safety Administration (Cal-OSHA) "Hazardous Waste Operations and Emergency Response" guidelines (CCR Title 8, Section 5192), IT prepared a Site-Specific Health and Safety Plan prior to the commencement of fieldwork. The field staff and contractors reviewed the Site-Specific Health and Safety Plan before beginning field operations at the site. The specific scope of work is discussed below: • Monitoring Well Installation. Four groundwater monitoring wells (MW-1 through MW-4) were installed on December 9 and 10, 1999 at the locations shown on Figure 2. The wells were screened from 5 feet above to 15 feet below the current water level. Initial depth to water in MW-1 was 36 feet, therefore the well was set at 50 feet bgs. Groundwater rose to approximately 30 feet bgs after well completion. All subsequent wells were completed to 45 feet bgs. All work was done in accordance with stipulations of permits obtained from the SJCPHD/EHD. • Soil Selection and Analysis. Soil samples were collected every five vertical feet in the borings. Selected soil samples were submitted to a California State- certified laboratory and analyzed for the presence of TPH-g, BTEX, and methyl tertiary-butyl ether(MtBE)by EPA Methods 8015 Modified and 8020. MtBE confirmation by EPA Method 8260 was conducted for the soil sample collected . from MW-3 at 15 feet bgs. No additional oxygenate analysis of soil samples was 11SACRFPIIC0MM0NVancfpI\ProjectsTrojects191 1101 I\I A101021Report.doe