SITE INFORMATION AND CORRESPONDENCE FILE 2

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i CONESTOGA-ROVERS &ASSOCIATES July 16,2010 Reference No.240778 -3- Historical Maximum- Concentration aximumConcentration(a) COPC (mg&g) Depth. Location - Date TPHg 4,400 20 MW-9 3/19/1990 Benzene 42 20 MW-9 3/19/1990 Toluene 350 20 MW-9 3/19/1990 Ethylbenzene 60 20 MW-9 3/19/1990 Xylenes 420 20 MW-9 3/19/1990 MTBE ND - - - TBA ° ND - - mg/Kg=milligram per kilogram ND=Not detected above laboratory detection limit. - No MTBE or TBA has been detected in any soil samples collected at the site. The highest concentrations of COPC were detected in samples collected.below 7 meters from MW-9. In summary: _ • BTEX is not present in groundwater above commercial vapor intrusion"ESLs. • Site use is not anticipated to change from a commercial fuel station. • The highest concentrations of COPC in soil or groundwater are in wells MW-2 and MW-9,located between 50 and 75 feet distant from the nearest-occupied building. • Wells located nearest the station building,(MW-3,MW-6,and MW-8) contain significantly lower.COPC-concentrations. • Current and anticipated site use iridicates-that no structures are planned in areas with the highest historical COPC concentrations. • Samples from these locations were collected at more than 3 meters depth,below the ESL ument'criteria for shallow soil or oundwater samples. Doc gr p • Onsite soil samples with the highest concentrations used in this evaluation were collected over 20 years ago:' Data trends show that groundwater concentrations have declined significantly since monitoring began in 1991,which likely indicates that natural attenuation processeshave also decreased the amount of remaining source material in soil. This in turn indicates a reduced risk of vapor intrusion. Based on these data,no vapor assessment activity appears-warranted for the site. Worldwide Engineering,Environmental,Construction,and IT Services