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20 October 1998 AGE-NC Project No. 98-0459 Page 5 of 7 5.2. PETROLEUM HYDROCARBON-IMPACTED GROUND WATER None of the analytes of interest analyzed for by EPA Method 8020 were detected in the water samples.The oxygenated fuel additive tertiary butyl alcohol(TBA)was detected in the water sample from boring SP1 at a concentration of 8.1 micrograms per liter(part per billion: ppb).None of the other analytes of interest analyzed by EPA Method 8260m were detected in the water samples. In response to the detection of 8.1 ppb of TBA in water sample SP1,the water sample from SP2 was analyzed for TBA and MTBE, although the sample was slightly over the hold-time, no TBA or MTBE was detected in the sample. The analytical results for the ground water samples are summarized in the laboratory report (MAI Sample Nos.95711 and 95712), quality control and quality assurance data(QA/QC) and chain-of- custody form are included in Appendix A. 5.3. CHLORINATED HYDROCARBON IMPACTED SOIL VAPOR The chlorinated hydrocarbon commonly associated with dry-cleaning activities (trichloroethene: PCE)was not detected in the soil-vapor column at the subject property where the soil borings were established. However, the compound dichlorodifluormethane was detected at concentrations up to 110 micrograms per liter (parts per billion: ppb) in the soil vapor samples. MAI verbally reported that this compound may be a degradation product of the common air-conditioning compound Freon 12. The Eleventh Edition of The Merk Index indicate that this compound is a commercial product known as Freon 12 among other names,and is used as a refrigerant or aerosol propellant. The Merk Index also notes that this compound has little, if any, anesthetic or toxic action. The analytical results for the soil vapor samples are summarized in the laboratory report (MAI Sample Nos.95713 and 95717), quality control and quality assurance data (QA/QC) and chain-of- custody form are included in Appendix A. 6.0. CONCLUSIONS Based on data collected from the site AGE concludes the following: • The ground water at the subject property has been slightly impacted by TBA, a fuel additive. Based on past site usage,the relationship of the site to the former Exxon station/current Shell