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GeobgicaLTechnics inc. C&B Equipment Page 4 Groundwater Monitoring Report �.1 Project No.336.2 "•.• fr S, April 13, 1998 i 2. Concentrations of benzene in MW-2 have fluctuated greatly while toluene, ethyl benzene, xylene and TPH-G have all shown a general decreasing trend. 3. The concentrations in MW-101 have decreased and order of magnitude in the past six months suggesting that the deeper aquifer has not been impacted significantly and the contamination is undergoing natural attenuation. 4. A thick fine grained silt-clay unit is present between 30 and 40 feet bgs. This unit appears to form a significant low permeability barrier to vertical migration of chemicals. 5. The groundwater plume appears to be defined laterally. j=a 6. The domestic well, which is located approximately 45 feet east of the former USTs, has not been impacted by petroleum hydrocarbons. ._ 7. MTBE has not been detected at the site since December of 1996. A 8. The other oxygenated fuel compounds have not been detected. 9. Groundwater consistently flows to the north-northwest between 0.007 and 0.0036 ft/ft. 10. A well survey performed in 1997 shows that there is a lack of water well receptors in this area. Recommendations _._ The following recommendations are made: 1. Given the lack of receptors in this area, it is recommended that not further investigation 4 or monitoring be performed. 2. Given the low permeability geologic unit below 30 bgs and the low concentration of chemicals in the groundwater, it is recommended that this site be considered for closure. 4.0 LIMITATIONS This report was prepared in accordance with the accepted standards and practices of the field of environmental geology, groundwater hydrology and good business practices. It should be recognized that definition and evaluation of environmental conditions is a difficult and inexact science. Judgments leading to conclusions and recommendations are generally made with an.incomplete knowledge of the site specific conditions present. The tasks proposed and completed during this project were reviewed and approved by the local regulatory agency for compliance with the law. No warranty, expressed or implied, is made.