SITE INFORMATION AND CORRESPONDENCE_FILE 2

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Site Background Information: Chapin Brothers Investments, Inc. Page 19 of 19 GENERAL OVERVIEW A soil vapor extraction(SVE)/in-situ air-sparging (IAS) system was installed and operated at the site from April 1996 to late June 1999 to remediate hydrocarbon-impacted soil and ground water. However,over the course of the SVE remedial action,rising ground water elevation had submerged a significant portion of contaminated soil,leaving a greatly reduced vadose zone addressable by SVE technology and apparently rendering IAS ineffective due to a thicker saturated zone and diminished ability to recover sparged air. Areas in the eastern portion of the site and at the northwest corner of the site had not demonstrated a sustained reduction of dissolved hydrocarbons.Subsequently a more effective remedial system was required. In accordance with EHD/CVRWQCB directives and approval,AGE conducted three separate ground water extraction pumping tests in March 2001.Analysis of the ground water extraction data indicted that ex-situ ground water treatment was feasible;the radius of influence generated by a pumping rate of three gallons per minute is interpreted to be adequate to control further off-site migration of contaminants toward the west. Under EHD directives and approval,a ground water pump-and-treat system began operation at the site on 02 April 2002;the system has operated for approximately 18 months. Over this time period approximately 2.5 million gallons of impacted ground water was treated and estimated cumulative totals of 5.69 lbs of benzene and 140 lbs of TPH-g were extracted. Between 15 April and 19 September 2003, the ground water extraction and treatment system processed approximately 302,703 gallons of water. The total volume of ground water treated as of 30 September 2003 is approximately 2,459,705 gallons. TPH-g and BTEX concentrations have decreased in the monitoring well samples over the remediation period.The overall reduction of benzene on-and off-site indicates successful removal of dissolved hydrocarbons and capture of the off-site dissolved hydrocarbons,based on monitoring trend analysis. The remediation-goals presented to the EHD by letter dated 10 August 2001 proposed that removal of 80 percent of the mass of dissolved hydrocarbons,or diminished remediation effectiveness,would be acceptable clean up goals for the site.Presently,at most impacted ground water monitoring wells, the contaminant concentrations have been reduced to approximately 1%benzene and 5%TPH-g of the pre-remediation levels. The ground water extraction system ceased operation on 10 May 2005,as approved in the Ground Water Monitoring-Natural Attenuation Work Plan dated 21 March 2005. Advanced GeoEnNironmental,Inc.