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Geologica[Teclucicslicc. Page 5 <br /> I Groundwater Monitoring Report <br /> Project No.750.2 <br /> December 10,2002 <br /> • The VETS is effectively g removin the contaminants from the soil that have been <br /> leaching into the groundwater. - Calculations show that the system has removed <br /> approximately 650 gallons from the subsurface. GTI is currently preparing a Vapor <br /> Extraction Treatment System Quarterly Monitoring Report. <br /> • Vertical groundwater gradient was calculated for the event of September 23, 2002, and <br /> was determined to be downward with a magnitude equal to the horizontal gradient of the <br /> water table. The magnitude of the vertical gradient has been getting progressively <br /> "smaller during the last several monitoring events. This may be a result of influence <br /> from the vacuum of the vapor extraction system. <br /> • Oxidation-Reduction Potential measurements (Table 4) are positive for all the wells. <br /> This suggests that the volume of contaminants leaching into groundwater has been <br /> stopped and that biodegradation of the contaminants is at a rate sufficient to mitigate the <br /> residual BTEX/TPH-G plume in the area around the source without depleting the <br /> oxygen to a level. <br /> Recommendations: <br /> L • Continue Quarterly groundwater monitoring at the site. The next event will occur by the <br /> end of December 2002. <br /> "� • Evaluate the status of the hydrocarbon removal by performing a spike test and measure <br /> the early withdraw of vapors to evaluate the residual hydrocarbons in the soil. <br /> 3.0 LIIVIITATIONS <br /> li 4 <br /> This report was prepared in accordance:with the accepted standards and practices of the <br /> - field of environmental geology, groundwater hydrology and good business practices. It <br /> should be recognized that definition and evaluation of environmental conditions is a <br /> difficult and an inexact science. Judgments leading to conclusions and recommendations <br /> are generally made with an incomplete;knowledge of the site-specific conditions present. <br /> The tasks proposed and completed during this project were reviewed and approved by the <br /> local regulatory agency for compliance with the law. No warranty, expressed or implied, is <br /> made. <br /> r l� <br /> L <br />