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C,ealogical Tedmics Inc. Page 5 <br /> Groundwater Monitoring Report <br /> Project No. 989.2 <br /> • July 29,2002 <br /> ' 3.0 CONCLUSIONS AND RECOMMENDATIONS <br /> The following conclusions have been drawn from the data generated from this site <br /> investigation work: <br /> Conclusions <br /> 1. The only BTEX constituents seen during this monitoring event are present in MW-1. <br /> This is the monitoring well closest to the location of the former UST. <br /> 2. Since MTBE is present only in MW-4, MW-5 and MW-6, and not in the wells near the <br /> former USTs, the source is not clear. <br /> 3. Changes in TPH-gasoline concentrations are associated with groundwater elevation. <br /> 4. DIPE, ETBE, TAME, TBA, 1,2 DCA and EDB are not present at this site. <br /> 5. Concentrations of TPH-G and BTEX have steadily decreased since 1996, suggesting <br /> ' that either the plume is migrating or is attenuating from natural causes. However, <br /> considering the ORP measurements are all positive (refer to Table 3), it suggests that <br /> natural attenuation is the cause for the significant decrease in concentrations of <br /> tcontaminants of concern. <br /> Recommendations <br /> 1. Additional monitoring well installation is scheduled for July 30, 2002. <br /> 2. Conduct a sensitive receptor survey within a 2000 foot radius of the site for risk <br /> ' evaluation associated with the contamination plume. A work plan proposing this work <br /> has been submitted. <br /> 3. Continue quarterly monitoring to evaluate how the new and existing wells will improve <br /> our understanding of the nature and extent of the groundwater contamination plume. <br /> 4. Include testing for dissolved oxygen in the next couple monitoring events. <br /> 5. Discontinue testing for 1,2 DCA and EDB. <br /> ' 6. Prepare a monitoring well installation report upon completion of the installation of new <br /> wells. <br /> ' 4.0 LINIITATIONS <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 process of defining and evaluating 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, <br /> is made. <br /> i <br />