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f C,eologlcalTecknicst4c. ; Page 5 I Groundwater Monitoring Report j Project No.750.2 } April 12,2004 plume area:,around the source without depleting - residual BTEX/TPH-G p i'n the a r p g the oxygen. L • The dissolved oxygen measured at the site is between 3.2 and 4.0 ppm and is conducive . to natural attenuation of BTEX/TPH-G. • It appears that soil contamination has been reduced significantly, oxygen has been added to the subsurface and groundwater contamination is absent. • Excellent progress has been made at this site. Clean-up goals have been met and the effort has exceeded MCL's for the known constituents at the site. • Biodegradation indicators suggest that the ;trace remnants of soil contamination will degrade by natural attenuation. Recommendations: • Continue quarterly groundwater monitoring at the site. • Perform vapor extraction as directed by the county in an effort to remove the trace amount of remaining contamination.. • After vapor extraction for 6 months, if not sooner, the site should be considered for t closure. 4.0 LIMITATIONS This report was prepared in accordance with the generally accepted standard of care and practice in effect at the time Services .were rendered. It should be recognized nized that g definition and evaluation of environmental conditions is an inexact science and that the state or practice of environmental geology/hydrol'ogy is changing and; evolving and that standards existing at the present time may change as knowledge increases and the state of the practice continues to improve. Further, that differing subsurface soil characteristics Lcan be experienced within a small distance and therefore cannot be known in an absolute sense. All conclusions and recommendations are based on the available data and information. _ 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.