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Geological TeChX&s lxc. Page 5 ' Groundwater Monitoring Report Project No. 989.2 April 30,2003 ' • Chart: MW-6 MTBE vs. Groundwater Elevation shows that MTBE fluctuates with groundwater elevation. It may also indicate that the MTBE plume is attenuating from ' natural causes. • Dissolved oxygen measurements recorded in the water table wells during the February ' 2003 monitoring event range from 0.28 to 2.22 ppm. This range is conducive to aerobic biodegradation activity. • pH measurements recorded in the water table wells range between 7.3 and 7.6. This ' range is conducive to aerobic biodegradation activity. • Groundwater analyses of MW-101 suggest there are no gasoline range petroleum hydrocarbons impacting deep groundwater at this site. The thick clay found during the ' installation of the deep monitoring well should form a barrier to contaminant migration. 0 The plume is defined to the south by MW-3, to the east by MW-2 and to the west by MW-7. • The MTBE plume is essentially defined to the north by MW-8 and to the northeast by MW-9. ' • We believe the petroleum contamination plume has been adequately defined vertically and laterally at this site. Recommendations 1. Continue quarterly monitoring for one more quarter. This will achieve the goal of four quarters of groundwater monitoring since the in of the new monitoring wells. ' 2. Collect samples for biodegradation indicators in order to determine the possible impact of natural attenuation at the site. 3. If the data shows the site condition are remaining stable, we recommend the site be ' considered for closure. 4. If the site receives closure, GTI recommends the proper abandonment of all monitoring wells associated with this site. 4.4 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 that definition and evaluation of environmental conditions is an inexact science and that the state or practice of environmental geology/hydrology 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 can 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.