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, Gealogtral Teclucicslftc. Page 7 Groundwater Monitoring Report Project No. 1030.2 March 18,2005 • The clay layer between 17 and 25 feet bgs provides a significant barrier to vertical plume ' migration. • Vertical groundwater gradient is historically positive (upward)making downward vertical migration unlikely. ' • The following factors may have a positive contribution to protection of the deeper aquifers and retardation of contaminant migration at this site: a Gradual groundwater gradient slope ' o Groundwater parameters show that the site is conducive to natural attenuation o Dominant upward vertical groundwater gradient o Fine-grained soils characterized by silts and clays ' o A thick clay unit between 17 and 25 feet bgs will help prevent downward migration of contaminants Recommendations • Continue quarterly groundwater monitoring. ' • Incorporate MW-1R into the quarterly groundwater-monitoring schedule. • Redevelop MW-5 in an effort to correct slow recharge encountered during this monitoring event. 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 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 t 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. 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.