ARCHIVED REPORTS_XR0004046 - Laserfiche WebLink

Home Browse Search

C#010 iral7ec/uucs fac. Page 4 Groundwater Monitoring Report Project No. 1030.2 August 27,2004 Site Characteristics ' a The plume is defined vertically by MW-101 (screened from 29.5 to 34.5) and laterally by MW-2 to the southeast and MW-3 to the southwest. o MW-4 appears to be located near the leading edge of the plume. ' ® The clay layer at 19 feet bgs provides a significant barrier to vertical plume migration. ® Groundwater slope is gradual (c0.0058 ft/ft) which impedes the migration of the plume. Vertical groundwater gradient is historically positive (upward) making downward vertical ' migration unlikely. ' Measurements of dissolved oxygen in the shallow monitoring wells range between 0.76 and 1.21 ppm, suggesting conditions at the site may not favor biodegradation (Table 4). • MW-2, MW-3 and MW-5 showed a positive oxidation-reduction potential (Table 4). • The following factors may have a positive contribution to protection of the deeper ' aquifers and retardation contaminant migration at this site: o gradual groundwater gradient slope o dominant upward vertical groundwater gradient ' o fine-grained soils o characterized by silts and clays o a thick clay unit at approximately 19 feet bgs 3.0 RECOMNMNDATIONS ' • GTI is preparing to submit an addendum for corrective action. • Continue quarterly groundwater monitoring. 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 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.