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' Geological Technics Inc. Page 9 Bank of Stockton-Western Lift Remedial Feasibility Study-Work Plan Project#358.3 September 28, 1995 5.0 ADDITIONAL OVER-EXCAVATION With the additional characterization data from the installation of VEW 1 & 2, a volumetric calculation will be made of the amount of material that would need to be i ' excavated in order to remove the source of residual ground water contamination. The cost to excavate and dispose of the material will be requested from licensed ' contractors and the feasibility of additional over-excavation will be assessed. 6.0 GROUNDWATER MONITORING AND MODELING Groundwater monitoring data that has been collected over the past several years displays a general trend toward decreasing contamination levels. Given sufficient ' time, the contaminant levels may decline sufficiently with no additional active remedial measures to allow site closure. This option will be examined as a part of ' the feasibility study. If this option appears feasible, it is anticipated that groundwater computerized fate and transport modeling using the programs SESOIL and AT123D may be used. 7.0 RECOMMENDATIONS AND REMEDIAL WORK PLAN ' After completion of the activities described above, report will be prepared the presents a discussion of the advantages, disadvantages, and anticipated costs of each of the remedial methods investigated. A set of recommendations will be made ' regarding the method or combination of methods that appears to offer the best chance of achieving the groundwater remediation sought in the most cost and time effective method. A remedial action plan will also be prepared to discuss the r implementation of the recommended remedial method. 8.0 CONTINUING SITE ACTIVITIES The existing groundwater monitoring wells are due for a quarterly sampling event. ' Geological Technics Inc. will propose in a separate Work Plan, a round of quarterly manitoring and sampling of the existing wells.