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SECTION 5 tSUMMARY AND RECOMMENDATIONS This section provides a brief summary and recommendations for further work 1 5.1 Summary ' Soil andrun w g o d ater samples were collected at site perimeter locations for the purpose of delineating the lateral and vertical extent of petroleum Hydrocarbon and associated oxygenate contamination This section summarizes the vertical and lateral contaminant extent in soil and groundwater for the primary contaminants MtBE and TPH-g and recommendations for further ' investigation and remediation Vertical delineation of TPH-g has not been completed in the source area The deepest ' Hydropunch® sample completed in the source area (CPT-1) at 108-ft bgs contained 1000 µg/L TPH-g ' A site conceptual model has been created and will be a dynarruc tool in determining critical paths in remediation decision-making 5 2 Recommendations ' Recommendations include further delineation of vertical extent of contamination in groundwater and lithology below 130-ft bgs BC proposes using CPT to determine lithology to 200-ft bgs and collection of groundwater samples below 110-ft The depth and number of water samples ' collected will be determined based upon lithology determined using CPT Based on the results of the deeper CPT investigation, groundwater monitoring of the deeper zone may be warranted ' In order to reduce the mass of TPH-g,BTEX, and MtBE in the soil, BC recommends conducting a soil vapor extraction pilot test If the pilot test results are favorable, the design and installation of a ' Soil Vapor Extraction and Treatment System (SVETS) as an Interim Remedial Measure should be considered to arrest the downward migration of volatile contaminants into the groundwater Other soil remediation alternatives should also be evaluated as part of a remediation feasibility study (FS) ' As part of the FS,groundwater remediation alternatives should be evaluated after the vertical extent of contamination has been completed 1