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is � • Work Plan for Destruction of Soil Vapor Extraction and Sparge Wells Former Ranch Market,Riverbank CA Page 4 6.3 DESTRUCTION OF VAPOR EXTRACTION WELLS The former air sparge test well (AS-1) was completed to a depth of approximately 45 feet bgs within the footprint of the former USTs with the filter pack placed between approximately 38 and 45 feet bgs. The soil vapor extraction wells (V-1 through V-10) were completed to a depth of approximately 30 feet bgs with the filter pack placed between approximately 11 and 30 feet bgs. The former air sparge well and vapor extraction wells will be destroyed by removing the well box, over-drilling the bore-hole and removing all material within the original bore-hole, including the well casing, filter pack, and annular seal, and completely filling the created hole with neat cement grout. The grout will be placed in one continuous operation if possible and the volume of neat cement grout will be recorded for each well. Any groundwater displaced from the wells will be collected and contained in DOT-approved drums, sealed, labeled, and characterized for disposal. Well construction details for the air sparge test well and soil vapor extraction wells, as well as the expected grout needed to fill each over-drilled bore hole, are included in the table below. Well Construction Details—Air Sp ar a Test Well and Soil Vapor Extraction Wells Boring Casing Total Sand Pack Depth Estimated Neat Diameter Diameter Depth Interval Cement (inches) (inches) (feet) (feet below surface) (gallons) AS-1 8 2 45 38-45 117 V-1 8 2 30 11-30 78 V-2 8 2 30 11-30 78 V-3 8 2 30 11-30 78 V-4 8 2 30 11-30 78 V-5 8 2 30 11-30 78 V-6 8 2 30 11-30 78 V-7 8 2 30 11-30 78 V-8 8 2 30 11-30 78 V-9 8 2 30 11-30 78 V-10 8 2 30 11-30 78 6.4 DESTRUCTION OF AIR SPARGE WELLS Each of the bore holes for the twenty sparge wells at the Site were drilled to a depth of between 43 feet bgs and 45 feet bgs.The sparge wells themselves were constructed with 0.75-inch diameter PVC casing and 1.25-inch sparge points installed to a depth of approximately 41.5 feet.The annulus around the PVC casing for each well consist of a filter pack from approximately 37 feet bgs to the bottom of the bore hole (between 43 and 45 feet bgs), bentonite seal from approximately 35 feet bgs to approximately 37 feet bgs, and neat cement grout from the ground surface to approximately 35 feet bgs. A review of the well logs indicate that the filter pack intervals in every sparge well (-37-45 feet bgs) correspond to sandy soil, and all but well S-9 was reported as grading to gravel and cobbles at the bottom of each bore hole(please see Appendix E). Due to the difficulty with over-drilling small diameter wells,the 0.75-inch diameter sparge wells will be destroyed by pressure grouting the casing, followed by over-drilling the upper five feet of the ;�� CONDOR