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GeosyntecO consultants surrounding the wells. Prior to destruction, each well will be sounded and compared to the well depths listed on Table 1 to verify the well is clear of obstructions. In accordance with San Joaquin County well standards, wells that are located outside an area of known contamination can be destroyed by leaving the well casing in place and completely filling the well screen and casing with flowable grout under pressure (i.e, pressure grouting). Wells of unknown construction or in areas of known or suspected contamination will be destroyed by completely removing the well components (i.e., over-drilling the casing, screen, sandpack) and filling the resultant borehole completely with grout. Pressure grouting will be completed by removing the well vault box and disconnecting/capping the conveyance piping as described in Section 3.2. A 24- inch diameter (i.e., 12 inches larger than the original borehole diameter) excavation around the wells shall be completed to a depth of 3- feet below grade. The well casing shall be cut 2.5- feet below grade. Neat cement grout will then be pumped into the well casing through a tremie pipe, filling the well from the bottom up in one continuous operation. Pressure will be applied to the wellhead at approximately 30 pounds per square inch (psi) forcing the grout out of the well screen and into the filter pack. Tremie grouting will then resume and the grout will be allowed to completely fill the well casing and flow into the excavation to a thickness of 1- foot. Groundwater is not anticipated to be encountered in the SVE or SVMW wells; however, if groundwater is displaced during pressure grouting, it will be pumped from the excavation and containerized in 55- gallon DOT approved drums to allow SJCEHD personnel to inspect the grout seal. Following setting of the grout the area will be returned to like conditions as described in Section 3.2. Over-drilling wells shall be conducted by removing the well vault boxes and disconnecting/capping the associated conveyance piping as described in Section 3.2. In order to ensure that all well materials are removed, (i.e.,well casing, seals, filter packs)the wells will be over-drilled with hollow stem augers the same size or larger than the original borehole as documented on Table 1. The original boring diameter for the majority of the air sparge wells was not documented; however,AS-1 and AS-2 installed during pilot testing were installed in an 8- inch diameter boring. The remaining air sparge wells were constructed with similar methods so all air sparge wells will he over-drilled with at least an 8- inch diameter borehole. The wells will be over- drilled the entire depth of the well. The boring created during removal of the well material shall then be completely sealed via tremie grouting the annual space from bottom up using the augers to stabilize the borehole walls. The augurs shall be lifted during tremie grouting operation to ensure that grout completely filled the associated System Decommissioning and Well Destruction Work Plan 7 07/18/2014