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0 • At monitoring wells TW-13 and TW-14, grout will be emplaced in the bottom of the well vaults to a thickness of 0.5 foot. The remaining void space in the vaults will then be filled with sand to within approximately 0.5 foot of surface and capped with concrete, which will be finished flush with and dyed to match the surrounding ground surface. Extraction Points Extraction points (EPs) EP-1 through EP-6 are constructed of 6- to 12-inch diameter PVC to total depths ranging from approximately 8 to 12.5 feet bgs (Table 1). Since these points were installed in gravel excavation backfill, overdrilling and grouting to the total depth of each point is not practical, as liquid grout will continually infiltrate the gravel in the borehole if the casing is removed. Additionally, EP-1 and EP-6 were fitted with horizontal slotted laterals at depth (see Figures 3 and 4), which cannot be removed. Therefore, abandonment of the EPs will consist of the following steps: • The EPs without laterals (EP-2 through EP-5) will be overdrilled to their total depths via hollow-stem auger. The resultant borings will be backfilled to within 1 foot of surface with hydrated bentonite chips emplaced through the augers from the bottom up. The upper 1 foot of the boring will be filled in with concrete dyed to match the surrounding ground surface. • The casing at EP-1 and EP-6 will initially be filled with neat cement grout comprised of approximately 7 gallons of water per 47 pound bag of neat cement (to ensure that the grout is thin enough to fully infiltrate into the laterals at these extraction points). Neat cement grout comprised of approximately 5 gallons of water per 47 pound bag of neat cement will then be emplaced into the upright casings from bottom to top using a tremie pipe to prevent air pockets or void spaces. At all times during the grouting procedure,the bottom of the tremie pipe will be maintained below the top of the slurry to avoid creating any voids during grout emplacement. The top 4 feet of casing (i.e., the section of casing above the backfill soil/gravel fill interface) at EP-1 and EP-6 will then be overdrilled via hollow-stem auger. The resulting void space will be backfilled with neat cement grout via tremie pipe, as described above. The grout column will be brought to within 1 foot of surface to form a "mushroom cap" within the existing well vault, which will ensure that any space remaining between the casing and gravel backfill cannot be a conduit for downward migration of surface contaminants. The remaining void space within the well box will be filled with sand to within 0.5 foot of ground surface, and the uppermost approximately 0.5 foot of void space will be filled with concrete, which will be finished flush with and dyed to match the surrounding ground surface. Soil Gas Probes All soil gas probes will be overdrilled to their total depths (5 feet bgs) via 3-inch diameter hand auger. All tubing, screen implants, filter pack, and bentonite seal materials will be removed, and the resultant boreholes will be backfilled with neat cement grout. Grout will be applied from bottom to top via tremie pipe. 5