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LYSMETER AND LEACHATE RISIER ECTENSIONS 0 The existing facilities for monitoring the vadose zone beneath the leachate collection sump, and for inspecting and removing any liquids present in the sump, include a number of vadose zone lysimeters and two leachate risers. Because the vertical expansion of the ash pit would otherwise bury these facilities, the lysimeters and leachate risers were modified to extend through the southern expansion berm prior to berm construction. The vadose monitoring facilities consist of two lysimeters which are used for ongoing vadose monitoring, and two additional lysimeters which are used as backup monitoring points if necessary. The leachate risers consist of one angled 12 inch diameter riser which contains a four inch diameter submersible pump for leachate removal. A second riser, a 48 inch diameter concrete pipe, was installed on top of the leachate collection sump and extends vertically upwards through the ash to the existing grade. This riser was installed to provide access to the sump in the event siltation and plugging effects the removal of leachate in the future. The lysimeters were extended through the southern berm to provide access for subsurface monitoring beneath the collection sump. The expansion berm was built along the existing southern berm approximately two feet above the original grade, at which point two trenches were cut through the compacted soil at locations adjacent to each lysimeter. Tubing extensions were spliced on the lysimeter vacuum and pressure lines and a polyvinyl chloride (PVC) 1.5 inch diameter - 90 degree elbow and extension pipe were placed over the tubes and secured into the existing locking vault. A 4 inch diameter PVC outer casing and 90 degree elbow were placed over the inner pipe and secured onto the existing vault. A concrete boot was placed around the PVC elbows and original locking vault to prevent movement during subsequent berm construction. Once the lysimeter extensions were positioned through the sidewall liner, the surface trenches were refilled with soil and compacted manually with the use of a gasoline powered soil compactor. All the lysimeters were tested prior to backfilling the surface trenches to ensure proper operation. •14 zN:XIV OR • verticalAdditional risers were placed on both the 12 inch diameter angled riser and the 48 inch • on riser r carried through the southernberm,a the submersible pump located at the base • - riser. This pump and riser is a closed system with PVC piping attached to the pump outlet and piped directly to the leachate evaporation pond. 11 n