126 Figure 17 – Ash landfill 4.3 Solution The closure phase for each cell ends once the surface of the tank that comprises it has been waterproofed and cleaned up. These will be closed in the order of their designation. The waterproofing and remediation package for the surface of the cell includes: • Levelling of the surface • Compaction of the surface • Installation of an HDPE geocell filled with soil cement on the filling surface of the cell. 4.4 Coverage Installation Procedure. The installation of the final cover began by placing a leveling soil over the ash, both on the sloped and flat areas. Next, 5 cm high HDPE geocells were installed. This material is a threedimensional confinement structure composed of honeycomb-shaped cells with perforated walls and indented rhombic corrugation, made of high-density polyethylene (HDPE). Its function is to retain the fill with high shear resistance, in this case the soil cement. Figure 18 shows the extension of the geocell. For ease of construction, 10mm diameter and 1m long steel rods were used to anchor the geocell to the ground. Once the geocell was installed, it was filled with soil cement. This material provides high resistance to uprooting within the geocell, greater resistance to wear and abrasion, and even allows light equipment to pass over the final cover.
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