Lubna landfill

Table 3. Annual water balance for the for the Lubna landfill bodyNo. Specification Symbol Unit VolumeIncome1 Precipitation on 21.64 ha of the landfill area P m 3 1150502 Water from waste moisture W m 3 60426Outgoing3 Evaporation from the landfill surface (21.36 ha) E t m 3 1068004 Evaporation from the open water reservoirs (0.28 ha) E w m 3 16485 Effective retention capacity of the landfill body ∆R m 3 30213Excess of the water balance6 Leachate from the drainage system Η 3 m 3 36815The total income amounts to 175476 m 3 per year, whereas the evaporation from the landfillsurface and water reservoirs, as the well as effective retention capacity equals to 138661 m 3 peraverage year. Comparison of these values shows that the excess of leachate for further utilisationis approximately 40.000 m 3 per year.Since 1996, the leachate has been transported by septic trucks to a sewage treatment plant inPiaseczno. In the nearest years, the preliminary purification of the leachate in the biologicaltreatment plant located close to the landfill is planned, followed by directing it by a pipe canal forfinal purification in a sewage treatment plant in Moczydłów.6. Slope stability analysis for reinforcement designIn 1995 a landslide occurred on the northern slope of the Lubna landfill. As a result, it becameobvious that reinforcements were needed to improve the stability of the slopes of the landfill toprevent other landslides. Therefore, shear strength parameters of solid municipal wastes weredetermined, i.e. waste density (ρ), angle of internal friction (φ) and cohesion intercept (c). Thedetermined parameters are presented in the section concerning investigations of wasteproperties. The shear strength parameters resulting from these tests were verified on the basis ofback-analysis of the landslide.The stability analysis results the Lubna landfill, according to classical and FEM methods, givefactors of safety in the scope of 1.05–1.15 for natural slopes, whereas for slopes with berms itsvalues increase to 13 from Bishop’s method (Fig. 12) and to 127 from FEM (Fig. 13).12