Engineering-geological comparative analysis of four cases studies of waste landfills

Abstract

The aim of the paper is to carry out a comparative engineering-geological study of four diferent waste landflls using the evaluation criteria for the geological subsoil as a natural sealing barrier. The study evaluates 4 localities (Velké Pavlovice, Kvítkovice, Prakšice and Horní Suchá) using three variants (based on two standards) which approach the geological barrier requirements as a combination of impermeability requirements based on a fltration coefcient limit value. and the required geometry represented by investigation depths. The research was carried out in landflls in Moravia, in the east of the Czech Republic. The study’s motivation is to point at the diferences in engineering-geological investigations of waste landflls (as for the requirements for impermeable geological subsoil as a natural sealing barrier) when compared with other engineering structures (where the main goal is to evaluate load-bearing capacity and settlement). The purpose of the geological barrier is to prevent the spread of contamination, and the paper shows this can be approached diferently, as shown in two diferent methodologies investigated herein. The frst model (Model 1) assumes there is a 3-m-thick subsoil below the landfll’s footing bottom, which manifests impermeability characterized by the fltration coefcient Kf ≤ 1.0 * 10–9 m/s, or a 30-m-thick subsoil of Kf ≤ 1.0 * 10–8 m/s. The second model (Model 2) assumes a 1-m thick, impermeable subsoil massif of Kf ≤ 1.0 * 10–9 m/s. We found that none of the landflls in the four selected localities had an impermeable layer in the required depth (a fltration coefcient Kf from 1.8 * 10–9 to 3.9 * 10–9 m/s), and thus did not comply with the limiting conditions. As a result, an anthropogenic technical barrier had to be installed. An important goal of the study from an environmental point of view was to assess the existence of a suitable geological barrier under the proposed landflls. The most important criterion from this point of view is permeability. An additional technical objective of the project was also the assessment of the possible creation of a technical anthropogenic isolation barrier. In the event that the natural sealing barrier would not be sufcient. This was shown in all solved case studies of engineering geological investigations of waste landflls.