Methodology

The main input of OVAM into the RAWFILL project is an application to support local governments, landfill owners, policy-makers, consulting engineers, etc. in the decision-making process, when dealing with old landfill sites. The application includes a two-step approach: Cedalion (DST 1) and Orion (DST 2). 

The first step, Cedalion, enables the user to screen a landfill database or inventory and to categorise and select the most promising landfills by means of a ranking algorithm. For this, the Cedalion tool is linked to the Enhanced Landfill Inventory Framework (ELIF), where all available information on landfills can be stored and managed. 

The Cedalion tool uses the most basic, available information, so input relevant to each landfill will be limited in the early stages. The output of DST 1 will give the user an idea about the potential of the landfill in terms of mining and redevelopment. If the mining potential of a particular landfill is not high enough in the foreseeable future, an interim use will be advised, on the condition that there is no risk for the environment. These temporary solutions will buy time, ranging from a year to several decades, and will deliver one or more (ecosystem) services to society. 

Landfills with a high valorisation potential, as indicated by the Cedalion tool, will be directed to the second step of the DST: the Orion tool. This tool consists of two different components, the Orion dashboard and a roadmap. The dashboard provides the user with an overview of existing models and tools, which could be used when making decisions on the valorisation and rehabilitation of landfills. The Orion roadmap, on the other hand, will determine the most feasible outcome for a specific landfill: remediation, landfill mining, rehabilitation or interim use. As a function of this outcome, Orion will indicate the most relevant models and tools to further assess a potential project. 

In collaboration with Technical University Wien, OVAM introduced one newly developed model on the Orion dashboard - ONTOL. ONTOL is an online tool for the economic and ecological evaluation of landfill mining, based on methodology from the United Nations Framework Classification (UNFC). This framework is based on research from TU Wien and provides a system, in the context of circular economy, for classifying anthropogenic resources according to their mining options. 

The Orion tool (interactive web application) can be accessed by means of the following link: Orion tool version 1.0 

Orion is a more complex application, for when more detailed information on landfill content and structure is required. The HADESS methodology for innovative landfill content characterisation will be a valuable strategy in this regard. Geophysical prospecting methods used are rapid, non-invasive, surface-based techniques for measuring bulk ground properties, such as electrical conductivity (or its inverse, electrical resistivity), density and stiffness. When correctly applied, geophysical methods help us to better understand landfill sites in terms of spatial extent/volume and/or composition/distribution of waste materials. Combined with a priori information and targeted sampling, they can help to identify the landfill extent and to characterise and identify changes in waste composition. The final aim is to construct a Resource Distribution Model (RDM) which describes the spatial/volumetric distribution of indicative parameters of the landfill materials, at a scale suitable for assessment of the economic viability of potential landfill mining operations. The availability of an RDM for a particular landfill makes the Orion tool very easy and quick to use.