Consideration of hotspots in the selection of supervision schemes to reduce illegal dumping of construction and demolition waste.

Illegal dumping of construction and demolition waste continues to be a problem hindering circular economy efforts. Controlling illegal dumping necessitates establishing an effective surveillance scheme and investigating the proper penalty value. This problem has previously been described as a game theory problem, with the government and construction contractors as the players. Taking into account illegal dumping hotspots, which can often be identified through topographical and geographical characteristics, is also important when establishing supervision strategies. This study develops an evolutionary game-theoretic model that can assist in devising effective supervision strategies to control the spread of illegal dumping, while taking into consideration hotspots. In specific, this study investigates the suitability of two alternative strategies: police patrols and hybrid monitoring through both patrols and the installation of closed-circuit television cameras in hotspots. The model was applied to two case studies, using parameters informed by real-world contexts, to demonstrate its potential for selecting suitable strategies according to local situations. The results suggest that nine possible scenarios govern the stable evolutionary strategies of game players, with five scenarios in which contractors converge to adopt legal dumping. Accordingly, based on the parameters of the region (hotspot areas, cost of supervision, efficiency of patrols, penalties, etc.), governments would be able to assess which of the strategies would lead to long-term compliance of contractors while also increasing their payoffs. Further analysis allowed to determine the minimum efficiency required, and simulations were performed to demonstrate the influence of different supervision efficiencies and penalties on the evolutionary strategies.

A multi-stakeholder digital platform for regional construction and demolition waste management.

Little attention has been paid to the interaction or synergy among construction and demolition (C&D) waste management stakeholders. A framework allowing for interaction among the various C&D waste players is especially important in regions with mature C&D waste infrastructure, where various recycling, reuse and disposal facilities are present. In such an expanded infrastructure, these facilities differ in terms of the C&D waste materials they accept, the nature of the waste accepted (sorted/unsorted), as well as the services they provide. This makes developing the optimal C&D waste management plan (WMP) more cumbersome for contractors. To address the challenges arising from the poor dynamics associated with the overarching waste management infrastructure, this paper proposes a novel digital platform, namely the 'Construction and Demolition Waste Management Kernel' (C&D WMK). The C&D WMK has three main objectives: it allows for data exchange between the different stakeholders, provides guidance to contractors when developing C&D WMPs and allows for governmental supervision and regulation. This paper introduces the concept behind the C&D WMK, presents the optimization model embedded in the system, and demonstrates its application in a case study leveraging real-world data. Finally, a scenario analysis is conducted to show how the C&D WMK can be used by governments to identify pitfalls in the state of practice at the regional scale, and to determine effective solutions to enhance the C&D waste management performance.

Using GIS and optimization to manage construction and demolition waste: The case of abandoned quarries in Lebanon.

Increased stress on raw material and limited landfill space due to increasing rates of urbanization have encouraged efforts to divert Construction and Demolition Waste (C&DW) away from landfills toward sorting, recycling, and reusing. While these efforts have been successful in some countries (e.g., Germany, Netherlands), developing countries tend to suffer from illegal and haphazard dumping of C&DW. This study presents an optimization based decision support tool to select a cost and environmentally effective set of abandoned quarries to serve as C&DW landfills and processing facilities. The tool is composed of a GIS model and a mixed integer linear program that accounts for the complete waste management chain. A case study in Lebanon served as a testbed for the tool: A multi-criteria analysis was first used in GIS to evaluate the environmental suitability of candidate quarries based on five thematic groups: socio-economic, topography, geology, hydrology and infrastructure. The most suitable quarries were then inputted to the optimization model. Two out of 148 abandoned quarries in Mount Lebanon were deemed suitable for rehabilitation under the objectives set yielding a profit of 125 million US dollars over a 20 year span. Future challenges include enhancing the model by incorporating time and accounting for more recycling technologies.

Pilot-based assessment of the economics of recycling construction demolition waste.

The significant amount of waste generated from construction demolition has become a chronic problem in many developing countries. Using data obtained from demolition contractors and various other sources, this paper proposes a framework for proper handling of construction demolition waste (CDW) to serve as a decision support tool in countries suffering from the lack of national CDW management guidelines. The framework is then demonstrated through a case study in the city of Beirut, Lebanon, and a sensitivity analysis is carried out to examine the economic feasibility of developing a recycling facility. The analysis showed that in order for a facility to be feasible, a gate fee should be charged in the presence of a market for recycled aggregates. The results confirm the significance of instigating and implementing legislation to control illegal dumping, constructing, and managing engineered landfills, and establishing markets for recycled CDW.