The solid waste disposal site at Maghtab was developed at a time when the full environmental impacts of such operations were not known. As a result, the Maltese Islands are left with a legacy of landfill sites that have no systems in place for the proper control of landfill leachate, gas and fires.
Over the years, concern has arisen over the potential human health and environmental impacts of this site and the need to raise the environmental standards associated with waste management in Malta.
The Maghtab waste disposal site and the Qortin dump in Gozo have now been closed in line with Government's commitment to reduce this potential human health hazard and its environmental impact. The waste dumps will be rehabilitated by WasteServ Malta Ltd on behalf of Government.
Since 1977
The footprint area of the Maghtab landfill is currently around 40 hectares. The main waste-filling area forms a complex shape with waste rising steeply from natural ground level in benches to a flat upper plateau around six hectares in area.
The maximum thickness of waste over the buried valley is around 90 metres.
The site was developed on areas of garigue and some former agricultural land. Before waste disposal operations began, the natural topography of the area was a valley lying between two low ridges; the general slope of the land was towards the sea.
Currently, the valley is entirely buried and the ridges form the land surfaces at the base of the western (Il-Ghallis ta' Gewwa) and eastern (Ta' Hammud) sides of the landfill.
Maghtab has been in operation since 1977 and has taken most of Malta's waste since the closure of Wied Fulija in 1995. Prior to 1997 no detailed records were kept of the quantity and type of wastes deposited. However, since then a weighbridge has been installed and records have been made of all wastes deposited.
Development of rehabilitation strategies
The rehabilitation of Maghtab by WasteServ follows an investigation and study of the site to develop environmentally sound strategies for its rehabilitation. This was achieved by an investigation of the waste masses, measurement and monitoring of aerial emissions, sea and groundwater quality and temperature profiles. These were used to assess the impact that this waste disposal site is having on the surrounding environment currently and potentially in the future should there be no intervention.
The site has a number of uncontrolled fires and waste is predominantly degrading in aerobic conditions where oxygen is present. Due to lack of adequate flow of oxygen in particular areas, locally anaerobic decay is also present releasing the typical landfill gas in low concentrations.
Carbon monoxide concentrations and gas temperatures are relatively high. In addition, other gases and emissions associated with waste combustion are being released to the atmosphere. The aerial emissions management system is designed to collect these high temperature gases for destruction before releasing them into the atmosphere.
Project viability and timetable
Potential capital funding for this project is being pursued as part of the funds made available through European Union structural funding. In this eventuality, the installation works will be undertaken under one or more contracts in accordance with EU requirements. After completion of the handover period responsibility for managing the system will rest with the developer (the government of Malta).
The initial stage of this project is the topographical surveys of both closed landfills to determine the final shape and the quantities of the materials to be shifted. The tender for these works was published and has a closing date of May 25.
Following the completion of the shifting of the material, the installation and commissioning of the aerial emissions management systems will be carried out in a number of stages.
It is anticipated that work will start as soon as the contracts have been awarded and the contract works, commissioning, training and handover periods are expected to last some 18 months in total. This will enable subsequent phases of the rehabilitation to progress.
Full restoration of these sites, which will include establishment of vegetation and development of after-uses, will take place when the emissions from the site are under control.
The results of the studies carried out at Maghtab have defined a number of immediate and longer-term actions for the rehabilitation which will be implemented in a number of phases.
The rehabilitation project will involve the installation of environmental monitoring systems, recontouring the waste within the site boundaries to form access roads and level working platforms, drilling into the waste for steel well installation and the construction of a secure compound to house a gas management plant where the gases collected from the waste masses on Maghtab will be treated.
A number of selected systems will be utilised to extract gases from within the waste masses and destroy the harmful components before venting to the atmosphere. Such a system will also accelerate the process of returning the sites to beneficial afteruses.
The installation of the aerial emissions management system is designed to reduce the environmental impact of the landfills; however, to minimise any impact the construction or operation may cause, procedures will be adopted to eliminate nuisances from vehicle traffic, litter, odours, noise, vermin, insects and other pests, fires/smoke, and dust.
This project will establish the initial phase of the rehabilitation of the Maghtab and similarly for the Qortin and Wied Fulija landfills. It is expected that this will be progressively followed over a number of years with further phasing-in of processes. Future phases will include recontouring of the waste and the establishment of a vegetative cover.
Decommissioning of the environmental control systems including the aerial emissions control plant and equipment will also be undertaken once the waste masses have stabilised some time in the future.
Following the implementation of the complete restoration, it is anticipated that the sites could, in the future, serve a number of after-uses.
Dr Ing. Ciantar is head of strategy, communications and development, Waste Serv