A major contractor stored hazardous waste in a quarry for several years and used the material to make concrete without being in possession of the necessary licence, The Sunday Times has learnt.
Enemalta contracted the disposal of fly ash from the Marsa power station to Polidano Brothers in 2004 until a 'stop order' was issued by the Malta Environment and Planning Authority four years later ordering the termination of the unlicensed operation.
During that period, Polidano Brothers stored the waste at Quarry Number 33 in the area known as Ta' Belula in the limits of Siggiewi. However, the quarry does not meet the conditions required for a hazardous waste disposal site and was not covered by the relevant permit.
Polidano Brothers confirmed the fly ash was used as 'bulking material' for concrete used to construct retaining walls in buildings.
The unlicensed operation came to light after The Sunday Times followed up parliamentary questions put by Labour MP Leo Brincat about a 'stop order' issued to Enemalta in July 2008.
When the Finance Ministry, the Office of the Prime Minister and Mepa were asked for more details, it emerged that the operation was terminated in December 2008 - by which time about 4,000 cubic metres of fly ash had been transferred to Polidano Brothers.
Fly ash is one of the residues generated in the combustion of fuel oil, and is usually collected from the scrubbing of filters that prevent some hazardous substances being emitted into the air. According to EU Directive 91/689/EEC, it is classed as hazardous waste.
The directive provides additional record keeping, monitoring and control obligations from the waste producer to the final disposal or recovery.
In addition, higher attention is required when different categories of hazardous waste are mixed with each other or with non-hazardous waste in order to prevent risks to the environment and human health.
While fly ash is present in concrete mixtures abroad to strengthen concrete, it can only be used under strict conditions and by licensed operators. In Malta the law states that such hazardous waste must be exported because the country does not have facilities for its safe disposal.
Almost a year after the contract with Polidano Brothers was terminated, Enemalta signed a new contract to export the waste - a much more expensive process than disposing of it locally.
However, both the finance ministry and Mepa confirmed that this led to Enemalta switching off the precipitators (filters) at the Marsa power station for seven months - which stopped the creation of fly ash and allowed unfiltered emissions to be released into the air.
Polidano Brothers' recently-appointed CEO Claudio Grech said the company had been awarded a tender for the disposal of the hazardous waste until the stop order was issued in 2008.
Mr Grech said: "The company had actively researched how this material was to be recycled... Polidano Brothers commenced using fly ash in the mixing process to create blocks used for retaining walls. The method adopted by the company was in line with the appropriate standards."
Prime Minister Lawrence Gonzi said in Parliament nobody had been found guilty in the process.
According to the law, the handling of waste is subject to licensing, and there are strict penalties if any entity is found to be trading in waste without a licence or breaching the conditions of the licence. The person is liable to a fine of €58,234 or up to six months' imprisonment, or both.
But Mepa told The Sunday Times it is still investigating the case and "evaluating its legal options" against Polidano Brothers.
Mepa said the company was ordered to provide a method statement of how the company would safely dispose of the remaining stock of hazardous waste after the stop order was issued. The contractor ignored Mepa's request and proceeded to mix all of the hazardous waste with concrete, according to the authority.