the pumping of groundwater by ENCI, and the emission of harmful substances into the air, partly due to the co-firing of waste materials in the clinker kiln. The limestone in the Sint-Pietersberg is mined in opencast mining, excavating an increasing part of the mountain, causing significant damage to the landscape and the flora and fauna living there. In addition, in 2006 a piece of ENCI forest on the Sint-Pietersberg was felled without ENCI having the required exemption, and in violation of the guidelines that the Ministry of LNV had issued to ENCI. In addition to the influence of the Albert Canal, ENCI's activities also contribute to the dehydration of the Jekerdal by pumping large quantities of groundwater from the quarry for marl extraction. Air quality In order to save on the use of fossil fuels and to limit the effective emissions of , fuels qualified as waste are co-fired in the clinker kiln. This concerns sludge from sewage treatment plants and sorted material from household waste processing. Residual material that remains after combustion is processed with the clinker. The parties are divided on the question of whether there is "responsible disposal of waste". Local residents complain about the nuisance of stench, dust and noise as a result of the combustion of residual materials. The incineration of this waste also produces additional emissions of, among other things, mercury. ENCI in Maastricht annually emits, among other things, about 70 kg of mercury and 30,000 kg of particulate matter. Protests and renewal of permit Although ENCI BV's excavation permit expired on December 31, 2009, it was extended once more in 2010, until 2018. In that year, the marl extraction on the Sint-Pietersberg was definitively stopped; clinker production was continued until 2019 using the accumulated marl stocks. From 2018, the clinker will be supplied from Belgium ( Antoing ) as the cement mills continue to produce. With the cessation of marl mining and clinker production in Maastricht, the long-lasting struggle of local residents and environmental activists against the cement company has come to an end for the time being. For decades there have been protests against the further deterioration of the Sint-Pietersberg, in order to prevent more damage to nature and the environment. At the end of 2007, the action group 'Sint-Pietersberg Breathtaking' collected nearly 5000 signatures from opponents of further excavation as a citizens' initiative. ENCI employees subsequently collected more than 12,000 signatures.