Over the past few days, Vassallo Builders has been responsible for the installation of cutting-edge gas mixing technology at the new Malta North Waste Treatment Plant in Maghtab. This has been another major milestone which Vassallo Builders has proudly reached as part of its contract with WasteServ Malta Ltd. for the Design and Build of a new waste treatment plant for the Northern regions of Malta. This contract is being jointly executed with Portuguese partners EFACEC Engenharia e Sistemas S.A. and German partners BTA International GmbH. This venture adds to the Group’s vast portfolio of prestigious construction projects delivered across Malta and Gozo throughout its 69 year history. The Malta North Waste Treatment project succeeds Vassallo Builders most recent accomplishment in the field of environmental management projects – this being the design and build of the Sant Antnin Waste Treatment Plant in Marsascala completed back in 2011. The plant encompasses a series of digestion tanks each having a capacity ranging between 2700 and 4500 cubic metres. During plant operations, these tanks are filled with a mixture of organic waste and water in order to generate the process by-products – these being biogas and compost. The digestion tanks are equipped with state-of-the-art mixing technology which uses part of the biogas extracted from the tanks and compressing it to high pressures by means of water-cooled industrial gas compressors. The compressed biogas in turn flows through a series of pipes (lances) installed within the tank to agitate the waste-water slurry thereby preventing any sediment formation within the tank. The lances, which are mainly one inch stainless steel pipes mounted onto a central stainless steel, 700mm diameter supporting column, were delivered to site in 12 and 6 metre lengths. These had to be meticulously welded together onsite through rigorous TIG welding procedures. The now 18 metre long stainless steel gas pipes had to be lifted in a delicate tandem-lift operation until the pipes were brought to a vertical position thereby fit to be lowered into the digesters tanks from a 2 meter wide opening atop each of the tanks. The gas lances affixed to the central column were then made to rest onto a stainless steel footing (or chair) which had been chemically anchored to the tanks high-grade concrete foundation slab. Ensuring precise vertical alignment of the entire stainless steel assembly was no mean feat. Subsequently, a stainless steel gas manifold was lifted to the top of each tank, with each gas lance connected to the manifold by means of flexible pipe connections.