The VEAS plant, opened in 1982, was built with eight large process halls (approximately 91 m by 16 m). From 1991 to 1995, 6 of the halls were refurbished to include a process for nitrogen removal. VEAS now wishes to refurbish the remaining 2 halls, PHA5 and PHA6. The work entails demolition of the existing constructions and concrete pools down to the underlying rock structure, removal of the demolition materials and rock mass, rock blasting and concrete work including molding/casting of new, deeper pools and assembly of corresponding equipment.