Estimated to cost about $40 million, the 30-month project will add 37,500 cubic metres a day (cm/d) of new capacity. The scope of works for phase 6 includes the installation of a new treatment unit, for use with an activated sludge process; demolition of certain facilities built under the first phase; relocation of a pipe rack; new inlet works; construction of a pumping station and a substation; and related civil, mechanical and electrical works. The consultant is the UK's Halcrow Group

The local affiliate of Belgium's Six Construct and the UK's Paterson Candy International carried out the third, fourth and fifth-phase expansions of the plant. Work on the AED 80 million ($21.8 million) phase 5 contract started in mid-1999, and involved the addition of 30,000 cm/d of new treatment capacity. Works included the construction of three aerated tanks and four settlement tanks (MEED 7:5:99).