The Greater Vancouver Sewerage & Drainage District (GVS&DD) is a major regional wastewater agency serving Vancouver, British Columbia and surrounding municipalities. In the late 1980’s it was mandated to upgrade its largest treatment plant from primary treatment to secondary treatment. From 1990 until the present the GVS&DD has engaged in Predesign, Design, Construction and Commissioning of the Annacis Island WWTP Secondary Upgrade. The size of the facility and the fact that no secondary treatment components were previously in place combined to make the upgrade a very large project valued at nearly $470 million CDN. This paper describes the major project components of the liquid stream process improvements. In addition to the major biological treatment components, other aspects of the project are described including, odour management, influent pumping, and primary treatment upgrades.