In the early 1990's, due to rapid growth in the Bedford-Sackville area, plans were initiated to again expand and modify the Mill Cove WPCP. In 1994, Porter Dillon Ltd. was retained to provide the engineering design services along with the selection of McAlpine (Atlantic) as construction manager of the project. A partnering team consisting of representatives from Porter Dillon, McAlpine, and Halifax Regional Municipality collaborated on an ongoing basis in order to fulfill the goals of the project. This expansion enables the plant to treat an average daily flow of 7.5 mgpd and peak flows of 16.5 mgpd, and was completed by April 1, 1997 at a total cost of $20 million dollars. The Mill Cove WPCP is the largest municipal secondary treatment facility in Atlantic Canada.

The new expansion design incorporates a number of modifications and specific objectives:

• Due to limited availability of land, a pure oxygen activated sludge process replaces the former conventional A.S. process. A surge/flow equalization tank located under an adjacent parking lot allows storm and peak flows to be retained and pumped to the treatment process during off peak hours. Direct by-passing to Bedford Basin without treatment will not take place. Advanced ultra violet light technology replaces the use of chlorine for disinfection purposes. A high level of odour control is achieved by covering primary and pure oxygen process stages and the addition of a two stage (wet phase/activated carbon) air scrubbing system located in the headworks complex. Building architecture and landscaping design ensures a high degree of compatibility with the surrounding residential and commercial development. A computerized process control system(PLC based) with Trihedral VTS software provides for optimized operations and precise process monitoring.
  
  
• Preservation of the Bedford Basin/Halifax Harbour ecosystem.