OWASA is currently constructing a $40 million Phase 1 expansion for the Mason Farm WWTP. Phase 1 of plant expansion includes the following: additional reactor cells, final aeration cells, secondary clarifier, new denitrification filters, new post aeration and ultraviolet disinfection facilities are being constructed. Other important changes include contact treatment of excess wet weather peak flows to avoid unnecessary new construction. Changes to the primary sludge fermenter, particularly to reduce the solids returned to the biological process, also avoids unnecessary expansion of the aeration tanks. The existing jet aeration system will be maintained. However, studies and field tests carried out during the design phase determined that the appropriate alpha for this aeration device is less than 65 percent of the value advertised by jet aeration manufacturers. This has a tremendous impact on the expected performance of this aeration system.