AWWA ACE95047

Intensive pilot plant experimentation was embarked on in 1993 as part of a study to upgrade the Glenmore Water Treatment Plant in Calgary. The original structures to this large conventional plant were built in 1933 and the adequacy of its performance had become increasingly questionable in recent years. Certain design features, such as lack of filter to waste, high sedimentation overflow rate, hydraulic chemical mixing, hydraulic flocculation and low filter submergence, imposed serious operational limitations. Modern water quality goals embodying growing public expectations and current industry standards could not always be met. Six major issues were recognized as central to any upgrading efforts: particulate removal capability; disinfection efficacy and disinfection byproducts; taste and odor problems; distribution system quality (ionic balancing and disinfection); aluminum levels; and waste residuals handling. In addition to electrical and mechanical refurbishment, it appeared that an adequate upgrade could ultimately require several process modifications, which multiply the permutations of possible upgrade scenarios. Extensive pilot plant experimentation was seen as the method for evaluating the various options and assuring the applicability of each possible combination. This paper highlights the significant dissolved air flotation (DAF) clarification and conventional gravity sedimentation (CGS) coagulation findings and their ramifications on upgrade plans.