AWWA ACE91017

The Greater Vancouver Water District (GVWD) is a wholesale water supplier. Water quality concerns range from acidic raw water and natural ammonia to turbidity and coliform/giardia contamination. These problems prevent the GVWD from complying with Canadian drinking water standards for coliforms, heterotrophic plate count, turbidity, lead, copper, and pH, and iron, at least during the summer, although the GVWD does not exceed the standard for trihalomethanes. Following a detailed investigation of water quality concerns, the GVWD came up with a three phase plan for improving water quality. Phase 1 is a nonfiltration step to reduce turbidity through source interchangeability. This phase would also upgrade the present chlorination facilities, raise the pH, and add ammonia to provide a chloramine residual. Phases 2 and 3 consist of adding filtration plants at two sources. A table shows each water quality concern, the existing problem, and the benefits to be gained from each phase of improvement.