Coquitlam Water Treatment Plant

The project involved the replacement of a gaseous chlorine system with a liquid bulk hypochlorite system at the Coquitlam Water Treatment Plant (WTP), one of two treatment plants in the Metro Vancouver Region. A critical step in the water treatment process, the chlorine disinfection process was continuously operated throughout this conversion.


  • Coquitlam, British Columbia, Canada

Project Value

  • $6.5 Million

Project Status

  • Complete


Located within the protected Coquitlam Watershed, Metro Vancouver’s Coquitlam Water Treatment Plant is one of two plants providing reliable safe drinking water for over 2.5 million residents in the region.

WSP worked with Metro Vancouver to replace the existing gas chlorination system, an essential step in the disinfection process, with a new liquid chlorine system to improve reliability and safety. This conversion was completed by employing a temporary liquid system prior to decommissioning the gaseous system. The transition between the three systems (gaseous, temporary liquid, and permanent liquid) without service interruption carried unique challenges that required significant coordination and planning amongst Engineers, Contractors, Operators, Programmers, Electricians, Commissioning Specialists, and Safety Officers.

Plant Ultimate Capacity
1,200 ML/day 1,200 ML/day
Number of feeders
6 6
Volume of hypochlorite storage
120,000 L 120,000 L
Number of storage tanks
4 4
Storage Tank Height
4 m 4 m
Potable water created on an average day
600 ML 600 ML


  • Conversion from gaseous chlorine to liquid bulk hypochlorite, improving reliability and safety at the WTP.
  • Construction with zero service interruptions at one of two critical WTPs serving over 2.5 million people.
  • Retrofit within existing building envelope, minimizing demolition, construction, and cost.
  • Demolition and construction occurred during operation at the active plant.
img-Coquitlam Water Treatment Plant Hypochlorite Conversion Project

New hypochlorite feeders at the Metro Vancouver, Coquitlam Water Treatment Plant.

Project Relevance

  • Project completed in collaboration and coordination with large inter-disciplinary groups and operations staff to ensure all perspectives were present, resulting in a seamless and safe construction phase.
  • Creation of “Maintenance of Plant Operations” procedures and checklists (MOPOs), to ensure continuous disinfection capabilities at the plant, providing safe clean drinking water to the service population.