The Iona Island Waste Water Treatment Plant was built in the early 1960s and had a self sufficient cogeneration system. Reciprocating generating sets, operating on digester or natural gas, powered the influent pumps, and some other plant electrical loads. Hot water from the engines heats the digester vessels and the buildings.

By the early 1990s, due to increasing age of the 1950s vintage generating sets, the plant could no longer meet the peak wet weather firm pumping capacity. In late 1996, Ausenco Sandwell was awarded the detailed design of the cogeneration system replacement project. After energy balance and other studies, five 900 kW spark-ignition engine generating sets were selected. Pumping and electrical system studies lead to decisions by the project team to refurbish the influent pumps. A construction staging plan was developed to maintain the required (summer) pumping capacity while one pump and one generating set at a time were taken out of service to be upgraded or replaced.

 Construction started in early 1998, and the completed, commissioned equipment was handed over to the plant in November 1998 - nine months ahead of schedule and under budget. Plant pumping capacity now exceeds required firm volumes, and the electrical system runs in parallel with BC Hydro. In addition, the use of digester gas has been maximised, reducing consumption of natural gas and power.

View the full factsheet here.