The problems began when an oil refinery injected a hydrochloric acid and ammonia solution into its cogeneration unit heat recovery steam generator boiler during a cleaning procedure. The plan was to rinse the solution and then neutralize the residual acid but the cleaning operation had to be stopped. A second attempt also went wrong when the drainage valves were accidentally left open allowing the acid to flow into the clean water sewer and eventually the St. Clair River. The oil company was found guilty of discharging low pH waste water into the River and fined $406K [Imperial Oil Ltd., Govt. Press Release, Jan. 30, 2019].