Improved Automated Control of Sewer Interception: City of Montreal – 20 Years of Experience in Innovative Real Time Control Technologies for Better CSO Control

Written by Alain Charron, Stephane Gagnon, Nathalie Laforte and Dao Dang Trieu Duong

IWA World Water Exhibition – September 19-24, 2010

In the mid-eighties, the City of Montreal began the construction of two new sewer interceptor tunnels along the north and south shores of the island of Montreal. 

They were to be the main branches of their interception system, with flow control structures that regulate flows from their combined sewers and conveys all of its wastewater to the treatment plant. For 15 years, the City of Montreal has been operating modulating gates at the flow control structures with real time control (RTC) and more specifically, by applying simple local reactive control rules. In 2000, the City investigated options to improve the automation of their system. They specifically looked at and decided to have their system evolve from a simple local reactive control RTC system to a system-wide and centralized decision-making system. The main additions are the use of rainfall forecasting, better monitoring of flow conditions, on line model calculations and optimization processes to coordinate the management of all the flow control structures. The approach is an evolved operation strategy to make better use of and maximize the available conveyance and storage capacities. The new system was implemented completely in 2004, and it has been in operation for the last four years. Some improvements of this system have also been made in the last year, with their completion scheduled for 2010-2011.  Over this twenty year period, the city has gained valuable experience in operating and maintaining gates, actuators, and instruments in their sewer networks, and has demonstrated the reliability and efficiency of the technologies necessary for the use of RTC and for the operation of their collection system.

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