Ontario, Canada's drinking water regulation (part of the country's Safe Drinking Water Act) was enacted to ensure that water intended for human consumption is free of disease-causing organisms or unsafe concentrations of toxic chemicals or radioactive substances. The regulation also stipulates that drinking water should be aesthetically acceptable and palatable—taste, odor, turbidity, and color are key control parameters.

All municipal water suppliers must provide quarterly reports on water quality, including a description of the treatment process, measures taken to comply with the regulation, and a summary of sampling results.

As a water supplier to approximately 230,000 customers in the cities of Windsor, LaSalle, and Techumseh, Windsor Utilities Commission (Windsor, Ontario, Canada) knew it was providing water that exceeded regulatory requirements. The utility also knew the plant floor held critical information that could be useful to further optimize the treatment process.

Windsor Utilities' director of water quality and production, Saad Jasim, says, "We knew our water quality exceeded government regulations. However, we needed a more efficient means of collecting the information and generating the required reports. We felt a manufacturing execution system (MES) would permit capturing accurate, real-time process data, share it with others in the company, and use the trend reports to help managers make real-time decisions on process changes."

When turning on the tap to get a drink, most people don't think much about what's required to ensure safe, odor free, good-tasting drinking water.

In 1994, Windsor Utilities Commission replaced its 1920's era treatment facility with its A. H. Weeks 227-million liter per day treatment facility.

Water from the Detroit River enters the Weeks facility and is mixed with ozone purified air and aluminum sulfate (alum) polymers. Water then moves through the coagulation and flocculation processes and fine suspended particles, not removed by settling, are removed by downward passage through a filter consisting of a bed of graduated gravel, sand, and anthracite.

Water first passes through a layer of coarse anthracite coal particles where the majority of suspended particles are removed. Next a layer of fine sand acts as a "polishing" filter and removes virtually all-remaining suspended matter.

Lastly, fluoride and a small amount of chlorine are added to kill any remaining bacteria. The result is sparkling clear, odorless water.

Plant floor devices used to automate and control the A. H. Weeks facility generate volumes of data about temperature, level, turbidity, pressure, ozone, chlorine, and alum concentrations, as well as other water-treatment-related data.

Operators manage the Weeks treatment facility using redundant Rockwell Software RSView operator interface terminals, Allen-Bradley PLC-5 and SLC-500 controllers, and a ControlLogix gateway.

"Providing operators and managers with access to real-time data helped us identify where process problems and inefficiencies were occurring and thus improve operational performance," says Jasim. "However, prior to implementing MES, we manually developed paper reports by writing down 15-20 sets of data each hour. By implementing a centralized information database we have been able to decrease paperwork and improve our ability to analyze and improve the water treatment process."

Working with Rockwell Automation Windsor Utilities used Rockwell's RSSql transaction manager, Microsoft's SQL Server database, and RSBizWare Historian to extend its control system to include new functionalities and create the MES architecture.

RSSql collects data from plant-floor devices and populates the SQL database. During installation, RSBizWare creates tables designed to meet common, time-series data-analysis requirements, so users may begin working with the historian with minimal set-up and training.

The historian also allows users to turn masses of production data into useful information, without requiring detailed knowledge of database technology. The results can be added to an existing RSView HMI program, extending an operators ability to view and analyze plant floor information.

"MES makes it easy for us to comply with the regulations because we can access and report on the required information," says Jasim. "Without this system, we would have been unable to prove to government regulators we were in compliance—a problem that could have resulted in fines, unnecessary 'boil water' advisories, and unhappy customers."

Windsor Utilities has already begun to re-engineer upgrades to its second treatment plant—including the addition of ozone treatment—to improve the treatment process and match the capabilities of the new facility. Eventually, Windsor Utilities plans to integrate data from both treatment plants into one MES database.

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