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Post at 30 Aug 2017

Background

Detroit’s Wastewater Treatment Plant is one of the largest in the United States, serving more than a third of Michigan’s population. The plant’s size and complexity are rooted in a convergence of three major forces: industry, water and weather.

The city’s population exploded in the 1920s with the advent of automobile production. The newly minted “Motor City” continued to grow, ranking among America’s top 10 major metropolises for the rest of the 20th century.

The city is also synonymous with water: Its name comes from the river that runs through it, which French explorers called Rivière du Détroit and translates to “River of the Strait.” That strait – today’s Detroit River – leads to Lake Erie and the rest of the Great Lakes.

Like many of America’s urban waterways, the Detroit River and its tributaries were once badly polluted by raw sewage and storm water runoff . Construction of the city’s treatment plant in 1939 and a major series of expansions and upgrades over the next 50 years signifi cantly improved effl uent water quality.

But a major problem remained: Heavy rains and snow melts sometimes overloaded the treatment plant, allowing polluted storm water to run into the Detroit River and the connecting Rouge River. The Rouge – which lies at the center of a large watershed in the metro Detroit area – was so polluted by chemically laden runoff that the river caught fire in 1969.

Challenge

Each combined sewer overfl ow facility diff ers somewhat in size and design, but all basically apply the same treatment process: retaining the overfl ow, mechanically screening out solids, and disinfecting the water with sodium hypochlorite (bleach). Basins also have equipment that operators use to monitor fl ow rate and volume, collect samples, remove residual water from the basins, and clean them after a wet-weather event.

Despite their similar functions, the basins’ process control instruments vary widely. That’s partly because the basins were constructed over the course of the last three decades at a time when automated control technology was quickly evolving. Another factor: The comparatively slow pace of public works projects was also an issue. From concept to commissioning, each basin required several years to complete because of strict municipal codes requiring public planning, open bidding and offi cial oversight. Meanwhile, federal and state water quality standards were becoming more stringent, adding another layer of complexity.

“Through the years, we’ve had to update the process control systems at various basins to comply with changing regulations,” explained Anil Gosine, Process Control System Administrator for the Detroit Water and Sewerage Department (DWSD). The result is a “myriad of diff erent process control systems at diff erent locations. At one basin, we have process control equipment from four diff erent vendors.”

Solutions

Rockwell Automation PlantPAx Process Automation System, which incorporated:

• Allen-Bradley ControlLogix programmable automation controllers to provide advanced processing capabilities, while continuously collecting critical operating data

• Tightly integrated HMI using FactoryTalk View SE to allow instant access to realtime information and operational trends

• PlantPAx Library, which includes the basic building blocks for the system, including HMI faceplates customized for specifi c plant roles, in addition to rich info-laden icons and full documentation

• Water Wastewater Accelerator toolkit helps rapidly deploy a project as it includes procurement specifi cations, a quick start guide, and sample controller and HMI confi gurations for common applications, such as lift stations, dosing pumps, head works and solids handling

Results

Reduced deployment time

• Resulted in a 50 percent reduction in design time, contract oversight, and post-contract documentation and support

• Provided process control with advanced networking and diagnostic capabilities

• Increased access to process data for better preventive and predictive maintenance

 

Reduced Engineering Hours and Costs

• Saved estimated $120,000 in confi guration and systems integration time

• Saved $90,000 in factory-acceptance testing and startup/commissioning

Category: Rockwell Software