Managing the metropolis: Innovation, information technology and smart systems are helping New York face the challenges of urban mobility and energy supply which comes with urbanisation. — Tan Cheng Li/The Star

New York City, a global hub for commerce, industry and tourism, has to run like a well-oiled machine. To meet the ever-growing need for better transit, cleaner energy and more efficient public services, the city turns to the cutting-edge automation technologies of Siemens Industry.

JUST over 11 years ago, Ground Zero was a smoking pile of rubble and human remains. On a recent spring day, it was a place of quiet serenity amidst the bustle of New York City. An expanse of trees and water has taken over the area to form the National September 11 Memorial and Museum.

The park is not only a shrine to the 2,983 victims of terrorism but is now also Manhattan’s newest tourist attraction. A grove of oaks open up to the site’s centrepiece: two enormous square sunken pools, which sit where the two towers of the World Trade Centre used to stand. Bronze plaques engraved with the names of those who had perished framed the pools. In each one, water pours over smooth granite walls into a flat basin before flowing into a void to be recirculated.

The cascades provide a soothing acoustic backdrop to the tranquil, reflective surface of the water in the centre of the pools. However, visitors would not be aware of the huge undertaking that goes into keeping the water in each pool flowing and sparkling clear everyday through New York City’s four seasons.

“People will be visiting the memorial every day of the year, so we have to ensure that the reflective and acoustic properties of the pools are the same no matter what the weather or time of day or year,” said Scott Johnston, a co-owner of Delta Fountains, which was engaged to build and operate the pools, in a press statement.

Keeping the pools running smoothly year-round is no small feat as they need massive plumbing, pumps, filters, water chemicals and precision controls. The operating complexities require a master control system with a sophisticated architecture and onboard central processing units. To do the job, Delta Fountains chose to work with Siemens Industry to obtain the best hardware and software for the project.

Their solution was the Siemens Simatic S7-300 master controller that provides local control for the motorised pumps that keep each pool’s water moving at 135,000 litres per minute and filtered at 27,000 litres per minute.

Variable frequency drives (VFDs) were attached to each pump so that engineers can have more precise control over water flow and pressure rates to help maintain the pool water’s consistency whether falling over weirs or in the reflective centre.

With the master controller, the engineers can take real-time inputs from sensors just about everywhere in the pools and plumbing that measure temperature, pressure, chemistry, wind and much more, then use the data to automate the controls and keep the water and systems in balance.

Delta Fountains co-owner and president Joe Petry noted that to help ensure a consistent visitor experience, the weirs along the top of the granite walls are all mechanically adjustable horizontally and vertically to within a sixteenth of an inch (1.5mm).

“This allows us to counter-balance the angle and fall of the water against any expansion in the concrete walls due to a rise or fall in the outdoor temperature,” he said in a statement.

In addition to providing precision flow control, the VFDs also reduce energy consumption and carbon emissions over time because they can continuously drive the 16 pump motors in each pool at optimal speeds. This also saves on motor wear and tear, ensuring a sustainable solution while reducing maintenance costs.

The Siemens automation and control components are based on the Totally Integrated Automation, which enables adaptability and flexibility of technology solutions. Petry and Johnston both said that without the Siemens solution, their technicians would not have anywhere near the degree of precision control that they do. “For example, the Siemens system can test-sample the water every five seconds and adjust the bromine levels to keep a constant pH,” explained Petry. “Manual sampling, in practical terms, could only sample the water four or five times a day. Even then the readings would not be as precise, nor would the response to an abnormal pH level be as fast.”

What’s more, because the automation solution allows day-to-day operations to be controlled remotely from 1,600km away at their home base in Jacksonville, Florida, Delta Fountain engineers avoid the additional costs of living in New York.

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