How river water valves saved New York's subway

River water valves played a vital role in saving the NY subway.

Growing up in New York City and watching the Twin Towers being built in the early 1970s, I am always tearful on September 11th. This day, twenty-two years ago, I lost two friends.

I played football with Tommy McCann, a New York City Fire Department firefighter, who like many of his fellow first responders, died heroically rushing in to save occupants as the Twin Towers collapsed on top of them.

Bob Twomey and I enjoyed talking American Civil War history as we worked together at a Brooklyn sugar refinery, before he left to become a trader for a financial firm located at the World Trade Center. He was having breakfast at Windows on the World restaurant on top of the North Tower when the first hijacked plane crashed into the building.

Both men are honoured at the 9/11 Memorial & Museum in NYC and at the small memorial park in downtown Napa, California, where I currently live.

When I visited the NY museum several years ago, I learned there exists a lesser-known tale of heroism beneath the Twin Towers, involving a subterranean network of river water valves that played a vital role in protecting the city's subway system. As reported by the 9/11 Memorial & Museum, these 8,000kg (17,800 pound) motorised valves were installed in 1993 as part of an upgrade to the World Trade Center's heating, ventilation and air conditioning, forming a crucial part of the building's infrastructure.

"The engineers' heroic actions ensured that the subway tunnels remained dry, preventing further disaster."

Jim Lauria, Mazzei Injector Company

Tasked with regulating the flow of water from the Hudson River to cool the massive air-conditioning system that kept the Towers comfortable year-round, these valves were designed with the foresight to be closed manually for maintenance or in the event of an emergency. As the Twin Towers crumbled in the aftermath of the terrorist attacks, the immediate concern was the risk of flooding the underground infrastructure, including the subway system that served millions of New Yorkers daily.

Amid the chaos and destruction, a group of dedicated engineers recognised the significance of these river water valves. With incredible bravery and determination, they ventured into the unstable wreckage, navigating the treacherous terrain to locate and close these valves manually.

The engineers' heroic actions ensured that the subway tunnels remained dry, preventing further disaster and allowing for a quicker recovery and reopening of the transit system. These valves may have been just a small part of a larger system, but on that day, they played an outsized role in preserving the city's essential transit infrastructure.

The story makes me proud to be an engineer and water professional, and is a testament to the importance of both infrastructure design and the individuals who safeguard it.

Tommy McCann and Bob Twomey are remembered at the memorial park in Napa

Jim Lauria is a writer, chemical engineer and leader in the field of wastewater treatment. He is vice president of sales and marketing at Mazzei Injector Company and his LinkedIn blog is called To Know Water Is To Love Water.