The Reason For Recurring Floods In New York City Is A Topic Of Concern

All drainage systems possess inherent limitations, and the maximum capacity of New York City's drainage system is 1.75 inches of rainfall per hour. Regrettably, the recent storm that inundated the region on Friday exceeded this threshold, with over two inches of rainfall between 8 a.m. and 9 a.m., and continued to pour down.

The primary reason for the flooding experienced by New Yorkers across all five boroughs was the limited capacity of the city's network of drains, pipes, and water-treatment plants. Experts predict that this will not be the last instance of severe flooding in the city as it struggles to keep up with the pace of climate change.

Commissioner of the New York City Department of Environmental Protection, Rohit Aggarwala, stated that "this changing weather pattern is the result of climate change, and the unfortunate reality is that our climate is changing at a faster rate than our infrastructure can adapt."

The rush-hour deluge on Friday overwhelmed the 7,400 miles of pipes that transport stormwater and sewage beneath the city's hard surfaces to treatment plants or nearby rivers and bays. The resulting runoff inundated the streets, causing flooding that submerged vehicles and infiltrated basements and subway stations in Brooklyn and Queens.The sight of water cascading over roads and sidewalks bore a striking resemblance to the events witnessed in 2021 during the devastating Hurricane Ida, which resulted in the tragic loss of 11 lives in Queens. This particular storm served as a clear indication of the impending dangers, as highlighted by Daniel A. Zarrilli, a distinguished advisor to Columbia University, specializing in climate and sustainability practices.

We find ourselves in uncharted territory, where we are witnessing an alarming increase in the intensity of rainfall events such as this one," stated Mr. Zarrilli, who previously served as a climate policy advisor to the mayor. "Once the capacity of the sewer systems is surpassed, it inevitably leads to these unfortunate backups. When the pipes are unable to cope with the excessive volume, the situation exacerbates."Approximately 60 percent of New York City is equipped with a drainage system that combines storm runoff with sewage within the same pipelines. In instances where the volume of flow exceeds the capacity originally intended for sewage treatment plants, the surplus, consisting of a mixture of rainwater and untreated sewage, is directly discharged into local water bodies such as the Gowanus Canal in Brooklyn, the East River, or Jamaica Bay.

However, as the sewer system becomes overwhelmed, a portion of this untreated wastewater infiltrates the basements of residential and commercial properties throughout the city. This observation has been made by Dave Balkan, the proprietor of Balkan Sewer & Water Main Service, located in the Richmond Hill area of Queens."When the water reaches such a high level, it causes a reverse flow," stated Mr. Balkan. "This is when ordinary individuals experience the unpleasant situation of sewer water bursting out of their drains or basement toilets."

On Friday, Mr. Balkan's company received numerous distressed and disgusted calls from homeowners. He mentioned that he responded to these calls as a gesture of goodwill, but unfortunately, there was nothing he could do for them at that moment.

According to Mr. Balkan, the only option for these homeowners is to wait for the system to clear and for the muck to be pulled back through the pipes. However, he was hesitant to provide an estimate of how long this process would take due to the prolonged duration of the storm.

"This is not the usual occurrence of a sudden storm, as it has been raining consistently throughout the week," he explained. "This is an exceptional event."

Mr. Zarrilli emphasized that addressing the city's increasing storm water issues will necessitate significant investments in infrastructure and innovative solutions.A report released in 2021 by the city, titled "The New Normal," has estimated that the process of recalibrating our sewer systems to handle storms like Ida will require several decades and incur a cost of $100 billion. The report specifically highlighted that the upgrade of the system in Southeast Queens alone amounted to $2 billion.

In the interim, the city has been collaborating with federal officials to establish alternative outlets for excess water, rather than directly channeling it into the sewer system and potentially contaminating waterways. Ben Furnas, formerly the director of the Mayor's Office of Climate and Sustainability and currently serving as the executive director of the 2030 Project at Cornell University, stated that various strategies have been implemented to create storage spaces for water, preventing it from overflowing into creeks or canals. These strategies involve investments in both "gray infrastructure," such as large holding tanks, and "green infrastructure," such as sidewalk gardens that can absorb rainwater.

Franco Montalto, an expert in flooding and engineering, acknowledged the complexity of the problem, attributing it to the outdated nature of our existing infrastructure, which is unable to cope with the increasing demands. He explained that the excess water can either be managed underground or on the surface.

Dr. Montalto cited an initiative in Copenhagen as an example, where officials redesigned streets to temporarily hold water. Specifically, certain intersections were designed to be depressed or sunken, diverting water away from residential areas and allowing it to accumulate at a safe depth for vehicles to pass through. Eventually, the water is directed into parks and other green spaces.Upmanu Lall, an engineer and the director of the Columbia Water Center, expressed his desire for increased installation of pumps within the city's sewer system to effectively manage excess water and prevent overflow occurrences. He emphasized that the current discharge capacity is limited, resulting in a higher risk of internal flooding.

Candace Agonafir, a researcher working alongside Dr. Lall, identified one contributing factor to the devastating flooding during Hurricane Ida as the obstruction of rainwater flow into the sewers caused by the accumulation of debris and trash.

Dr. Agonafir participated in a study that examined flooding in the city by analyzing 311 complaints. The study revealed that infrastructural complaints were indicative of street flooding complaints in a significant number of ZIP codes.

The study further suggested that addressing this issue involves enhancing both the internal and external components of the drainage network. By doing so, it is possible to mitigate some of the physical and economic consequences associated with street flooding in metropolitan areas.