August 16, 2022 — Flooding and Heatwaves: Infrastructure Challenges in the Face of Extreme Weather

Good morning, Chairs Kagan, Brooks-Powers, and Gennaro and Members of the committees on Transportation and Infrastructure, Resiliency and Waterfronts, and Environmental Protection. I am Rohit T. Aggarwala, the Commissioner of the New York City Department of Environmental Protection (DEP) and the City’s Chief Climate Officer, in which capacity I oversee the Mayor’s Office of Climate and Environmental Justice (MOCEJ). Thank you for the opportunity to speak today about the challenges the city’s infrastructure faces from extreme weather events. I am joined today by Chief Operating Officer at DEP Vincent Sapienza, Senior Program Manager for Infrastructure at MOCEJ Erika Jozwiak, and my colleagues at DOT.

I’d like to start with a story. The main contours of it you know, but I think the specifics are highly instructive, so I’ll ask you to bear with me.

Hurricane Henri arrived in New York on August 21, 2021. Henri set a record for the most intense rain event in the city’s history, at 1.94 inches between 11pm and 12 midnight. Previously, the most intense rainstorm had been 1.76, in 2004. Prior to that, the record had been 1.58 inches per hour, in 1967. The records for hourly rainfall go back to 1943. Of course, as with all storms but particularly the violent, intense storms like Henri, rainfall was not uniform across the city.

New York’s sewers are not designed to handle 1.94 inches of rainfall in one hour. It was not necessary. Prior to the 1970s, sewer standards were set by each borough president, which is one reason that unfortunately some parts of the city, especially Queens, have many sewers that are designed for only 1.5 inches or rain, or less. Today, our standard is 1.75 inches per hour, which we are currently re-evaluating. When that amount of rain occurs, more water is attempting to enter the sewer than can fit inside of it. This increases the pressure on the sewer walls. A rain event like Henri is, quite literally, a pressure-test of the system. And what a pressure test does is find weaknesses, and turn them into leaks.

Underneath Radcliffe Avenue, the pressure test of Henri was likely having its first impact. Back in 1916, the Bronx Borough President had embraced a new technology for sewer construction, called Interlocking Vitrified Block. The sewer under Radcliffe Avenue was constructed of this material. The sewer had done its job well for more than a hundred years. But in retrospect, it seems likely that this particular design begins to get weakened when it is pressurized and water reaches the top of the sewer.

As we all know, only a few days later, Hurricane Ida shattered Henri’s record, with 3.15 inches falling in Central Park between 9 and 10 pm. Ida’s rainfall was most intense—up to 3.75 inches per hour—in several parts of the city least able to handle it, especially the Bronx and Queens. Of course, the greatest impact of Ida was that 13 New Yorkers lost their lives. But, for our sewer infrastructure, it was another pressure test—with even greater levels of pressure than Henri had used.

During and the morning after Ida, of course, we saw the visible impacts of climate change on our infrastructure. Roads flooded, subways flooded, equipment and possessions destroyed. In our sewers, we began to see the impact of those two pressure-tests. DEP reports sinkholes in the Mayor’s Management Report. From FY 2018 to FY 2021, the number of sinkholes—which includes everything from a mild depression in the roadway to what we saw on Radcliffe Avenue—had been declining, from 3,769 to 2,839. In FY22, the number shot up, to 3,920.

One of those was on Radcliffe Avenue. Weakened by the pressure tests of the two storms, the roof of the sewer had failed, and soil from above was seeping in and being washed away. Over time, the failure expanded to the point that a large amount of soil from above was falling in. The pressure of that failing soil, of course, also widened the hole in the roof of the sewer. DEP received a call that there was a street cave in at 1640 Radcliff Avenue. DEP responded quickly, alongside other city agencies. Happily no one was injured. DEP’s response was appropriate. The collapsed length of sewer was repaired with 152-linear feet of reinforced concrete pipe. On either side of the collapse, the sewer was inspected. There was no visible weakening to the sewer on either side.

This summer, of course, the rains came again. Providing another pair of pressure tests to this sewer in the Bronx. On July 16, 2022, Morris Park experienced a storm which had a maximum rate of 1.88 inches in one hour. Then on morning of July 18, another storm that had a maximum of 1.64 in/hr. This July 18 storm highlights just how widely rainfall can vary across the city—Central Park received a total of 1.01 inches of rain, but the Fordham weather station in the Bronx recorded a total of 3.35 inches through the night.

These two pressure tests found, and expanded, another weakness in the interlocking vitrified block sewer, just down the street. DEP received notice from the Fire Department about a “street collapse” at about 4pm that day at 1613 Radcliffe Avenue. It seems that someone had called it into 911, rather than 311, in which case it would have gone first to the Department of Transportation. A DEP crew was onsite in less than an hour, and quickly was also accompanied by Con Edison, DOT, NYCEM, FDNY, and NYPD. The reality is that once a cave in is underway, there is little that can be done to stop it except shut off the flow of water and wait. DEP engineers had sent a television scope down through a nearby manhole to see what was going on, and realized the sinkhole was going to get bigger before it stopped. While DEP cleared and secured the area, NYPD tow trucks moved cars away from the site—except, of course, one unfortunate white van that was too close to the edge to reach safely.

Ultimately, the sinkhole grew to 15 feet wide, by 58 feet long by 20 feet deep. The void also undermined a water main, and so water service to nearby homes was off for several hours until a repair was made. As we do whenever there is a major water main break, DEP established two water on the go stations to provide water to local residents while their water was out. Water was restored within a few hours.

All of the volume of soil from the sinkhole entered into the broken sewer, thereby blocking much of the normal wastewater flow. To avoid a major backup of sewage into homes, DEP staff quickly deployed large pumps to convey sewage around the broken pipe.

Over the course of the next five days, DEP staff and its contractors began removing soil from the sewer, which had been carried more than 200 feet downstream by the flow of sewage. Crews worked around the clock.

Unfortunately, while that work was ongoing, a cloudburst on July 21^st—with a maximum intensity of 1.6 inches per hour—generated runoff that exceeded the combined capacity of the partially-blocked sewer and the pumps that DEP had installed. Several homes on the block got water in their basements. DEP staff handed out claim forms to homeowners so that they can apply for compensation for damages. We prioritized getting our engineering report to the Comptroller’s office, which has now been delivered, so that the Comptroller should now be able to process claims.

DEP ultimately replaced 157 feet of sewer that was impacted by the break and the cleanout.

The story of the Radcliff Avenue sinkhole demonstrates a number of key points about the intersection of climate change and infrastructure.

The first is that the impacts we are dealing with are exactly what has long been predicted. In 2000, the first report by NASA’s Goddard Center described the likely effects of climate change on New York City. These were repeated in Mayor Bloomberg’s PlaNYC in 2006. We knew then what was coming: more intense storms like Ida; more hurricanes, like Sandy; more heatwaves like the ones we have experienced all summer, and those that have set records this year in Europe, the Pacific Northwest, Texas, and South Asia. Drought, like the hundred-year drought Europe is enduring and the thousand-year drought that the drying up the Colorado River. Recently, New York State declared a drought watch for all of New York State outside of New York City and Westchester County. Thankfully, our massive reservoir system provides us greater ability to withstand dry periods like this summer—which, despite some violent short storms, is well below average rainfall. But it is entirely likely that at some point in the coming years and decades that New York City will face a serious drought, and that such likelihood is greater as a result of climate change.

All of this we knew was coming. Of course, when you’re in a hole, the first thing to do is stop digging, which is why it is so important that we reduce our greenhouse gas emissions. As you know, that is a priority of the Adams Administration, and we are working hard to implement Local Law 97 and congestion pricing; expand electric vehicles; and undertake new projects such as NYCHA’s recently-announced heat pump initiative, the Department of Sanitation’s recent announcement about universal organics collection in Queens, and the Department of City Planning’s Zero Carbon Zoning initiative.

And we are working hard to adapt to climate change, using a multi-layered approach. This means that we are focused on establishing multiple layers of resiliency at different scales across the city to respond to the multiple hazards. As we have seen, all these layers of support, such as green infrastructure, grid redundancy, coastal protection projects, emergency communication, Building Code and Zoning Resolution, and flood insurance are critical components of our system, and our work to develop and strengthen our infrastructure in response to climate change must move forward with urgency, funding, and partnership with government and individuals. We will do all this with a fierce commitment to environmental justice, and prioritizing the most vulnerable communities.

I’ll highlight two programs at my agencies. At DEP we have invested dramatically in green infrastructure to help keep rainwater out of our sewers—with 11,000 rain gardens around the city, a network of ponds that capture stormwater called bluebelts, and a new regulation that requires private developers to design their properties to retain more stormwater onsite through porous pavement, green or blue roofs, or other approaches. With MOCEJ in the lead, the city has also issued Climate Resiliency Design Guidelines, updated in May 2022, to ensure that new public infrastructure can withstand the more extreme flooding and other weather events that we expect in the future. Anytime the city builds a library, school, pumping station, bridge, and more it should be designed with changing future conditions in mind.

And I’ll move on by reiterating that extreme heat—not water—is the deadliest climate hazard in New York City as well as in the United States. Each summer an estimated 370 New Yorkers die prematurely because of heat exposure. The lack of access to affordable home air conditioning is a significant risk factor. The impacts of extreme heat are not felt equally—Black, low-income New Yorkers face the greatest risk to extreme heat because of social and economic disparities stemming from racist housing policies such a redlining and unequal access to health care. Since 2017, the City has invested over $100M towards Cool Neighborhoods, resulting in over 11,700 trees being planted in the highest heat vulnerable neighborhoods, over 11 million square feet of cool rooftops, and the launch of two programs aimed at strengthening community resilience through partnerships with community based organizations and community health workers.

The second thing Radcliffe Avenue demonstrates is that there are still going to be climate change impacts that take us by surprise. The sinkhole on Radcliffe Avenue would not have been easy to predict given what we know and the tools we currently have. That sewer’s particular combination of materials and design was not appropriate to a world in which the sewer would be full and pressurized on a regular basis—which is what the last twelve month’s many extreme storms have done. As a result, DEP is now planning to rebuild that stretch of sewer—3,300 feet of it—by lining it with a new cured-in-place materials. That essentially means we’ll be putting a new liner inside the existing sewer to make it stronger. Work will begin in a few months on the new line. We are also going to be looking through our records—thousands of as-built drawings—to identify where there are other locations where the same design was used, and which can reasonably be expected to be weakened as well. At the moment, we don’t think this design was used very long, and we haven’t found another location that has it.

We have certainly been thinking about how we might have predicted that this particular sewer design would fail. Generally speaking, sinkholes (like water main breaks) occur fairly randomly, so they are hard to predict. Only when we can start to see a pattern can we make any predictions. Now we know we have one type of sewer was weak, and we may be able to consider what indicators might tell us in advance that we have further risk.

It’s also important to note that the sewer did not fail because it is old. We rely on lots of old infrastructure—the Brooklyn Bridge is nearly 140 years old, for example. Sewers, particularly, are very long-lived assets; the city of Rome still has a few in service that are more than 2,000 years old. There are lots of other sewers—many much older than Radcliffe Avenue’s—that we expect are going to have no structural issues whatsoever under our new normal conditions. So age is not a good indicator of risk.

Finding the weak spots—identifying where climate change causes the most acute risks to our infrastructure—will require learning, and only some of it can be predicted well in advance. We saw this also during Hurricane Sandy: while the flooding was predicted, the regional impacts on gasoline supplies was not. No one had noticed that refineries are all coastal, so that when a coastal storm happens, all of the refineries are out of service at once. After Sandy, of course, we’ve now done a lot more planning around climate change and supply chains. But it was a surprise lesson, just as Radcliffe Avenue was.

The third thing Radcliffe Avenue reminds us is that we will not be able to change our infrastructure as fast as the climate is changing. Adjusting to our new climate will take time, lots of money, difficult tradeoffs and potential controversy. We will have to give up things we like. We wil have to put up with inconvenience. While it won’t be easy, these projects are necessary to ensure that our children and grandchildren can enjoy the gifts of living in New York City. Making these investments is a delicate process that will require all hands on deck and a shared understanding of the challenges we face.

We are working hard to speed up the City’s ability to change our infrastructure. First Deputy Mayor Lorraine Grillo has, as you know, an interagency project underway to streamline projects, with the participation of the Comptroller, the private sector, and labor. At DEP I have initiated an internal effort to identify and correct what slows our contracting and procurement processes. But the reality is that heavy construction takes time, and public engagement takes time, and sound planning takes time. So even if we operated under pandemic-like emergency processes, it would still take a long time to change our infrastructure.

And it will cost money. Infrastructure is expensive. We look forward to partnering with the City Council to ensure New York City receives its fair share of funds from the federal government and from the state. However, we should remember that New York City pays for the vast majority of its own infrastructure investments. For water and sewer infrastructure, that is the water rate. Whatever level of protection we want, we must be willing to pay for it.

Finally, the failures on Radcliffe Avenue are a reminder that our new climate will require that New Yorkers play a role individually. For centuries, New York City has enjoyed a very mild climate. Aside from a few major hurricanes and some blizzards, New York does not have a history of earthquakes and wildfires like the west coast, tornados like the Midwest, or the mudslides and hurricanes that affect of the southeast and the Caribbean. New Yorkers generally assume that our infrastructure will work, regardless of the weather.

Our new climate is not as generous. Extreme storms like Ida gain intensity quickly; we often can’t predict a cloudburst even an hour in advance. And because we cannot change our infrastructure as quickly as the climate is changing, New Yorkers cannot be as confident as before that our infrastructure will function as reliably as we expect in extreme conditions.

We need New Yorkers to take steps to protect themselves. Pay attention to weather reports. Plan to protect your property. Don’t take risks, like going out in a violent storm. Don’t put others in danger; if you don’t think it’s safe to be outside, don’t decide that it is safe for a deliverista or a police officer. Don’t keep valuables in your basement. Get flood insurance.

Since Ida, the City has taken a number of steps to help New Yorkers protect themselves in these new conditions. Our colleagues at NYCEM have enhanced our Notify NYC system, to let people know when cloudbursts are coming. Notifications are available in 14 languages, and messaging has been updated since Ida to focus on those living in basement apartments to alert them to move to higher ground when flash flooding is likely. More than a million New Yorkers are signed up, but we know we are not thoroughly reaching all communities in the City, especially those least connected to the government. We are working with organizations that are trusted by those communities to see how they can relay messages of warning.

Similarly, we recently launched Rainfall Ready, an effort that is very much short-term but is designed to help New Yorkers prevent death and reduce destruction from flooding. DEP issued a new map, available online, that identifies those properties around the City that we believe to be most susceptible to flooding. For the absolutely most susceptible properties, DEP has been offering inflatable water barriers to protect their properties. This is not a long-term solution; they require the homeowner to fill them up and install them, and take them down and store them after a rain event. But it’s the kind of thing that both raises awareness and could reduce damage. We started our giveaway program just this past weekend.

I’ll close here. There is so much more I could discuss: DEP’s new data-driven approach to scheduled catch basin cleaning; the FloodNet sensor program that will install 500 sensors over the next 5 years to provide real-time, street-level flood information; the potential for funding from the Bipartisan Infrastructure Law, the Inflation Reduction Act, and the potential New York State Environmental Bond Act. DEP is beginning to model how climate change will impact our water supply. The US Army Corps of Engineers just released their preferred option for how to protect all of New York harbor from coastal inundation. Every week I convene the climate leads from more than 15 agencies to update each other on progress and provide assistance. There is a lot we are doing.

I want to thank the Council again for the opportunity to speak today and for your attention to this critical issue. The challenges that climate change is bringing cannot be avoided. I am confident that we can get through them if we work together, and do so wisely, and thoughtfully, but with the urgency that this climate emergency requires.

That is where I am particularly hopeful with this Council. We will be looking to you to advocate for this work in your communities, using your influence to lead your communities when we must accept change, sacrifices, and inconveniences necessary to protect ourselves and our children. I appreciate the Council’s ongoing partnership in all that we do, and I look forward to continuing to work with you on this critical issue. My colleagues and I are happy to answer any questions that you have. I turn now to my colleagues at DOT, who will read their testimony.