Flooding in Hoboken feels like it never goes away, and in the past few weeks, two intense storms have flooded streets, submerged cars, and destroyed property — and with the occasional hurricanes during this season, it’s time to have a serious conversation about it. Government officials have noticed the storms getting worse, too. In a recent press release, Mayor Ravi Bhalla described the last storm in the summer of 2020, as the most rainfall Hoboken has seen in a decade.
Some Hoboken residents have expressed frustration on social media about the persistent flooding and wondered whether Hoboken’s sewer system is prepared to keep up against growing concerns of climate change and rising global temperatures. Read the interview with Jennifer Gonzalez, Hoboken’s Director of Environmental Services, who answered frequent concerns from residents for Hoboken Girl in August 2020, about the current state of Hoboken’s flooding issue and explained how the city is investing in new flood defense systems.
HG: What influenced the recent two “50-year storms?”
The big difference between past storms and these storms is the intensity of the rainfall. Climate change projections for the northeast show that rainstorms will become more frequent and intense.
You’ll see in some other areas, they’re calling these cloudbursts—very intense rainfall, all of a sudden. These are different from storm events of the past, where an inch of rain fell over several hours. Now we are seeing storms with an inch of rainfall in eight minutes, and storms like this will increase with climate change.
HG: What is Hoboken’s flood infrastructure built on, and how does our location affect flooding?
Hoboken was largely once tidal marsh, and the tidal march reflects the floodplain as it exists today in Hoboken. If you look at the majority of the city that’s located in the floodplain, a lot of it is in the area that was filled in around the turn of the 20th century for development.
Southwestern Hoboken sits at sea level, and that’s the area where we experience the most significant rainfall flooding, largely due to typography. We have a gravity-driven sewer system, so topography and the fact that Hoboken is largely built on a former marshland both contribute to current rainfall flooding conditions.
HG: What is Hoboken currently doing about flooding?
Hoboken has a comprehensive water management plan, and that is in partnership with the state and federal government, as well as with the North Hudson Sewerage Authority. Our plan is called “resist, delay, store, discharge.” The delay, store, and discharge components are what help the city to mitigate rainfall.
By “delay,” we mean that we are using green infrastructure to keep rainfall from entering the sewer system during the storm event. “Store” is storing that rainwater in large underground detention tanks so that it doesn’t enter the sewer system during the event. Those storage systems are like 7th and Jackson Park, which stores approximately 470,000 gallons; Southwest Park, which stores approximately 200,000 gallons; and the system we’re currently building at Northwest Park, which when complete, can store up to 2 million gallons of rainwater during storms.
Our resiliency parks keep millions of gallons of stormwater out of the sewer system, which increases the capacity of the system to manage the water during the rain event. “Discharge” is actively pumping water out of the city and during a rain event. We have two wet weather pump stations right now that the North Hudson Sewerage Authority constructed; each station pumps more than 40 million gallons of water per day out of the city.
Over the previous decade, Hoboken has invested over $140 million in flooding infrastructure through flood pumps, resiliency parks, green infrastructure, and other flood mitigation strategies.
HG: Residents have been complaining of sewage in the street, even after minor flooding. How is sewage being cleaned up from the storms? And why is this happening?
Debris in the streets results from backups in the combined sewer system. When the system reaches capacity or if water can’t flow to a specific location, water backs up into the streets through the catch basins.
When this water backs up, it ultimately does recede into the sewer system. It just takes time. The purpose of the pumps is to pump the water out as fast as possible, which then allows the water that has overflowed onto the streets back into the system. Ultimately, the water that comes out of the system goes back into the system and then heads to the water treatment plant where it’s treated and discharged. During the case of a combined sewer overflow event, it would overflow into the Hudson River.
Directly after the storm event, after the water has receded, the Department of Environmental Services and the North Hudson Sewerage Authority work together to clean streets, sidewalks, and intersections where the sewers may have backed up. We use water trucks and power washing equipment to do this cleaning so that water goes back into the sewer system where then it is treated at the sewage treatment plant and discharged.
HG: What can you tell people who live in basement apartments and have been dealing with this situation every time it rains, particularly what happened last Wednesday night?
What happened [that] Wednesday night was a very, very intense rainfall, and that was actually twice as bad as Tropical Storm Fay, which was about two weeks ago.
Hoboken floods when we have the significant intensity of rainfall, so if we receive more than approximately 0.8 inches of rain in one hour, the lowest-lying areas of Hoboken could see flooding at intersections. This is because the sewer system doesn’t have the capacity to manage that intensity of rainfall. Replacing the entire sewer system would cost up to $3 billion, according to the North Hudson Sewerage Authority.
If we had the same amount of rainfall over a longer period of time, the system could manage the water, and flooding would either not occur or would not be as significant. What we saw on Wednesday was actually the most intense rainfall since the NHSA started tracking rainfall intensity in Hoboken. It was more intense than Tropical Storm Fay; more intense than the Cinco de Mayo storm in 2017; possibly as intense as Hurricane Irene.
On Wednesday, we had one inch of rain in eight minutes—that doesn’t typically happen. Unfortunately, it caused a series of impacts in areas that don’t typically flood during rain events such as some basement flooding.
So, what can we say for them moving forward? Hoboken has developed Resilient Building Design Guidelines (found here!) that require property owners to install backflow prevention systems, so if there’s any new or substantially rehabilitated home where they replace their sewer service line, they’re now required for backflow prevention. Some of the older homes may not have backflow prevention right now, but they could install it. Backflow prevention measures and other strategies recommended in the Resilient Building Design Guidelines would keep sewage from backing up into homes and basements.
I would encourage someone who had a residential impact from the flooding to look at the resilient building design guidelines or to contact the NHSA (the website) because the NHSA can evaluate and make recommendations for specific properties.
HG: What resources is Hoboken offering residents who are dealing with flood damage from the last few storms?
The resources that the city are offering are all of the city’s infrastructure investments to mitigate future flood risks, especially in the face of climate change. The city has invested millions of dollars in our resiliency parks, which are going to increase the capacity of the sewer system to hold water during a storm event and, therefore, lessen the impact during rainfall flooding.
The city’s few resources are our investment in flood mitigation infrastructure. We also have technical resources, like our resilient business building design guidelines that provide recommendations for individual property owners who wish to make upgrades at a property level and a more local level.
HG: Southwest Hoboken is particularly underwater during mild rainstorms. Do you know why this is happening, and is there something that can be done, or should residents just have to understand the situation living there?
The geography of Southwest Hoboken and the topography of Southwest Hoboken really contribute to the flood risk in that area. That is the lowest part of Hoboken. It’s really at sea level in most places, which means that it’s very difficult for water to flow out of that area.
So, the Northwest Hudson Sewerage Authority has a pumping station that actively pumps water out of Southwest Hoboken. Prior to that pumping station going online, water would sit in the streets for hours longer than it does currently. The benefit of the pumping station in Southwest Hoboken, which we call the H-1 pumping station because that’s the H1 drainage area.
That H-1 pumping station pumps 50 millions of gallons of water out of Southwest Hoboken, meaning that the floodwaters recede much quicker than they did previously.
HG: How does the North Hudson Sewerage Authority (NHSA) prepare and respond to storm events?
Prior to the storm, they go out and make sure that all the catch basins are clear, that all the lines are clear, that we don’t have any issues with the system functioning, and make sure all of the pumping stations are operating well and functioning well before the storm.
During the storm, if, for example, a specific catch basin got clogged with some sort of debris during a flood event, they’re going to go out there, vacuum that out, and make sure the catch basin is flowing and working. They work during the storm event to address any individual issues that might come up with the system. After the storm event, the Department of Environmental Services and the NHSA work together to remove anything that might be on the streets, sidewalks, or intersections that came up during a flood. For NHSA’s data-gathering after every storm event, they look and they see how many millions of gallons were pumped from the two pumping stations.
The NHSA has a hotline (866.689.3970), which is a really great resource for our residents. If you see a clogged basin, we highly encourage anyone to call the NHSA hotline, so that can be addressed, even during a storm event. They’ll provide us with a summary after the event of how much rainfall occurred, a log of any resident complaints that came in, the intensity of the rainfall, and how much water got pumped out.
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HG: Do you think there will be parts of Hoboken that will be uninhabitable soon or in the future due to flooding?
No. I think that we’re adapting to climate change. The City has invested millions of dollars in flood risk mitigation infrastructure, including our resiliency parks and other green infrastructure. We are, like many other urban coastal areas, learning new and different ways to adapt to flood events. We have implemented policies, such as our flood damage prevention ordinance, and methods of construction, such as backflow prevention, on-site stormwater storage, and flood vents, that are mitigating flood impacts.
We are also doing our part to mitigate climate change, through our climate action plan which sets targets and outlines a path for Hoboken to become carbon neutral by 2050.
The best available science shows us that rain events are becoming more intense and more frequent. This is something that brings an urgency to all of the infrastructure investments that the city is undertaking. We need to make these investments now, and we need to provide the resources to our residents like our resilient building design guidelines, so that we’re all making decisions that collectively mitigate flood risk. We are putting these policies in place and making sustainable investments to prepare for future climate impacts.
HG: Hoboken was once an island. How does this play into the situation?
Hoboken’s former geography as a tidal marsh really mirrors the modern-day floodplain. The areas that were filled in the early 1900s for development are the areas that are the lowest-lying, and they’re the areas most at risk for flooding.
These are also the areas in which the City and NHSA are making a significant investment in flood mitigation infrastructure, such as Southwest Park, which can manage up to 200,000 gallons of stormwater during flood events; and the Northwest Resiliency Park (under construction), which can manage up to 2,000,000 gallons of stormwater during flood events. All of these are in areas that are low-lying, where Hoboken was once a marshland.
Hoboken’s ongoing flood defense strategy
To prepare for the threat of hurricanes, intense storms, and possible flooding, Jennifer shared that Hoboken has launched several flood defense projects to strengthen Hoboken’s flood infrastructure. These projects, which will start construction soon or are ongoing, include:
Rebuild by Design
In 2017, the U.S. Department of Housing and Urban Development awarded a 230-million-dollar grant to the Rebuild by Design Project (construction starting soon), a flood resiliency plan designed to prevent flooding in Hoboken during a superstorm comparable to Hurricane Sandy. The project will include a public park, which will resist water from the Hudson River through storm surge events, such as what occurred during Superstorm Sandy. Hoboken expects to begin construction on this project this year.
Two Flood Pumps, with a Third One to Come
Hoboken has two flood pumps, both in flood-prone areas. The H-1 flood pump, completed in 2011, is in southwest Hoboken, and the H-5 flood pump, completed in 2016, is in northwest Hoboken. Combined, the two pumps can pump out over 90 million gallons of rain per day. During the most recent storm on Wednesday, the two flood pumps pumped out over 8 million gallons of water.
The third flood pump will be constructed along with the Northwest Resiliency Park.
Hoboken’s new resiliency park at 7th and Jackson (along with the Southwest Resiliency Park) can hold hundreds of thousands of gallons of rainwater during storms through above-ground green infrastructure, along with underground detention systems. The Southwest Resiliency Park can hold over 200,000 gallons of rainwater, while the 7th and Jackson Resiliency Park can hold over 470,000 gallons of rainwater.
Hoboken’s Northwest Resiliency Park (soon to be New Jersey’s largest resiliency park!) is currently under construction. It includes an underground detention system that can store up to 1 million gallons of water below ground and delay up to 1 million gallons of water above ground through green infrastructure.
Porous pavement at City Hall, the Southwest Resiliency Park, the Police Department, and Fire Department headquarters helps absorb and keep rainwater out of the sewer system.
City Hall Project
The “City Hall Sustainable Stormwater Demonstration” is projected to retain all rainwater that falls on City Hall during a 25-year storm and prevent it from contributing to flooding. The project includes four 1,200 gallon above-ground rainwater tanks (cisterns), more than 1,000 square feet of rain gardens, 100 square yards of pervious concrete sidewalk, raised planter beds, and a green wall.
Creation of Green Infrastructure Including Rain Gardens and Bioswales
Rain gardens and bioswales, which are designed to withhold rainwater during storms, have been installed in numerous spots around Hoboken. On Washington Street, 15 rain gardens capture rain before entering the sewer system during rainfall.