6 Tips When Planning for Intense Storms

The city releases a rainfall plan to help combat extreme weather.


The city releases a rainfall plan to help combat extreme weather.


Mayor Eric Adams, along with NYC Department of Environmental Protection (DEP) Commissioner Rohit T. Aggarwala, and NYC Emergency Management (NYCEM) Commissioner Zach Iscol recently released the Rainfall Ready NYC action plan, a plan to prepare New York City for more extreme rainfall in the future. Last year, Hurricane Ida was a wake-up call for New York leaders. There were 13 deaths in the city caused by flooding from Hurricane Ida’s torrential rains, and most of the deaths were located in basement apartments.

At one point, on Sept. 1, the Central Park Automated Surface Observing System registered 3.15 inches of rain in an hour from Hurricane Ida, shattering the previous record set by Hurricane Henri just 11 days prior. The mayor’s newly announced plan acknowledges that climate change will bring more extreme weather to the five boroughs and the plan outlines the additional steps residents can take to protect themselves and their property. “Climate change is the city’s biggest environmental threat, and while we continue to invest in resiliency and infrastructure projects to protect us for generations to come, the Rainfall Ready NYC action plan will help every New Yorker to protect themselves, their families, and their homes,” stated Mayor Adams.

The city is committed to making important investments to improve resiliency and prepare New York City for the effects of climate change. NYC has over 7,500 miles of sewers capable of capturing rainfall from an intense “five-year storm.” Additional short-term infrastructure projects will be implemented to mitigate flooding. The Department of Design and Construction (DDC) and DEP will work together to complete three high-level storm sewer projects, six traditional sewer projects, and install 1,300 more green infrastructure assets by June 2023.

In addition, there are immediate steps you can make to help prevent death, injury, and property damage when these intense rainfall events do occur. We’ll go over some tips to help you plan for extreme weather.

Tip #1: Stay Informed, Understand Flood Risk for Your Building

DEP has developed a new, interactive map to help owners understand the level of risk they may face today during an intense storm and which areas in their neighborhoods may experience flooded roadways. The interactive maps show three levels of stormwater flood scenarios—moderate stormwater flooding scenarios under current and future sea level rise conditions, as well as an extreme stormwater flooding scenario under futures sea level rise conditions. You can find the maps at https://nyc.gov/stormwater-map.

These maps are the first step to better understand the impacts of increasing rainfall in NYC. They’ll help you understand how stormwater flood patterns may change over time. They assume that rain occurs uniformly across the city, that the drainage network is functioning as designed (for example, that catch basins don’t have leaves matting over the tops), and that large properties, such as airports, have their own on-site drainage systems. And they don’t account for the potential benefits of coastal protection projects currently under design or construction.

You should also sign up for Notify NYC, the city’s dedicated emergency public communications program. Notify NYC staff operate 24 hours a day, seven days a week, out of Emergency Management Watch Command, where they constantly monitor emergency activity in New York City and the metropolitan area. It started as a pilot program in December of 2007 and went citywide in May 2009 as a means to communicate localized emergency information quickly to city residents. The city wanted a way to update New Yorkers quickly with official information after several incidents occurred in 2007, such as: tornadoes, a steam pipe explosion, and crane collapses. Enrollment and mobile app download information can be found at https://a858-nycnotify.nyc.gov.

Tip #2: Obtain Flood-Specific Insurance Policy, If Applicable

Flood insurance covers damages to property or personal contents from flooding caused by excessive rainfall, tidal flooding, or wind-driven storm surges. If your building is on a street at risk for stormwater flooding, check that you have a flood-specific insurance policy, which is typically purchased separately from traditional property insurance.

Most flood insurance policies are administered by the National Flood Insurance Program (NFIP), a federal program run by the Federal Emergency Management Agency (FEMA). NFIP policies are separate from property insurance, but are often sold through the same agents. Flood insurance premiums are affected by various factors such as deductible amount and the amount of insurance coverage you buy. In addition, the higher the risk of your flood zone, the higher the flood insurance base premium will be. Also, the higher the lowest inhabited floor (any floor not used solely for storage, access, or parking) is elevated relative to the Base Flood Elevation (BFE), the lower the premium may be. You can learn more about your building’s risk and flood insurance requirements by visiting https://floodhelpny.org

Tip #3: Develop Communication Protocols to Notify All Residents

In case of a weather emergency, it’s helpful to maintain an inventory of all residents’ phone numbers, emergency contact numbers, and emails. With this information, you can notify all residents of flood conditions and advise them on procedures to minimize damages such as removing items from below-ground levels.

Special considerations must be made if you have any residents living below flood elevation levels. During Hurricane Ida, 11 people drowned in basement apartments during the storm. If your building has any residents living below flood elevation levels, develop communication and evacuation plans for potential flood situations.

Tip #4: Survey Entry Points for Flood Waters, Repair Issues

You should visually survey the property for locations where flood waters might enter the building, including foundation wall cracks, gaps, and below-grade openings such as exterior stairs or sloped driveways, and basement or cellar floor drains. At the street level, when an intense storm is predicted, be sure to clear debris from the curb line and on top of catch basins so stormwater can flow freely down the street and into the sewer system.

Also, you should make repairs to any issues identified during the visual survey of the site. You should seal cracks or openings on exterior walls or the foundation, covering entry points below the flood elevation level, protecting against seepage inside the building, and protecting mechanical and electrical systems.

You can also consider having flood shields on hand to make a structure watertight below flood elevation. Flood shields are temporary, watertight barriers erected in front of building openings such as doors and windows before flood events. They’re constructed of aluminum, stainless steel, or plastic, and use neoprene rubber or similar materials to seal the barrier. The shields are then put in place in preparation for potential flooding or after flood warnings are issued. Most flood shields are able to effectively protect buildings from floods of 1 to 2 feet.

Tip #5: Consider Implementing Backwater Valves

Evaluate ways to reduce flood risk by installing a backwater valve in consultation with a plumber. Sewage backflow occurs when stormwater backs up into a building basement because of sewer line blockage or storm drain overflow due to flooding. A backwater valve is a relatively inexpensive retrofit that can prevent significant problems from sewer line failure by blocking reverse flow from entering the building through wastewater pipes.

Backwater valves are installed where the wastewater pipe exits the building, so sewage flows outward only. Valves have a hinged flapper that remains open to allow outward flow, but seals tightly if there’s backpressure. Although sewer blockage can occur any time, it’s most likely to happen during storms when large amounts of water and debris move through the system.

Owners outside flood zones should also consider backwater valves because sewers can back up any time, not just during extreme weather events. Once installed, you need to inspect backwater valves frequently to ensure there’s no debris in the device or cleanout port and the valve functions properly.

Tip #6: Make Special Considerations for Elevators

If your building is high enough to utilize elevators, you must provide special consideration to them in your plan for intense storms. Elevators are often the only way vulnerable residents have to reach higher floors, making them a critical building system. Flooding to any building can cause extensive damage, but elevators tend to be the most susceptible because the pits of elevators are usually one of the lowest points in a building, giving rise to floodwaters. Even outside flood zones, elevators can be damaged by plumbing failures, sprinkler system runoff after a fire, and sewer backup.

Here are some important items to consider if you have elevators on your site:

  • Ensure elevators have a surge protection system;
  • Ensure the standby power generation system works. Sizing of elevator motors is an important consideration when determining backup power requirements;
  • Inspect vents, windows, and doors in the machine room for leaks. Elevator shafts that extend below the DFE should be designed and built to resist the hydrostatic pressure of floodwater. Appropriate shaft construction materials include reinforced masonry block and reinforced poured concrete;
  • Replace corroded doors and add weather stripping around doors that open to the outside in the machine room;
  • Check that sump pumps are operating or purchase one to use after the storm;
  • Install a float switch to stop elevators from running to the bottom landing if the pit floods;
  • Install flood alarms in pits; and
  • Install controls to keep the elevator cab out of a flooded shaft.

Before a flood, bring elevator cabs to an upper floor, park them, and shut off power. If one elevator is kept operational on emergency backup power, it should be prevented from descending to a flooded floor.

After a storm or flooding event, make sure no one is trapped in elevators. If people are trapped, call emergency personnel. Also, you shouldn’t resume elevator operation until your elevator has had a thorough inspection. Inspect the machine room and pit for water, and check for water on control panels and in the machine room before restoring power.

If water is found, call your elevator service company. If there’s any damage, record as much information about damage as possible. Take photographs of any damage and save damaged components in case insurers need evidence. If an elevator has been damaged, ensure that a technician services it before it’s returned to use.

NYC Government Actions to Prepare for Intense Storms

Alongside the actions owners in affected areas may take to prepare for extreme weather events, as part of the Rainfall Ready NYC plan, the city will undertake the following actions:

  • DEP will conduct direct outreach to property owners that could experience nuisance or substantial flooding as well as provide sandbags and other flooding barriers that can be deployed to protect their properties.
  • The city will promote and expand FloodHelpNY (https://floodhelpny.org), a website run in partnership with the Center for New York City Neighborhoods, that provides information and resources about flood risk, flood insurance, and flood retrofits. FloodHelpNY will be expanded to include additional stormwater resources, incorporate a stormwater risk address look up, and improve accessibility by expanding language access.
  • The city will launch an annual flood insurance awareness campaign in partnership with FEMA.
  • DDC and DEP will complete three high-level storm sewer projects, six traditional sewer projects, and install 1,300 more green infrastructure assets by June 2023. These projects will complement the existing sewer system and help manage stormwater in Brooklyn, Queens, and Staten Island.
  • The city will expand FloodNet, a network of street flooding sensors designed to better understand the frequency, severity, and impacts of flooding in New York City. These sensors will be installed in the most vulnerable areas for real-time data collection and will be accessible via a dashboard.