Daylighting Tibbetts Brook

Van Cortlandt Park Alliance supports local learning! 

This information was compiled and written in Summer 2022 by Nayise Gonzalez and Natalie Sweet as part of a project prepared for a fellowship with Global Leadership Human Impacts Institute. Nayise is a rising junior at SUNY New Paltz and Natalie is a rising sophomore at Wesleyan University.

_{Scroll down to the “Project Components” section for more information on Nayise’s and Natalie’s work.} 

How does the sewer system in NYC operate?

About 1.3 billion gallons of wastewater enter the sewer system in New York City every day. It travels through 7,500 miles of sewer pipes, 135,000 storm drains, 96 wastewater pump stations, and 14 treatment plants. However, only 40% of NYC uses a separate sewer system for wastewater and stormwater, which is the modern approach to treating sewage. This approach consists of two separate pipes underground: one for wastewater that goes directly to the treatment plant; and another pipe that carries stormwater directly to local waterways. Wastewater is made up of the water that leaves your sink, shower, and toilet. Stormwater is the water that enters the sewer, through a grate, on the street. 

The other 60% of NYC relies on a sewer system that was installed in the 1800s— a combined sewer system that carries wastewater and stormwater together to one of the 14 wastewater treatment plants in NYC. One plant can take up to 700 million gallons in a day of both sewage and rainwater. Storm water from Tibbetts Brook contributes to this combined system.

How does this relate to Tibbetts Brook?

Tibbetts Brook is a body of water that flows from Yonkers into the Bronx in Van Cortlandt Park. This water currently flows partially in pipes under roadways while other parts are visible in Yonkers and within Van Cortlandt Park. The brook ends in Hester & Piero’s Mill Pond (formerly known as Van Cortlandt Lake) and enters the sewer system to be treated unnecessarily. On a dry day, 4 to 5 million gallons of water from the brook enter the sewer system. The combination of the water from the brook and from the sewer system creates overflow issues for the sewage system when it rains; these are also known as Combined Sewage Overflow (CSO) events.

With an increase of water in the sewage system, the sewage plant can not treat all of the discharge, and the excess water goes directly into the Harlem River. According to the NYC Department for Environmental Protection, treatment plants are unable to handle flows that are more than twice their design capacity. When it rains, a mix of excess stormwater and untreated wastewater discharges directly into the city’s waterways at certain outfalls to prevent upstream flooding. This becomes a problem as CSOs create pollution, cause gasses such as methane to rise, and decrease the quality of the environment for the local communities surrounding the areas where the system makes its deposit. CSOs are discharged at an outfall location. For Tibbetts Brook, this combination water is discharged at WI-056. 

Tibbetts Brook is added into the sewer system unnecessarily, so environmental activists have been advocating for it to be removed from the sewer system and “daylighted.” Daylighting a body of water is the process of moving the water that has been diverted to an underground pipe above ground and adding in components to enhance the space. 

Green infrastructure is one component of this process, to reduce flooding and mimic how the natural land would deal with water. The goal of daylighting Tibbetts Brook would not only be to decrease the amount of CSOs that enter the Hudson River, but also to benefit the park and surrounding communities. The project will extend an existing greenway, add better access to the area, and will become a new stretch of public park for the community to enjoy.

How it Started

Advocacy for this project started in the late 1990s. Van Cortlandt Park Alliance (and its predecessor group, Friends of Van Cortlandt Park) and the Bronx Council for Environmental Quality have been working to get the project approved ever since. 

Van Cortlandt Park Alliance and BCEQ were ahead of the curve, understanding the environmental impact of CSOs and the potential for improved permeability, so it took a while for New York City to catch up! 

In the early 2000s, NYC Parks started to support the project when the benefits became clear: daylighting would help reduce combined sewage overflow and increase the capacity of the wetlands in Van Cortlandt Park. The plan for Daylighting Tibbetts Brook was then included in the City’s Van Cortlandt Park Master Plan for 2034, created in 2014. A few years later, when NYC’s Department of Environmental Protection was tasked with preventing flooding into the Harlem River, they included daylighting as a solution for CSOs in their Long Term Control Plan, which was finalized in 2020. 

The daylighting project extends beyond the southern end of Van Cortlandt Park into a parcel of property that is owned by CSX Transportation on what was once a railroad bed. Negotiations with CSX are currently in progress to buy the land to implement the project.

Van Cortlandt Park Alliance was instrumental in securing approval and funding for the open channel Daylighting Project to proceed. As of 2022, NYC Parks and NYC Department of Environmental Protection are working together, designing the project.
The plans to daylight will change where the brook flows and will also include significant plans to change and improve areas in Van Cortlandt Park. 

The addition of a greenway along the daylighted stream from West 230th Street into the park will make the park more accessible for the community. An increase of greenspace reduces the amount of flooding the park will experience.

The design is projected to be completed in Spring 2023. From 2023-2025, improvements to the mill pond will take place through the removal of non-native invasive species. Construction is projected to start in 2024 and is expected to last five years.

New York City Department of Environmental Protection Website

Municipal Separate Storm Sewer System (MS4) Map

Combined Sewer Overflow Long Term Control Plan For Citywide/Open Waters Executive Summary

Tibbetts Brook Daylighting Project – PDC Conceptual Review

Click here for press coverage

By Nayise Gonzalez and Natalie Sweet – Summer 2022 

1. Research 

2. Public Education

This project will consist of multiple interactive and physical elements that will come together at the Van Cortlandt Park Alliance’s public movie screening on July 28th, 2022 at 7:30pm. We will have a table set up with coloring sheets, stickers, and flyers educating people on the importance of fixing New York City’s sewage system and encouraging people to support daylighting Tibbetts Brook. 

We will also have photos capturing our site visits to the area to provide people with visual context of the importance of daylighting Tibbetts Brook.

Additionally, we will present a physical clay sculpture of the landscape of New York City that we will use to demonstrate the instability of the current system New York City uses to deal with rainfall and sewage overflow. People at the screening will be able to pour water on to the sculpture, making the piece interactive. As water is poured through the waterways of this unfired clay structure, it will erode over time, demonstrating the need for green infrastructure to keep the city from eroding.

3. Public Information 

We will also work with the Van Cortlandt Park Alliance to create a page on the VCPA website with documentation of this event and more information on Combined Sewage Overflows and Daylighting Tibbetts Brook.

4. Call to Action

We want to work with the Van Cortlandt Park Alliance to help community members become more involved with local programs in the park and environmental issues in the area.