Dewatering Pump Supports Tappan Zee Bridge Construction

Aug 12, 2025 |

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Construction dewatering pump problem

Pumping large volumes of water 150 vertical feet
24/7 operation to cure concrete foundation
Maintaining water temperature
Potential negative impact on ecosystem

Project overview

In late 2013, Tappan Zee Constructors (TZC) began replacing the existing 3.1 mile bridge across the Hudson River in New York. The existing bridge (est. 1955) served more than 138,000 vehicles a day, but had corroded. The city invested $3.98 billion to build the new Tappan Zee bridge to accommodate more lanes, a pedestrian and bicycle path and an integrated new mass transit system.

There were two big concerns for this project. First, the bridge’s concrete foundation had to cure properly, which required cooling water to run 150 feet into the air at a flow rate that would maintain the integrity of the structure. Second, ensuring the Hudson River water temperature would remain at viable levels for the underwater ecosystem.

Solution

After much research, TZC purchased customizable Stancor P/S Series high head dewatering pumps.

These heavy-duty pumps are rated at 30 hp and pump up to 430 gpm or generate up to 165 psi. This helped TZC achieve the required head and psi to move river water at a speed and temperature that would help cure pylon concrete. P/S Series pumps feature cast 356 aluminum motor housing and Class F motor insulation for thermal protection. This not only ensures the pump motor runs at correct temperature, but also that surrounding river water temperature vacillates by no more than 3 degrees F. The stainless steel handles and discharge connections allow for easy handling in these challenging environments. The 316 stainless steel impellers are abrasion resistant, which is ideal when there are small rocks and other debris flowing in river water.

To address ecological concerns, Industrial Flow Solutions customized the pumps with wedge wire screens designed to fit intakes. The wire screens’ 5 mm openings helped prevent fish, eggs and larvae from being drawn into the pump. This protected both the ecosystem as well as the pumps’ mechanical systems.

In total, TZC placed over 50 P/S Series high-head dewatering pumps with heavy-duty, jacketed 50-foot cables along the span tower pylons. “A project of this size has unique challenges, and collaborating with Industrial Flow Solutions on all aspects, including power supplies, flow rate and head pressure allowed us to develop a comprehensive solution,” says Martir Ortex, TZC field engineer for the NY Bridge Tappan Zee project.