Waterproofing the Bronx Zoo River Under Crocodile Supervision

The project:

The Bronx Zoo, one of the largest metropolitan zoos in the world, faced a critical construction challenge in the spring of 2024.

Celebrating its 125th anniversary, the Bronx Zoo spans 265 acres and is home to over 6,000 animals. One of their key attractions, JungleWorld, features an Asian crocodile exhibit with a man-made river that winds through the exhibit, providing an immersive experience for visitors while ensuring the animals thrive in a simulated environment.The exterior foundation wall of this river had developed significant cracks, causing leaks.

The leaks allowed water from the neighboring Bronx River to seep into the exhibit, contaminating the water environment meant for the crocodiles, threatening their health. Conversely, water from the exhibit also leaked into the Bronx River, disrupting the natural ecosystem. These issues led to considerable expenses for the Bronx Zoo in maintaining the correct water quality for the crocodile exhibit.

Challenges:

The project had numerous technical challenges and unique obstacles to repair the leaks in the exterior wall of the crocodiles’ river.

• Limited Access: The zoo's layout made accessing the cracks difficult, and the breach was at the lowest level. The water had to be lowered to inspect the crack, and the waterproofing contractor had to physically enter the river with the crocodiles.
• Complex Wall Composition: The brick foundation wall required precise application and expertise for the waterproofing injection.
• Material Safety: Ensuring the waterproofing materials were safe for both the exhibit water and the Bronx River was crucial. The materials had to be certified to avoid any contamination.
• Proximity to Crocodiles: The zoo had limited facilities to relocate the crocodiles. The repairs had to be done with the crocodiles present, necessitating zookeepers to keep the reptiles at bay, adding a unique safety risk and the need for efficiency.
• Tight Timeline & Preservation: The work had to be done with minimal disruption to the zoo’s operations and visitor experience. This required careful planning and execution to avoid closing down the exhibit or affecting the zoo’s daily activities. Preserving the exhibit’s presentation during the repairs was a priority for the zoo.

These challenges required an innovative waterproofing solution and close coordination with the zoo staff to ensure the project was completed quickly and successfully.

The Solution:

To address these technical issues and physical challenges, the Bronx Zoo’s General Contractor examined the cracks and brought in experts from GCP Specialty Building Materials’ technical waterproofing team to determine the solution. 

After careful evaluation of the low level breach and unique environment by the technical waterproofing team, it was determined that DE NEEF® CFL PURe, a hydrophobic polyurethane designed for barrier wall grouting, was the best solution. The grouting material was chosen for its proven performance and environmentally-safe properties for both the treated exhibit water and the natural waters of the Bronx River. The Bronx Zoo required documentation to ensure the chosen waterproofing solution met their environmental requirements. 

DE NEEF® waterproofing solutions are environmentally-safe due to four key factors:

1. Phthalate-free formulation: DE NEEF® products, including CFL, Flex LV, and Sealfoam, are formulated without phthalates, which are chemicals often used as plasticizers but have raised environmental and health concerns.
2. TDI-free reformulation: The products have been reformulated to be free of toluene diisocyanate (TDI), a chemical that can be harmful to human health and the environment.
3. Non-toxic and non-corrosive: DE NEEF® waterproofing injection solutions are described as non-corrosive and non-toxic, making them safer for use in various environments, including water-related applications.
4. Safe for water applications: DE NEEF® solutions are suitable for use in potable water structures and have received various approvals from water authorities worldwide.

These features contribute to making DE NEEF® waterproofing solutions more environmentally-safe compared to traditional alternatives, allowing for their use in sensitive applications such as potable water systems and ecological areas near water bodies.

In addition, DE NEEF® CFL PURe is a fast curing grout that quickly cures and is a single component, making the application efficient and highly effective. It does not dilute in water and is resistant to most organic solvents and micro-organisms. Ideal for barrier wall grouting, DE NEEF® CFL PURe is easy to use for applicators and contractors, and can be applied quickly.

Next, GCP connected the Zoo’s General Contractor with Expert Concrete Repair & Restoration to apply the DE NEEF® to the exhibit’s cracks.

GCP, the manufacturer of DE NEEF®, consistently reviews and refines its products to provide the highest levels of safety, both in production and application, exceeding chemical and construction industry standards for environmental, safety and health issues.

Results:

Despite numerous challenges, the project was completed in just a few days with no disruption to the crocodiles and zoo's visitor experience. The waterproofing injection process was carried out by Expert Concrete Repair & Restoration with meticulous attention to detail while zookeepers held off the 7 to 9-foot crocodiles with brooms! The team  minimized their footprint by setting up in a corner less than 10x10 feet and running all hoses into the area, ensuring that the habitat remained undisturbed.

Key Outcomes:

• Effective Crack Sealing: The team used a specialized injection method to apply DE NEEF® CFL PURe, effectively sealing the cracks in the exhibit wall. This method ensured precise application and maximum efficiency, even under the unique conditions of the zoo environment.
• Minimal Disruption: The work was completed with little impact on the zoo's daily operations and visitor experience, demonstrating the efficiency and careful planning of the project team.
• Improved Water Quality: By preventing water exchange between the exhibit and the Bronx River, the waterproofing solution helps maintain appropriate and healthy conditions for the crocodiles, and keeps their specialized water out of the natural Bronx River.
• Cost Reduction: The zoo anticipates significant savings on water quality maintenance due to the waterproofing, allowing funds to be allocated to other essential projects.
• Long-Lasting Protection: DE NEEF® CFL PURe is a long-term, lifetime solution, providing leak protection for over 200 years.
• Client Satisfaction: The Bronx Zoo was highly pleased with the outcome and plans to use the team and  DE NEEF® CFL PURe on future repair needs.

The GCP and Expert Concrete Repair & Restoration teams delivered a specialized and environmentally-safe waterproofing solution for this unique and challenging Zoo environment. Their ability to adapt to the specific needs of the Bronx Zoo, including working around live animals and respecting the facility's policies, demonstrates their commitment to closely identifying a project’s needs while prioritizing environmental safety. The seamless execution and the effectiveness of the waterproofing injection have not only safeguarded the Asian crocodile exhibit but also preserved this one-of-kind exhibit for zoo visitors to enjoy for another 125 years.