More Room to Roam with Redi-Rock at Zoo’s Elephant Exhibit

THE CHALLENGE

With Elephant Trek marking the Cincinnati Zoo's most significant habitat expansion to date, the zoo’s construction team faced some unique challenges:

• Maximizing Usable Space Landlocked by the surrounding Avondale community, the Zoo had limited room to grow. For any expansion to be possible, the Zoo needed to create new, usable land, requiring retaining walls strong enough to support a larger exhibit footprint. With over 1.9 million visitors to the zoo annually, Elephant Trek also needed to be spacious enough to handle high volumes of pedestrian traffic comfortably.

• Curbing Elephant Curiosity Elephants are known for their playful, inquisitive natures. Zoo officials needed wall solutions able to withstand elephant interactions and keep the walls undisturbed.

• Achieving a Natural Look The zoo’s naturalistic aesthetic is a key part of the guest experience, so the retaining walls needed to blend seamlessly into the lush surroundings. Maintaining this visual harmony was essential to make Elephant Trek feel like an organic extension of the Zoo’s landscape.

THE SOLUTION

To overcome space limitations and ensure a safe environment for the elephants, the Cincinnati Zoo turned to several trusted local experts in their respective fields: Arcadis Engineering Services for design, Redi-Rock Structures of OKI for materials, and Decorative Paving for installation.

"Working with local businesses is important to us, so we needed to meet the local Redi-Rock manufacturer in-person and see their operations. They were super responsive, we had zero issues with lead times, and had direct access to staff members when needed, which was greatly appreciated."

Mark Fisher, Vice President of Facilities and Sustainability, Cincinnati Zoo

In one of their early discussions with Redi-Rock Structures of OKI, the zoo raised an important concern: the elephants’ natural curiosity. As playful creatures, they might be inclined to interact with the retaining walls, so a secure solution was essential. Redi-Rock OKI presented an innovative hybrid system of 41 in (1030 mm) and freestanding Hollow-Core retaining wall blocks, secured with rebar and concrete, to ensure structural integrity and withstand the elephants’ playful behavior. This system wouldn’t require geogrid reinforcement, so excavation boundaries could be kept to a minimum.

“We were able to use 41 inch and freestanding Hollow Core block and tie them all together with rebar and concrete to alleviate this concern, which helped us land this job.”

Josh Turton, Redi-Rock Structures of OKI

With this retaining wall solution, the Cincinnati Zoo could expand its elephant habitat while staying true to its values—working with local partners, creating a safe home for its animals, and enhancing the elephant experience for visitors.

THE DESIGN

Creating the Elephant Trek exhibit was no small feat. The Zoo envisioned a space with waterfalls, streams, enrichment zones, and expansive yards that would delight both elephants and visitors. The zoo needed a design for seven retaining walls that could match the exhibit's natural beauty while meeting the site’s structural challenges.

In the initial design stages, the Zoo considered traditional cast-in-place, small block, and shotcrete wall options. "From an engineering standpoint, the process of designing and approving a big block wall is much faster than cast-in-place alternatives,” explained the Zoo’s Fisher. With poor soil conditions, surrounding trees, and limited space near property lines, these alternatives posed significant obstacles. The zoo needed retaining wall solutions that maximized space without the need for extensive cutbacks—a feat beyond the capabilities of conventional concrete wall systems.

Turning to Redi-Rock, the zoo partnered with Arcadis Engineering Services to design hybrid gravity wall systems for a total of 12,445 sq ft (1156.2 sq m) of walls, featuring a selection of Redi-Rock blocks:

• 41 in (1030 mm) Hollow Core
• F-HC Hollow Core, 60 in (1520mm)
• 28 in (710 mm)
• 52 in (1320 mm) XL Hollow Core
• 72 in (1830 mm) XL Hollow Core

This combination of Redi-Rock solutions provided the stability needed for installing walls in tight spaces while also allowing the Zoo to reinforce the top blocks with concrete and steel to prevent curious elephants from disturbing them. "We chose the Hollow Core blocks since we needed to fill the top three courses with additional concrete and reinforcing steel so our elephants wouldn't play with them,” explained Gary Gilbert, the zoo’s Director of Construction Management. “We liked the naturalistic look of Redi-Rock and the fact that this type of wall project was a standard offering for Redi-Rock, which competitors don't offer or only offered as a specialty solution."

THE INSTALLATION

With multiple walls needed and phased timelines, installer Decorative Paving faced the challenge of delivering the wall construction on time. Meeting the zoo’s high standards, Decorative Paving completed each phase on time and exceeded expectations, bringing the zoo’s vision to life with precision and efficiency.

Upon completion of the retaining walls, a painter was contracted to provide a matching stain to the walls to further blend with existing architecture.

Adding to the excitement, the zoo kept a video diary of Elephant Trek’s construction, allowing eager visitors and the public to follow each stage of the exhibit’s development and watch the space take shape.

THE OUTCOME

The Cincinnati Zoo & Botanical Garden set out to create an immersive space for its new Elephant Trek exhibit—an environment that would offer ample room for the elephants, blend seamlessly with the zoo’s natural landscape, and maintain the highest safety standards. They needed functional and beautiful retaining wall solutions.

With its fieldstone-inspired aesthetic, deeply textured faces, and simple installation, Redi-Rock helped the zoo achieve its vision, creating an inviting and secure environment.

"We wanted a stacked stone look that resembled actual fieldstone, and Redi-Rock exceeded our aesthetic goals."

Mark Fisher, Vice President of Facilities and Sustainability, Cincinnati Zoo

Officially the Harry and Linda Fath Elephant Trek, the zoo’s most ambitious project to date has paved the way for another exciting expansion. In spring 2025, the new development will feature habitats for siamangs, Asian small-clawed otters, and rhinoceros hornbills, further enriching the zoo’s offerings.

Thanks to the zoo's careful planning and Redi-Rock’s innovative retaining wall solutions, Elephant Trek has become a lasting testament to the zoo’s dedication to animal welfare and its commitment to creating unforgettable experiences. With a retaining wall design that blends seamlessly into the landscape and will withstand the test of time (and curious elephants, of course), the exhibit promises to captivate and inspire visitors for generations to come.