Ponds, Plants, and Freestanding Walls Help Zoo Reduce Water Use

By Lindsey Manthei O’Connor, Communications Specialist for Redi-Rock International

Above & Below: Approximately 4,125 sq. ft. of Redi-Rock Freestanding, Garden and Column blocks were used to line the fountain, ponds and part of Bird Lake. Most of the walls are 3 1/2 to 6 feet tall. These walls feature Limestone texture on both sides and were all topped with cap blocks. A filtration system was built in the center of Bird Lake — accessible by a brick paver path that leads to the fountain area. Water from the lake is pumped to the fountain lined with blocks where the filtration process begins.
Photos courtesy of Redi-Rock International

Responsible use of water is a major priority in landscape designs across the country and the Philadelphia Zoo is leading the way in reducing its water use and inspiring visitors to do the same. “With our recent initiatives, the zoo has already reduced water consumption by almost half,” explained Chris Waldron, Sustainable Operations Manager at the Philadelphia Zoo.

One of the biggest projects the zoo has undertaken to reduce its water use by half was the renovation of it’s biggest water-guzzling attraction — Bird Lake. This man-made lake is a popular attraction where visitors can take swan-shaped boats for a spin. “We calculated that Bird Lake used more water on a daily basis than any other system, as we had to run fresh water in to minimize algae growth and maintain water quality. So that became a primary target in reducing our water use even further,” said Waldron. The goal of the Bird Pond renovation project was to develop an “innovative man-made wetland around Bird Lake that would maintain good water quality while greatly reducing the need for water use,” explained Nina Bisbee, Vice President of Facilities at the Philadelphia Zoo.

The Solution
With these goals in mind, the zoo turned to PS&S, a design firm with experience in creating man-made wetlands. Finding a material to contain the wetland was a major factor of the design.

“Redi-Rock was chosen to contain the wetland areas with a cost effective structural solution that is compatible with the historic architectural fabric of the Zoo,” explained Project Manager Donald Sharp of PS&S. Each block in the large, modular block system weighs about one ton, harnessing the power of gravity to build tall walls that require no reinforcement in many applications. Blocks are available in three natural textures to match the aesthetics of a project. For this project, designers chose the Limestone texture to match the historic architecture of the zoo.

The Design
The design of the project included creating a series of planted pond areas with a special soil mix to filter the water. “The system is like a natural wetland, filtering the water through beds of wetland plants. This way, the zoo can re-circulate water in the lake rather than continuously adding new water,” explained Bisbee. The filtration system was built in the center of Bird Lake — accessible by a brick paver path that leads to the fountain area. Water from the lake is pumped to the fountain lined with blocks where the filtration process begins. Several additional ponds step down from the highest point at the fountain, each filtering the water through soil and plants before the water is reintroduced to the lake. An interesting design element was the use of the company’s Garden blocks in this project.

Garden blocks have a trough or void in the top that is usually used to create space for soil and plants. However, the designers of this project utilized Garden blocks in a unique way. Because one side of the modular block walls acted as the side of the ponds, the pond liners were pulled up and tucked into the trough, then secured in place by placing a Redi-Rock Cap block on top.

As part of the project, the zoo also created a system to divert rain that falls on the roof of nearby McNeil Avian Center into the lake, helping to replenish its water level in dry periods and reducing the amount of water going into the city’s storm water treatment system.

The Outcome
The pond area re-opened in 2011 and the zoo reports that guests have responded positively to this new and beautiful area that surrounds Bird Lake. Plus, reducing water use by almost 50 percent is a definite plus for the zoo.