Shedd Aquarium's Pondless Waterfall Feature Redefines Its Outdoor Landscape

By Ed Beaulieu, chief sustainability officer at Aquascape, Inc.

The 12-foot-high grade stream cuts through a slope running down toward Lake Michigan. The reservoir at the bottom helps to capture storm-water run-off that would otherwise flow into the lake. The system uses three 120V Tsurumi Submersible Solids Handling pumps. The pumps were all located in the Aquascape Snorkel Vaults in the main 2,000-gallon reservoir. The water is pushed from the bottom to the top and then flows by gravity over the waterfalls and stream. They're on a timer system for electrical savings. Filled to capacity, the stream will run for 40 days without rain, which is rather lengthy for Northeastern Illinois. There's 500 gallons in transit, providing 2,500 gallons total. The feature is not connected to the city water supply, as it will never be needed unless the area experienced a very long dry spell. In such an instance, the reservoir would have to be filled manually. The pumps shutdown in a low-water situation. It is the responsibility of their landscape maintenance personnel to monitor. Photos courtesy of Aquascape, Inc.

The Shedd Aquarium in Chicago, Illinois continues their long history of environmental awareness by extending visitor experience to the outdoors, with the creation of a self-sustaining stream. Not only attractive and dramatic, this water feature keeps storm-water runoff from polluting Lake Michigan.

Designed and installed by St. Charles, Illinois-based Aquascape, the Pondless Waterfall features a 2,000-gallon reservoir that captures the spring rains and re-circulates the water for a never-ending stream. Shedd Aquarium chose an area adjacent to a dining terrace. Aquascape's ecosystem designs are very simple but effective in their purpose. The first step in the Shedd Aquarium project was to design a stream that fit with the topography of the site and overall vision of the landscape master plan. The area adjacent to the food terrace was the perfect location with the right topography.

Snorkel and Centipede pump modules were situated in the deepest portion of the excavation to capture every bit of water. Sixty-two Aquablox D-Raintanks were carefully positioned inside the excavated area, and then backfilled with washed sand. Once backfilling was completed, a layer of river rock was placed on top of the tanks, allowing the water to flow back down into the reservoir.

 

20 tons of gravel were used for the project, which included a deep layer on top of the reservoir, (8 by 12 inches), the bottom of the streambed, and backfill behind boulders.

The next step was to calculate the water budget for the site; Aquascape used the RainXchange website (www.rainxchange.com) to assist in their calculations in regards to the surface area draining into the system, which included the patio and any precipitation that falls directly on the water feature. For every square foot of impervious surface, the stream collects .6 gallons of water. The stream actually has more surface area than needed to operate the system. The reservoir holds 2,000 gallons, and there are 500 gallons in transition going down the stream. The stream can run for 40 days without rain, which is rather lengthy for Northeastern Illinois.

The soil from the reservoir excavation was used as material to reshape the hillside into the form of the stream. The designers' goal was to give the appearance that the stream had been there forever.

Materials Used

Aquascape trucked in 60 tons of weathered native Illinois limestone. The stream is surrounded with native plants resistant to diseases, as well as plants that require less water than other decorative species.

Soil from the excavation was used as material to reshape the hillside into the form of the stream. The designers' goal was to give the appearance that the flowing water eroded away the hillside, exposing the bedrock.

The initial excavation and earth work took only one day.

The reservoir was excavated to 13 by 10 by 5 feet, and then the base was compacted and leveled with sand. Following this, a non-woven geo-textile was placed into the excavation and then covered with a 45-milimeter EPDM rubber membrane. After that, another layer of geo-textile was placed on top of the rubber liner for extra protection.

Making it Look Natural

The key to making naturalistic streams and waterfalls is material choice and size. The best results occur when a range of sizes is implemented to mimic natural systems. As a water feature designer, one must always be thinking like running water when placing stones and gravel - especially in the waterfalls area. The key to making naturalistic streams and waterfalls is the choice and size of materials. The best results occur when a range of sizes is implemented to mimic natural systems.

The last step in constructing the Shedd Aquarium's self-sustaining waterfall was to trim the remaining liner above the water level and finish the edging with a combination of soil, rock, and gravel creating a seamless transition into the surrounding landscape. As the completed project matures, it will continue to improve in appearance.

After all the rocks were placed, expandable polyurethane waterfall foam was used to seal the joints of the rocks around the waterfalls. This was done to force flowing water over the top of the rocks instead of allowing water to sneak around them. Concurrently, other crewmembers placed a layer of mixed river rock over the remaining flat areas and streambed. The gravel not only disguises the lining material, but also acts as a biological filter.

The setting is so natural that it attracts birds and other wildlife. The self sustaining water feature provides a riparian zone, which is instrumental in water quality for surface run-off.

Visitors to the site can witness the beauty and function of a properly designed ecosystem that manages our most precious of all resources . . . water!

For more information on Aquascape's water features, log onto www.aquascapeinc.com. To plan a visit to the Shedd Aquarium, visit www.sheddaquarium.org.

Ed Beaulieu is chief sustainability officer at Aquascape, Inc. in St. Charles, Illinois He can be reached at ejbeaulieu@aquascapeinc.com.