Window Treatment

More than 12,000 sf of acrylic windows break down barriers between humankind and the 125,000-plus marine species at the new Georgia Aquarium in Atlanta.
August 11, 2010

The recently opened Georgia Aquarium, said to be the largest such indoor facility in the world at 450,000 sf, was designed to evoke the image of a ship crashing through the ocean's waves—a wondrous addition to Atlanta's cultural, architectural, and scientific landscape.

The $200 million project, sited adjacent to Centennial Olympic Park in downtown Atlanta, is the work of local firms Thompson, Ventulett, Stainback & Associates Inc. (architect) and Heery International (program manager), with the Kennesaw, Ga., office of Birmingham, Ala.-based Brasfield & Gorrie (general contractor) and Peckham Guyton Albers & Viets of St. Louis as exhibit designer.

Yet, for all the good work of these Building Team members, the aquarium would have been just another fish tank without the unique contribution of a specialty materials provider located more than 7,000 miles away in Kagawa, Japan: Nippura Company, which manufactured the 12,000 sf of acrylic windows that now enable visitors to view the 125,000 marine species in the new facility.

The story of these massive, thick acrylic windows—one of which may be the world's largest, at 63 feet wide, 26 feet high, and two feet thick—is a testament not only to the skill and craft of Nippura's technical staff, but also to the Building Team that hired them and designed, inspected, and installed the finished product.

The vagaries of acrylic fabrication

Because the acrylic panels were to be so huge, it was clear to the designers that the aquarium would have to be built around them, not vice versa. They knew that it would have been difficult and extremely costly, if not impossible, to pull out flawed or damaged panels once they were installed, so the windows had to be absolutely perfect from the start. This is not easy to achieve; in fact, there are just a handful of companies worldwide capable of producing acrylic window panels of the size specified for the Georgia Aquarium.

Only two of these firms submitted competitive bids, and Heery selected Nippura based on the company's pricing, ability to meet the project's tight timeline, and reputation for quality.

The first step in the creation of the windows was the fabrication of multiple layers of acrylic sheets, which were then laid on top of each other to achieve the correct thickness. This complex, multi-step process was performed at Nippura's facility in Kagawa.

Building up layer after layer of acrylic can result in distortion that renders the panels unusable. Any panel with less than absolute clarity was quickly rejected. Worse still, dirt particles and bubbles can be trapped within the acrylic layers, so the process had to be painstakingly carried out in a sterile, clean environment.

Heery sent designers, aquarium staff, and construction team members to the Nippura facility in Japan, where they worked alongside Nippura staff to inspect each panel during fabrication. The fabrication of the panels took several months to complete.

Once all the panels passed inspection, they were loaded onto boats and shipped to Savannah, then trucked 263 miles to Atlanta. In all, 328 tons of acrylic was shipped from Kagawa, in southern Japan, to Atlanta. But that was just the start of the journey.

Adding the finishing touches

At the job site in Atlanta, the Building Team erected a white tent inside the building's framework. The tent would serve as a giant thermal oven stretched over a wood structure to heat and gradually cool the acrylic panels used to create the enormous viewing windows.

In this climate-controlled work space, the Japanese fabricators bonded together the acrylic panels to create the building's underwater transparency. At the project's busiest point, 10 fabricators worked on site.

The aquarium's largest window, the one looking into the 6.2-million-gallon tank that's home to the now-famous whale sharks Ralph and Norton, is composed of the six 20-ton panels. These were bonded together by Nippura's expert fabricators underneath the thermal tent.

The six panels were positioned just a few feet outside of the window opening with a 3mm gap between them. A special bonding agent was injected between the panels, and the temperature inside the tent was gradually raised to 176 degrees F and kept hot for a couple months. Generators supported the heaters during the bonding process: If the heat was suddenly disrupted, the panels would cool too quickly and crack or break, bringing the project to a virtual standstill.

After the panels were cooled to a uniform temperature, the seams were polished to make the individual panels appear to be one large picture window. Hydraulic jacks were then used to slowly, carefully position the window into place. Finally, the finished window—and all the other windows installed early in the construction process—was encased in a protective framework as construction continued around it.

The Georgia Aquarium has 60 different habitats, so the acrylic windows looking into these underwater worlds come in all shapes and sizes. The six largest panels, each measuring about 10-1/2 feet wide by 26 feet long and weighing 20 tons, could only be brought in overhead and had to be installed before the building's roof was constructed. Installation required fitting the panels into openings in four-foot-thick concrete tank walls poured by contractor Brasfield & Gorrie.

Typically, aquarium windows are set within a border that creates a picture-frame effect that the designers wanted to avoid. Instead, in certain instances, the panels extend about a foot past the concrete edges on all sides so the viewing windows meet the walls, ceiling, and floor for maximum exposure.

The construction process was coordinated by Heery, the aquarium's Atlanta-based program manager, which oversaw a challenging schedule that required the Building Team to erect huge portions of the aquarium around the acrylic windows.

The windows were unveiled in December 2004, when the aquarium's test fills began. A temporary certificate of occupancy was issued in March 2005 so that the fish could be moved in, and the facility held its grand opening last November 23.

         
 

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