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September 28, 2018

Grand Award
Low-rise structures (nonresidential)

Photo provided by WACA
Polished concrete covers 80 percent of the floor area inside Tacoma’s Science and Math Institute.

SAMI at the Environmental Learning Center

Location: Tacoma

Owner/developer: Tacoma Public Schools

Team: Forma Construction, general and concrete contractor; McGranahan Architects, architect; PCS Structural Solutions, structural engineer; Miles Sand & Gravel, ready-mix supplier

The Environmental Learning Center is a unique partnership between Tacoma Public Schools and Metro Parks Tacoma where students can learn about sustainability, ecology and nature conservancy.

Built on the Point Defiance Zoo & Aquarium campus, this multi-use facility houses formal learning spaces for Tacoma’s Science and Math Institute (SAMI), as well as community spaces, collaborative and interpretive learning areas, and coordination and work spaces for zoo staff and volunteers.

Producing a 30,000-square-foot school on a very constrained site — and in the middle of an occupied zoo campus — required creative approaches to designing and building concrete forms, footings and shoring. Sited on a steeply sloping hill just 10 feet from the zoo’s busy Animal Loop Drive, the west and north foundation walls — at 15 feet tall — were designed to serve a dual purpose as both foundation and retaining walls.

Collaborating with a local structural engineer on shoring plans, the general contractor installed a soil nail wall to support the road until these foundation/retaining walls were complete and the second floor was placed.

At its south entrance, the center features enormous concrete walls soaring 20 feet from their footings. Exposed on the exterior and interior of the building, these walls included numerous reveals and openings designed by the architect.

Bringing on a subcontractor to create shop drawings for these exposed walls helped streamline communication between the general contractor and architects, assuring that none of the details were lost in the process.

The restrictive site size and its proximity to the road through Point Defiance Park required that all concrete wall forms be hand-built with MDO using a typical strong back system — no tilt-up or precast concrete elements could be incorporated.

To take advantage of every inch of the construction site, the general contractor stored a majority of the construction materials 1,000 feet down the road, carefully coordinating the delivery of materials to the site within the project schedule. Allowing all trades on site at the same time meant subcontractor crews were overlapping in schedules, requiring site electrical and excavation of power and utilities to run concurrent to excavation and backfilling of foundations.

During concrete pours, the contractor worked with Metro Parks Tacoma to close Animal Loop Road — requiring additional coordination with the zoo to ensure these closures were not limiting access for the zoo and the park’s other ongoing improvement projects.

Inside, the gleaming, polished concrete floors on the first and second levels make up 80 percent of the school’s floor area. The second-floor slab, installed over metal decking, required customized, detailed layout and saw-cutting of joints.

Several mock-ups of the floor polishing were created and tested on to help develop the best procedure for cutting the joints on the finished floors. These floors were then water cured and protected with filter fabric after placement, which was removed prior to crews using the Retro-Plate 99 system to polish the concrete floors.

Though not extremely large, the center and its site included extensive concrete work. Besides its traditional concrete stem walls and footings, concrete soil nail walls, and concrete basement and retaining walls, the project also included concrete amphitheater steps, new outdoor stairs and concrete walkways, exterior hardscape, exposed and polished concrete floors, and interior concrete shear walls.

The general contractor’s self-performance of the concrete on the center brought to fruition the architect’s design goals through efficient, cost-effective and long-lasting materiality.

Just like the environmental conditions that SAMI students study, the finished Environmental Learning Center looks like it was always meant to be there.

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