A contractor contacted Symons® by Dayton Superior about forming a pair of complex stilling basins. He explained that the basins differed in size, but that both featured penetrations, and multiple blockouts, plus baffles and decks that needed to be poured monolithically with the walls.

After discussing this challenging project with the contractor, Symons came up with a scheme to form the stilling basins with the Steel-Ply forming system. To form the 3'-1" wide deck around the top of three walls, taller forms were used on the outside and inside corners were used horizontally along the to edge of the shorter inside forms to make the transition to the deck. The deck layout consisted of Steel-Ply panels laid flat and supported by lumber. Along the edge of the deck, outside corners were used horizontally to attach Steel‑Ply fillers.

The baffle was formed in a similar fashion, except that corners commonly used for culverts replaced inside corners to accommodate a 6" chamfer on the bottom of the baffle deck. A combination of horizontal and vertical panels were connected to these important elements to complete the plan.

When constructing the first stilling basin, the contractor encountered unforeseen jobsite conditions that occurred after the project was already underway.

The first challenge was that the 90" pipe that penetrated the headwall was at an angle, contrary to the original structural plans. That meant that the formwork layout had to be adjusted to accommodate this unexpected change. The contractor was relieved to discover that the variety of panel and filler sizes simplified the change from the original building plans supplied by Symons.

Another problem that the contractor encountered was water and mud infiltration of the excavated site. After some consideration, it was decided that the contractor would pour the first 8' of the basin walls to block erosion and then simply leave the lower panels in place while erecting the remaining forms.

Construction of the second basin commenced with most of the same equipment required for the first one. Symons designed the layouts for this slightly different structure to utilize as much of the original components as possible, minimizing the amount of idle equipment on the site.

The contractor was pleased with the accurate and detailed drawings provided by Symons. The plans helped both phases of the project progress smoothly and quickly.

The contractor was also impressed by how little job-building, which slows down progress and adds to labor costs, was required. They reported that the versatility of Steel-Ply helped complete the project on time and under budget, despite unusual specifications and unforeseen jobsite complications, and that they are looking forward to working with Symons again.

Steel-Ply® Concrete Forming System

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