This massive concrete construction project presented several unusual forming conditions. The concrete tank enclosure required easy access for vertical and horizontal post-tensioning devices during forming operations. In addition, unpredictable weather over the months of construction meant that it must be designed to withstand hurricane-force winds.

The Flex-Form system was chosen because it is shipped to the job site with rolled ribs for the proper inside radius and outside radius already installed and because of the smooth concrete finish that the steel form face provides. Mounted on a jump form system for simple lifting by crane, the rollback feature allowed workers adequate access for rebar installation and post-tensioning operations. In addition, the assembled components met the hurricane resistance requirements.

Project Engineer Luis Uzcategui directed the Aireko construction crew to set the first 6' of forms all the way around the circular structure. Once that pour was completed, they added a row of 4' forms so that subsequent lifts would build 9' of wall with a 1' overlap of the previous pour.

Workers appreciated the walkway and the easy access for the installation of rebar, imbeds and post-tensioning tubes. PDM and Aireko officials commented on the safety advantages and convenience of the wide working platform.