A decision in favor of site casting combined with an ingenious removable spreader invented on the job helped save time and money on a unique 500,000 dollar Sea Arena at Marineland of the Pacific. A major factor in the success of this project was the removable spreader invented by the job superintendent, in order to maintain a constant 6 inch thickness directly beneath the bench seats. The superintendent simply took an 18 inch length of 2 by 2, with one corner beveled in order to reduce the width and provide for easier removal following the pour. A vertical support for the exterior riser form was secured and two dowels were fitted into holes drilled approximately 6 inches apart, parallel to the flat beveled surface. Inserted between form and re-bar at 4 foot intervals, the spreader dowels butted at right angles against the inner plywood forms and maintained the desired beam width. After the pour the spreader was simply grasped at the top, given a one quarter turn, and was easily withdrawn.