The delay had been so long between formulating the blueprints and delivery date that I completely forgot one little detail: shims. The foundation was engineered to be higher at each end than in the middle, ostensibly to account for any sagging and also to avoid high-centering the box during placement. When it was set into place, there was a gap between the top of the middle foundation and the middle of the box’s bottom rails.
I was a little dumbfounded with how to proceed at first, but after a couple of days I snapped out of it and started making some phone calls. I found a place called Metal Supermarket in OKC that could frank ate some plates for me, and then I also contacted a local welder who could weld the plates to the box, the foundation and each other.
Here’s a pic of the finished result, taken months after the fact so the welds and plates have oxidized:
There was some spalding of the concrete from the heat of the welding. In the future it may be beneficial to build the foundations with a metal cap that covers the edge of the concrete. Otherwise, the whole thing was welded into place at all four corners and the shims fit perfectly. I forgot to mention above that, in addition to a welder, I also had to hire a forklift to come lift up one end of the container so the shins could be placed on the middle supports. Personnel from Allied Steel, the same company that had the boom trick for the container’s placement, did that work. Kent from Metal Fusion did the welding work.