The United States has such a large GDP because 1/3 of it is the private healthcare industry. Another massive chunk is the government throwing tax dollars at a shell company of a shell company of a shell company that moves a government contract for construction around to each other 4 times, all subsequently increasing GDP.
Temporary floating docks are literally just a common thing that you use on offshore construction, what the fuck 
Seriously, they could have just hired Bubba Joe's Floating Dock Company to install this for like $750k. They install shit like this all. the. time. And in fact, I'll bet they did do just that and just pocketed the rest.