alt Hacker NewsTbh I'm not entirely sure I'd trust a partial plane body to have the mechanical strength for the job. In flight the pressure is pushing out not in, and I assume that's what the thing is designed for.
Though the thing is only barely buried so I suppose it doesn't actually have much external pressure to deal with.
He is pouring concrete re-enforcement around it. Biggest issue is during the pour which he seems to have planned in stages to not put too much pressure on it.