I would guess by coating the floors/ground with sealing coating (and walls and ceilings if you're underground). It might need to be nice and thick to withstand

I would guess by coating the floors/ground with sealing coating (and walls and ceilings if you're underground). It might need to be nice and thick to withstand wear, but maybe not that thick depending on how tough the sealant is, how regular the surfaces and how well maintained.