Yes, tanks would corrode so it would be temporary but it would also be immediate. Concrete lined pits are also temporary and subject to evaporation which spreads contaminants, and to rain which can overflow the pits. As all concrete cracks, pits are subject to leakage. Synthetic liners can be tricky to install... not as time consuming as clay liners, of course. Perhaps a combination of the two could be considered.

In any case, if they nixed tanks, it ain't the way to go I guess.