Hi I don't think air will ...

Published May 26, 2017 04:55 by LOKESH PUNJ, A B.TECH. Agr Engg, PGDM-SPA IIMA (1977-9) 25 yrs in Water Piping / Irrigation/Infra Projects

I don't think air will behave differently wrt vertical or horizontal dispersion. Consider to inject/ release air in a slow process , in small bubbles at depth sufficient to allow its effect on top cover (thru porosity above the tunnels ). Suggestion from a layman.