If you optimize around the container, i think it should be fine, if not i'd try what Tetsuo said and start by placing a horizontal hint brush across the map at the height of the container, in case there's a leak at roof height.
There's also the purplish looking brushes from 2nd screenshot which i believe is Hammer way of drawing func_walls? If those func_walls are "touching" any leaf that is visible from outside, you done goofed
A word of warning : don't abuse HINT/SKIP brushes and use it intelligently otherwise you will have the exact opposite effect of optimization, they are here to help but not replace the job of the compilers.I've managed to finish my last goldsource map without any surface splitting from the compile tools by basically organizing my map in volumes, aka abusing the F out of hint brushes