Seals for aluminum dome covered tanks

[nbuc7]

Hi everyone - I have large (90 ft. dia.) concrete sludge storage tanks covered by aluminum domes. I am designing an odor control retrofit for the tanks and need to seal the gap (approximately 1-2" but it varies) between the top of the concrete walls and the aluminum domes. The walls are 2 ft thick and the edge of the dome sits above the centerline of the walls. I've seen some foam seals and structural inserts with a polyvinyl coating, but I was wondering if anyone has had any experience with these or with another type of system. H2S levels are fairly low - range from 2-5 ppm; vacuum pressure 2-3" water.

Thanks for any help you have to offer!