What ? We need more info but that damper can’t be lower than ground level it would make no sense.

@Patricia Colwell Consulting The damper needs to connect to the return on the furnace, which is in the basement. The ceiling in the basement is right about ground level so that's the limitations we are working with. There is an old grate in the basement wall to the outside that happens to be in the perfect location for us to repurpose so we were going to knock that out and install the damper/ducting there... there's kind of a window well there built around it that protects it from flooding since it is right at/slightly below ground level.

But that all said, we need something else built around this or connected to it to keep it from getting blocked. So perhaps an enclosure with a little roof and a grate to allow air flow? Or perhaps connect ducting to the outside of the damper and put a cap on top like on roof vents?