Actually that cache is at -2 meters, as can be seen in your list of badges. The text when you hoover on the badge clearly says that the unit is meters. My guess is that a change here would mostly give new problems since the conversion between the two would be a bit messy, 1 meter is 3.28084 feet so the tiers in feet would be: 0, -3.28084, -16.4042, -32.8084, -82.021, -131.2336, -196.8504 and -328.084 and the badges would have to have the same requirements because badges can't be easier/harder based on your settings. :) And if you put "-3 feet" instead of "-3.28084 feet" when the requirement in the database is -1 meter there will be somebody with a find at -3.0 feet asking why they didn't get the silver badge. ;)