The image below shows the south side and back of the privy, located in area 5 on the site map.
Note the framed opening on the back of the privy, near its base. There is another similar opening on the second-seat side of the privy as well. We suspect there exists only 2 or 3 feet of space beneath the privy interior, before it hits solid bedrock. These openings may have been created as vents, or may have served to drain off the privy refuse onto the downhill slope immediately behind the privy. Such a stone privy located on shallow ground would have necessitated periodic cleaning to keep its refuse space open.