Subterranean barrel cellars are the nicest way to achieve cool, stable temperatures and humidity. Safety procedures must be built-in to ventilate the room. Some years ago I worked with a group that wished to do a very large hole in the ground for both tanks and barrels. My solution was a 3-foot diameter tunnel to let the gas escape. 15 years later, no one has been asphyxiated.
Some larger wineries stack full barrels six high.
This stacking produces a pressure of 450 to 550 psi on the points supporting the bottom barrel. I have seen a few dented barrels, but none with sufficient damage to cause leakage. Most forklift drivers would appreciate a clearance of more than one foot from the lowest lights. Based on information from John Lansingh of Western Square Industries. There are countless examples of winery layouts that show that almost any arrangement can be made to work.