Just to add to dcasto's points:
-Before using the drain system you need to get it dry, otherwise during use water and CO2 will freeze out onto the piping and possibly (depending on line size) plug up the works.
-You need a heat sink on the other end to vaporize the cryogenic liquid. Air is a heat sink, but only small flows can be safely routed to the ground. Any large sustained flows must be vaporized using some energy input (atmospheric vaporizer, forced air, etc)
-Fogging will be an issue in the area of the drain outlet, keep in mind for facility siting (roads, walkways, neighbors).
-Be aware of the asphyxiation risks when routing the drain discharge, a small amount of cryogenic liquid becomes a large amount of gas.