i'll update these in due time, but if i recall, these maps have been mostly integrated into Hobbes' terrain pack (please correct me if i'm wrong)
They're not on the Terrain Pack because this terrain has a lot of issues: sewers never got implemented (and they would prolong missions in finding the last alien); explosions can create craters and get units stuck; and some maps are very TFTD like in design (i.e. too complicated with a lot of rooms to search for the last alien).
Previously it was a major pain to covert them by removing the lower levels, since I'd have to redesign the entire route nodes, due to MapView issues when deleting levels (although MapView issues just got recently solved by an upgrade to it).
Terrains should simply be designed with the 50x50x4 original dimensions in mind, to prevent missions from dragging too long, with exceptions possible but they need to be justified (i.e. my Dawn City terrain is 6 levels height but all the buildings are designed so that the floor of each building actually consists of 2 levels), and avoiding TFTD's mistakes of a lot of compartments.