NMD90 is not approved for wet locations. Underground is wet not damp so if you really want to put the cable in a raceway then the cable and the raceway must be approved for wet locations.
A cable like NMWU that is approved for direct burial can be installed in Non Electrical raceways like poly pipe. City lighting was often done by direct bury of a poly water hose using a ditch witch and then using jacketed xlink to feed the light standards. More municipalities now use ENT and regular wet location wire. The big advantage of the poly pipe was the direct burial which removed the dig, install, sand the trench, mark the trench, inspect and bury. The alternate was drive a tractor down the street and tamp the sod down behind the tractor. I think ENT can be installed like this where acceptable.
