Pipe burial apparatus are disclosed that include sets of rotary nozzle cutters configured to straddle a pipe that is to be buried and a nozzle array connected to a nozzle supply pipe in a manner that places the nozzle supply pipe in a cutting path of a rotary nozzle cutter. The nozzle supply pipe may be actuated to alternatingly move the nozzle array between a position straddling the pipe being buried and a cutting position that is below the pipe being buried.