A vacuum system for use in excavation operations. The system uses a tank having an open end that is closed by a door. The door is opened and closed by a door lifting assembly made up of an upper linkage arm, a lower linkage arm and a hydraulic cylinder. A socket is formed in the upper linkage arm, and a shaft housing is formed in the lower linkage arm. The shaft housing engages with the socket to latch the door closed. The upper linkage arm is attached to the door at a first pivot axis and is attached to the lower linkage arm at a second pivot axis. The lower linkage arm is attached to a side of the tank at a third pivot axis. When the door is open, the second pivot axis extends below a reference plane that contains the first and third pivot axis.