Abstract: A transport tank and a spreader tank with a communicating conduit system for the transfer of liquid sludge to the latter tank. A conduit shut off and venting system includes a receptacle into which a first conduit discharges with a remaining flexible conduit segment leading to the spreader tank. The receptacle mounts an air cylinder provided with a piston actuated valve assembly operable to close a receptacle intake port and open a receptacle vent for venting and evacuation of the flexible conduit segment. When oppositely positioned the valve assembly closes the vent for normal fluid transfer. A valve in circuit with a fluid level sensing device controls air cylinder operation.