Abstract: A first low pressure storage tank is provided including a liquid inlet and a valved liquid outlet as well as a vapor outlet. Gas pump structure is also provided including suction and discharge ports and a high pressure storage tank is provided including a gas inlet and a gas outlet. First pipe structure is provided including an inlet end for communication with the liquid trap or sump of a gas transmission pipe line and an outlet end communicated with a gas inlet for the low pressure storage tank. A second pipe communicates the vapor outlet of the low pressure tank with the suction port of the gas pump and a third pipe communicates the discharge port of a gas pump with the gas inlet for the high pressure tank. Further, the second pipe includes a gas/liquid separator including a valved out communicated with the first pipe and the high pressure storage tank includes a lower valved liquid outlet communicated with the first pipe.