Patent ID: 7891439

Claim:
A method of making a borehole between two pits, comprising the steps of: drilling a pilot bore in a first direction from a machine pit to an end pit and lining the pilot bore with a pipe casing to form a pipe string; expanding the pilot bore in a second direction in opposition to the first direction to form an expansion bore lined with a pipe casing by attaching first pipe sections with interiorly arranged screw conveyor sections in the end pit in succession onto the pipe string of the pilot bore to form the pipe casing of the expansion bore; thereby transporting loosened soil into the end pit in opposition to the second direction as the pilot bore is expanded; successively attaching in the machine pit finished second pipe sections of a same diameter as the first pipe sections with interiorly arranged screw conveyor sections onto the first pipe sections; and removing the first pipe sections from the end pit.