Sometimes blasting is not an option due to close proximity to existing structures or pipelines. Using a hydraulic hammer to break the rock is costly and could add weeks or months on to a project.
A way to lessen the burden of hammering is to line drill or "swiss cheese" the rock. This involves drilling lots of holes close together. In certain shale or other softer rock this process may make the material diggable without the need for a hydraulic hammer. In harder rock like granite or limestone, line drilling significantly reduces the time needed to hammer out the rock.