RQD denotes the percentage of intact & sound rock retrieved from a borehole of any orientation. All 100 mm (4 in) or longer pieces of intact and sound rock core are summed and divided by the total length of the core run. Judgment may be required when determining "intact and sound."
One complete run, as determined by the engineer. Either a drill run, a complete core through one type of rock, or a complete run through a selected zone of concern.
Classification, index, logging, quality, rock core, RQD