Interval ORP

orp on a PurgeInterval is monitored to confirm the redox character of the groundwater is stabilizing during the purge. ORP (typically in millivolts) often fluctuates early in a purge as air-exposed stagnant water is displaced. A stable orp across the final two or three PurgeIntervals confirms that the well is now pumping representative formation water. This trend is part of the stabilization documentation required for many low-flow sampling protocols.