The Effects of Groundwater Samplers on Water Quality. A Literature Review

This report reviews both field and laboratory studies that test or compare the ability of various types of samplers to deliver representative groundwater samples. Several types of grab samplers, positive displacement devices, and suction-lift devices are evaluated. It was found that most of these devices can, under certain circumstances, alter the chemistry of a groundwater sample. Gas-lift pumps, older types of submersible centrifugal pumps, and suction-lift devices are not recommended when sampling for sensitive constituents such as volatile organics and inorganics and inorganics that are subject to oxidation/precipitation reactions. Generally, of the devices reviewed in this report, bladder pumps gave the best recovery of these sensitive constituents. However, better performance could be achieved for several devices if better operational guidelines were developed by additional testing. Clearly, further research is warranted. Issues that need to be addressed in future studies include pumping rate, use of flow control mechanisms, and dedication of samplers. Grab samplers,