Multilevel Monitoring Wells: Zone Isolated Sampling Technology

Zone Isolation Sampling Technologies

Purge volume reduction can be an important consideration for long-term groundwater monitoring programs. Early technical guidance from the US EPA Superfund Program prescribed the concept of 3-5 wet casing volume purging and was quickly adopted by many regulatory agencies throughout the US. This can lead to time, transport and storage problems when purging large volumes of water from a well, especially in remote or hard to access locations.

Zone Isolation Sampling Technologies (ZIST)™ In-Line Systems isolate the well screen, allowing for a low-flow sampling and fast parameter stabilization, in which pumps do not draw stagnant water from the riser pipe above the screen. As a result, data quality is improved, costs are minimized (system components, drilling, installation, and operation over time), and sampling time reduced. BESST’s Panacea Pumps dock with the ZIST™ Well Screen Receptacle located between the well screen and riser pipe and draw samples only from the well screen. The pump can easily be removed for maintenance, pumping tests, or use of other monitoring devices.

Benefits of ZIST™

Reduces costs
Eliminates drawdown
Reduces purge volume as a result of sampling mechanism
When 3-5 wet casing volumes are required, purge volume is reduced by as much as 60% by ZIST displacement systems