|
Page 3 of 5
Technical Copy from an Informational Sales Booklet
Are you ready to stop purging
Under most conditions water in the screened section of a monitoring well is considered to be representative of water quality in the surrounding aquifer. This is because flow of aquifer water through the well screen constantly refreshes the water in the screened area.
So why purge? Conventional purging of monitoring wells is based on the fact that traditional practices of portable sampling and/or high flow rate pumping mix stagnant, altered water from above the screened interval into the sampling zone. The very insertion of a portable sampling device (such as a bailer) mixes and agitates the well contents and the surrounding aquifer.
These practices require the removal of multiple "well volumes" to ensure adequate removal of all stagnant water from the sampling zone. High-volume purging can require hours to complete, and result in tens or hundreds of gallons of purge water which often must be contained for disposal as a liquid hazardous waste.
With the MicroPurge sampling process, the use of dedicated low-flow sampling devices such as bladder pumps can eliminate conventional high volume purging by removing a small volume of water from the screened zone of the well without disturbing stagnant water within the casing or mixing water from other vertical zones. MicroPurge sampling results in much smaller purge volumes (often less than one gallon) and frequently reduces purging and sampling time, especially when compared to bailers.
Copyright © 1997 The QED Environmental Systems.
|
Copyright © 2010 Bauer Dunham & Barr
