What is the minimum amount of volume/time to purge a well while using the low-flow method?
What is the minimum amount of volume/time to purge a well while using the low-flow method?
There is no minimum volume or time requirement for low-flow purging prior to sampling. The purge time and volume are dependent only on achieving indicator parameter stabilization after achieving a stable pumping water level. Typical purge volumes for many 2"-4" wells with screens 5-20 feet long are in the range of 4-20 liters (1-5 gallons) in 15-30 minutes of purging.
Is it ok to sample after as little as 20-30 minutes?
As stated above, as long as both pumping water level and indicator parameters are stable within the established criteria you can sample the well.
There is no minimum volume or time requirement for low-flow purging prior to sampling. The purge time and volume are dependent only on achieving indicator parameter stabilization after achieving a stable pumping water level. Typical purge volumes for many 2"-4" wells with screens 5-20 feet long are in the range of 4-20 liters (1-5 gallons) in 15-30 minutes of purging.
Is it ok to sample after as little as 20-30 minutes?
As stated above, as long as both pumping water level and indicator parameters are stable within the established criteria you can sample the well.