What purge method would you recommend for regional studies utilizing private domestic wells?
What purge method would you recommend for regional studies utilizing private domestic wells?
For private domestic wells, you generally want to look at the water as it’s being consumed. So for private domestic well sampling for water quality, I generally would not use low flow purging sampling. The best methodology is the traditional approach of turning on the actual pump that’s being used in that well and allowing it to run until electric conductivity or specific conductance is stabilized. That’s about the best indication that you’ve got stable conditions. Now, take a sample either right from the pump if you’ve got a sample tap there or from a point of discharge if you are looking at water quality at a point of consumption. If you are looking at regional water quality and using those wells for that purpose, then if you have a sample tap at the well head that’s the best method. Having said that, we’re seeing quite a number of both municipal and rural water supplies that use groundwater as a primary water source moving toward the use of sentinel wells for determining changes in water quality before they get to the actual extraction wells. So, when you are sampling from a domestic well, you want to sample that well by purging it at a higher rate. But, when you’re sampling a sentinel well for water quality, then you would switch over to low flow sampling.
For private domestic wells, you generally want to look at the water as it’s being consumed. So for private domestic well sampling for water quality, I generally would not use low flow purging sampling. The best methodology is the traditional approach of turning on the actual pump that’s being used in that well and allowing it to run until electric conductivity or specific conductance is stabilized. That’s about the best indication that you’ve got stable conditions. Now, take a sample either right from the pump if you’ve got a sample tap there or from a point of discharge if you are looking at water quality at a point of consumption. If you are looking at regional water quality and using those wells for that purpose, then if you have a sample tap at the well head that’s the best method. Having said that, we’re seeing quite a number of both municipal and rural water supplies that use groundwater as a primary water source moving toward the use of sentinel wells for determining changes in water quality before they get to the actual extraction wells. So, when you are sampling from a domestic well, you want to sample that well by purging it at a higher rate. But, when you’re sampling a sentinel well for water quality, then you would switch over to low flow sampling.