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Frequently Asked Questions

First of all, the purpose of development is to move fine material out of the sand pack and its surrounding formation after the well is constructed because there will be a lot of artificial turbidity there just from the well construction and drilling process.

If you are in a formation that produces enough water and it’s hydraulically conductive enough that you can easily or readily develop it, then by all means it should be developed. That being said, I have worked at a number of monitoring wells where development won't work. The main reason being that we were dealing with extremely fine formation material and sand pack, and the slot size of the screen was selected without doing analysis of this very fine material.

With extensive well development, as much as 8-10 hours of development in a given well, you can many times get even wells like that to clear up.  But here is one thing about low-flow sampling that’s important to know: low-flow purging and sampling can work really effectively as a mandate to reduce turbidity.  I have worked at sites where turbidity from samples that were bailed or pumped using traditional methods was as high as 1,000-1,500 NTU.  We effectively used low-flow purging and sampling to get turbidity down to 20-50 NTU.

As long as there is not a stated drawdown limit that you have to meet, stay at the highest practical flow rate. Provided that the water level stabilizes very quickly, the preference would be to stay at that higher flow rate and greater drawdown. But, if you have continued drawdown that will not slow down you have no choice but to back off on the flow rate so as not to dewater the well.

That traditional order of bottle-filling starts with what we call the most volatile to the least volatile. VOCs, SVOCs, metals, and filters is based on old research that used predominantly bailers for sampling.  If a bailer is pulled out of a well, you want to take the most volatile sample first since it has the greatest effect of changing that sample with time.  But if you’re pumping from a well at a low flow rate, under steady state conditions, and with stabilized indicator parameters then the bottle filling order no longer matters; what does matter is the flow rate.  So if you start out at a flow rate of 500 or 300 mL per minute and have larger bottles to fill, fill those first, then reduce the flow rate and fill smaller bottles, and finally, pause momentarily to install the filter, and take the filtered parameters.  So the old bottle filling order is still correct if you are using a bailer, but if you are using a low flow pump and a low flow approach, bottle filling order really goes from largest to smallest bottles.