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# Help with Determining Radius of Influence of Groundwater/Wells

## Help with Determining Radius of Influence of Groundwater/Wells

(OP)
Currently I am looking the radius of influence for a well for ground water. The data that I have is the bore log, sieve analysis , Resistivity/electric log soil test, constant pump test with both drawdown and residual drawdown versus time. I do not have data from any observation wells. I know majority of the soil type in which drawdown occurs is within clayey sand type. Currently the two wells are located 300 feet from each other and I was told they do not effect each other when pumping occurs. I can theoretically use the Sichardt equation and higher range of permeability to be conservative for clayey sands but the calculated radius of influence surpasses the current distance between the two wells. I have also used the Theis method and graphed the drawdown versus time and calculated a higher permeability than what I am looking for. I can use a smaller permeability value within the range for clayey sands and have good results. The problem is that I need to defend my claim on this project. Does anyone have any other suggestions that could help give a more finite way of determining the radius of influence?

### RE: Help with Determining Radius of Influence of Groundwater/Wells

It' been a long time since I worked with this. Does the drawdown test give you transmissivity of the formation, and is this sufficient to determine the drawdown curve?
Perhaps you can't prove that the well doesn't influence the adjacent well, but could show it has minimal effect under conservative assumed conditions, which only slightly reduces the maximum possible sustained pumping rate for the adjacent well.

### RE: Help with Determining Radius of Influence of Groundwater/Wells

To many variables to say without data from several wells.
I had a dispute where one well was contaminating another well.
We had a fairly shallow aquifer and also had the effect of natural water movement.
That is, an underground river.
I suggest finding an area with copious data on wells and do a comparison between two or more sites.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

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