[TowerTalk] ground rods and wells

[Roger (K8RI)]

On 1/5/2011 11:13 AM, jimlux wrote:
> On 1/4/11 7:20 AM, WA2PUQ wrote:
>> Correct me, if I'm wrong, but doesn't the well casing only run down to the
>> bedrock, the pump being possibly much deeper in the hole?
>> If so, even the connected ground and casing might not be of that great a
>> help.
>>
This is another ...It all depends. Much of the country, or maybe most of 
if is not mountainous and bed rock is a very long way down so the wells 
do not extend all the way to bed rock. Here bed rock (shale) is only 
about 470' down. On top of that are various layers of sand, gravel, and 
clay.  Under that shale are various layers of salt water, crude, and 
other noxious stuff with many spots where that *stuff* is leaking out 
contaminating ground water.  BTW Shallow crude is usually sour (contains 
high sulfur content and other *stuff* including bromine)

You may get good water at 50 feet or 150 feet just a few feet over. 
These various aquifers usually slope, so what you have at 150 feet may 
actually come to the surface only a few miles away, or it could be 20 or 
30 miles.  By the same token, you may have good water for decades and 
then have it turn bad.  You may drill a new well and have good water for 
30-50 years, and it may only be good for weeks.
These wells have an outer casing as well as in inner one with the 
"point" or points attached to it.  These points are gasketed to the 
casing at the top and can be placed series for more capacity. These 
screens are a tube with a network of fairly large holes covered with a 
fine screen.  These screens can plug up and in areas where there is a 
lot of lime in the water they can plug up rapidly.  The lime can 
sometimes be removed by "acidizing" a well .  The acid reacts with the 
lime (calcium carbonate) and dissolves it. Any excess acid is quickly 
neutralized by the lime in the water. Other times the inner casing with 
points attached have to be pulled and the point or points replaced. Then 
again lime collects around the points and it may be necessary to drill a 
new well which is not cheap.  A 150' 3 or 4" well is going to run some 
where between $6000 and $10,000 around here.  More if there are lots of 
rocks.

Agricultural wells in the Great Planes and South West may be 1500 feet 
deep or more

But to comment on the strike where the water from the well was cloudy. 
The lightning may create enough of a mechanical shock (steam or 
magnetic), or electrical impact to actually remove the coating of lime 
on the point and inside the well casing. It *may* also blow the screen 
right out of the point.

73

Roger (K8RI)
>> Stan
>>
>
> Could be.
> I'm pretty ignorant on wells and such.
>
> I was just wondering what the failure mechanism would be.  Is it current
> flowing from the earth into the pump and up the power wires (or vice
> versa)?  Or something else?
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