Well controls?

[rshackleford]

Yes raw hiding is surging. There is definite groundwater flow or migration. When people talk about an "underground river" it really is an underground river, but things move pretty slow. Without surging, well treatment is not very ineffective. With well surging I think that effectiveness improves. I don't feel that the chlorine is in the aquifer long enough for it to be moved past the well. I also don't think that it is pushed out into the aquifer enough for it to remain their after pumping. Ten feet of 5" well screen probably only has 15 gallons of water in it. This volume is easily pumped out on the last step of the treatment process.

Also, if the chemical is moved into the aquifer, there is a significant volume there and I would expect the small amount of chemical to be diluted by the time it reaches another extraction point.

If I am wrong or have a flaw in my theory, please inform me. I am trying to be open to new ideas here.

[speedbump]

I used to use Nu-Well tablets in Michigan years ago. We used them on 4" wells with Stainless steel 3" screens since they couldn't be pulled. It would work well as long as the screen wasn't plugged so bad that the acid couldn't get through it. The way I did them was to put the required amount of acid tablets in the well, then continuously add water. The water would dissolve the tablets and push it through the screen's slots to dissolve the sulphur and iron. They worked well and the water and acid did of coarse run into the vein. The crust around a screen can get pretty large in diameter, and this is why the acid must be forced out into the vein around it. I agree with Shack, it wouldn't have to go very far before it gets totally diluted.

Gary, from I have learned, water moves in an aquifer of sand and gravel about 3 feet per day. That's pretty slow, but then where has it got to go anyhow?

bob...

[Bob NH]

Here is a brief quote from a University of Maine site. The essence of it is that there is minimal risk of THMs from chlorinating ground water. I added the bold emphasis.

http://www.umaine.edu/waterquality/p...tions/7115.htm
When chlorinating water supplies, you need to be careful that trihalomethanes (THMs) don't form in the process. These chemicals form when free chlorine reacts with natural organic substances.

Methylene chloride, bromodichloromethane and chloroform are examples of THMs. These chemicals are considered carcinogens. Several studies have shown that they may increase your risk of getting pancreatic, bladder or rectal cancers (Ijsselmuiden et al., 1992; Morris et al., 1992).

However, remember that
1. there is very little organic material in groundwater;
2. the potential for human exposure to THMs from drinking water varies with the season, contact time, water temperature, pH and disinfection method; and
3. the health risks from drinking contaminated, untreated water are higher than the risk of cancer from THMs.

If you shock-chlorinate and purge your well system, the chance of having any THMs is very low. On the other hand, if you take water from a lake or pond and super chlorinate the water, there is more organic material in the water and the potential for THM formation is higher.

[rshackleford]

I agree with you Bob NH. That makes sense. I had wondered about the amount of organic material in ground water. Excellent article from the extension service, this article pretty much sums up our discussions here.


What about tannins (sp) or water from coal? Will these types of formations have more organic mater? Any thoughts?

[Gary Slusser]

The problem with the article is that it doesn't address the many residential wells with surface water intrusion, or those that are not very deep with short/shallow casing in rock bore wells with recovery water running in just a handful of feet below the end of the casing, etc..

IOWs, IMO it's a blanket statement to support shocking wells, and until I see the data they used to arrive at the no organics conclusion... I wonder if they ever did any tests, I don't see any references in the article.

BTW, I've never seen a Chlorox bottle that didn't say something on the label like Caution, not for use in water treatment.

Gary
Quality Water Associates

[rshackleford]

BTW, I've never seen a Chlorox bottle that didn't say something on the label like Caution, not for use in water treatment.

Gary
Quality Water Associates

Remember, though, we aren’t treating water. We are treating the well casing, the screen, the drop pipe, and the formation material not the water when we are shocking a well.

[Gary Slusser]

Remember, though, we aren’t treating water. We are treating the well casing, the screen, the drop pipe, and the formation material not the water when we are shocking a well.

Shocking a well has nothing to do with water treatment...? I don't believe that nor do I know or know of anyone in any state DEP that would agree with that. And I'll add the US EPA.

Bob(speedbump), groundwater moves in any direction any distance it can at whatever speed it can, IMO there is no constant. It moves (in)to gaining streams, creeks, rivers, lakes, swamps etc.. Gaining streams are fed by groundwater. It moves away from losing streams, they feed the groundwater, they are the water table.

From http://www.groundwatersystems.com/rehabinv.html
Chlorine alternatives for biofouling removal

The use of chlorination in wells is becoming more restrictive in parts of North America and Europe (not entirely a bad thing). Both because of this, and because shock chlorination is seldom the most effective treatment, several other treatments are being used for biofouling control. NOTE: The operation of other well chemicals are described in detail in Borch et al. (1993) and Smith (1995).

And then see this, if you really want to understand well rehab.
http://www.agr.gc.ca/pfra/water/swwidev_e.htm

Gary
Quality Water Associates

[speedbump]

Gary, I remember that from years ago at a meeting the Well drillers association had with a Geologist I believe. It was his belief (since no one has been in an aquifer that is made in sand and gravel) that ground water moves through the sand/gravel at about 3' per day. I am not talking about any kind of surface water to include lakes, streams, rivers etc. Strictly the aquifer. I agree it will go any way it wants to but I would think that direction is the same from day to day.

I'm no expert, I'm just repeating what I heard years ago.

bob...

[rshackleford]

There is a definite flow for ground water. It can be seen in well swl. It is the reason for springs. Aquifers often contribute or take away from streams and lakes. Some aquifers move rapidly and some slowly (relative to other ground water). As we all know water will seek a state of lowest energy and this is the reason for the movement. I would also agree that the water typically moves the same direction from day to day, but may change with the seasons.

Here is a better though to ponder: Does ground water move in the same fashion as the tide? If so, then aquifer flow may not be the same from day to day.

[speedbump]

You could answer that Shack by the fact that here in coastal Florida, we have salt water intrusion from drought conditions and over pumping along the coast.

Near as I can tell, the only thing that keeps the water fresh under Florida is enough rain to keep the salt water out.

What were we talking about in the first place???

bob...

[rshackleford]

LOL! This thread is way off topic!

BUT, Do you think ground water moves like the tide?

[speedbump]

Nope, the moon can't see it!

bob...

[Gary Slusser]

Around here we have some wells with recovery rates in the 20-40 gpm range. That's in rock bore wells, which you'd think would flow slower than sand and gravel wells. Some of them are 300-500' deep. So when we look at groundwater movement, who knows how fast or far BUT... a spring is flowing fairly strong, or only 5 gpm, that is groundwater that has breached the surface and has to be replaced from underground, that water is flowing much more than 3' per day or the spring fed stream would stop flowing shortly after midnight....

I think shack's eyes have glazed over but, do you guys know about/understand gaining and losing streams etc.; like flux lines? If not do a google search for flux + groundwater, in a short time you may be asleep!

Gary
Quality Water Associates

[speedbump]

The springs you mention Gary are flowing out vertically because of the static level as opposed to the ground level at the spring. Same with flowing wells, but the horizontal movement is said to be (I only heard this and I ain't Goggling it cause it's too boring to listen to any Geologists theory) around 3' per day. And this is in Michigan where most of the wells are screened in sand and gravel aquifers. I don't know about other states and their formations.

I saw a well in Michigan that had 12 lbs of pressure on it at ground level. Uncapped it went pretty high above the pipe before it started back down again. So the static water level above this location was almost 28 feet higher somewhere in that aquifer. I guess this guy lived in a deep hole.

bob...

[rshackleford]

I think shack's eyes have glazed over but, do you guys know about/understand gaining and losing streams etc.; like flux lines? If not do a google search for flux + groundwater, in a short time you may be asleep!

You want to talk about glazed over try this topic in an 8:00 am lecture with a research scientist as a professor. Worse yet, spread flux lines out over six weeks because there is nothing else to cover!

On the flowing well topic, have you ever seen any curves for well production? I have always wondered what the characteristics of these wells are as they are shut off. If they are like their artesian cousins, this curve would be fairly linear.

As for 3’ per day, I don’t know. You would need to know where the waters coming from (h1), where it is heading too (h2), how far it has to go to get there (L), the transitivity of the aquifer (K), and the porosity of the aquifer (η). Oh, you would also have to know Darcy’s law. I guess we’ll just have to accept 3’ as a good rule of thumb?