Question For An Expert

We have a 145 foot sand well with 4 inch casing and a one horsepower submersible pump. The well was drilled in 1978 and has never given any problems other than having to replace the submersible pump.

Just a couple of weeks back, we started experiencing sprinkler heads binding or not wanting to turn freely. Upon closer examination, I discovered small amounts of very fine sand in the the sprinkler head "workings". We still do have plenty of water, but the need to clean the sprinklers every other day is frustrating.

What might be causing this problem all of a sudden?

Side note: A friend of a friend who dabbles with drilling wells around our part of the country (South Carolina) has stated we should disconnect the piping from the well head and let it run for about an hour to purge the system of any buildup. He has stated that all wells will normally have a buildup of residue after a number of years AND the fact that we are in a drought and the water table has dropped several feet doesn't help matters. Does this sound reasonable?

If it does sound reasonable, then why doesn't the system simply purge itself as we irrigate with the sprinklers. Or stated another way, why would I need to take the piping loose at the well head and run the pump for an hour or so to purge the system? To me, whether pumping water through a sprinkler head or directly onto the ground at the well head is the same .......... I can't quite understand how his approach will clean the system any better???????

Thanks!

The increased amount of flow is what helps purge sediment from the pipes. Your sprinklers put backpressure on the system slowing down the flow.


bob...

Valveman

In a sand well, when the water level drops, the sand on top dries out and starts sluffing off into the well. When the water level is high, the sand is wet and stays together like beach sand does. This is common in our area so we use .035 slotted casing with a gravel pac for filter that uses gravel almost as small as the sand. Gotta filter the sand before it enters the casing or you just have to pump it out as best you can.

Thanks Speedbump and Valveman!

Saturday, I plan to disconnect the piping at the well head and purge the system. I hope that does the trick! However, if it doesn't take care of the sand, would either of you be willing to recommend some type filter I could install that would help. It may have to be cleaned monthly ???, but that would certainly be better than digging a new well. I have plenty of water!

Thanks again!

I can make you a simple backwashable filter that will trap all the sand and not give much backpressure.

You need to think about what the sand is doing to your pump. If you are pumping much sand, it can destroy a pump in a hurry.

bob...

speedbump said:

I can make you a simple backwashable filter that will trap all the sand and not give much backpressure.

You need to think about what the sand is doing to your pump. If you are pumping much sand, it can destroy a pump in a hurry.

bob...

Click to expand...

Thanks again Bob!

I disconnected the piping at the well head today and let the system flow freely for 4.5 hours (pumping approxiamtely 15 GPM). At the end of the 4.5 hours, I let the water flow into a 5 gallon bucket and overflow for about 30 minutes. At the end of the 30 minutes, I checked to see if there was any sand in the bottom of the bucket. There was a little and it was fine as beach sand. The amount measured approximately 1/10 (one tenth) of a teaspoon.

I'm hoping this is acceptable? We will know in a couple of days if the sprinklers are going to perform better. If this small amount of sand is not acceptable, what should I do. I certainly don't want to drill another well. I have plenty of water!

Tell me more about the simple backwashable filter.

Thanks again!

If your sprinklers still plug up after the running for 4.5 hours, the only thing left is to filter the sand out. I use a water softener tank and an in/out head. The tank has sand in it that will catch the finer sand which can be backwashed out later. You can make it automatic if you don't mind spending the extra money. The manual filter is made backwashable with several ball valves.

Hopefully that small amount won't give you problems. When you attach the piping again, the backpressure will help slow the sand a little more than running open discharge.

Keep us informed.

bob...

Thanks again Bob!

It's been 4 days since I disconnected the piping at the well head and purged the system for 4.5 hours ................ thus far, we have had no problems with sand in the sprinklers. I hope I'm not speaking too quick, but this must have been the remedy.

Thanks!