sediment in well

[farmkid]

My well has been having some issues lately. It started a month or two ago when I suddenly had a lot of sediment in my water. I ran some sprinklers outside for a day or so and it cleared out, but the sprinklers were full of sand by the time it was clear.

Since that time, it has happened a couple more times. We will suddenly see lots of sediment in the water and it clears after a day or so. I installed a filter for the inside water and it is working fine, but whenever this happens, it will plug up and need to be replaced.

What is going on here? My guess is that this is being caused by a cave-in or something in the cavity at the bottom of the well, but I don't know for sure. This spring there was a change in the local groundwater level that I won't go bother explaining (unless someone asks) that resulted in the water level in my well casing dropping from ~10-15 feet below ground level to ~35-40 feet below ground level. Could that be the cause? Is there anything I can do, or do I just need to keep filtering my water and wait for it to settle down?

 

[slownsteady]

Okay, I'll ask.

it's always a concern for any well owner (me) when local conditions can change your supply

 

[JoeD]

The change in level could be the cause of the sediment. I don't know what level you pump is at or how deep the well is but raising the pump level to keep it above the sediment layer might help. But then again the sediment may just build up to the new pump level.

Or perhaps the casing has cracked and is letting the sediment in.

 

[farmkid]

Okay, I'll ask.

it's always a concern for any well owner (me) when local conditions can change your supply

I was afraid it would just be a distraction, so I didn't explain earlier. But, since you asked, here's the story. Our water level has always been very high. Whenever the farmer would water the field next door, and when the snow would melt each spring, it would get high enough that our drain field couldn't get rid of water and it would make the downstairs toilet run very slow. At these times, the water level would get to about the surface.

There are field drains buried all over the area. These are pipes buried at about 7-8 feet to drain the water to make the fields more farmable. There is one that runs diagonally across the field next door and across my property. I have thought for years that there was blockage in that drain somewhere on my property. This is because every spring I could see a diagonal line that would thaw before everything else. Where that line ends on my property is a spot that was always wet. Sometimes there was even water standing on the surface, and it's not the lowest part of the yard. It just seemed to me that the drain was right there, and the water was entering in the field, flowing down to my yard, hitting the blockage, and then flowing back out. Well, this year, there was a large part (about 100-150 ft diameter half circle) of the field right next to my property, and centered around that wet spot on my property, that was too wet for the farmer to plant. He brought in a backhoe and dug it up. When they found the pipe, they had it cleaned out and my suspicion turned out to be correct. Since then, I've had no more high water problems, but my well has been acting up. I can't help but think the clearing of the drain is the cause of the drop in water level in my well.

ETA: I'm not so concerned about the change in water level because it so precisely coincides with clearing that blockage and I think is explainable by that. I have nothing to suggest any geological change, although I can't rule it out either.

 

[farmkid]

The change in level could be the cause of the sediment. I don't know what level you pump is at or how deep the well is but raising the pump level to keep it above the sediment layer might help. But then again the sediment may just build up to the new pump level.

Or perhaps the casing has cracked and is letting the sediment in.

Unfortunately, I don't know the answer to that either. I did drop a weighted line down the well last fall to calculate the volume of water when I was chlorinating the well subsequent to a changed pressure tank. I found that the pump was at about 65-70 feet, but I don't know how much casing is below that. The well is about 40 years old and I've only lived here 9 years and have no records regarding the well.

I've also wondered about a cracked or corroded casing. I would think that if that were the case I would be getting more or less constant sediment rather than large amounts once in a while, hence the thought of a cave-in in the well cavity. However, I readily admit ignorance on this issue and could well be wrong.

 

[slownsteady]

How far is your well from that wet spot? Could the digging have damaged your casing either by a direct contact or pressure from a lateral movement. And an open question: can a well be pressure tested?