To Clean or Not to Clean sand out of well

Discussion in 'Pumps and Tanks Well Forum & Blog' started by tvl, Jun 10, 2013.

  1. tvl

    tvl Member

    Messages:
    139
    Location:
    South Carolina
    I decided to begin another thread as the other was getting too long & too wordy .................. hope this is acceptable!

    As of today, I have spoken with two different well drillers and have received similar options with a small twist and would like some guidance from you guys:

    I first explained to each driller our well was 35 years old, 4 inch PVC pipe, 145 feet deep with a 1 HP 10 GPM submersible pump. It wasn't until a year or two later that I actually measured the distance the pump hung AND the distance to the bottom of the well. My notes then indicated the bottom of the well was at approximately 134 feet. My latest and MOST accurate reading shows it is just slightly over 132 feet. The three pumps I have used over the years have ALWAYS hung at about 130 to 131 feet (to the bottom of the pump).

    I do remember when the original driller poured gravel between the hole opening and the well casing, a good amount also went down into the casing itself. I am assuming this is why the bottom measures less than the reported depth ........ there is possibly 12 to 13 feet of gravel on the very bottom of the well casing. Neither of my two neighbors are experiencing water issues (one has a well the exact same depth as mine and the other is shallower by about 40 feet.

    Driller #1: Based on these facts, he is leaning towards a well issue and not a water issue (he does admit this is an educated guess). He feels he can clean the well with very, very high pressure which will open any possibly clogged strainer openings AND purge what is on the bottom of the well ....... if anything at all. He has indicated this may or may not resolve my issues and the cost is $1500.

    Driller #2: He also feels I have a well issue and not a water issue. He has dug several wells in the surrounding area and knows one can't go any deeper at out location without hitting rock. He also states he does NOT believe any of the strainer openings are clogged as the water doesn't have any minerals that are famous for clogging up a well strainer. BUT, based on the water depth in this aquifer, he FEELS this well was primarily a bottom feeder. And, over the years, the bottom 12 feet of gravel packing as become clogged with sand .......... if the bottom 12 feet truly does have gravel in it?? Therefore, he wants to pressurize the well casing and PUSH/LIFT out any debris that may be at the bottom; gravel or whatever. He does not have a rig like driller #1 that can also utilize very high pressure to clean the strainer, but again, doesn't feel it is needed in my case. The cost will be $300 if I pull the pump myself. He states he will be using between 150 and 200 PSI to purge the well.

    So, what do you guys think? $300 is a lot better than $1500, but can one use the lower pressure to clean out the debis from so far down?
    Last edited: Jun 11, 2013
  2. valveman

    valveman Moderator Staff Member

    Messages:
    4,586
    Location:
    Lubbock, Texas
    There are many ways to clean the sand out of the well. However, if the gravel is too large or not placed in the well correctly, the well will always make sand. Sand should not "clog" the gravel pack. The sand locked in the gravel is what makes the filter to filter out more sand. If the sand is coming through the gravel pack, most likely the size of the gravel is too large.
  3. tvl

    tvl Member

    Messages:
    139
    Location:
    South Carolina
    Thanks Valveman!

    So, if I am interpreting your reply correctly, there would probably be nothing to gain by having the well cleaned OR by having the "debris" removed from the bottom 12 feet ....... in other words, it would not allow the well to provide more water?????

    And one last thought ..... if there is 12 feet of gravel blocking the bottom 12 feet and I had it removed, that would allow me to lower the pump a few more feet. Could this help OR would that be a mistake in your opinion???

    Thanks so much!
  4. valveman

    valveman Moderator Staff Member

    Messages:
    4,586
    Location:
    Lubbock, Texas
    You can blow or bail the sand out as deep as you want, and probably get as much water as you need. But if the gravel isn't sized and placed correctly, you will get more sand than water out of that well. A new well with a properly installed gravel pack would save you a lot of problems. But if the drillers there don't know how to gravel pack correctly, as it sounds, you may just end up with another sandy hole in the ground.
  5. tvl

    tvl Member

    Messages:
    139
    Location:
    South Carolina
    Thanks again Valveman!

    I agree my best course of action will be to get a new well dug. But, with everyone so busy, I need to "buy some time" and try to get by until this fall. The driller that will use 150 to 200 PSI to clear the well has the best price ($300). The other driller has very high pressure equipment and charges $1500. Do you know if the guy who uses the lower pressure can adequately blow all of the debris from the bottom OR does that take much greater pressure???? I do like his price and if that would buy me some time, it would be WELL WORTH IT!

    Thanks so much for your help!
    Last edited: Jun 11, 2013
  6. valveman

    valveman Moderator Staff Member

    Messages:
    4,586
    Location:
    Lubbock, Texas
    It is not the pressure so much as the CFM you need. But you can blow it too hard, so bigger is not always better. Just need enough to get the sand out. Could probably bail it out as well. I think "buying a little time" is maybe all you will get.
  7. VAWellDriller

    VAWellDriller Member

    Messages:
    171
    Location:
    Richmond, VA
    $300 is too cheap for a professional to do the job...and you haven't been clear on exactly what the other guy was going to do with his high pressure. For such a shallow well, you could easily airlift out the debris, which means running a line of pipe to the bottom and blowing. A towable 185 cfm compressor from a rental place and a roll 150' roll of 1" poly will be more than adequate to remove the fill in the well. It is an easy diy job since your well is shallow. If you are correct in assuming that the fill is from the driller spilling gravel pack into the well when it was first drilled, and there is 13 feet or so of fill inside the screen, this may very well help a lot. You mentioned the well was a bottom feeder.....screened wells always are...that's how they are designed. Valveman is right though, that a correct gravel pack should not allow any sand in, and it may be difficult or impossible to correct a bad gravel pack job from the start.
  8. tvl

    tvl Member

    Messages:
    139
    Location:
    South Carolina
    Thanks VAWellDriller!

    For $300, the one well driller is simply going to flush any or all of the sediment/sand/debris from the bottom of the well ............ hopefully, allowing more water to flow OR give me the option to lower the pump a few more feet. I seriously doubt the lower pressure he will be utilizing will do anything for a possibly plugged strainer?? Anyway and hopefully, this will buy me some time until someone can get out this way! And by the way, that price is if I pull and re-install the pump; which I don't mind doing

    The other driller only stated his $1500 included cleaning the well of any sediment/sand/debris AND his high pressure rig would also clean all strainer openings. That's all I heard him say. Of course, if I do have clogged strainer openings, then his equipment is exactly what is needed. However, the other well driller does not feel I have any clogged strainer openings being I have PVC casing and has stated that is generally rare around our area.
    Last edited: Jun 12, 2013
  9. tvl

    tvl Member

    Messages:
    139
    Location:
    South Carolina
    OK ................... here's what happened today:

    I had the well blown out. The procedure only yielded an additional 4 feet 1 inch until we hit the very bottom. So, the well wasn't quite as deep as I had been informed. Anyway, I lowered the pump some more and the 1 HP 10 GPM pump emptied the well in less than a minute.

    For 35 years I have been using a 10 GPM pump ............... so, when I ordered my new pump last week, I had no reason not to stay with a proven winner. But, my old pump had been masking the real issue.

    So, I closed off the ball valve today until the pump didn't overtake the well ................... 6.1 gallons per minute is my new target. Anything more and the well is pumped dry.

    Now, as I had mentioned earlier, at the moment I am using a F&W 1 HP 10 GPM pump. I have a few important questions:

    1- Will it shorten the life of the pump pumping higher pressures and only 6 GPM versus what it was designed for??

    2- Would it be better to purchase a new pump head for the motor ....... maybe 5 GPM??

    3- Would a dole valve be a better method of restricting volume versus using a ball valve?? If so, would this be considered a good setup for my 10 GPM pump??

    4- I just returned from Lowe's & Ace ....... no Dole valves in stock. Where do you purchase these??

    Sometime later this year, I will look at putting in another well!
    Last edited: Jun 14, 2013
  10. valveman

    valveman Moderator Staff Member

    Messages:
    4,586
    Location:
    Lubbock, Texas
    A ball valve will work just like a Dole valve until it wears out. It should last a long time with a 10 GPM pump restricted to 6 GPM, because there is not much pressure differential.

    You could also use a Cycle Stop Valve, as it will restrict the pump to match what you are using. So with the CSV, you just don’t turn on more than 6 GPM, and the CSV works like a 6 GPM Dole valve. However, the CSV is infinitely adjustable. So it will also turn into a 1, 2, 3, 4, or 5 GPM dole valve if that is all the water you are using.

    And no it doesn’t hurt to restrict that pump down to as little as 1 GPM. It actually makes the motor run cooler and last longer. It is better to restrict a 10 GPM pump than the same horsepower 5 GPM pump, as the 10 GPM pump won’t have as much pressure differential.
  11. tvl

    tvl Member

    Messages:
    139
    Location:
    South Carolina
    Thanks for the reply Valveman!

    1- I will definitely take a serious look at the cycle stop valve ...... can you provide a link to a website that explains how one works and how to go about purchasing one?

    2- I always thought is was BEST to run a water pump near its designed specification ....... very interesting! You stated: It is better to restrict a 10 GPM pump than the same horsepower 5 GPM pump, as the 10 GPM pump won’t have as much pressure differential. Can you explain this a little better. I really would like to understand what you are saying!

    3- You also stated: You could also use a Cycle Stop Valve, as it will restrict the pump to match what you are using. So with the CSV, you just don’t turn on more than 6 GPM, and the CSV works like a 6 GPM Dole valve. However, the CSV is infinitely adjustable. So it will also turn into a 1, 2, 3, 4, or 5 GPM dole valve if that is all the water you are using. If I understand this correctly, the user inputs how many GPM he wishes to pump and the cycle stop valve does the rest? If so, this is what I want! I can adjust as the well deviates in the future, which will be great!
  12. tvl

    tvl Member

    Messages:
    139
    Location:
    South Carolina
    Valveman,

    Are you able to comment on my last post ............ thanks!
  13. valveman

    valveman Moderator Staff Member

    Messages:
    4,586
    Location:
    Lubbock, Texas
  14. tvl

    tvl Member

    Messages:
    139
    Location:
    South Carolina
    4 inch OR 6 inch

    4 Inch OR 6 Inch

    Well, I don't know who all has been following my post, but I've decided to bite the bullet and try a new well. Based on what the local well diggers are telling me, we probably won't be able to go much deeper than the well I already have ....... maybe 15 feet. But, since my neighbors don't seem to be having any known issues and all of theirs are about 15 foot deeper, I going to take the gamble. We will certainly go deeper if we don't hit rock, which is what is expected at or around 150 or so feet.

    I'm torn between a 4 inch well versus a 6 inch well. A 6 inch should allow more water to enter the casing, thereby providing more GPM ...... that's providing we hit the same stream I'm already in or another better stream. Is this correct thinking? A 6 inch well does cost about 2X the price of a 4 inch well. Any thoughts ........4 inch or 6 inch?
    Last edited: Jun 18, 2013
  15. VAWellDriller

    VAWellDriller Member

    Messages:
    171
    Location:
    Richmond, VA
    If this is a mud rotary drilled, screened well in a sand formation (which I think it is), you won't get any more water with 6" than 4"....the only reason would be to accomodate a 6" pump, but you certainly won't need to do that. I don't do it because you can't clean it very well, but a lot of guys around here install 4" wells with 2" screens....and get just as much water as straight well would...they just save money on pipe and gravel pack...Some screened formations, like the "shell rock" around here, sort of a limestone formation, known as the piney point in VA, the Castle Haynes, in NC...and I'm not sure in what it's called in SC, will yield more water with a larger borehole....(still being gravel packed an screened). The most important thing is to find a good driller...maybe see who drilled your neightbors wells.
  16. tvl

    tvl Member

    Messages:
    139
    Location:
    South Carolina
    You are correct ............. sand well for sure!

    Again, my thinking was that a 6 inch pipe/screen would have more "slots" around the circumference of the pipe versus a 4 inch pipe, thereby allowing more water to flow into the casing ........ which would provide more water to the pump? So, that is not a correct assumption? Shucks!

    Well, are there any other reasons I might want to consider a 6 inch well before I make my final decision?

    Thanks so much!
  17. valveman

    valveman Moderator Staff Member

    Messages:
    4,586
    Location:
    Lubbock, Texas
    If the gravel pack is done correctly, you won't see much difference between 4" and 6" casing. However, if you ever have any problems down the road, you will have more options with the 6" casing.
  18. tvl

    tvl Member

    Messages:
    139
    Location:
    South Carolina
    However, if you ever have any problems down the road, you will have more options with the 6" casing

    OK ......... I would love to know what those options might be. Would you please let me know. Thanks again!
    Last edited: Jun 19, 2013
  19. valveman

    valveman Moderator Staff Member

    Messages:
    4,586
    Location:
    Lubbock, Texas
    You not as likely to get the pump stuck. If the pump gets hot and melts the casing, the 4” will grab the pump and you can’t get it out, and you will need to dig a new well. You have room to install a 4” liner should the 6” casing develop a hole or crack. We can get more equipment down the 6” hole like bailers, surge blocks, fishing tools, etc. And with 6” casing I can put a 4” shroud on the pump, which I think is very important for the longevity of the pump/motor.
  20. tvl

    tvl Member

    Messages:
    139
    Location:
    South Carolina
    Thanks a lot Valveman!

    You mentioned: with 6” casing I can put a 4” shroud on the pump, which I think is very important for the longevity of the pump/motor. So, if I do go with the 6 inch well, it appears I need a shroud for my pump. The well digger did not mention anything about this. Where do you get this item? And how is it installed?
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