sand filling up well, how to clean??

Discussion in 'Pumps and Tanks Well Forum & Blog' started by hadalgo, Jul 11, 2008.

  1. hadalgo

    hadalgo New Member

    Messages:
    1
    long story short..

    well depth is about 200 feet, pump is down about 180.

    Every few years we need to raise the pump up another few feet because of sand accumulating in the bottom of the well and now its to the point of affecting the output of the well.

    Is there an easy way of removing this sand? I was thinking of maybe lowering a pipe down, filling the well to 15ft of the top and sucking it out with a trash pump or similar.

    The well is in use and I dont want the well guys coming out with dirty equipment to comtaninate the well.

    many thanks.. james
  2. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    Water will flow both ways in an aquifer. If it is a good well you might have trouble filling it to within 15 ft of the surface. You would certainly be pushing sand into the fractures from which you are withdrawing water.

    The sand is settling in the well because it is too large to be entrained at the velocity in the well. That means that you must substantially increase the lifting velocity with greater flow, or you must get the same flow in a pipe that is much smaller than the bore.

    I don't drill or develop wells but I apply engineering to solve problems.

    My approach would be to drop a deep well jet into the well and keep it down in the top layer of the sand. I might try jetting a little of the flow (maybe 25% of the expected production of the deep well jet) out the end to stir up the sand in the well.

    You will need a pit or large tank at the top to let the sand settle out before you send the water back down for another load of sand. The surface area of the settling tank is the important factor. A small diameter but deep tank is no good. A piece of plastic lining a shallow pit is the best way to settle out the sand.

    You don't need a real deep well jet pump but you need something that will produce enough pressure and flow. It is possible that your submersible pump could do that. It will be pumping mostly clear water from which the sand has been settled. Whether or not that pump would work depends on the depth to water and the selection of the deep well jet.

    You may wear out the jet but that is a small cost compared to the cost of the operation.

    You should assume that the well will be contaminated by the process and you should sanitize the system with chlorine before you use the water.

    Someone with a big air compressor might be able to blow it out with an air-lift operation. I'm sure the well guys have equipment and processes for doing the job.
  3. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    A deep well jet won't work at 200 feet.

    bob...
  4. Wet_Boots

    Wet_Boots Sprinkler Guy

    Messages:
    798
    Location:
    Metro NYC
    I kind of like the idea of the drop tube and an air compressor. Push in air faster than the well's recovery capacity, and the excess flow is bound to push sand laden water out of the well shaft.
  5. Gary Slusser

    Gary Slusser That's all folks!

    A well driller or pump guy will clean the well by bailing with their pump hoist/derrick truck or air lift with an air line down to the bottom of the well and blowing the water and sand etc. out the top of the well.

    Depending on the type of well, rock bore or fully cased and screened sand and gravel, that may help or make the sand problem worse. A rock bore well usually wouldn't have a problem, they rarely have a sand problem to begin with.

    You may want to have a camera inspection done to see why and where the sand is getting into the well.
  6. ecpgroup

    ecpgroup New Member

    Messages:
    22
    air lift the bore with a rotory rig and foam injection. what is the pumping water level? pump should only be as deep as needed. really needs to be kept in the plain section. if it was a sand bore and stocking has not been put around the casing if its a fully cased bore then this may allow sand it.

    was the bore test pumped after it was drilled and all the fines cleared?

    regards max
  7. valveman

    valveman Moderator Staff Member

    Messages:
    4,586
    Location:
    Lubbock, Texas
    A pump man with a good bailer could dip that out in a short while and have your pump back on bottom. Then if you use a piece of 4", 100# PVC pipe for a shroud over the 3.5" pump, and cut it flush with the bottom of the motor, it will have enough velocity to pick up the sand so it doesn't fill up around the motor. This means you will continuously be pumping sand instead of it settling to the bottom of the well, so you will have to filter it out up top. And of course when you pump sand, you wear out the pump.

    Best to drill a well that doesn't make sand. Some use a screen or a sock, some gravel pack over the well perforations to filter out the sand, so it can't get into the well. A good well will easily pay for itself, because a bad well will cost you forever.
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