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Thread: Draining pool, water table question

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    Draining pool, water table question

    Hi;

    Need to drain my 16x32 ig concrete pool to do some plaster and tile repairs. I've read up on the risk with high water tables and all. I live in Virginia and usually this time of the year (early spring) the ground is pretty wet. My yard slopes down, so 10' behind my pool the ground elevation is below the deep end of the pool. The retaining wall is designed to let water drain.

    Is this a safe situation for draining since the water table is well below the pool? I would like to have the pool drained for a couple weeks as I plan to take care of a few different issues. Does a pool only float due to high water tables or are there other cases?

    Lastly, and maybe most importantly, there's 4 "plugs" on the bottom, 2 in the shallow end and two in the deepend. They look like they unscrew. Are these meant to be unscrewed to relieve possible water pressure?

    TIA,
    Kevin
    16x32 Concrete IG, 20+ years old and going strong
    Equipment: DE Filter, Jandy Gas Heater, Solar Panels, 1hp Hayward Pump with 3/4 HP AO Smith 2 Speed Replacement Motor, Aquarite SWG
    Automation: Pentair Suntouch controller w/solar valve
    Cleaners: Polaris 280 (replaced an Aquabot)

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    Re: Draining pool, water table question

    Are there hydrostatic plugs in the floor? If so, as they appear from under the lowing water, remove them.

    Even though your wall lets water drain, your soil type will play a role in how much and how fast its drained or held. Heavy clay content soil holds water and slows draining while sandy soils drain quickly.

    Do you know what the soil looks like down there? Do you have any pictures you could post from when the pool was being built?

    Scott


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    JasonLion's Avatar
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    Re: Draining pool, water table question

    It is unusual to have hydrostatic relief plugs, though not unheard of. I think that it is more likely that they are part of an abandoned in-floor cleaning system or a set of some other kind of deep returns.

    Ground water is probably the only risk you need to worry about when draining a gunite pool in VA at this time of year. At the peak of summer there is a risk of expansion and contraction, caused by solar heating, cracking the plaster, however this is usually only an issue in hot dry climates (Arizona, Nevada, etc).
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Draining pool, water table question

    Nearly all the gunite pools in my neck of the woods have 1.5" removable plugs specifically for hydrostatic relief when pools are emptied. Typically, there are two in the deep end and one near the top of the slope. If the homeowner has a high water table, it's not uncommon to find a dry well too. The rarity here is hydrostatic valves. I usually find them near a river or lake/reservoir.

    Scott
    Owner of - PoolGuyNJ LLC
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    Re: Draining pool, water table question

    I don't think the 4 valves are for a cleaning system. This pool is about 30 years old, built by Anthony Sulivan. Good pool over all. Anyways, as far as I know they didn't have in floor cleaning systems then.

    When I drain the pool and remove one of these plugs what should I see? Assume an opening through the concrete and to the earth.

    In virginia the soil does tend to have a lot of clay, depending on region.

    Sorry, no picts.

    Kevin
    16x32 Concrete IG, 20+ years old and going strong
    Equipment: DE Filter, Jandy Gas Heater, Solar Panels, 1hp Hayward Pump with 3/4 HP AO Smith 2 Speed Replacement Motor, Aquarite SWG
    Automation: Pentair Suntouch controller w/solar valve
    Cleaners: Polaris 280 (replaced an Aquabot)

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    Re: Draining pool, water table question

    I assume they have a cross pattern and are white . You may see dirt, gravel or water. Let the water in! I doubt there will be a lot. The ones in the deep end may have more.

    Scott
    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

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    Re: Draining pool, water table question

    Yup, white with a cross patern. Always wondered what they were there for. Awesome....now I can drain the pool with little worry.
    16x32 Concrete IG, 20+ years old and going strong
    Equipment: DE Filter, Jandy Gas Heater, Solar Panels, 1hp Hayward Pump with 3/4 HP AO Smith 2 Speed Replacement Motor, Aquarite SWG
    Automation: Pentair Suntouch controller w/solar valve
    Cleaners: Polaris 280 (replaced an Aquabot)

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