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Thread: french drain behind raised beam wall?

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    french drain behind raised beam wall?

    A new discovery for a rookie is that carving the pool into slope at rear of yard means
    I will need a french drain and the PB doesn't do that nor did we discuss addressing the slope
    runoff prior to my questioning the ditch they are planning to leave for me.
    1a) PB carted off a ton of dirt yet now I am looking for it to fill in the ditch after I address drain.
    There seems to be plenty of free dirt on Craig's list but shouldn't they have offered to save some
    of my dirt for this issue?
    1b) Can I request/demand that they bring back enough dirt to backfill trench?

    2) I have not done a lot of DIY and no experience in landscaping.
    Can a guy like me lay a french drain on Saturday morning ?
    32ft of Perforated pipe, wrap in landscape material and lay/connect/install pipe 12-18" deep, leading
    away from pool to my side yard drain? Is that what it takes?

    3) I read in another thread that I should water proof back of wall with sealer - is that a must?

    thanks
    Tom
    TomCa - IG, gunite, Freeform, 30 x 17, raised beam wall w/ledgestone and flagstone cap, 3ft spill, radiant fusion blue frost, 480sqft concrete decking. SWG filtration, 2 returns, 1 skimmer. 2" & 2.5"PVC . JEP15 Jandy ePump 1.5hp Variable Speed, AquaLink PDA P4 Pool Control , SAVI-MELODY100-J Nexxus 14W 12V Pool Light X 2, J Series, Polaris - 360 Cleaner, Model F1B.

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    Re: french drain behind raised beam wall?

    I would backfill with rock. You want all the porosity you can get. sealing the backside may help with calcium deposits weeping out the front.

    If you are not familiar with this work, get someone to do it for you.......I would not let them backfill with dirt, regardless.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: french drain behind raised beam wall?

    PEA GRAVEL ?

    THANKS
    Tom
    TomCa - IG, gunite, Freeform, 30 x 17, raised beam wall w/ledgestone and flagstone cap, 3ft spill, radiant fusion blue frost, 480sqft concrete decking. SWG filtration, 2 returns, 1 skimmer. 2" & 2.5"PVC . JEP15 Jandy ePump 1.5hp Variable Speed, AquaLink PDA P4 Pool Control , SAVI-MELODY100-J Nexxus 14W 12V Pool Light X 2, J Series, Polaris - 360 Cleaner, Model F1B.

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    Mod Squad Jimrahbe's Avatar
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    Re: french drain behind raised beam wall?

    Tom,

    I'm not sure I understand the problem, but here are a couple of thoughts..

    1. French drains generally get rid of ground water, not surface water. So if you are building a wall at the bottom of a slope, a French drain is often installed behind the wall to divert the ground water away from the back of the wall. A French drain is not just a piece of perforated pipe wrapped with cloth... for the drain to work, the pipe is normally in the center of a gravel/small rock filled trench about a foot or so square. This is normally something the builder of the wall does.

    2. If the problem is surface water, French drains might help, but only slightly. Maybe that is why your PB is wanting to install a ditch..

    3. Anything I have ever planned to do on a Saturday morning has always ended up taking me three days..

    If you can post a pic of the area we might be able to better understand the problem.

    Thanks,

    Jim R
    Finished in 2015 - 17K Gal, IG, 20' x 25' Almost Rectangular Pool, Pebble finish, three rockport water falls. Pentair Equipment: EasyTouch 4, IC40 SWG, 3 HP VS Pump, CCP520 Cartridge Filter.
    TF100 with SpeedStir and SampleSizer, ColorQ Pro 7, Dolphin Premier Robot Cleaner, added Screen Logic 2, added small 3 person Calder Spa.

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    Re: french drain behind raised beam wall?

    The PB stated that because the slope is modest and the land above it is flat and graded
    that he doesnt think a french drain is necessary. While we are clear, he is not responsible for
    a french drain install , he did acknowldge that the trench is deep, some exposed pipes and he
    would bring some dirt and gravel and fill it in. Here is a pic of current trench. Thoughts on how to
    proceed are appreciated.
    Thanks Tom.
    Attachment 44179
    TomCa - IG, gunite, Freeform, 30 x 17, raised beam wall w/ledgestone and flagstone cap, 3ft spill, radiant fusion blue frost, 480sqft concrete decking. SWG filtration, 2 returns, 1 skimmer. 2" & 2.5"PVC . JEP15 Jandy ePump 1.5hp Variable Speed, AquaLink PDA P4 Pool Control , SAVI-MELODY100-J Nexxus 14W 12V Pool Light X 2, J Series, Polaris - 360 Cleaner, Model F1B.

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    Mod Squad Jimrahbe's Avatar
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    Re: french drain behind raised beam wall?

    Tom,

    Normally French drains are installed where there is ground water that you need to get rid of. I don't see a ground water problem in your picture, but they may be just because it hasn't rained in California in the last few years..

    My gut says that a French drain is not necessary but it would not hurt anything to put one in if you think that you might have an issue once it starts to rain. Obviously, if you are going to do it, now is the time. Did you ask your PB what it would cost for him to do it? I would not think it would be too expensive since he is going to have to fill the trench anyway.

    Jim R.
    Finished in 2015 - 17K Gal, IG, 20' x 25' Almost Rectangular Pool, Pebble finish, three rockport water falls. Pentair Equipment: EasyTouch 4, IC40 SWG, 3 HP VS Pump, CCP520 Cartridge Filter.
    TF100 with SpeedStir and SampleSizer, ColorQ Pro 7, Dolphin Premier Robot Cleaner, added Screen Logic 2, added small 3 person Calder Spa.

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    Jaimslaw's Avatar
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    Re: french drain behind raised beam wall?

    I too do not see a Pressing need for a French drain system. Hydrostatisc pressure would be troublesome only if there is an appreciable slope on the otherside of your fence - if so, hydrostatic pressure picks up quite exponentially. If that is the case (steeper slope on other side of fence), I would consider a French drain. Try to get a proper install of the French drain. Seen a lot of improper installs: drain pipe laid with perforated holes facing up, no filter/fabric sleeve for the pipe, inadequate amount/size of gravel, improper placement of pipe in gravel, wrong diameter pipe, etc.).

    In any case, would coat the back side of your wall with some heavy duty sealer...Asphalt based, applied in multiple coats (can't tell from pic if a portion of the wall is already getting that treatment). This will minimize efflorescence.

    A simple surface swale for diverting surface water during a heavy downpour is a good way to go, given that it looks like your soil is poor draining clay...once saturated, water runoff can be quite abundant.
    Pool: 13k gal. in-ground; Stonescape Mini Pebble - Tropics Blue; Connected Spa - dual spill-over; Aqua Rite T-15 SWCG; AquaLogic PS-4 Automation; Sta-Rite DE Filter; Sta-Rite Max-e-Therm 400k BTU pool heater; Intellifo 2-VST Pump; Stenner 45mp2(25psi/10gpd) acid injection; Bulbwizard color LED pool lights; Poolvergnuegen 2 wheel side suction cleaner; FAFCO rooftop solar. TF-100 w/ speed stir.

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    Re: french drain behind raised beam wall?

    Guessing a bit, but it seems to me that without a french or surface drain. ALL the water off that hill is either gonna' settle into the soil behind it or come over the wall. Personally, I would put a drain there.

    I put one around the base of my pool (it's pretty flat) and ten years later it still removes thousands of gallons of groundwater during a major storm.....I am a big fan.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: french drain behind raised beam wall?

    I agree with Dave you need some kind of drain to prevent water from traveling into your pool.

    PM me and I can give you some Sacramento landscaping contractor referrals.
    22k gallon IG pebblefina, Jandy 1.5 HP VS, Jandy CV Cartridge filter, Fafco solar panels, Polaris 360 supply side cleaner, waterfall

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