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Large rocks & liner

Discussion in 'Water Features' started by BrendonTW, Aug 17, 2010.

  1. BrendonTW

    BrendonTW LawnSite Senior Member
    Male, from Oklahoma City
    Posts: 551

    I installed my first pond a few weeks ago. Not very big, about 500 gallons or so. I learned a lot, and it turned out well. I was really worried about the liner the whole time, afrait to step on it, afraid to step on the small river rock once I put it on top of the liner. I doubled up on underlayment, but I was still worried that I would puncture it.

    Also, I placed a pretty heavy and large rock in the stream which hands out over the pond and the water falls off of it. I was worried, however, that I would somehow puncture the liner doing this. On here I see guys putting rocks which look like they weigh a ton, literally, right into waterfalls and on liners.

    How concerned should I be about this?

    Also, I excavate the dirt under the liner as best I can to the shape of the rocks I want to place, but there may be 1-2 inches in some spots, and even bigger gaps in other spots where the water will run behind the rocks. Do all fo you use the expandable waterfall foam to fill these gaps and route the water?
    Last edited: Aug 17, 2010
  2. amscapes03

    amscapes03 LawnSite Senior Member
    Posts: 398

    I double up on the underlayment too. On the last pond I built, I used around 11 (3 to 5 ton each) granite boulders for the falls. The weight of them kinda freaked me out. We lowered the boulders down real slow, when they were maybe 6 inches from touching the liner I'd look for the boulders pressure point. My added protection (may just be in my head) was sliding one, sometimes two tractor trailer mud flaps between the boulder and the liner. Their maybe 1/2" thick, pliable, and tough as hell.
  3. BrendonTW

    BrendonTW LawnSite Senior Member
    Male, from Oklahoma City
    Posts: 551

    What did you use you lower the boulders in?
  4. tadpole

    tadpole LawnSite Bronze Member
    Posts: 1,216

    Pack the larger holes and gaps with either pea gravel or #57 then foam the gravel, when the foam starts to set add more gravel to disguise the foam. This eliminates using a sh*t-load of foam.

    Using underlayment between large boulders and the liner is good insurance even though 45 mil EPDM is tougher than most people believe. It would take an pretty sharp rock to puncture the liner. You are doing good to excavate the placement area before you set the boulder. This distributes the weight of the boulder over a larger area and by sitting lower in the ground the boulder looks more natural.
  5. STL Ponds and Waterfalls

    STL Ponds and Waterfalls LawnSite Bronze Member
    Posts: 1,177

    They make rock pads for larger boulders but are pricey. I usually just double up the underlayment under the liner and on top of the liner if the boulder is angular. Like Tadpole stated this 45 mil liner is pretty darn tuff. If you have the liner to work with make sure it isn't really tight/taught by folding excess at the bottom of the boulders ledges etc. Ohh and sometimes I use carpet under the liner if the soil is really rocky and has a lot of roots.
  6. pitrack

    pitrack LawnSite Bronze Member
    Posts: 1,049

    Any pics? Sounds cool.

    Everything else looks like it's been covered.
  7. alf500series

    alf500series LawnSite Senior Member
    Posts: 257

    i have a friend who is a carpet store owner and whenever i get ready to install i ask him for padding scraps, or scraps from the carpet he is pulling out of the house. its usually pretty thick and plus its FREE.

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