Apr 11
25

Need advice on how to build a fish pond retaining wall?

2 Comments

retaining wall

I am planning to build an above ground fish pond in an area in front of our house between the sidewalk and our front porch.  The pond size will be ten feet long by four feet wide by two feet deep and I need to build a two foot high retaining wall along the sidewalk.  This is a box or frame to hold a pond liner.  I think I will need to use 4″x4″ or 4″x6″ posts.  There is also retaining wall lumber I have seen that is curved on the sides but flat on its sides.

This wall along the sidewalk is ten feet long and two feet high and has to hold back the pressure from about six hundred gallons of water in the fish pond. I plan to reinforce the wood by using rebar through each of the pieces of wood.  I am figuring to drill holes through the posts and drive the rebar deep into the ground below the wall leaving about two feet above ground and slip the wood posts over each piece of rebar. I am thinking that driving the rebar two feet into the ground below the wall should be enough with two feet above the ground level to place the wood on.  Do you think that is enough? How deep should the rebar be driven into the ground?  I still have questions about what size rebar is going to be strong enough.  I want to avoid getting rebar that is too big.  I also wonder if I should drill the holes in the wood posts one size bigger and fill the space with a mortar or cement.

Am I approaching this in the right way?  Any constructive suggestions on building this fish pond are welcome.

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Posted in Ponds by Pond Manager 2 Comments

2 Responses to "Need advice on how to build a fish pond retaining wall?"

  • Dan the brick man says:
    August 25, 2010 at 8:25 pm
    Reply

    doug seemed to cover it pretty well , i would add that i would use number 5 rebar(5/8ths in.) and drill it maybe a 1/16th big and use an epoxy to firm the fit…if you dont mind the beating you could drill it 5/8ths and hammer the 4 bys on but that seems like a lot of work…

  • Doug Boyd says:
    August 25, 2010 at 8:25 pm
    Reply

    There are 7 1/2 gallons per cubic foot, so at 8 pounds per gallon, one cubic foot of water weighs about 60 pounds. If the water will be 2 feet deep, the lateral water pressure will be 120 pounds at the foot of the wall, 90 pounds 6 inches up, 60 pounds at the 1 foot mark, and virtually zero at the top. So engineer accordingly. Without knowing the soil condition, nobody can guess it’s bearing capacity as concerns rebar depth. I’d suggest sinking the pond a foot into the ground, and building up the ground around it (grass it in) a foot over a run of about 3ft, if space permits. This way, it’s easier to look into the pond, and you don’t have worries about the pond collapsing outward. Remember, no matter how you do it, you must allow rain to escape the foundation to avoid problems there. Fish don’t like concrete, and neither does wood, so use a plastic liner if near concrete, and if you use rebar dowels with landscape timbers, don’t use concrete to glue them in.

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