New Patio Pond build

[Patrick Collings]

Hello.

This is my first ever pond build so here goes..

As you can see from the picture I have already dug the main section of the hole and the basic shape that I wish to have. With a deep section closest to the patio and shallower section at the back for plants and hopefully a place to build a waterfall later on.

Bit of information before I ask the questions:

• My soil is very solid, a lot of clay and rocks.
• I have already purchased a filter and pump so sadly I cannot put in a bottom drain no matter how much you persuade me.
• There are a few roots sticking through the sides of the walls which aren't quite visible in the pictures.
• I will only be looking to keep goldfish in the pond.

Now that I have dug the center of the hole I would like to get to work on a concrete collar. Can anyone guide me in some direction for width and thickness? The grey strip around the pond in the picture is where I would like to put the collar. On top of this will be paving slabs similar to the patio we already have but much smaller about 30 x 30cm. Due to this the collar and sides of the walls will have to withstand people standing right on the edge. I was thinking 10 inches x 6 inches? And what mixture of concrete should I use?

My main worry is that the pond walls would collapse so I've come here for a bit of insurance really so any input would be great. Ideally I'd like to make it a bit deeper with maybe steeper sides but this is not necessary obviously as the structure of the pond is my greatest concern. I can't tell you the exact angle of the walls but its very roughly 60 degrees.

How would I go about installing the collar from here? I am thinking I just dig a trench the width I want all the way around what I have now then use slats of wood and stake them in around the edges to stop concrete falling into the hole. Does there need to be a flat step in front of the collar or is it okay to be a little raised and start sloping down into the pond directly next to the collar?

I am also going to be putting a layer of sand across the whole pond before I lay the underlay and liner down on top of it.

 

[tbendl]

Have you considered using concrete blocks as a collar? I used them as the form for my bog and they are easy to place and you wouldn't have to worry about them crumbling.

 

[Patrick Collings]

Have you considered using concrete blocks as a collar? I used them as the form for my bog and they are easy to place and you wouldn't have to worry about them crumbling.

Thanks for the reply, I considered them but wasn't sure if they'd be strong enough to be under the patio so thought a concrete collar with rebar would be much more secure

 

[tbendl]

Hmmm I filled mine with sand and walk on them but if you are planning on tying it into your patio there may be an issue of them shifting. I was thinking ease of installation, especially since you have corners in your pond.

 

[Patrick Collings]

I agree that would be much more simple to install and I'd get nice clean edges and probably cheaper as well..

 

[sissy]

I used concrete block this shows only 1 block high but is 2 blocks high and has a half block on top of that .I have clay soil so it packed inside blocks with rebar real good

 

[sissy]

Mine had an existing sidewalk next to it and there was no problem with shifting.I even have a bridge across mine

 

[Patrick Collings]

Mine had an existing sidewalk next to it and there was no problem with shifting

That looks very promising, nice build! How does the rebar work inside the blocks? Does having it 2 high make much of a difference do you think?

 

[sissy]

nope and we stand on the edges to feed the fish and sit on the bridge .I have a pics of my rebuild last year after moles chewed through my liner .It was built the same way before i just made it longer and a little deeper i also made the sides straighter down except one side and there is a drain pipe there for my gutters and that is where my over flow is

 

[Patrick Collings]

nope and we stand on the edges to feed the fish and sit on the bridge .I have a pics of my rebuild last year after moles chewed through my liner .It was built the same way before i just made it longer and a little deeper i also made the sides straighter down except one side and there is a drain pipe there for my gutters and that is where my over flow is

so do you think something like this would be okay?

 

[Patrick Collings]

I've not really considered an over flow, we get a lot of rain here in Scotland...

 

[sissy]

I did not put sand I just tamped the top row level and used a string line to keep my level right .I offset each block as if you were building a wall with mortar .I put down tar paper and then my underlay.The reason it is like it was in pic is because we were expecting snow and I had 1 day to dig it bigger and get the liner back in .After storm was over I laid the next layer of block and put the rebar in the blocks and the layer of half block on top and then pulled the tar paper and underlay back over the whole thing .Afraid i was in a hurry again as another snow storm was coming and I had to work fast .I was working alone so it meant carrying the block all the way from the driveway in snow and working as fast as I could .No pic taking as no time

 

[sissy]

I used this and wrapped window screen around it and just use a brush to clean the screening off

 

[tbendl]

I was told not to worry about using sand as an underlayment. It won't stay on the sides and really doesn't do much as far as protection on the bottom. You may have another use for putting it down though.

 

[DrCase]

As far as the collar goes 2 to 3 " thick has always done what I need ,
12 " wide will give you a nice stable edge
Quick Crete works good
1 90 lb bag will do 8 sq ft 1" thick