Pond over Pond

[Ginger1969]

Hi,

I have a kidney shaped sunken pond at present, 5.1 m x 2.1m about 500mm deep. What I'm thinking about doing is building over the top - raise the sides up about 1.2m. Sleepers are so expensive now days and the amount I would require would put this way of building the raised part well out of my price range. about 36 sleepers. £1100

What I was wondering is, if I were to build a box section frame and line the frame with 18mm ply, what size timber should I go for for the box section considering the volume of water above ground would be in the region of 2800 gallons and, would a box section frame actually be strong enough to hold that amount of water without bowing?

I couldn't find if there was anyplace or anyway of working this out with an online calculator or anything. so I came to you guys for advice.

 

[j.w]

@Ginger1969
I've never built a pond like that so I am of no help

 

[Mmathis]

Hello and welcome!

 

[addy1]

Welcome to the forum!

We have some construction ponders let them chime in.

 

[WaterGardener]

Welcome!

I can't answer your question, but the weight of water in that pond would be over 23,000 pounds! It would need some serious support.

 

[mrsclem]

I currently have 2 partially above ground ponds built from wood. Used 2x12 pressure treated lumber. The one 10x10' that was over half above grade bowed out after 10+ years but it was 5' deep. Can you remove the preform and just dig down and put a liner in? I will never build another above ground pond.