Converting sess pit to pond

[Bucknallbear]

We are replacing our two sess pits with a biodisc klargester system. The obivous thing is to use the soil from the pit we dig for the new system to back-fill the old pits but could I convert them to a pair of ponds? I would probably need to make them quite a bit shallower but is this a good idea or are the cement walls going to be too contaminated? I thought I could even leave the drains that feed the pits and connect the house ends to the downpipes from the gutters? Comments, examples etc please.

Peter

[Kayleigh]

I have no idea..
But I know concrete needs to be treated as chemicals can leach out..

[dampflippers]

How big and how deep is it?

If you did, you could line it with pond liner to stop chemicals and other contamination leaching into the water.
You would also need to add a ramp or beach for easy access, and to put in some shelves for marginals.

Filling it with rainwater is a good idea. Not sure about the pipework, but I can't reall see a problem apart from in very heavy rain you would get quite a throughput of water which might wash your pondlife out.

[Bucknallbear]

The pits are probably a metre wide, 1.5 - 2.0 long and 1.5 - 2.0 metre deep. They definitely need sloping off because as they are they would even be dangerous for humans! It just seemed a shame to fill them in if they could be used as ponds. Hadn't considered the possibility of too much rain or the leeching from the concrete. Interesting that there were no negative comments so will definitely give this more thought rather than just back-filling them.

Peter

[Kayleigh]

Originally Posted by Bucknallbear

The pits are probably a metre wide, 1.5 - 2.0 long and 1.5 - 2.0 metre deep. They definitely need sloping off because as they are they would even be dangerous for humans! It just seemed a shame to fill them in if they could be used as ponds. Hadn't considered the possibility of too much rain or the leeching from the concrete. Interesting that there were no negative comments so will definitely give this more thought rather than just back-filling them.

Peter

The pond liner sounds a great idea. Solves the problem of the concrete

[dampflippers]

How about part backfilling so they are about 1 metre deep, then using a pond liner? You could build in some ledges at this stage under the liner.

[brianwaugh]

yes back fill with a load of sand and then use a conventional liner to form your pond. Concrete alone can be toxic and porous on its own unless treated first.
2 meters deep is an awful hazard to have around and takes a lot of water to fill !

[Tursiops2]

I don't know how practical this would be - never had anything to do with cess pits - but if this was my project, I think I'd be looking at collapsing the sides to create a shallower pond with sloping edges and a larger surface area. Maybe join the two to make one unit?

I don't like the idea of re-using the foul pipe to fill them though - yuk!
T2

[Bucknallbear]

This is all good stuff and thank you all very much. Will definitely leave the holes until after the new system is installed and then when they are pumped out have a detailed look. I like the idea of sloping the sides and using that to reduce the depth significantly. No option of joing the two as they are about 30 m apart.

Thanks again!

Peter

[dampflippers]

If you use rubble to fill in, you must put a protective smooth layer of sand over it and then some other sort of protection to protect it from punctures.

[coasty]

If the pits have been in a few years and especially given there previous use I wouldnt worry about chemical leaching,, The concrete will be so well cured that there will be no risk,,, I would avoid adding any new concrete at all and wouldnt waste my money on a liner...

I would connect your house RWP to the pits and fill them and just let them stand for a few months,,,Empty and refill. You could make them shallower by part backfilling with clay,, Dont use soil as the nutrients will create havoc . You could then add some mud and water from an existing pond if you wanted to kick start things... Trust me Im a builder,,,,

[Jez]

Originally Posted by Tursiops2

Maybe join the two to make one unit?

I like the idea of this. How about a 30 foot chunnel about 1ft deep, 1ft - 2ft wide with a bridge going over?!? Just a thought

Oh and make it wavey, all the more interesting than just a linear link.

[Kayleigh]

Originally Posted by Jez

I like the idea of this. How about a 30 foot chunnel about 1ft deep, 1ft - 2ft wide with a bridge going over?!? Just a thought

Wow, like a Japanese water garden..I can see it now..