Pond Wall Collapse

[Chriss]

Does anyone have any sensible ideas on how to shore up a collapsing wall of a large pond. It's 6 metres deep and since the wife had it drained part of one wall is collapsing.

Had a couple of quotes to fill the whole thing in which are out of my price range at 350-400,000bht. even to fill in the end that is collapsing is quoted at 50-70,000. Was looking for a cheaper option.

[stattointhailand]

Not a lot of useful info there Chriss. Is the pond 6m deep next to the wall? What type of wall (earthen/brick)? How much appears to be collapsing, and what sort of dimentions are you talking about? It's not that I am likely to have an answer, but may be one of our builder members might, if he has all the info.

[Dokya]

With Statto on this one Chris. Please give dimensions, i.e width/length of wall to be shored up and also current materials used.

[Chriss]

OP wasn't written very well, I mean the side of the pond is collapsing, the dirt around the edge. There used to be a walkway round the pond and this is falling into the pond area, there's no actual wall, I just called it the pond wall... sorry.

[Dokya]

Oh, so it's the full perimeter of the pond then? 6m deep is rather deep, depending upon the actual size/surface area of the pond. If it had been just one sidewall I would've suggested shuttering it off and using reinforced concrete as a membrane on the one side however this would be very costly to do the whole thing. Have you thought about graduating all of the sidewalls and creating a shallower outside perimeter? If you use a lot of largish plants/trees around the outside, the root systems, (once established), will stop the banks slipping away. Without actually seeing the pond, I'm afraid this is the best advice I can give. At least the pond is drained therefore would be very simple, albeit labour intensive, excercise to undergo.

[Chriss]

It's about 40m x 20m, not all of the perimeter is a problem just one section about 6m long. Don't really want to put trees etc where it's collapsing as it will block the view from part of the house. Was thinking about building a wall from the base of the pond to ground level where it is collapsing and backfill, but not sure it would be strong enough.

[Dokya]

Not so drastic then Chris. As I said, shutter it off, back fill and leave a gap of about 20-30cm and fill with concrete and reinforce it by placing rebars in before pouring to create a membranne where the side has failed. Once set make sure you have properly back filled to the membrane and compact the soil down ensuring no air spaces are left. Do not use blocks or bricks as these will severely deteriorate over time and you would probably find yourself doing the same again in a couple of years. I can't see this costing more than 30 - 40k, (maybe cheaper), depending upon the cost of the concrete and also a bit of hard work.

[kopkei]

didn't they dig the pond in layers ( i mean 6m deep, dig3m vertical than platform horizontal 1m wide and go back down 3m)
maybe they can dig (or fill up)a platform on the collapsed side, it is never recommended to drain a pond or a swim in the rainy season, as the ground water pressure will make your wall collapse or break , always wait summertime when the groundwater levels are low .............

[Chriss]

Thanks Dokya, looks like the way to go. would ceiling board be gpod enough for the shuttering, have a lot left over from a building project. And have plenty of family members who'll do the back breaking work.
I've never used them but are C Pack worth using to pour the crete?
Kopkei, no it was dug 3m, then an additional 3m without a shelf, was done when I was away, I think I'd have had a shelf put in half way. So it's just sheer drop on the 2 long sides with the ends having graduation.

[Dokya]

I would think so Chris, as long as you prop it at regular intervals to take the weight of the concrete, and as it is 6m in depth I would do it at 2m intervals if I were you due to the weight of the concrete. Once dry remove the ceiling board and move up a 2m stage and repeat process. It may also be worth doing the base lay of concrete a little thicker to create a step and give more stability, also dig down an extra foot or so to create a footing. Don't know about C-Pack but seen many of their cement wagons on the road. Good luck.

[Chriss]

Thanks, sounds like a plan

[BobHelm]

Not sure about C Pack readymix Chriss as I have never used them. I imagine that they come into their own cost wise when you need a complete load(s) to do something like flooring. I think it is a bit of a mathematical calculation for you.
As Dokya suggests it is undoubtedly best to do it in stages rather than to try & do the whole 6 meter in one hit - which I would think would mean a lot of prep work on the 'framing'.
So it would need a few visits from C-Pack, so not sure how cost competitive that would prove to be.
It if is concrete done the old fashioned Thai way - so complete spade work or a small mixer - then the concrete is going to be done over quite a time & so will be curing & hardening as you go - & a lot easier to ensure you are getting an even coverage.
Don't forget if you are doing in the dry season then the 'wall' will need to be watered at least a couple of times a day as it dries - for at least a couple of weeks I guess - to stop it drying too quickly & cracking.

[parrot]

Things to consider with pond walls in Thailand. Our neighbor had a pond with a graduated berm. After about 5 years, one part of the berm was riddled with rat holes that compromised the integrity of the berm. Big forest rats....the kind some Thais like to eat.....not the little things that get up in your engine compartment and eat away at the wiring.
Catfish are another problem. They'll burrow deeper and deeper in the walls of a pond. In one of our smaller ponds, they burrowed through the wall and we lost about 300 8" catfish that escaped into the adjoining reservoir.
Good luck with your repairs.

[Chriss]

Thanks Bob, The local builders in the vilage say C Pack will be too expensive and they too say it's better to complete the concreting in sections as Dokya suggested. They said building a wall would be a cheaper option and no problem with any degradation as the pond is drained every two years anyway, so I need to get some prices going. And they showed me a mixer I can use for free.....

[kopkei]

chriss,
worker 200 bath a day , don't take to many ( 3) (they have time enough , no rain now, what i have learned in thailand if you work with more workers , the work is not finished more quick, it will only cost you more..), or leave them make price for all...( they can work with 20, who care's ), remember when building a wall , if you fill up at the other side make sure it is in the dry season ,because if the level in the pond is to low the outside ground water pressure will make your wall break again....,you need equal pressure on 2 sides.., and draining the pond only in the summer is a must....

[Chriss]

Thanks Kopkei

The wife drained the pond 2 weeks ago, when I was out of the country..... thats when she found the collapse. We usually drain it in Feb or March but for some reason only she knows it was done early this year.
No problem with the workforce, we have a few young building guys in the family who will willing do the work for lunch and a bottle of Lao Khao a day.