Backyard Aquaponics
A place to discuss aquaponics

Last night's rain has caused some issues to my budding aquaponics system. In the pictures below you will see that the IBC tank which was buried and empty was lifted out of the ground by the saturating rain. The sump tank hole is flooded which caused the tank to lift to the point of moving and knocking over the empty growbed which was placed over top of it.

It is unknown at this time if the hole has been partially filled with dirt and sand as a result of the flooding. I'll have to wait and see after the water drains off. It is my guess that the bed and tank will need to be removed and I'll have to clean out the hole before everything is put back together.

Now the question arises, is this design safe? Will this happen again? Would this have happened if the sump tank contained a normal operational amount of water? I had planned on having the sump tank about half full during operation. Would that have been enough water to keep the sump tank in place? My guess is that a half full sump tank would have lifted out of the hole when exposed to this much flooding. Granted, it probably wouldn't have lifted enough to knock over a filled grow bed but even lifting a few inches would be enough to allow sediment to collect under the tank not allowing the tank to settle to it's former depth after the water drains away. This would gradually lift the tank over several flood and drain cycles and an eventual redo of the design would become necessary over an extened period of time.

I can't do much with it today. The hole is still flooded and I have to work later on so I can't invest a lot of time into this today. Hopefully the rain will not continue and the ground water will drain away allowing me to assess the damage and formulate a plan of recovery which will avoid any future damages due to ground water flooding.

This is what I found this morning when I woke up.






You can see the ground water had flooded to the very top of the sump hole.

The water in the sump should keep it weighed down. With nothing in it, it empty hull will push it right out.

Can you mound dirt around the edges? To stop run off getting into the hole?

Maybe this would have helped:

http://www.backyardaquaponics.com/forum/viewtopic.php?f=1&t=21492&hilit=sump

I really don't think the water ran in from the edges. The soil is quite sandy under the topsoil and I'm pretty sure the ground is saturated to the point where water is flooding through the walls. Therefore, I don't think building up earth around the edges will help. Thanks though. Actually, the downpour was so intense last night (island wide flooding and road closures) I don't think any reasonable amount of mounding would have helped.



I remember reading that before burying my tank. That thread is the reason for the addition of the steel cage from the IBC and the sealant treated plywood into the hole. I am quite sure those additions prevented a complete cave in of the sump hole.

So to get this straight...

The hole has flooded and the sump tanks are empty so water pressure has crushed them but the soil has been retained?

I think so. The hole is still full of water so I can't check to see how much dirt/sand may have entered the hole. I did drop a stick into the hole to check for depth and it seems okay.

If you check back deeper into this thread you will see that I added the IBC cage to the hole as well as some asphalt treated plywood around the outside of that cage. This was done to prevent the surrounding earth from caving in. It appears those precautions have paid off.

The problem was that the sump tank itself was empty and the hole began to fill with rain water due to the heavy tropical storm we had last night. The water lifted the empty tank right out of the hole. It even lifted the empty GB that was positioned over the ST and knocked it off the blocks it was sitting on.

I will get the water out of the hole, inspect for damage/integrity and then put everything back in place. I think I am also going to dig out a small notch on the side of the sump tank hole and drop a sump pump in there to prevent this from happening again. I will also fill the sump tank with water to anchor it down while I get the rest of the system up and running.

I think to keep the skeeters away I'll pick up a small "back up" pump and cycle the water from the sump to the fish tank and back while I finish the build.

Yesterday I moved the GB and pulled the tank in order to inspect the damage.











The IBC tank seems none the worse. I was able to press it back into shape. I poked around in the flooded sump hole to check for sediment. It feels like there is a little unwanted sand at each corner of the hole that will probably have to be removed in order to get the IBC tank to sit properly. I'll tackle that on my upcoming days off.

Today I got these from Amazon. 1" for GB overflow lines and 1.5" for GB drains. I think this will be all of the bukheads I'll need for the AP system. I'm pretty sure the rest of the plumbing can be managed with uniseals which I will source locally. Looking forward to going forward.

It doesn't look like you have any footings under those concrete bricks.

Probably want to add a large concrete paver or the equivalent under each one.

I was hoping it wouldn't be necessary.

I really don't like sitting the GB's on blocks. I'd rather build a base with legs out of 2"x4" and rest the legs on pavers. I think the blocks could be prone to toppling albeit a slim possibility. I'll look into both options.

I can agree with Stu from experience.

My beds started sinking, probably 20 cm, it popped out the uniseals, drained the sump dry. And it's a pain in the butt to lift up several tonne worth of GB.

You could get away with pouring a concrete footing.

I think I might end up building bases with legs to set the GB's on and then rest those on pavers.
It seems this flooding may have been a blessing as it has allowed me to re-examine the design.
I can find another use for these blocks.

I'm nearly ready for rocks!

I managed to finish off the plumbing. Nothing is glued yet. I want to be able to make changes if needed after
rocks are added. I also built the surround for the fish tank. I still need to make the lid. I'll probably make a little
mini surround for the sump tank since it does get some direct sun at certain times of the day. As you can see, I
have water running to all three beds. I still need to make my bell siphons and media guards. I just need a few
more nicks and nacks for that. Most of the plumbing has been secured. I just need to make something a little
more permenant for the bits behind the fish tank. They are just resting on blocks at the moment. I'll probably
tackle that after I finish the lid for the fish tank. After that I suppose it will be time for paint and "make nice" stuff
for the wifey.

Still cant see any footings for your bricks.

Taking a risk.

A concrete paver under each brick would be a good idea.

Thanks for your concern. I thought about adding pavers under the brick stacks but I got lazy. I rationalized that if they did start to sink it would be a gradual process. I could easily wedge the beds back to level if the need arises. I have a 2-1/2 ton jack at my disposal.

You know what's really funny, I had that exact same thought!

It was probably the second week I had it up and running, then it rained, a lot. The ground got muddy, the beds sank. One end was too low, and the water was just pouring out one end of the bed, just draining onto the ground, making it muddier and sinking quicker.

So going out in the dark and pouring rain, I start to jack up the bed. The jack is at its limits height wise, so I'm putting the jack on pieces of wood, and other pieces between that a few more pieces of wood to make the distance. I get it up enough, and the weight it all on the back part, which starts to sink also, I try to move, and the whole bed starts to shift to the side instead, and starts to topple over. Luckily it just slipped off the jack, and stayed upright, otherwise a few tonne of gravel would have been all over my backyard, the liner would have ripped, and it'd have been a nightmare to sort out.

Trust me when I say, it's far easier to jack up now while it's empty, before the media. Put some post hole concrete below and in the cinder blocks, and rest it back in place.