Simply Koi and More Koi

I’m in the process of building my new pond which will be 12x12x6ft and have just completed the digging out.

My neighbour has raised some concerns that the base will not be strong enough to cope with the weight of the water and that it may fail and leak onto his property.

The base will be 1ft steel reinforced concrete with the walls built 8in from the sides of the base in 18in blocks. The base is being built into a plastic sheet to prevent damp ingress and the final pond will be fibre glassed.

Is there a way to calculate what thickness of concrete would be required to be strong enough to support a pond that will be 6ft deep?

I thought that 1ft thick reinforced concrete was over-engineered but if there is a way to demonstrate this it would help me. I don't want to fall out with the new neighbours if I can avoid it.

Thanks in advance for your help

Dave.

Hi David,

I don't know about calculating it but my pond is 12ft x 9ft and 5ft 8inch deep and has a steel reinforced base which is 8inches thick before the block work i then added a slope from the top of the first block to the centre/drain, making the centre of my pond still only 8" thick.

IMHO 12" reinforced base would be ample. I'm sure someone else would confirm this or point us in the right direction

Hi Dave,

I hope that 1ft deep would be more than over engineering-if not i need to make my hole deeper! Im glad you raised this as im hoping to get the base laid in my pond the weekend after next. From memory(please check!) im sure that there was a post a while ago that said 6 inches would be ok as long as reinforced with steel bar-Jules is probably the best man to speak to!

Cheers Andy

Ps any pics of build so far???

Hi Dave

The sizes that you have given will give you 5400 gallons of water plus the filters the water that will be in the pond will weigh just over 24.50 tons
What you are doing 1ft thick reinforced concrete will be a slight over kill

My pond was built over 12-years ago and the base was 6-8" of reinforced concrete - no leaks yet!

12" of concrete - overkill

I am in the prcess of building my pond and I have gone for about 8" of reinforced concrete for the base. I have used hollow blocks and drilled the base thru the holes and put in rebars to give support to the bottom row of blocks to help prevent them splaying out. I have also filled my blocks with concrete.

Thanks for your replies. My neighbour has booked a structural engineer to take a look next week to give his assessment…so who knows what he will ask for, but they have agreed for me to be there so I will hear it first hand.

More importantly I’m installing the bottom drain pipe work tomorrow in anticipation of the base getting poured on Monday.

If I get this right then I have attached a couple of pictures of the most problematic hole I have ever dug!!

Your new neighbour sounds like a right pain in the a***.

Tell him to bog off and mind his own business

I hope he's paying for the engineer!!!!!

There will be a hole full of wet cement when he arrives....could be tempting

dont argue with the neighbours .......convert them ...when they see how nice your pond is gonna be......12" reinforced base more than adequate , that aint gonna give way ...ever

the majority of houses are only build on a 9" footing

dave339 wrote:There will be a hole full of wet cement when he arrives....could be tempting

That's it make him some concrete wellington's

Hi Dave
When you are blocking up the side of your pond by your neighbour’s fence leave a 3-inch and back fill with concrete and that will even out the pressures between the soil and your pond thus no gap

Hi Dave,

That will be strong enough believe me i know how hard it is to try to knock Bobs filter bay down

If they do raise concerns which they shouldn't don't forget to ask for written conformation and also ask the guys background as i very much doubt he has ever had anything to do with ponds

Hi, please don't put your neighbour in the concrete mix as this will undoubtedly make your base become weaker as he de-composes
best to put him under the slab because at 1 ft deep when he rot away,the base will be more than adequate to bridge the gap left behind
Seriously though,as said,it will be more than thick enough,to put his mind at rest,again as said leave a good gap from the boundary line and maybe reinforce the side bordering his property just my thoughts SD