How to stop overflowing water from other properties?

[Barbara35]

I have an existing colourbond fence as a boundary fence between my property and the adjoining property.

I continually have flooding when heavy rain pouring through from their  place. It is like a dam has burst and we have renewed all of our storm water and drains  at a cost of $9000.

Our drainage accommodates water on our property but not the extra from behind. When this happens it floods the top level which becomes like a swimming pool and over the garden and is like a waterfall coming down over the steps  to the patio. When the water gets to the patio we have to broom it to the side so that it doesn't enter the house. We have had to have SES provide sand bags.

We have spoken to the neighbor who says his yard floods as well but says it is nature and is not prepared to do anything .

We have spoken to the Council on a number of occasions and one again they are looking into it.

We are having quotes to build a wall across the back but this is very expensive. We thought we would get cement sheeting and put that across the back to prevent this flooding. We were thinking  of making it approx 3ft high. and to go across approx 405ft 

Not sure what product to use and really need help.

[MitchellMc]

Welcome to the Bunnings Workshop community @Barbara35. It's wonderful to have you join us, and many thanks for your question about garden drainage.

Natural watershed, especially on sloped blocks, is a difficult issue to deal with. Depending on the properties' layout and if there is a significant amount of water entering your property, then the neighbour likely has it entering theirs as well. The issue gets compounded for the lower blocks as the higher ones drain into them. Building a wall or installing cement sheeting could be effective in preventing the flooding, but it's important to ensure that any solution you choose is both effective and within the regulations and guidelines of your local council.

I'd suggest installing drainage along the fence line to collect this intruding runoff would be more effective than to try and block it with sheeting. I know it's a difficult situation, but be aware that if you divert the water from your property into someone else's and this additional flow causes damage to the property, there would be a liability issue. This seems particularly unfair when others are not interested in assisting in resolving the issue. I have a concern with cement sheeting because it's not designed to be used in water retention/diversion systems. If it were to hold back a considerable amount of water and debris before failing, you would be dealing with a deluge from a dam burst. 

Would you be able to dig a ditch across the fence line and install a drainage coil into it? That way, the water will be captured and directed to your stormwater. Here's a helpful step-by-step guide: How to install garden drainage.

Let me mention one of our knowledgeable members, @TedBear, to see if he has any thoughts.

Please let me know if you have any questions.

Mitchell

[Barbara35]

Do you think I  could put some treated pine H4 at the bottom of the fence between the bottom of the fence and the ground level to slow down the flow.

[MitchellMc]

That could potentially work @Barbara35. It really depends on where that water is then diverted to. If you can use the timber to slow down the flow and send the water to a collection point, that would be best. Where's the closest stormwater pipe or pit to this location?

Mitchell

[Barbara35]

What would be the best timber to use that would not deteriorate over time

[TedBear]

Hi @Barbara35 , that sounds like quite a problem to tackle. You mentioned the proposal to build a low wall 405 feet long!  Two things that we don't know....

1) how exactly does the water get into your property?

Does it seep under the 400ft steel fence? Would it be possible to use that fence as the "dam"  to keep the water on your neighbour's side?

If it sneaks under the fence then perhaps you could dig plastic garden edging (widest you can get) into the soil to seal the gap between fence and soil. You'd need to put steel pegs (e.g. short star pickets) behind it to hold the pressure back. Ideally it would  actually go on the neighbour's side so that the fence itself holds this seal in place. 

2) what are the options for letting the water out of your property?

If it is impractical to stop water from entering  at the fence line, then is there a road further down that the excess water can be directed to? Excess water would be that which any drain that you build across your property can't accommodate. After you collect the water you may be able to drop it into a series of long standpipes (or soakwells) that you would install in a pipe running downwards away from the drain. If there is a road at the bottom, install a final standpipe close to it, covered with a grate and then stones. If that one overflows any excess water will then overflow onto the road which should accommodate it ok. (Just as rain runoff from a verge lawn would do.)

You can find details of such systems on Youtube.

[Barbara35]

Hi,

on the other side of the fence he has a three or four brick high wall around the back up the sides and across the back like a swimming pool.

This fills up with water and floods over this wall under the colour bond fence through my garden pushing all bark mulch out onto the grassed area floods the top level so that it looks like a swimming pool then through the garden between the two level and over the 3 steps like a waterfall.

We do have ag pip right across the top of the garden right in front of the fence which does take our storm water down and through our drains and out the storm water at the front however with this flooding the pipe does not cope with the amount coming over this small wall.

Could you suggest the type of timber required for this job that will last and not deteriorate please?

[Barbara35]

This bricked up area he has was a vegetable garden but hasn't been for over 20 years.

[Barbara35]

I think the size of the wall  is the nearly the width of my land and the land is 50ft so I thought the wall would be approx 40ft not 400ft.

[MitchellMc]

Hi @Barbara35, 

You could use 150 x 25mm 4.8m Plinth H4 Treated Pine Sawn Wet, but sleepers would last longer. As @TedBear mentioned, you'll need to install posts or stakes to hold the sleepers in place. 

Mitchell