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How to stop my courtyard from flooding?

Three times in the last two years my courtyard has flooded without a trace of where it came from. We had rain on all three occasions so I thought one of the down pipes was blocked as there was no overflow from the gutters. I placed a hose on high in the downpipe and the water came out under the house to the large grated storm water pit/drain in the driveway. As the yard was looking like it was sinking on a slope I wanted to pull up and re lay sand under the artificial turf to even it up. While I was there I thought I would check out the situation and put the hole in the downpipes again. No flooding but this is what I found while digging.

image of the kitchen windows on the left and the door in the centre leads into the garage which is the area that it flooded into.

The side view - the small white pipe going into the drain at the bottom left is from the air conditioner

the down pipe on the right

As I was digging I found 2 smaller pipes higher up that were full of dirt. However they were cracked at the ends and in-between them was a pile of bricks, which is right at the door where most of the water collects. Not sure they served any purpose.

what I found between both pipes.

I live in the second unit of a block of four with the front being two storey and the rest single storey. Purchased it brand new back in 2008. Any advice on moving forward is greatly appreciated

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Comments

EricL

Hello @oneteaspoon

This definitely sounds like a job for a plumber. Some of the possible causes of flooding that come to mind is that it is a uniform flood that you and your neighbours experience. A deluge comes and the rain drains uniformly across your properties. Another theory is that there is a broken storm drain that is passing through your property and is flooding your area.

Whatever the cause may be, I think it's important that you have a drain solution handy for those times when it looks like there is too much water coming into your yard.

Let me call on our experienced members @Dave-1 and @Nailbag for their recommendations.

If you have any other questions we can help with, please let us know.

Eric

oneteaspoon

https://www.workshop.bunnings.com.au/discussion/comment/45751#Comment_45751

Thank you for your reply. I agree if stormwater pipes related definitely would need a plumber. However it’s odd that I’ve lived here since 2008 and only in the last few years has my courtyard flooded. None of the other units on my block flood, the storm water pits in our driveway never overflow and as our fence line is shared with a driveway of another block of 3 single story units that their land is higher than ours I always check their driveway and stormwater pits and it’s all clear.

EricL

https://www.workshop.bunnings.com.au/discussion/comment/84972#Comment_84972

Hi @oneteaspoon

It definitely has to be investigated, it's very unusual that only you get flooding while the others don't

Eric

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/107601#Comment_107601

Good Evening @oneteaspoon

You have given me flashbacks to my stormwater pipes 🙂 And yeah it can be a pain to step through to solve. I had leaky gutters, so replaced them, then had water under the house and went what the? Turns out the stormwater pipes were broken and that was where the water was traveling.

Have you had a plumber out to put a camera down your stormwater pipes? That would be my first step, they will be able to tell you the condition of the pipe. Mine were compressed to the point a camera on flex could not go through. Compressed with clay just being clay. You can have a look at my bookmarks for stormwater and it will show you waht I mean 🙂

If your pipes are clear, then the question becomes "Are you pipes linked to others in your block?" If so maybe your yard is the lowest point that the water can exit when you get a "flood" coming through with downpours. If thats the case then either a larger pipe, second pipe or the ability to hold the water for a short time as it empties are the things that I would step through.

You mention the block next to your driveway as a block of three... It makes me think the runoff from a large hard surface could also be causing you your inundation as water will take the easiest path. So water backing up in your yard, entering from higher surface water. For that issue I would have a chat with the neighbours bodyt corporate and/or install grill drainage along your fenceline to capture the water and feed it to stormwater.

Dave

btw I am impressed with your trench digging 🙂 I am not laughing as my trenches were actuall deeper! 🙂

I am not sure whatthe small pvc pipe was for, at first I thought maybe old telecom lines but the pipe seems to be too large, gas is yellow so thats a nope as well.

Nailbag

Hi @oneteaspoon

My advice is simple and the same as @EricL . This is clearly a job for a registered plumber. Not only for experience, but its actually a legal requirement across all states that if you're not a plumber, you can't perform this type of work.

That aside, that 60mm pipe could be obsolete as nothing of that diameter should be servicing stormwater. Everything underground is 90-100mm. A plumber with a camera will be able to work out the issue for you.

Nailbag

oneteaspoon

https://www.workshop.bunnings.com.au/discussion/comment/121054#Comment_121054

Thanks for the reply. Would you believe me if I told you that I only used hand tools, including a trowel to do all of my digging. I find digging very therapeutic so for me it’s not about speed.

in regards to the neighbouring property being on a higher level, if it were the cause wouldn’t all the units on my block flood?

In another experiment last night. I decided to run the hose on shower to mimic rain just to see where the water flow goes and this is what happened

the grass on the right stayed dry

I also went out into my driveway and the stormwater pit was bone dry.

here is a photo that I took this morning.

for my own understanding. How is the drainage system in a backyard set up? Obviously there’s the downpipes connecting to the stormwater. However where is the excess water? If we have a heavy downpour meant to go? Is it just meant to seep into the soil and dry off?

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/129424#Comment_129424

Morning @oneteaspoon

🙂 I really understand how therapeutic is.

Stormwater rectification stage 1

Stormwater rectification stage 2

Fixing water ingress issues in garage

Are some of the digging projects Ive done 🙂

So a question, underneath your "alternative grass" is that concrete or a hardened surface? Also have you put a spirit level across any of your yard (including the grass and concrete?) You may need to find a long piece of timber to sit a shorter level on and make sure its level to get a good guide (if you dont have a long level)

Going through the pucs again, I notice that your soil is like mine. Solid clay... It makes me think their may be cracks/pathways within the clay that drain/pool the water and as your trench is open thats why the water shows. To me it suggests that whatever drainage had been done in the past or you dont have any isnt working and we are back to getting a plumber out with a camera to check the state of the pipes. That Junction means the pipe potentaly heads towards the down pipe but also?? A plumber with a camera could chase the pipe and recommend which way to step forward. I know its extra money but you will know then for sure what has been done.

Dave

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