How to install rubble / gravel pit for drainage?

[Aidsy]

Hello everyone,

I'm looking into rectifying a few storm water drainage issues at my newly purchased house. My house is a post war property which falls away from the curb, there are no storm water connections i can easily join into and there is no easements i can utilize. Right now my shed down pipes disperse the water right down on the ground which is not sustainable.

My plans are to install a 5000L rain water tank, and from the overflow of this tank I'd like to run it into a rubble pit (gravel pit, seepage pit - I think they have a few names). to reduce how much surface water run off i have. The ground is full of clay, so i'm sure this will cause issues though. 

council websites show some designs but hoping to get some real-world advice, and ideas from this great community. My understanding is i can dig a pit, 1m x 1m x 1.3m deep. Have an socked and slotted ag pipe running into this pit, filled with gravel. Geo fabric ontop and then 2-300mm of top soil to get it back to a level surface. Do i just run the ag pipe into the middle near the bottom of this pit? or do i coil it in the pit and support it with 20mm blue metal gravel? 

I've tried to search for old posts but haven't had much luck!

[EricL]

Hello @Aidsy 

Welcome to the Bunnings Workshop community. It's marvellous to have you join us, and thank you for sharing your question about installing a gravel pit for drainage.

Theoretically when water enters the surface of the pit it slows the speed of the water down as it drains down the gravel to the bottom giving the soil enough time to absorb the water flowing in. Placing the drainpipe exit at the bottom of the pit will defeat the purpose of the pit as it will get filled with water and not give it enough time to absorb it. I propose placing the exit of the drainpipe just below the surface of the gravel pit which will make full use of the pit's function.

However, this is a serious piece of drainage you're about to install into your yard. I recommend engaging the services of a registered plumber to oversee your drainage plans. Because of its size and depth, I also recommend checking the rules and regulations of your local council regarding the installation of the gravel pit. 

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

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

Eric

[Dave-1]

Afternoon @Aidsy 

Love storwater questions, hate the issue but love it when its solved! (Also would like to say welcome to the workshop community )

When I was doing my stormwater rectification I came across two of those type of pits you are describing. They use to be used years ago but have been supperceded by new laws/policys I think.

As @EricL  suggests I would feed the overflow from the tank towards the top of the seepage pit as its supposed to seep away. I have lined my stormwater trenches with gravel to the height of the stormwater pipe and this alone has changed the dynamics of how sub-surface water flows downhill on my property. (I have a few projects on it if you want to look up my bookmarks) 

A question I have is what is below your property? As I was firstly thinking of a run-out style trench for excess water (trench filled with gravel and a socked ag pipe)

Do you have a photo of the block you could post to give as an idea of how you are thinking?

Dave

[Noyade]

As above.

We discovered the storm-water on the southern side of our house was connected to a rubble pit on the nature strip.

This discovery was made after a severe storm and water backed up to and over the front verandah guttering.

The reason was seventy years of dirt, leaves and rubbish which accumulated and eventually completely blocked the pipe.

😔