I have just finished renovations that included excavating a fair amount of dirt from our back yard. This has left me with an area about 5m x 10m that I need to fill with dirt to the depth of about 20~30cm. The ground is now a very hard clay in some areas, mud stone in others.

The plan is to lay some ag pipe connected to the storm water system on the low side then lay a base on top of that, then put top soil on top of that. Grass will then be planted.

What base should I use - sand, gravel,....?

1 Answer 1


What you're trying to do is called a French drain system. If you google for French drain you'll find a ton of info and useful diagrams.

Coarse gravel is typically the base. This is then topped with finer gravel and landscape cloth so as to help prevent clogging. If you use sand too, you definitely want to use a cloth to keep the sand from draining out.

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    Also check with local codes to see if you're even allowed to tap into the storm system. Lots of places now ban that (in which case you'll want to look into using a dry well of some sorts).
    – DA01
    Feb 28, 2011 at 16:26
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    I'd also recommend a French drain - use 20mm+ stone and some sort of membrane into the unfilled drain and over the top of the filled drain to stop soil washing into the drain and clogging it over time.
    – bochgoch
    Mar 8, 2011 at 16:33

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