Stormwater drainage

Discussion in 'Development' started by Arnel, 23rd Jan, 2016.

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  1. Arnel

    Arnel Well-Known Member

    21st Jun, 2015
    Hi guys,

    Doing a development with class "s" soil, from ground level it becomes clay @600-700mm depth.

    Now I need to provide a stormwater management plan, can I use soak wells here? Any ideas as I have never worked with clay sites before :(

    Thank you in advance
  2. WestOz

    WestOz Well-Known Member

    19th Jun, 2015
    Hey mate, 600x600mm the depth of the standard soakwells from bunnys - Our Range

    Can't imagine nor seen any clay we have here on the coast causing any issues but if everything around it is sandy soil you'll have no probs.

    Consider what the runoff volume to each capacity with a big downpour will be though, if you think one won't be able to handle it join a 2nd to it with some pipe for overflow (similar to a septic setup).

    Also a good idea to have venting at the bottom of downpipes so if they do fill up it won't blow out or lift anything above them, like pavers.

    Post a pic of a mud map and I might be able to offer better suggestions.

    This is my prefered method so it also catches surface water.

    Leo2413 likes this.
  3. hematite

    hematite Well-Known Member

    13th Jul, 2015
    Arnel, I remember you posting about Geotech some time ago. Did you get a geotech report? In the report, they usually advise on what the drainage requirements would be (along with footing design etc).

    If your soil drains well (i.e. sandy), and you have a low water table, then soakwells may be okay.

    However if you have clay soil and a high water table, then you will probably need to drain offsite, which costs money for infrastructure contributions, more pipework etc. This is because the water will just 'sit' there on your block and cause issues.

    Best to ask your geotech - they will help you out.
  4. bob shovel

    bob shovel Well-Known Member

    18th Jun, 2015
    Penrith, NSW
    I'm not familiar with WA and soaks wells etc, but clay at that depth I think it would be unlikely to get wells in. Check out the neighbours.
    But clay no soak wells is easy, just have down pipes run out to the street and down the road. Easy.
    For a DA I did fit an extension, I just did a sketch of the existing stormwater which didn't need modifying. I just drew where the down pipes were and where they ran to the gutter.

    Your builder /plumber should be able to sort it