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Water issue from higher ground .... how to fix ?

Discussion in 'Property Management' started by Honeydew, 9th Jul, 2015.

  1. Honeydew

    Honeydew Well-Known Member

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    Hi All,

    Just wondering if there is any drainage expert on the forum who could shed some light on this issue:

    I'm considering buying a lovely property in QLD which has a backyard on higher ground than the house. Being in QLD I'm a bit fearful of water/the rain getting into the house as it is on lower ground and not sure if its worth the risk.

    The agency says there is a “gully trap” behind the house where all the water coming from the higher ground is diverted into. This gully trap is connected to the storm water drain system which also diverts the rainwater from the roof to the front street.

    Is this sufficient ? Is there a solution which can be used to prevent water from flooding into the house ?

    Image of the backyard is attached.

    Any suggestion much appreciated.
     

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  2. Perp

    Perp Well-Known Member

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    Pay a hydraulic consultant for a report pre-purchase.
     
  3. Honeydew

    Honeydew Well-Known Member

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    hi Perp, can hydraulic consultants offer solutions to this or what do they usually do?
     
  4. bob shovel

    bob shovel Well-Known Member

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    That looks sufficient. It may be worth getting a plumber out as part of the inspection. They could even put a camera through the line to check condition.
    Even point it out to building inspector and check the area for any mould or signs of excess water, look at the brickwork for signs of mud/dirt if water has come up.

    There isn't to much you can do apart from additional or larger gully.
    You could get a bobcat in to re shape the lower section of yard so the water runs away from the house to a new gully near where the ophotographer was standing
     
  5. Perp

    Perp Well-Known Member

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    Yes, they're usually firms who employ both plumbers and hydraulic engineers. They can tell you whether what you've got is adequate, and if not, whether and how it can be rectified. They're experts on drainage, basically - spend their whole lives dealing with standards for drainage, negotiating with Council and neighbours, designing drainage systems, etc.
     
  6. Pistonbroke

    Pistonbroke Well-Known Member

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    Remember $#!+ doesn't flow uphill. ;)
     
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  7. Heinz57

    Heinz57 Well-Known Member

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    I am not a drainage expert. But as a Queenslander I can picture water pouring down those steps.
     
  8. Honeydew

    Honeydew Well-Known Member

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    thank you all for your replies and terrific suggestions! I will definitely make use of these tips when doing the pre-purchase inspections. Also forgot to mention that at the front of this property it is actually on elevated land of about 2-3m from the street(as shown the attached images). Would in the event of heavy rainfall, water flow from the backyard around the house through to the front yard and down the street by any chance or would having too much water flowing from the back high ground likely get inside the house and cause damage to the inside & building ?

    Thanks muchly :)
     

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  9. Honeydew

    Honeydew Well-Known Member

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    Hi bob, are gullies expensive to install ? how much do they usually cost ? Plus the pipes underneath the ground which collects water from the gully, do they need to be extended or modified ? and if so how much would this cost roughly ?


     
  10. bob shovel

    bob shovel Well-Known Member

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    Whats its like around the side of the property? Its got heaps of fall from the back to the street, so as you said its likely it will just run around the house and out the front if the the gully and pipe couldnt keep up with a downpoor.
    Id just check whats happening around the side for good consistent fall/slope. doesnt have to be steep just gradual to the front.
    As heinz said it would catch a lot of water in the backyard and come down, but no a worry providing there is fall around the side plus gully/pipes arent blocked.

    Gullies arent expensive, just a plastic box with a grate, around $50 depending how big you go, plus a couple of hours work for a plumber or a handyman. you can get them from reece and plumbing stores. depending the size you may go a bit bigger mainly so the grass doesnt grow over. Is it an IP? if it is perhaps look at a bigger gully just for clear visibility so its kept clear, and if the yard is let go it would take a while for grass to grow over and be an issue.

    and leave the existing pipe as is unless in obvious need of repair. it would just be a 90 or 100mm pvc
     
  11. Honeydew

    Honeydew Well-Known Member

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    Thanks bob!!! This is an IP. Land is higher at the back, flat on left & right sides and alot lower at the front.
    So in that case we can just purchase and install multiple gullies in the backyard to catch the water without having to alter the pipes underneath ? many thanks. These info are gem to me :)

     
  12. bob shovel

    bob shovel Well-Known Member

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    If there are no signs of water building up, I'd just put in a bigger gully where the current one is for starters. And maybe look at getting some soil in to build up close to the house to ensure water falls away and the sides.
    You should be able to get a gully around 300mm square and be easy swap. The current one looks about 150mm
     
  13. BuyersAgent

    BuyersAgent Well-Known Member Business Member

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    Best practice for that site would be a whole lot of blue metal gravel and a porous ag line pipe behind the wall draining into a stormwater pipe that runs beside the house and discharges to the street. Further the gully on the flat should also have ag line and pipe. Getting a pro to inspect to see what is there is probably best.
     
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  14. BuyersAgent

    BuyersAgent Well-Known Member Business Member

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    rather than a spoon drain I would probably get a trench dug across that flat fill with ag line and gravel and drain it to the street. I would actually avoid adding soil near the house as this may raise termite risk if any is piled next to bricks. You cant chance the floor height of the house you can only intercept the water before it gets there.
     
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  15. bob shovel

    bob shovel Well-Known Member

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    That's a big job digging up the retaining wall! there should be an agg line behind it when they built it.best not to touch it, it would be rubbish fill and clay so usually compacts good, pending the area. I wouldn't dig anything up in a newish development it's utter rubbish they throw in.
    The water shooting across the top will be the problem in a storm coming potentially into the house
    Raising soil would just be top dressing, hard to tell from photos but the verandah could use 50mm against the slab
     
  16. Honeydew

    Honeydew Well-Known Member

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    Thanks Bob & Buyer's Agent!! :)
     
  17. Honeydew

    Honeydew Well-Known Member

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    Hi BuyersAgent, I once visited a property in QLD which had a 10cm wide and long drain running along the retailing walls in the backyard to catch water coming from the higher ground ....is this the solution you meant ?

    what's blue metal gravel and a porous ag line pipe ?? To implement the solution you suggested, usually how much would this cost ? i.e in the hundreds, thousands or tens of thousands etc ??


     
  18. Honeydew

    Honeydew Well-Known Member

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    Hi Bob, I'm hoping so too, the selling agent tells me there's been no water building up issues and that their agency has managed this property for years with no records on file of water issues etc. The old PM
    left and the current one has only been to the property once. I asked to speak with her but he wouldn't let me, saying I can only do that through him. Hrmmm....:rolleyes:

     
  19. dabbler

    dabbler Well-Known Member

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    I cannot see the the inside of the house, but if it is gyprock, it will be very evident if it has flooded inside in the recent past.
     
  20. Honeydew

    Honeydew Well-Known Member

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    Hi dabber, is gyprock plaster walls ? what would be the obvious signs that would show if water has got into the house ? i.e stains or marks on the walls along skirting boards etc ???