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Hi all,
I have drainage issues with my lawn. In certain areas of the lawn water pools for 2 - 3 days after medium / heavy rain. I have dug inspection holes (20cm x 20cm x 20cm) across the lawn to understand what may be causing the water to sit at the surface and have come across hard light grey / sandy / rock type soil. If I keep digging away at this soil / rock slowly breaks apart but it is does take a bit of effort (see pictures).
Does anyone know if this is some clay variant or something completely different? Also, any recommendations on how to help with drainage i.e. digging auger holes 1m down and backfilling with gravel and top soil?
The lawn is approx. 40 sqm and is a mix of Kikuyu and Sir Walter Buffalo with approx. 80% of the lawn in shade all day and I'm located in Melbourne.
Thanks!
So many things can cause drainage issues. Hard to know the problem without knowing more about your property.
What's the extent of the pooling water? How much of the lawn pools, how big are the pools?
What's the slope of the land? Include neighbouring properties. Ideally your lawn would slope from your house toward the street.
Is the water just from the rain or is coming from a neighbours property?
Do you have any drainage at all around the place? (Think french drains, dry wells, dry river beds - all options).
When was the last time you dethatched the lawn? If there's a build up, it can affect drainage.
A good landscaper can help you with solutions and designs.
Where abouts in Melbourne ?
Looks like weathered sedimentary rock maybe Silurian or Ordovician. I am predicting you are on the side of a hill
and may have a site cut property?
So many things can cause drainage issues. Hard to know the problem without knowing more about your property.
What's the extent of the pooling water? How much of the lawn pools, how big are the pools?
What's the slope of the land? Include neighbouring properties. Ideally your lawn would slope from your house toward the street.
Is the water just from the rain or is coming from a neighbours property?
Do you have any drainage at all around the place? (Think french drains, dry wells, dry river beds - all options).
When was the last time you dethatched the lawn? If there's a build up, it can affect drainage.
A good landscaper can help you with solutions and designs.
Hopefully this diagram helps with explaining my situation in more detail. What I have found out since purchasing the property:
- The retaining wall does have agi pipe installed which is draining to a channel drain which connects to a stormwater pipe which drains to the kerbside. This channel drain is constantly draining water during wet weather.
- Both properties to the rear are discharging their roof and tank stormwater directly onto my property with a PVC pipe. After a few discussions with the property owners and council they will have been given notice to fix within 60 days.
- Noting the above point I suspect that the pooling will subside but will still exist due to natural water run off from the land and the clay type soil I have my lawn on
Diagram from reference:
(Brown are bricks)
Where abouts in Melbourne ?
Looks like weathered sedimentary rock maybe Silurian or Ordovician. I am predicting you are on the side of a hill
and may have a site cut property?
I'm in inner city Melbourne (Moreland). And your prediction is right, I'm on the side of a hill and have a site cut property (done 100+ years ago). I will look into rock types you mentioned.
"Both properties to the rear are discharging their roof and tank stormwater directly onto my property with a PVC pipe"
Yeah - that's a huge problem. You should see a massive improvement once they fix that.
How old is the agi pipe? Sounds like it's still draining which is great - but the socks are notorious for getting clogged up. Is the agi pipe on their side of the retaining wall or yours? Given the slope, they should have drainage on their side of that wall to stop any water from draining to your property.
Capilliary/syphonic drainage can be an alternative to agi pipe. Something like Capiphon.
If your block slopes back to front, strange that it would be pooling at the high point (unless your lawn doesnt follow the general slope?). Might need a regrading.
If 2 properties are dumping their water onto your land - I think you'll see a huge improvement once they divert it.
"Both properties to the rear are discharging their roof and tank stormwater directly onto my property with a PVC pipe"
Yeah - that's a huge problem. You should see a massive improvement once they fix that.
How old is the agi pipe? Sounds like it's still draining which is great - but the socks are notorious for getting clogged up. Is the agi pipe on their side of the retaining wall or yours? Given the slope, they should have drainage on their side of that wall to stop any water from draining to your property.
Capilliary/syphonic drainage can be an alternative to agi pipe. Something like Capiphon.
If your block slopes back to front, strange that it would be pooling at the high point (unless your lawn doesnt follow the general slope?). Might need a regrading.
If 2 properties are dumping their water onto your land - I think you'll see a huge improvement once they divert it.
The agi pipe is installed on my side of the property and is suspected to be 20+ years old. I will try and flush it out this weekend and routinely. Apart from the roof and water tank run offs the rear properties have no other drainage system in place.
You are right, the lawn area is level so the water has no where to go. I will be re-turfing so will think about regrading it.
I was thinking about installing agi pipe (or
Capiphon - which looks interesting) under where the water pools and channeling it into the channel drain which leads out to a legal point of discharge and replacing the bricks that butt up to the rear retaining wall with a long channel drain as well to cover as much run off from the properties located at a higher point.
If the agi pipe is 20 years old I'd be surprised if its draining anything at all. The sock surrounding the pipe will be totally clogged, You'd need to dig it up to have a look.
So the land slopes towards your property and the neighbours have no drainage at all along that retaining wall? What's the surface like on their side of the wall? Does it pool there at all? How high is the retaining wall?
Don't discount dethatching your lawn area - can have a significant impact on ground absorption.
I'd still wait and see what things are like once the neighbours stopped dumping all their water directly onto your property. Don't spend a bunch of cash yet, that might fix the issue.
It will pond at the high point because that is where your cut is and rock has been exposed. Water will travel through clay and tend
to accumulate on top of the rock.Once you cut into soil profile you change the normal flow patterns.Sounds like the drain behind the retaining wall isn't working if there is one. This would be difficult to fix. One method is to dig a spoon drain in to the rock at the base of the retaining wall and divert into the storm water system or away from the lawn area. You can further improve the spoon drain by using builders plastic on your house side of the trench and even make it like an apron sloping towards the spoon drain.
If the lawn areas has been cut virtually flat then normal rainfall catchment will not run away you may need to run some small drains at right angles to the main spoon drain at the base of the retaining wall these trenches should slope towards the main spoon drain.
I'll take a guess and say your in the Pascoe vale sth or West Brunswick area going off that rock type in Moreland council
probably not too far from the freeway, just a guess.