Stormwater discharge

[neil_sullo11]

O.P.
Just raised our Queenslander house, previously the rear downpipes went to sewer, so we need to get them to a stormwater drain now.

We have a single storm pipe discharge to the Street currently being used by front downpipes.
We also have (according to BCC plans) a storm drain running through the back of our yard.

Am I better off just running all the house downpipes to the street discharge (and if so is it ok to run 4 downpipes into the one street discharge?) or do I stump up the plumber/ excavator costs to tap the rear downpipes into the council storm pipe?

[Wrongwayfirst]

Not sure how it works in brisvegas but normally you cannot tap into the council main without permits etc. suggest you connect all to the front, don’t see any drama with doing it like this nearly every property runs one roof through 90mm to front (or rear) but one point of discharge.
cheers

[rwbuild]

Minimum size for stormwater pipe to street is now 100mm

[truckjohn]

Remember that water flows downhill. The drain piping in the the ground needs a specific drop of so many cm per meter of pipe run or water will not flow.

As such your first challenge will be to determine if the road discharge will provide you sufficient drop from the furthest part away, taking the bends around the house into account. If your yard is sloped (most are slightly sloped) - it may be fine.

Next will be the same question, but now looking at the underground elevations of the existing drain pipe. It won't do much good if the run from the back lands half a meter below the piping on the front where you'd like to tie in.

Same question for the back yard storm sewer. Does it allow for sufficient elevation drop for water flow to the tie-in.

Remember gravity. Water doesn't like to run uphill. Having to add a little more depth to a tie-in is ok, less is not.

[forrestmount]

The rear storm water drain that is shown on your drawings is common in older Brisbane suburbs. From my perspective they were a great side a but not executed very well. The property owners are responsible for repairs not maintenance and there was never any legal contracts covering obligations.

This means a blockage may occur 6 houses down and requires a neighbour’s yard to be dug up maybe tress removed etc. but the blockage may not affect this property and this unaffected owner may be on a pension etc.

We have had this system at two houses we have lived in and both worked fine and it was the easiest to connect to.


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[rambunctious]

O.P.
Just raised our Queenslander house, previously the rear downpipes went to sewer, so we need to get them to a stormwater drain now.

We have a single storm pipe discharge to the Street currently being used by front downpipes.
We also have (according to BCC plans) a storm drain running through the back of our yard.

Am I better off just running all the house downpipes to the street discharge (and if so is it ok to run 4 downpipes into the one street discharge?) or do I stump up the plumber/ excavator costs to tap the rear downpipes into the council storm pipe?

In Qld storm water comes under the building dept not plumbing dept which means any one can do storm drains and this is the reason owners down the track have so much trouble with storm drains.
100mm DWV as mentioned is the norm and never use 90mm as it is rubbish
Running one x 100 to the street is not a good idea, most new builds have 2, plus an extra drain for surface water, never connect the downpipes and surface drains together.
You can run storm drains uphill,(within reason ) just make sure all joints are cleaned and glued thoroughly then the head of water coming down the downpipes will push the water uphill, I have done it a few times and it has been signed off by the certifyers.
Running to the storm drain at rear is what it is there for meaning your land must fall back to the rear of the property so entirely your call as in which is the easiest/cheapest run ?
As also mentioned the storm drain at the rear is the responsibility of all property owners but of course as we know from our experience here no owner behind us gives a dam, besides the drains themselves are usually undersized as well.
The drain behind us is 250 and should be 450
And don't expect the certifyer to care too much, I have seen properties with large extensions where the builder simply ran the downpipes into the ground and they spew out every time it rains.

[truckjohn]

So the building authority may not care if you try to run water uphill, but I have it on good authority that it does not.

What will happen is that every single speck of dirt and leaves will settle in that low spot and form clogs, which then results in water backing up all over the place.

If you're going to pay the money, do it right.

[rambunctious]

So the building authority may not care if you try to run water uphill, but I have it on good authority that it does not.

What will happen is that every single speck of dirt and leaves will settle in that low spot and form clogs, which then results in water backing up all over the place.

If you're going to pay the money, do it right.

Nah, you forget that Australia is down under, so in fact the water flows upside down and all clogs fall out.

[neil_sullo11]

As the house has been raised I have no problem with drainage slope either to the front or rear, just trying to get a handle on capacity and cost of options.
The land slopes down from street level to the council storm pipe at the rear of the block.

From what you are saying then maybe I’m better sending the front downpipes to the street and the read downpipes / any surface drainage to the council storm pipe?

If as you say stormwater doesn’t need a plumber, I’m guessing I probably would need one if teeing in to the council pipe, with council permit needed?

[rambunctious]

As the house has been raised I have no problem with drainage slope either to the front or rear, just trying to get a handle on capacity and cost of options.
The land slopes down from street level to the council storm pipe at the rear of the block.

From what you are saying then maybe I’m better sending the front downpipes to the street and the read downpipes / any surface drainage to the council storm pipe?

If as you say stormwater doesn’t need a plumber, I’m guessing I probably would need one if teeing in to the council pipe, with council permit needed?

Correct except you don't need a plumber to tap into a drain YOU own and are responsible for.
Dig down and see what material the pipe is.
Depending on when the area was developed it may be earthenware, maybe pvc, maybe concrete pipe, or at worst asbestos cement.
I would pick the lowest point in the rear of the property and install a sump or manhole up to ground level with grate or sealed lid on top and spud your storm drains into the sump/manhole.

If you want to pay a plumber for that it is up to you, or as I have stated, you can do it yourself

Phone the council plumbing inspectors and ask and they will tell you basically what I have stated.
Cutting the pipe is simple with a battery angle grinder and diamond blade, and use water if necessary.
By all means talk to council if you wish but at the end of the day the certifyer (building inspector ) has the last word and all he/she will ask is where does the storm water go.

[truckjohn]

Well, that knife cuts both ways. If it's done wrong, you are on the hook to fix it. I would recommend getting a pro to at least do the tie-in's.

Personally, while I'm fine with measuring and laying drain line, I'm no fan of trenching. I would be happier paying someone to dig the hundred meters of ditch. That's me, though.

[rambunctious]

edit to #10

Run the storm drains so they will not be in the way of future sheds/pools etc and if you plan on sheds/pools in the future put in capped junctions for later connection.

Also keep a plan of the storm water drains including depth for future reference because while the sanitary sewer will be drawn up by the plumbing inspector, storm water AND water supply are usually never drawn by anyone.

[rambunctious]

What was I saying about storm drains in Queensland ?

Kevin's House of Pain from today's Courier Mail.

DSCN1140.JPG

QBCC's idea is a downpipe must be installed every 6 metres but what is under the ground is not important for anyone to inspect it.