House downpipes into old school soakpits

Forums › Home Workshop DIY › House downpipes into old school soakpits - blocked

AklBen

102 posts

Master Geek

#272717 11-Jul-2020 17:16

Our house is fairly old and we bought it knowing that it needed some modernising. One of the tasks will be eventually connecting the downpipes to the council stormwater system. In the meantime two of the three soakpits are fine, one gets filled up with water and eventually drains away. This points to me that the drain to the soakpit (somewhere under the lawn) is clogged.

Does anyone have experience with maintaining these? Should I dig up the drain that leads to it and clear it out?

Thanks!

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4098 posts

Uber Geek

Subscriber

#2521241 11-Jul-2020 18:19

We have a house in central Auckland built around 2000 - It has a soak pit.

I understand they can get a bit silted up - which slows down the absorption into the surrounding earth.

It may be that the soak pit needs to be cleaned out.

Might be a job for a company that specialises in them:

https://www.buildmagazine.org.nz/index.php/articles/show/soak-pits

Ours is approaching 20 years old - when there are HUGE deluges it sometimes overloads. Probably needs to be looked at. Not sure about the comments in the articles about every year - but....

Nothing is impossible for the man who doesn't have to do it himself - A. H. Weiler

Jase2985

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#2521244 11-Jul-2020 18:26

you are better off sorting out the soak pit because any new connection to the council stormwater system will likely need a retention/detention tank and all the consents etc that go with it. from others who have done this due to subdividing its gonna cost north of 20k to do.

AklBen

102 posts

Master Geek

#2521250 11-Jul-2020 18:46

Jase2985:

you are better off sorting out the soak pit because any new connection to the council stormwater system will likely need a retention/detention tank and all the consents etc that go with it. from others who have done this due to subdividing its gonna cost north of 20k to do.

I was worried about that. I think maintenance will be good!

SATTV

1648 posts

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#2521252 11-Jul-2020 18:48

Jase2985:

you are better off sorting out the soak pit because any new connection to the council stormwater system will likely need a retention/detention tank and all the consents etc that go with it. from others who have done this due to subdividing its gonna cost north of 20k to do.

When next door was being subdivided ( 3 - 4 years ago ) I enquired are the council if the new houses were going to have retention tanks as we get flooding from over subscribed storm water pipes.

I was told no, to be a good neighbour and I was not a water engineer and did not know what I was talking about.

Personally I believe that any subdivision should have retention takes to ease pressure off old infrastructure especially in the likes of central Auckland where the sewer and stormwater are still in the same pipe.

I am surprised that a house built in 2000 was allowed a soak hole.

As for the issue it might need to be dug up, cleaned and refilled.

John

I know enough to be dangerous

snnet

1410 posts

Uber Geek

#2521263 11-Jul-2020 19:07

AklBen:

Jase2985:

you are better off sorting out the soak pit because any new connection to the council stormwater system will likely need a retention/detention tank and all the consents etc that go with it. from others who have done this due to subdividing its gonna cost north of 20k to do.

I was worried about that. I think maintenance will be good!

FYI in auckland, retention tanks no longer need consent

Jase2985

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#2521264 11-Jul-2020 19:16

snnet:

FYI in auckland, retention tanks no longer need consent

got a link to that?

i thought they just removed the fee for it

snnet

1410 posts

Uber Geek

#2521282 11-Jul-2020 20:45

No link sorry, I haven't looked into it myself as my water bill averages under $30/month - just seeing a lot of builders doing it as they've spoken to their usual inspectors and I asked one last week when he was getting a pad poured for some retention tanks. Said there was no consent needed and no fee.

There's probably still some stupidly excessive fee for connecting into mains stormwater etc though

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zenourn

271 posts

Ultimate Geek

Trusted

#2521286 11-Jul-2020 21:19

I hate soakpits. We live on a rural property and had numerous soakpits. Any reasonable rain event and water would start overflowing from most of the drains. So I began the process of figuring out where they were and digging them all up, most were completely silted.

I've changed to making them into open mini wetlands surounded by carex secta with an interlinked network of channels and pipes that flow to a pond that then overflows to a stream. Handles rain events much better and makes maintenance trivial. Even put little bridges over some of them to make it more interesting (see photo below, flows from there to the pond which can't see in foreground).

nickb800

2719 posts

Uber Geek

Trusted

#2521325 12-Jul-2020 07:00

If you can't find a manhole or clean out then it's pretty much toast - there's not much you can do. You would be better off laying a new system - with a silt trap at the start. The soakfield could be a line of perforated pipe, or just a big hole with geotextile and rocks.

If you can access the existing system then it's worth flushing out any silt in the line and scooping out any gunk from the silt trap

Jase2985

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#2521338 12-Jul-2020 08:06

snnet:

No link sorry, I haven't looked into it myself as my water bill averages under $30/month - just seeing a lot of builders doing it as they've spoken to their usual inspectors and I asked one last week when he was getting a pad poured for some retention tanks. Said there was no consent needed and no fee.

There's probably still some stupidly excessive fee for connecting into mains stormwater etc though

so its just hairsay then?

TheMaskedOnion

51 posts

Master Geek

#2521346 12-Jul-2020 08:47

I wonder if a drain jetter would be able to sort out the drain pipe?

Bung

6485 posts

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#2521354 12-Jul-2020 09:11

I remember as a child my father digging a huge soak pit and filling it with broken concrete. Years later it had stopped working and when I took the top off it was completely full of very fine silt. It was so dense that it would have been a waste of time trying to dig it out compared with digging a new soak hole.

AklBen

102 posts

Master Geek

#2521360 12-Jul-2020 09:24

nickb800: If you can't find a manhole or clean out then it's pretty much toast - there's not much you can do. You would be better off laying a new system - with a silt trap at the start. The soakfield could be a line of perforated pipe, or just a big hole with geotextile and rocks.

If you can access the existing system then it's worth flushing out any silt in the line and scooping out any gunk from the silt trap

I'm sure I will be able to find the "big hole" by following the pipe, unless it leads me off the section!

And yes, I was thinking overnight about about creating a silt trap at the start which could be an easier way to maintain it:

robjg63

4098 posts

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#2521366 12-Jul-2020 09:48

Bung: I remember as a child my father digging a huge soak pit and filling it with broken concrete. Years later it had stopped working and when I took the top off it was completely full of very fine silt. It was so dense that it would have been a waste of time trying to dig it out compared with digging a new soak hole.

There are companies that will clean them out. They usually use vacuum trucks to clear the silt:

https://duttonstormwater.co.nz/stormwater-maintenance-services-auckland/soak-hole-maintenance/#:~:text=Soak%20Hole%20cleaning&text=Soak%20holes%20are%20manholes%20that,and%20this%20can%20cause%20flooding.

Nothing is impossible for the man who doesn't have to do it himself - A. H. Weiler

Bung

6485 posts

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#2521422 12-Jul-2020 13:00

A vacuum truck might work with a chamber style soak pit but not with a hole backfilled with rubble that won't go up the suction hose.

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