Any septic outfield experts out there?

The lovely Spoook is already helping but I'm hoping that someone has some experience that will help us.

We are building our house to a very, very tight budget. Which we have already exceeded [][] We had a pc sum of $4,000 for the effluent field and an engineers report so thought we were all sorted. However, the drain layer took one look at the proposed field and said no way! He looked at another couple of options too and we've now got the result.

Option 1 - as in the plan. The drainlayer won't do it as he is certain it will slip and the cost will be $19,800 plus GST

Option 2 - pipe from the tank to another, much further away spot with potential problems as pipe would have to skirt an existing unstable area. Cost $14,150 plus GST

Option 3 - Solo power AX 15 sewerage system with 400m of dripper lines. $17,700 plus GST.

We can't afford any of them and are wondering if anyone has got sink hole or other 'non-standard' effluent field sytem that we may be able to persuade the council into allowing without it costing us a kitchen [!][!][!]

We are about to do our 3rd drainage field, and I'm glad that I have a tame plumber that did the last one 12 years ago. We were astounded that that one cost $2000 !!! This one I'm going to do myself when I get a round tuit.
In your situation I would firstly ask the Inspector to come out, and to give you some advice. If the land does slip, will it stay on your property? Why might it slip? How steep is the drainage slope and has any of the pasture around it slipped? If you have a slip and the sewage drains at surface level, will that matter? If you plant 15m downhill to stop the land slipping, will that do? What plants?
Then find a neighbour with a plumb level and get him to mark out the line. Remember to make the first line as low as possible, so that when you need another soak field in 10-20 years you can go 5m uphill, then 5m following.... etc. Get the Inspector in to check yor level.
Then find a neighbour with a digger than can follow that line and dig a trench the right depth, and leave his digger there until it is ready to refill.
Then find a neighbour with a tractor and a trialer that can put the correct sized gravel into the trench. Get the Inspector back to inspect and advise.
Then lay the soakpipe on the gravel. Ours is 80mm plastic downpipe with holes drilled in it every 30cm. Over this lay drain matting to stop the soil getting into the gravel, which you buy from Mitre 10 Mega. Cut it so that it fits snugly in the 30cm trench.
Then put the soil over the top with the digger.
Lots of photos to show the Inspector.

Maybe a photo of the terrain might assist some ideas. The amphitheatre scene might be good. []

Thanks

The amphitheatre is no go...it's below the house so they're looking at the knob of hill around from that. I'll try to get a photo...

The land is quite uneven and situated above a slip and with slips to each side. This is northland clay

LR, we're building on the edge of a 220acre block and the drainage field is into our property so we're nowhere near a neighbour. The slope below the property is steep...everwhere is steep...and that is what is causing the problem. If we trench then we need retaining walls, $7,500 worth of retaining walls.

If I can get a photo then I'll post it....

Cheers
Kate

I've found an old photo. It shows our hut and the house is being built to the left of the hut on ground that has been excavated. I've marked two lines of the effluent field and the other three are around the other side of the hill.

Does that make sense?

Cheers
Kate

Attached files

Hi Kate, in my humble opinion soakage on clay is asking for trouble, especially if there are slip fields. We were required to put in an "evapo-transporation pad" for ours. This is basically a shallow rectangular bed with 20m of drain pipe laid in it and filled with gravel, topped with soil and grass. The theory is that the grass will transpire the moisture into the atmosphere. Great theory but as nothing grows here in winter (too cold) we end up with a smelly, boggy mess. Might work in your more temperate climes and certainly a lot less costly than a soakage trench.

Failing that, composting loo.

Go for a composting system? Clivus Multrim would be my first choice. Don't let the council tell you that you can't because you can. Alternatively continue with the outhouse you are presumably already using until such time as you can afford to upgrade.

We have clay slip prone soil, and our proposed (and consented) septic dispersal system is on a slope, but we have terraced it for an orchard. The Council was concerned only if the original slope was greater than 20 degrees. (which is a relatively shallow slope compared with most of our land)
The new profile is cut into a series (moving downhill) of:

• steeper banks,
• retaining walls of about 500mm max,
• fairly narrow terrace.

Because we have kept the retaining to a minimum, we can build them ourselves of old concrete fence posts we are gradually collecting.
The terraces (with orchard tree in the middle,) have to slope gradually inward so run-off does not wash down the steep banks in between.
The banks are going to be permanently vegetated with bushes, with the edge above the retaining wall being berry fruits at a nice height for picking (at least that is the plan )
We have done the excavation work ourselves, partly with a hired digger and partly with our own (which is not really a functional beast). The terraces are now planted with a herbal ley, to compete with the gorse and poroporo, while we get ready for the next stage - the retaining. The soil is capable of holding the upstand of 500mm in the meantime.

The treatment system is proposed to be Biolytix.

Kate, I would consider moving the field to the same level as the proposed one but above the single totara or teatree (whichever it is). There you could do a single long one, or better still, 2 single long ones connected together with a ball valve tap so that you could swap the field over every 5 years or so, and keep both going for longer.

Thanks all...

Powerguy, the plan is for trans-evaporation beds.
Igor, we're looking at Naturalflow , a system recommended by Pumkingirl.
Hawkspur, that is very interesting, we were planning to put an orchard below the house anyway, I'll talk (again) to our drainlayer.
LR, above the totara is the farm track and the trenches need to be level so one long trench would mean a lot of excavation...which is where the problem lies.

Thanks all, it's going to have to wait until we can afford one of the solutions.

Hi Kate

My Mother is planning on building her home a couple of bays up from you. They are wanting to use a worm composting system which requires the worms to do the work rather than the septic system.

Might be something to think about...

BTW our house is closed in now - sheds are up as are our two water tanks - our trees are pretty much in (ok, they still look like sticks - but some of the sticks have flowers on them now)

Just looked up that website Kate. Strange that a kitchen sink drain is classified as black water along with the toilet (of course) but a dishwasher drain is grey water as are bathroom and laundry drains. One would think that both kitchen sink and dishwasher would be the same hazard class.

Kate, I've just sent you an email with another option that might be even more helpful, just in case it gets lost in your inbox

Thanks

There is the same amount of excavation in 1 long trench as in 2 short ones.
You can hire 5 tonne diggers that are able to work at 90 degrees to the angle they are parked. It doesn't take much more time to crab across the slope than to move in the direction of the trench.
I would not want the drainage field to be directly below the house.
Our drainage field is a few meters below a track across the slope. Unless you are doing lots of vehicle movements, or heavy traffic, on the track then it will be almost as safe with the drainage field as without it.