Minimum pipe depths?

Originally Posted by AdamS

Hi!

I've got a renovation in progress which involves relocating sewer pipes to a onsite wastewater treatment system and fixing up inadequate stormwater drainage around my house. I'm lucky that the fall of my block is 1:50 so everything can be pretty much laid at minimum allowed depth.

I'd like to have a plan before getting a quote from a plumber, so my questions are:

1. How far below ground must stormwater run?
2. How far below ground must sewer pipes run?
3. How far below ground must copper water supply pipes run?
4. How close together can stormwater & sewer run? (ie, in the same trench?)
And I know 240v electrical must be 600mm below ground, but:
5. How close can electrical conduit cross below stormwater or sewer pipe?

Also, I currently have a grease trap located directly outside the house from the kitchen sink, right where I want the deck to go. Can it be relocated it further down the line, say after 10 metres of a 1:60 run of 100mm pipe?

Thanks!

Stormwater can be laid just below the ground if you like, common sense prevails here really just under the surface is more likely to get damaged.
Sewer and water need to be a minimum of 300mm.
do not lay stormwater and sewer in the same trench
electrical conduit not a problem long as it does not get damaged whilst digging
I would just put a trap door in the deck, hell of a lot easier.
grease traps are supposed to be as close as possible to the outlet of the fixture, they are there to stop all the grease going down the drain after all.

If this is just your residential property you dont need to have a grease trap, so get it removed.
Just my 5 cents worth

Thanks Reno, that helps a lot.

Unfortunately we've got to keep the grease trap, because the new advanced secondary system (21st century septic tank) needs it.