Can you dig a trench next to a concrete slab and foundation?

[djb783]

We're looking to extend water to the side of the house that has no garden taps. We've been advised two different options, one is to run the copper pipe along the side of the house attached to the brick, and the other is to dig a trench and bury the copper pipe.

We're going to dig the trench and have a plumber connect pipes up after. The suggestion was to dig a trench directly to the side of the slab (and go around existing pipes), and if we do that it wouldnt need to be deep (100mm was the suggestion) as there's nothing that will run over it. Is there any risk with digging next to the house slab? Any risk of digging this shallow? Is it worth backfilling with any material in this case, if so, what would be the ideal material?

[EricL]

Hello @djb783 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing question about your plumbing.

Instead of digging right next to the wall of your house, I propose digging a channel 200mm away from your wall and then turning back to the wall where the tap will be installed. In this manner should any leaks occur, it will be a bit of a distance from your wall and will be easily spotted when mowing. 

In regards to digging the channel, I propose using a Spear & Jackson White Steel Mouth Concrete Shovel. Your goal is to cut a channel that is 100mm wide and 100mm deep. I suggest digging it in such a way that you cut neatly and deeply into the soil and not ruin the lawn surface.

By keeping the dug portion aside neatly you'll be able to re-use the soil and the lawn top to cover the channel. It might take you a bit longer, but you won't have to source other materials to cover the pipe channel.

Let me call on our experienced members @Dave-1 and @homeinmelbourne for their recommendations.

If you have any other questions we can help with, please let us know.

Eric

[Dave-1]

Afternoon @djb783 

I would be digging probarly 300-400mm off the wall. I have found my foundation to be around the 200mm mark is the main reason, plus the chance of other pipes (sewage pipes/stormwater pipes) right next to the concrete foundation. I would go deeper then 100mm for sure, Id go 300mm and cover the pipe with gravel by 5cm before putting soil back and then tthe grass. Mainly suggest it for protection of the pipe, 100mm is nothing for general struff (A hole for a bush, tree, garden bed especially down the track when you may have sold your place or it has passed to someone else)

Dave

[djb783]

Thanks for both your messages, that's very helpful and it makes sense.

RE backfilling with gravel, is something like this appropriate, https://www.bunnings.com.au/bastion-10mm-blue-metal-20kg_p0106948?store=7213&gad_source=1&gclid=CjwK...
or should the gravel be smaller diameter than 10mm, like https://www.bunnings.com.au/bastion-20kg-aggregate-crusher-dust_p0135857?store=7219&gad_source=1&gcl... ?

Original reasoning behind having it next to the wall was a mini excavator might drive over the area in the next couple of years, so having protection would be important if I was to bury the pipe off the wall, wouldnt want it to get damaged.

[EricL]

Hi @djb783 

Another alternative to your pipework is using Vinidex 25mm x 25m Metric Blue Poly Pipe. It is robust and flexible and if buried at 300mm as @Dave-1 suggested will survive being runover when compared to copper pipes. Please speak to your plumber regarding this alternative.

Using the Bastion 20kg Aggregate Crusher Dust would be better, as it will not pierce the surface of the pipe should a heavy vehicle run over it.

If you have any other questions we can help with, please let us know.

Eric

[Dave-1]

Afternoon @djb783 

I would go with crusher dust, I used 8mm sized gravel around my copper pipes and also around my stormwater pipes as it gives a nice base and allows some movement and wount piece either piping. I am not sure if crusher dust becomes solid with time? but if its smaller then 10mm I would prob use it.

Dave