Experts' advice urgently needed on the type of sand near the foundation

A hacksaw will not cut those rocks. Willair must not have read your post properly.

The rocks might be old concrete. I would lever it up as suggested by Wylie.

If you must cut the rocks, you could use an angle grinder with a masonry disc. I have one made of metal. You can ‘shave’ the rock off bit by bit. Cutting in at right angles, first, will speed it up.

A cheap Ozito brand from Bunnings will be fine for the angle grinder. But you must wear safety glasses, long pants and long sleeved shirt and hearing protection - and be careful. It will create sparks but they won’t hurt with the right clothing.

In the past (on a strict budget) I have even broken up concrete by drilling lots of holes with a wide masonry bit until it broke apart. It took a while though!

The Bunnings link for this product (is yours the compact version ot the one linked below?) says that sand can be used to bed it underneath - but it does recommend concrete on the sides (& a few other things).

I would call the manufacturer and ask how essential concrete is on the sides.

Here’s a quote from the instructions:
1 Dig a trench of at least 185mm deep x 250mm wide and place compacted bedding sand or concrete in the base. Ideally the trench should be sloped at a ratio of 10cm per 10m of channel to prevent water pooling along the length of the channel. Use a string line to ensure straightness and the correct ...’

https://2ecffd01e1ab3e9383f0-07db7b...duct/c9443c7b-9fda-4d88-b496-8ff2758225ef.pdf

I would not use pebbles as the water will soak through them.

Make sure that the drain slopes towards the front of the property or somewhere it can safely drain. The idea is to move the water down the drain to somewhere better than your foundations.

How far did the plumber say the drain should extend?

 

That's concrete, not rock. Looks like an old concrete path or slab has been covered with silt - dirt washed on top of it.

 

Sensei just want to update our progress over last two days: we...finally removed all compacted soil outside our bedroom !

All soil removed:
grade

Our drainage location:
direction

Closer look of the drainage:
direction1

~~~

But now we're facing another challenge, when we take a closer look, the landscape looks like that :
step

And we have three plans but not sure which one is the best:
--------->>> 3-plans

These three options can be carried out by getting the parts and materials from bunnings, so the cost should be affordable. But not sure which one is the best in terms of appearance and and time effectiveness.

Brick paver seems to take most time , also might be difficult to do without experience. But it can ensure the water slide away from the house.

Big pebbles plan are simple and easy. Peddles would ensure the water to get through them and follow the graded soil near the foundation to the drainage pipe. But it might look a bit weird? Only the area outside our bedroom is full of pebbles while other areas outside the house is sealed in bricks..

Angle grinder , seems workable too and also not expensive :
Ozito 100mm (4") 850W Angle Grinder

Wish sensei a prosperous New Year

Henry

 

Hi Angel, thank you for the tip, we've mistaken it as rock haha

With the old concrete higher than the level drainage pipe, do you recommend grinding the old concrete, or ignore it and just put some peddles to elevate the other side of the channel?

We are thinking which plan is the smarter way to go with:
3-plans

Thank you Angel

 

Or the 4th option of levering the concrete out. How big are the pieces?

Of the 4 options, which does the plumber recommend?

How are you going to connect / sit the new drain to the storm water drain in your picture?

You need to ask the manufacturer if it is OK not to use concrete down the sides (might be fine since vehicles won’t be driving across it (I assume) or it might be required. If it’s required, ask if Quickset concrete is OK.

Pebbles will accumulate dirt and leaves and are hard to keep clean. After a while weeds will grow.

 

Hi Joynz, the drainage is already connected to storm water drain. It has been around for a very long time. The plumber said he was fully booked for the time being, i think he probably will come visit us for the second time next week or later than that, we will keep in touch with him to see if he can come earlier

The black square is the area elevated by old concrete underneath and the size is roughly 5m x 5m


We haven't asked for quotes for the idea of option 4 yet, but we guess it will probably be quite costly.

Not long before we asked for quote about sealing the area into brick paver outside our bedroom (the size is 5m x 2 m), the quote we got was $1450.

If we want to deal with the concrete, we will probably try to follow your suit - "drilling lots of holes with a wide masonry bit until it broke apart"

Alternatively, one more direction we could follow, option 5 :

Find a builder to make it a good looking step by smoothen the uneven surface of vertical section:


~~~
We'd need some more time to think carefully about all these options,

but right now we want to decorate and protect this area by preventing heavy rainfall from splashing, eroding and loosening the soil we graded



We are thinking to purchase this:
Geofabric - Drainage Fabric | Upper Coomera Landscape Supplies

or

Geofabric | Geotextile Fabric | Drainage Filter | Sunshine Coast | Brisbane

and lay this kind of drainage fabric under the soil. Therefore when there is heavy rainfall, the fabric will faciliate water to flow down to the trench.

And for anestheic purpose, we could also put some gravel / peddles above the fabric and soil near the foundation? Since our pest inspector reminded us not to use mulch since it can attract termites

Pebbles will accumulate dirt and leaves and are hard to keep clean ---> But if we dont use pebbles, anything else we could use for decoration?

Conceptual example:

 

You said you are installing a linear drain. Where is that going to flow to?

The fabric you linked to will allow water to soak through - that is what it is designed for. Do a bit more research - and reread my advice in above posts.

Good luck.

 

Yup.. thanks so much man.

Trying to digest a ton of useful info in this thread. Our family has been reread your advice a lot and we are discussing, devising our next plan. Just in case we can't come up with a perfect solution to the interruption of this old stubborn concrete slab we might consider a $200 consultation session with a landscaper to see what he think on this

This is the map where the blue line is the pipe we bought from bunnings to be installed, and the red line is the existing pits and underground drainage discovered by the plumber from the last inspection.

The red line will divert the water to the street.

 

Many articles mention Weedkiller Ro_ _d Up is a reliable herbicide that can last for a fairly long time. But there have been rumors and lawsuits in recent times about its safety. Though scientists say if its used only for domestic purpose, like we use it lightly on a small area, probably wont cause any health hazard concerns.

But now we are going to coles to get some cheap vinegar. To see if it can be a natural weed killer as effective as many online websites assure. Will try spraying those vinegar on the soil. If no weed appear in the next 7 days, might then proceed with pebbles.

Slightly raised garden ... yup .. its a really good idea.. it can facelift the area as well , we will look into that Probably need to grow some plant that can repel wasps and flies

 

Hello Henry

Great work so far!

You will have to run a drain along the side of your house to protect the house from water coming against the other wall of the back bedroom.

I use vinegar to kill existing weeds. You can safely use roundup in small areas like your backyard and you can use it again later when more weeds grow. It is more dangerous if you use it every day like if it was your job to be a weed killer person.

 

Yea... we are making some real progress thanks to a lot of practical advice from many experienced users here.. really grateful for that

Trench progress:
signal-2020-12-28-121028

We basically finished the trench digging all the way from the area, but its not a straight line due to the protruded concrete and yesterday we bought an angle grinder and will test it. Hope it can grind and cut the concrete nicely!

We just discovered the drainage pit which our trench will connect to is blocked with debris. Some members suggest: vaccum + hand scrapping. Now we are trying to use hands to scrape out as much as possible