Front yard

[saveasteading]

weed membrane will do fine if you have some around. FYI The random fibres type is better than the woven in keeping everything out but it will be marginal for your circumstances.

[JohnBishop]

Hi again All,

  I continue to work on it and I realised I need to address the runoff rainwater on the side wall. There is tarmac and concrete between the houses and there is a bit of slope down towards my house what you can see on the picture.
Neighbour's DPC line is at least a foot above mine and rainwater that hits this hard surface between the buildings, I would say 15-20 sqm runs towards my wall and have nowhere to go.
Not sure why they did it this way but this whole bit next to the wall filled with gravel is contained, rainwater has nowhere to go without soaking the wall at the same time. You can see it being wet. I mean the gravel is no longer doing it's job as over the years mixed with soil, it holds moisture, some weeds pop up, also fat worms present in it tell me it's not gravel anymore.

While excavating this material I hit sand in few places but I still don't believe this is how the rainwater should be directed just next to the wall.
So I am thinking about extending this drainage to the existing one in the front yard. What do you think?
Orange on the picture is the existing soakaway that goes somewhere, the French drain with a 60mm perforated pipe (red on the picture) will go over that soakaway and next to the retaining wall

This is how it looks in relation to the schematic:

 

Just so you know this is not square but of this shape because of the concrete footing that redirects rainwater even closer to the wall.

 

We will see if I can dig out a hole under the concrete to run the pipe or will have to cut the concrete.

Edited May 26 by JohnBishop

[saveasteading]

7 hours ago, JohnBishop said:

the gravel is no longer doing it's job as over the years mixed with soil, it holds moisture, some weeds pop up, also fat worms present in it tell me it's not gravel anymore.

That is normal. remove the gravel then either wash it and reuse or replace it. The mucky gravel can be renamed 'free draining compost' as loved by succulents and herbs,

 

7 hours ago, JohnBishop said:

extending this drainage to the existing one in the front yard

Good idea. A small pipe will be enough to shift that small amount of water.  Make sure hat it can't work in reverse.

[JohnBishop]

while digging we come across some pipe, it's yellow, it's either water or gas. This looks like is going to be below a new layer of new material (MOT) 20cm MOT and 5cm grid with gravel.
Do we have to cover this pipe with anything to protect it from vibrations at this depth 25-30cm?

[ProDave]

Yellow is GAS.  (water is blue or older pipes black)  So get advice what to do with a GAS pipe.

[SimonD]

19 hours ago, JohnBishop said:

Do we have to cover this pipe with anything to protect it from vibrations at this depth 25-30cm?

 

Gas pipes need to be buried to at least 450mm under a driveway with light vehicular traffic. If you can't reach that depth then you need mechanical protection, like a concrete slab at least 100mm above the pipe. If you've got heavy vehicles, then you may need more depth, like 600mm. The pipework should be bedded in sand.

[JohnBishop]

36 minutes ago, SimonD said:

 

Gas pipes need to be buried to at least 450mm under a driveway with light vehicular traffic. If you can't reach that depth then you need mechanical protection, like a concrete slab at least 100mm above the pipe. If you've got heavy vehicles, then you may need more depth, like 600mm. The pipework should be bedded in sand.

Thanks SimonD
We are going to expose the pipe and see how deep it is. I think it slopes down towards the house so it could be between 35cm-60cm deep or it doesn't go parallel to the fence.
So I understand the idea is to bed the pipe in sand and cover with a slab, so we don't need to create a void, a bridge over it just make sure the pipe is 10cm in sand below the slab.

[JohnBishop]

it looks like the gas pipe had a bit of a slack on it and it waved up to about 35cm deep however once we exposed it we were able to lower it to 50cm. I slowly slopes down as it goes away from the public pavement. We also come across a water pipe (blue) at about 70cm.


Can someone recommend a suitable membrane to put to cover the driveway area before we put MOT aggregate? This is going to be a 20cm layer of mot then 5cm grid+gravel

[saveasteading]

47 minutes ago, JohnBishop said:

recommend a suitable membrane

As long as it is heavy duty, not just weed control, then almost any will do.

 

like this.https://www.toolstation.com/heavy-duty-landscape-fabric/p62380

 

if you need to lap it, then the lines show you how much.

 

Non- Woven membrane can be  stronger and doesn't get the little gaps between fibres that the above woven one does.  but the Toolstation one is for weeds only and I can imagine it tears easily.

[JohnBishop]

On 21/05/2024 at 22:47, Alan Ambrose said:

Only for v heavy duty or v long life.

I can see this installation guide for Ecogrid

https://ecogrid.co.uk/wp-content/uploads/EcoGrid-Gravel-Fill-Installation-Sheet.pdf

 

Did you work out the thickness of your subbase?

There is a table for "Field guidance for estimating sub-grade strengths".
I understand this is basically how much clay is in the soil what makes it soft or firm. In my case it's no clay at all but soil and pretty much all sand underneath.
I reckon the subbase supposed to between 200-100mm

I see some installers putting the grid directly onto the membrane without screed (sharp sand)
some don't even use the membrane:

 

Edited June 16 by JohnBishop

[saveasteading]

In approximate terms , the load of a wheel will spread at 45 degrees into the ground.  With dry hard earth you don't need much spread. With wet, weak earth you do.

 Plain grid will work a bit, but you really need sub- base.

The membrane isn't for strength but to keep the sub base separate from mud beneath. Or to keep the pretty stones in the grid above the lower layers, which isn't usually necessary.

 

[JohnBishop]

3 hours ago, saveasteading said:

In approximate terms , the load of a wheel will spread at 45 degrees into the ground.  With dry hard earth you don't need much spread. With wet, weak earth you do.

 Plain grid will work a bit, but you really need sub- base.

The membrane isn't for strength but to keep the sub base separate from mud beneath. Or to keep the pretty stones in the grid above the lower layers, which isn't usually necessary.

 

It looks like some of them use two membranes which makes sense to keep different materials separate. Nidagravel grids (not sure if all) have a built-in membrane into the grid.
I agree re sub-base. I am just not sure how deep 10, 15 or 20cm.

[JohnBishop]

I think I go between 10 to 15cm. I think this should be enough. I just have a hard time sourcing MOT Type 3 aggregate locally. They all have Type 1.

[saveasteading]

4 hours ago, JohnBishop said:

hard time sourcing MOT Type 3 aggregate

Type 1 will allow the rain to pass through, but doesn't have voids for storing it. Remind me if you were required to use type 3 or store water.

[JohnBishop]

13 minutes ago, saveasteading said:

Type 1 will allow the rain to pass through, but doesn't have voids for storing it. Remind me if you were required to use type 3 or store water.

Last time user Temp said "You might consider MOT type 3 hardcore instead of MOT Type 1. I believe Type 3 is water permeable where as some versions of Type 1 can be like concrete."

[saveasteading]

1 minute ago, JohnBishop said:

You might consider MOT type 3

OK. so it was a very good suggestion, but hard to find. Type 2 will drain a bit better but it ruts until covered over.

 

But who said you need highway quality sub-base? It isn't  a motorway.  My go-to is recycled road planings. ask a haulage company what they have.

[JohnBishop]

We built the retaining wall using dense hollow blocks. it's just two courses of blocks. One course of decorative brick will go on top.

Edited Sunday at 22:34 by JohnBishop