Who knows about stacked-block retaining walls?

[2manyrocks]

Idk, seeing the hand dirt tamper in the photo looks like work.

 

[Sodo]

I made this image with photoshop from an install doc posted by airbiscuit.
I was real happy aircommuter asked for it - because then I had a diagram for the wall builders.
I was ready to do it all by armwaving.
A drawing is much better.

The height of the standing blocks is the final 42".
I have not purchased any top-caps.
I decided to "conserve gravel" a bit because I have a sand mine "on-site".

Here it is at the end of the 1st day.
5 blocks up.
You can see the plywood separator between the gravel and the (packed) sand.
No fabric between the gravel and sand.
I'll put a level fabric sheet ontop below the topsoil.

I cannot believe the cost of gravel here.
The economics of scarcity makes sense,
but gravel pricing seems controlled by a local cartel.

Remember, the holes for the pipe go on the bottom.

Eddie can you explain why? I told the builders that the holes go down, but he said that doesn't make sense.
He turned them upward and I didn't protest because what he said made more sense than my foggy memory.
I remember your mention for sure.
Can you remember the reason?

 

[KennyG]

If the holes are on top, the water level has to be at the top of the pipe to drain. I've always used drain pipe with holes all around.

 

[jonsstihl]

your going to have an extra 1 1/4 of water before your drain pipe starts evacuating. You are paying extra for the transport of small quantities. unless you went and picked it up.

 

[Sodo]

Here's what my guy said.
On your hillside it's not going to be flooded behind the wall.
You will have water coming down from above at one or two places.
If you put holes down it will distribute water over the whole base.
If you put holes up it will carry that water out.

 

[aircommuter]

Lots of good info in this thread. Looks like I will be joining the wall building club. Our “new” place we moved to has a retaining wall on one side of the property line that’s about 55 feel long. It starts at 5 feet high and goes down to 2’ heading to the back of the property. The current wall was just stacked rocks and it finally collapsing. No idea how old it is. Cheapest quote to rebuild was 22 thousand, and that’s reusing the existing rocks. So yeah I will be following this for sure.

Compacting with a track machine next to not doing anything.

 

[EddieWalker]

Eddie can you explain why? I told the builders that the holes go down, but he said that doesn't make sense.
He turned them upward and I didn't protest because what he said made more sense than my foggy memory.
I remember your mention for sure.
Can you remember the reason?

The purpose of the pipe is to provide a path for water to drain. Water will go to the bottom of the gravel and then into the pipe through the holes.

If the holes are at the top of the pipe, the water will sit there with no way to get into the pipe.

Putting the holes at the top creates a pond at the bottom of your wall. Basically, you have created a dam that will allow the water to remain there and soak into the base of the retaining wall.

 

[2manyrocks]

The drain slots need to be on the bottom and pitched correctly in a bed of gravel to carry water to daylight. I would cover the gravel/pipe with filter fabric in a situation like this.

 

[airbiscuit]

I think your wall will serve its purpose over your lifetime. That said, I wonder if having the holes facing down reduces the likelihood that sand/silt will infiltrate/plug the pipe over time.

 

[2manyrocks]

With the drain slots only being on the bottom, there is the risk of clogging with fine material. This is why I posted the importance of bedding the pipe in gravel and covered with filter fabric.

Correct installation of drain pipe is actually a tedious process.