Two quick questions. I didn't want to gum up the feed with 2 posts, so I'm combining them.

First, I'm building a retaining wall. I posted a few years back with some questions and am now finally getting to the project (better late than never I guess...). It will consist of 2 half circles in front of 2 windows to the right of our sidewalk. The window closest to the walk it will be 1 & 1/2 foot tall at the highest point. The other window will start at about 1 & 1/2 foot and end up at a little over 4 at the tallest section.

My question is, where the 2 walls meet, should I just butt them up against one another or interlock (for lack of a better word) them?

My second question is about a French drain. I have about a 10'+ section of yard between our circle drive and the sidewalk. Because it is a low spot, we get standing water there quite frequently after it rains. I'd like to put in a drain to move the water towards our woods. Do I need to put in a catch basin/drain in the yard or will just burying the wrapped pipe in rock be enough (pipe only, no basin)? Would one pipe/run be enough or should I consider 2 (because of the width of the area)? Overall, it will be probably 30 feet long.

Thanks in advance.

Interlocking is always best, if you can arrange it correctly. If you leave the ends isolated then they make potential weak points, unless you right angle them into the hillside.

Similar latitude, read here for ideas about permaculture, rain garden, and managing runoff LINK

Also, this will help you. WOrking at that height of wall means preparation, and the stuff below grade that will never be seen are of paramount importance Retaining wall

There is a YouTuber by the name of French Drain Manhttps://www.youtube.com/channe...9Xm81fnqfuilUKJvKyPw

I have found his videos very informative. You can get some really good ideas from his videos. He also sells the pipe.

At my last house, I ended up putting in about 100' of retaining wall using interlocking wall stones.

There is no reason to run drainage behind the short wall (tall), unless the slope you are removing is abnormally long, and are filling with gravel. For example, you put in a 2' wall that makes a space level, but the slope you are removing is 14'. This means you have 14' behind the wall that can potentially gather rain, and means you removed an 8% slope. IF you were to fill this with gravel, the water would run through and undercut your wall. If you filled with dirt & grass, you would be fine.

As for tying the 2 walls together, it will look more professional, but unless it is being done for landscaping (flowers, bush, etc) it may look odd to have such a shallow wall with nothing behind it. I have done it both ways. If you do it as one, expect it to take longer as you will need to level more stones as you go across more distance.

As for the French drain, how far will you have to take the water, and is it downhill? I put in three catch basins at my last house, and put in one wrapped pipe in another location. IMHO the wrapped pipe is better to put around a house so water does not infiltrate. It did not work well during heavy downpours, but would suck water up in the hours afterwords. The drains worked better for heavy rain, but keeping them clean is a necessity.

Wrapped pipe I used:https://www.homedepot.com/p/NDS-4-in-x-10-ft-EZ-Drain-Prefabricated-French-Drain-with-Pipe-EZ-0802F/202259347

Part of the pain in using this is that the top need to be 4" below the surface, meaning you are essentially digging a trench over a foot deep, and that gets old fast. IF you want to improve the performance, cover with pea gravel.

Also, depending on the space you are trying to drain will determine if corrugated is the best option. During heavy rains at my last house, my out spout would look like a fire hydrant because I used smooth wall 4" pipe and had 12' of elevation drop.

quote:

Originally posted by 280nosler:
IF you were to fill this with gravel, the water would run through and undercut your wall. If you filled with dirt & grass, you would be fine.

I am going to have to respectfully disagree with this. There are a lot of variables that go into a wall, and your wall is quite short, but I've always read to put 3/4" wall rock behind the walls. I built a 10' Allan Block wall a few years ago and did a ton of research and everything I read said to use rock. The dirt, particularly clay soils hold the water and will have a tendency to blow your wall out. You want the water to drain, not held behind the wall.

The Allen Block website has tons of information on retaining walls if you're interested.

Allen Block Walls

quote:

Originally posted by 1967Goat:

quote:

Originally posted by 280nosler:
IF you were to fill this with gravel, the water would run through and undercut your wall. If you filled with dirt & grass, you would be fine.

I am going to have to respectfully disagree with this. There are a lot of variables that go into a wall, and your wall is quite short, but I've always read to put 3/4" wall rock behind the walls. I built a 10' Allan Block wall a few years ago and did a ton of research and everything I read said to use rock. The dirt, particularly clay soils hold the water and will have a tendency to blow your wall out. You want the water to drain, not held behind the wall.

The Allen Block website has tons of information on retaining walls if you're interested.

Allen Block Walls

Way to cut out the part where I said he needs to put drainage behind it if he were doing this, and this was only applicable to a 2' wall and under.

quote:

Originally posted by ChuckFinley:
Also, this will help you. WOrking at that height of wall means preparation, and the stuff below grade that will never be seen are of paramount importance Retaining wall

I have a 12" deep X 24" wide trench dug for the upper wall. Both will be lined with 6" of compacted 3/4" minus. I'm just waiting for the rain to stop. Everything is covered with tarps to keep things dry, but it's supposed to rain the next few days.

quote:

Originally posted by will347wax:
There is a YouTuber by the name of French Drain Manhttps://www.youtube.com/channe...9Xm81fnqfuilUKJvKyPw

I have found his videos very informative. You can get some really good ideas from his videos. He also sells the pipe.

Yet another rabbit hole I went down last night after reading your post… LOL. I wish I could source some of that pipe local, it looks like some real slick stuff.

quote:

Originally posted by 280nosler:
There is no reason to run drainage behind the short wall (tall), unless the slope you are removing is abnormally long, and are filling with gravel. For example, you put in a 2' wall that makes a space level, but the slope you are removing is 14'. This means you have 14' behind the wall that can potentially gather rain, and means you removed an 8% slope. IF you were to fill this with gravel, the water would run through and undercut your wall. If you filled with dirt & grass, you would be fine.

I will be backfilling both walls 12" back with 1" clean and drain tile with the 4' wall, draining out the front of the wall.

quote:

Originally posted by 280nosler:
As for the French drain, how far will you have to take the water, and is it downhill? I put in three catch basins at my last house, and put in one wrapped pipe in another location. IMHO the wrapped pipe is better to put around a house so water does not infiltrate. It did not work well during heavy downpours, but would suck water up in the hours afterwords. The drains worked better for heavy rain, but keeping them clean is a necessity.

It will need to be about 30 feet long, and yes, it does run downhill.

quote:

Originally posted by 280nosler:

quote:

Originally posted by 1967Goat:

quote:

Originally posted by 280nosler:
IF you were to fill this with gravel, the water would run through and undercut your wall. If you filled with dirt & grass, you would be fine.

I am going to have to respectfully disagree with this. There are a lot of variables that go into a wall, and your wall is quite short, but I've always read to put 3/4" wall rock behind the walls. I built a 10' Allan Block wall a few years ago and did a ton of research and everything I read said to use rock. The dirt, particularly clay soils hold the water and will have a tendency to blow your wall out. You want the water to drain, not held behind the wall.

The Allen Block website has tons of information on retaining walls if you're interested.

Allen Block Walls

Way to cut out the part where I said he needs to put drainage behind it if he were doing this, and this was only applicable to a 2' wall and under.

Sorry, it was not intentional. I don't understand what you are saying, my apologies.

We put in a French drain all along the back of my son's house, which is at the bottom of a hill and had standing water problems. We actually put in two-one right where the hill breaks up from the back of the yard, and one right along the back of the house. Dug a trench, lined it with filter fabric, put 6" of crushed stone in the bottom of the trench, then perforated drain pipe clad with a filter sock, then more crushed stone, covered all that up with filter fabric, then a 4" layer of decorative stone to top off the trench and bring it level with the lawn. It took care of the drainage problem and looks great.