Water leaking out under wall

Hi All,

I recently built a 800mm high retaining wall using treated pine sleepers on a steep slope.
Last time it rained heavy, water was flowing out in a few spots under the bottom sleepers.
Now it seems the water has 3 or 4 exit points and is flowing out fast.
There is an aggi pipe behind the wall, and this is covered with gravel up to 3 sleepers high.
Some water comes out the aggi pipe, but a lot is pouring out under the sleepers.

I guess the water is just finding the easiest way out.
In hindsight, I should have placed builders plastic under the pipe and up the wall a little, to trap the water and force it into the pipe.

But my question is how to fix now the wall is complete?
It's difficult to get to the front of the wall as i built a shed about 200mm from the wall.
So I was thinking of trying to scoop out a narrow trench below the bottom sleepers, and filling with concrete?
Basically I'm trying to block the water so it stays in the pipe??

Any other ideas welcome to solve this issue.

Is there any chance of you digging a drain in front of the wall, that's lower than the lowest part of the wall, to collect the water and take it away? If so, you might cement it, possibly as part of a cement footpath between the wall and the shed.

What you're describing reminds me of a situation I had. Mine was a stone wall, and it was my house, not a shed. I didn't use aggi pipe but chucked some gravel behind my wall and left some weep holes between the rocks. I fully intended to build a drain on the outside. My main driver was not water leaking through the wall, but on occasions during heavy rainfall the house gutters would overflow and the pathway between the retaining wall and house would flood badly. Your shed gutters may overflow too and provide another headache as water flows under and into the shed.

Ag pipe needs to be below the lowest sleeper, 150mm is good, if not then that may be the problem.
Also depends on the size of ag pipe and the exit point.
And where does the storm water from shed and house go ?? could also have a bearing.