To prevent the water pressure behind the retaining wallsa drainage layer is generally needed. The convetional method is to use gravel behind the wall and leave some holes on he wall. The water leakage from these holes causes bad view . And sometimes the gravel may be expensive with the transportation costs.
One of the easiest methods is to use geocomposite drainage sheets.
In this project seen on the pictures a geocomposite drainage sheet have been used. The drainage material was made of a 3 dimensional drainage core which lets water go to any direction and a special filter which is resistant to clogging.
The drainage layers were installed vertically by simple methods. They nailed.
The most important thing is you should pay attention to the overlap direction. Because if you start backfilling with the help of a heavy machine like an excavator the overlaps should look to the opposite side of backfilling.
If you backfill from the front (directly on the drain) there is no problem.