Hillside Retaining Wall French Drain
I think you are on the wrong side of that retaining wall.
Hillside retaining wall french drain. A good retaining wall will help slow the water but the gravel perforated pipe is t. Steep hills are difficult to control water. The size of the gravel used can vary from pea gravel to larger. Drain pipes go behind the wall on the side with the surcharge the soil that that wall or foundation is holding back.
Otherwise water moving down the hill will build up behind the wall and undermine it. Some of these drains are vented through the front of the retaining wall while others may run the length of the wall and drain out to the sides. About 8 inches to 2 feet deep should be sufficient for many water diverting projects though related systems such as those built around foundations and sub ground living spaces as well as the bases of retaining walls may be deeper. You want to intercept the water in the soil before it reaches any structure that water will corrode or erode.
If you re building a retaining wall on a hillside. The pipe should rest on the same compacted gravel base or concrete footing that supports the wall. Pipe drains are usually installed at the base of the wall but taller walls and those with additional drainage needs may require multiple pipe drains at varying heights. A wall that leans into the soil it retains is less likely to be pushed outward by soil pressure than a plain old vertical wall.
French drains need to have a slope of at least 1 so the force of gravity will work for you. A good french drain will help. Depending on the size of your trench either dig the trench with shovels or rent a trencher. Design and build your retaining wall to slope at a minimum rate of.
If you re building a retaining wall add a french drain behind the first course of stones or blocks. This means that the drain should slope down a total of at least 1 inch for every 10 feet of pipe.