Upper Retaining Wall Drain System

Pipe just to end of upper wall, looking downhill

As part of extending and making the Upper Retaining Wall higher; our experience after some years now at Alazan was that we needed to include a drain system in the wall design. 

The crew dug out behind the upper wall and layed in a system composed of landscape fabric, gravel, PVC pipe.  They manually drilled holes into the topside of the pipe so that water could percolate into it and be carried away. 

This is a low flow system, so water never really gets going in a rush; but rather the hydrostatic pressure behind the retaining wall never builds up - and thus this serves to relieve pressure and make the entire system safer.

Upper wall, house foundation joined

These fist two photos show the pipe terminating at the end of the wall syatem, and then the 90 degree bend to route it downhill and past the lower corner posts of the house. 

It is, admittedly, hard to discern the height off the ground of that wall whose block is slightly exposed near the center right side of the second photo.  But when I stand on the ground at that point, it is about chest high.  The drop to the corner post at the bottom (top right of photo) is about 1.5 stories of drop. 

Perf pipe end

This third photo shows the pipe with all the holes
our crew drilled to make it from a solid pipe to a perf pipe.  Unlike commercial perf pipe, the holes are only on the top half of the pipe.  And top half determined after it was layed in place. 

You can see a piece of PVC elbow sitting there wiating to be installed. 

Perf pipe under gravael

 In this fourth photo, you can see the trench behind the upper wall, with landscape fabric and gravel.  The perf pipe is buried within that gravel. 

At end, this wall was raised one full block higher making a more appropriate transisiton from ground level into the wall.  What we are seeking to avoid with these changes is any water at all that might come downhill during heavy rains from flowing OVER the wall, but rather have that carried away by the pipe. 

Drain extended downhill

In this final photo, you can see the pipe (non perf at this point) running downhill past the end of the house.  This year for rainy season, water will now be safely carried away. 








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Jim and Dick