Is Drainage Behind A Retaining Wall Important?
When people think of retaining walls they tend to think about all the solid materials that go into making the job, from how strong and thick the steel beams are to the strength and beautiful design of the concrete sleepers, the drainage is an afterthought and is like "really drainage?, is it even necessary or is it just one of those overdone engineer things to make you feel like the engineer actually did something when you paid him all that money to design the wall".
Back Filling With Aggregate
Where does all the water go?
Getting rid of the water that builds up from moist conditions or a lot of rain can be very important to the strength of the retaining wall, when water fills the soil behind the wall and has nowhere to go it can put huge amounts of pressure on the wall and if you don't get rid of this water backup it could ruin your wall costing you $$$.
Back filling with Aggregate is a popular solution that lets the water drain quickly and freely to the bottom of the water to be guided by a Ag drain that collects the water and guides it to the front of the property or storm water drain.
Ag Pipes And Weep Holes
Every so often weep holes could be put in the wall to allow proper drainage behind the wall. or like i said before an Ag pipe to direct it to the nearest storm water drain. do the job properly and listen to the engineer and his report even if the drawings and plan seem over the top. If you are going to put that much effort and money into a job especially a retaining wall you only want to do it once.
We have seem many retaining wall fails in our time, mainly due to not following the plans by the engineer and following the simple guidelines of digging those holes deep, like really deep! retaining walls are a heavy structure and the last thing you want is to hire a company to try and dismantle a failing wall, if anyone even wants to do it that is.
Do the job properly and get some adequate drainage behind your wall and make sure it is draining correctly by checking up on it once and a while.