Retaining Walls With Large Drainage Structures

By Doug Blackburn
Sep 17, 2008 - 1:45:00 PM

Today, what we’re looking at is a retaining wall that’s located in Loveland, Ohio.  This retaining wall is over 20 feet high and you’ll notice at the top of the wall there is a valley.  Coming down that valley is a relatively large creek.  That creek dumps into a reinforced concrete structure that comes down vertically right through our retaining wall and passes into a pipe below the retaining wall into this structure, which is beneath my feet, and is carried out to the creek.

            What we’re going to do right now is take you up to the top of the wall and show you the concrete structure.  We are also going to discuss the engineering of the retaining wall, with respect to that structure, so you can understand how we can incorporate that structure into the wall without the retaining wall having problems. 

            We are above the retaining wall now and you’ll notice that this structure is a reinforced concrete box that goes down about 25 feet from this top.  This is approximately equal to the top of the retaining wall.  On my right and on my left are concrete walls which prevent the water coming down hill from overtopping our block wall.  They contain the water and they force it into these openings. 

            These openings are formed using No.8 epoxy-coated rebars spaced at approximately six inches on center.  The creek feeding this structure comes down from my right and it encompasses a relatively large drainage area.

 (Brief pause while panning with camera)

            During the design phase of this wall…early in the design phase, the owner and civil engineer discussed in depth, the requirement, that this wall would have to accommodate this structure.  In order to accommodate this structure, we used 100% angular No.57 gradation stone, surrounding the structure.  We also used an increased number and strength of geogrid layers on both sides of the structure from the bottom of the wall all the way to the top.  We also capped off that drainage stone with a clayey layer so that any water that might collect in this area would be trapped by the clay and be forced into this drainage structure, not into our retaining wall system.

            Today we took a look at the G.E. Credit Union retaining wall in Loveland, Ohio.  This was a retaining wall that was able to accommodate a relatively large drainage structure, collect and remove a large volume of water from a creek, and do so without jeopardizing the structure of the retaining wall or the drainage structure.