Memorandum

It has come to my attention that there have been some construction problems associated with the concrete fill for soldier pile walls. In some cases a minimum concrete strength (say 1000psi) has been specified. In these situations, the removal of the concrete from the face of the soldier pile for placing lagging is very difficult and time consuming. In order to enhance construction, the following approach should be used:

                    1.   Soldier Pile Walls with No Tiebacks

                    For this application, Lean Concrete (145# of cement per cubic yard) should be used for the fill length
                    of the pile. In this situation, the lean concrete only needs to be strong enough to transfer active and passive
                    loads between the soil and the pile. For a wet hole application, the lean concrete mix will have to be modified.
                    The special provision for lean concrete will address this situation.

2.  Soldier Pile Walls With Tiebacks

                    For this application, structural concrete (Concrete Class 4000P) should be used below final grade (below the
                    cut line in front of the soldier pile wall), and Lean Concrete should be used above final grade. Concrete Class 4000P
                    can be used in a wet hole application. Structural concrete is needed below final grade to assure vertical load transfer
                    from the soldier pile through the concrete into the soil supporting the bottom portion of the soldier pile. The load is
                    applied to the soldier pile from the vertical component of the sloping tieback soil anchors.

The BDM will be updated to include these design provisions. Draft revisions are attached.

CCR

Attachment

cc:     J. A. Weigel, (w/attach) 7354

        Higgins, (w/attach) 7340

        J. Fahoum, (w/attach) 7340