</font><font color="blue" class="small">( I might add you probably will have to let the wall cure for some 28 days I believe, At least that's what I did and then waterproofed,backfilled with stone and of course drain lines.
The pilasters helped immensely as well. )</font>
He could also use the fast setting concrete that obtains more of its strength more quickly. Can the concrete truck get close to the site or is it going to be pumped? My estimate is that it will take 20 yards of material for the wall 54'x9'8"x12". I believe that the wall should be vibrated to avoid any voids. Have you contacted the concrete company to see if they have a engineer on staff???? Also, if it were my project, I would want to wait till warmer weather to make this pour. I don't like putting calcium chloride into th concrete to inhibit freezing..
You haven't commented on the two 30' walls.... are you going to be putting any re-bar in them? Are they going to be poured at the same time as the 54' wall? If so, are you going to run the re-bar around the corner?? More questions than answers, but that is the way we will figure this out together... If so, then this well add an additional 22 yards (approx.) of concrete to this job.