This engineer visited the site again, to continue our structural observations, and to witness further installations of piles and tiebacks, and to help solve a few construction problems caused by the unfortunate site conditions, including poor soil, in concert with recent rather heavy rains.
The piles were installed using a really noisy 90 lb jackhammer, and I had to stand very close to the operation in order to check the movement of the piles. (Fortunately, I keep earplugs in the car for just such occasions.) The “piles” are 2 inch diameter steel pipes, installed in segments with screw joints.
Due to the very wet, loose soil, the construction process is slow and difficult. Any any soil that is dug away is quickly replaced with more wet soil, sliding down from above, and hence the contractor has to move efficiently in order to get the 2×12 wood lagging boards in place. Installing the “Manta Ray” anchors also proved difficult, as the clay layer we are relying on 9to provide an attachment point for the anchors) is very dense, it is nearly impossible to penetrate.
We decided that installing lagging behind the piles, and pushing the lagging down as soil was removed from beneath, was the only way to get the wall in place without all of the soil falling away. Meanwhile, the contractor decided to drill pilot holes into the clay before attempting to install the manta ray anchors, in order to get an easier installation.
I’ll be going out to the site several times, during the next few weeks, in order to check on the progress using the new drilling approach.