I will have to get with my husband to find out about the shell of the pool material and how/where it was mixed. I was at work when all of that took place. They were supposed to be here to drain the pool Monday, but just now showed up. They've had problems with another pool in the area (not our same problem). The soil in our area can be extremely sandy and tends to cave in when digging deep. We found this out when we dug out for our storm shelter, and the dirt around it just kept caving in continuously. Lost a rose bush and almost an ac unit. We did warn the pool builder of that problem before hand, but it still was still extremely difficult.
I do know that the original plaster was mixed on site as we had it sitting here for a few days on pallets waiting on them to get started. It did rain like crazy and we covered it the best we could with several tarps, but a few bags were lost. They've already delivered the plaster for this job too and we immediately put it in our garage so something like that doesn't happen again.
On an interesting note, the glass tile that I ordered, from a different company, with a totally different manufacturer name, and color name, looks exactly the same as the tile they are going to have to replace. Now that was funny.