Client wants us to design the SOE but also guide in the installation of the SOE. We've calculated that the sheets have to go down to 72 feet so that we can excavate down to 42 feet for the mat foundation. However, within the proposed area, there's an existing 60" RCP that runs through the proposed area at about 38 feet deep. The portions of the existing pipe that's within the proposed area will be demo and replaced with a pump chamber, but the portion of the existing pipe outside the proposed area has to stay intact as the pump chamber will connect to it. The area is within a coastal plain deposit with mostly all SP. We also need to install piles for the mat foundation. So a portion of the area would be difficult to install piles with an existing 60" RCP going through it. Area is roughly 30'x30' and borders on neighboring properties.

How exactly would we be able to get the sheeting down to 72 feet if there's a pipe at 38 feet? I don't imagine the sheeting being able to do a clean slice of the RCP like a knife as it goes down. We have an exact similar situation at another location for this project but the excavation only needs to go 12 feet deep. So we may or may not need to employ the same strategy for that one. Any tips or idea for the strategy on how to do this?

We asked if there were any existing sheeting in place from the previous construction, they said they have no idea.