I am trying to read the soil file that someone has sent me and can't seem to do it. They sent me the .SOI file but I can't figure out how to view it in the buried pipe modeler.

What file should I be sent so I can view the soil properties used for the soil model?

You need the "_A" file that goes with the ".SOI" file. The Buried Pipe Modeler uses these two files to generate the buried model.

test._A \
> combine to generate "testB._A"
test.soi /