How to extract from feature class those entries that have a single value based on one attribute?

I have a line feature class (with a field SURVEY), which I want to separate into 2 feature classes. In the first one I would have those features that have more than one feature with the same value in the field SURVEY - and in the other one - those features that have a single entry for a value in the field SURVEY.

I believe I could explode the original Feature class by the value in the SURVEY field, then count features in each of them, then test for value "1" and merge if required. But I don't know how to create separate features based on the value in the field.

Just to give you a context: For the first one I will later create convex hulls based on field SURVEY, but for the other one - buffers (as the convex hulls wouldn't look too good for a single lines). But this is not part of the question - as I know how to do it.

Please advise.