The first line continues the theme of contradictions that runs through the album, and "the sewage of indecision, on which all sense of self is afloat," is a very vivid image. If "resolute in purpose its choking flow" refers to the sewage, then we're back to contradictions; other than all this, I don't see any separate meaning that can be extracted. The album is, after all, one long song; it would probably be best to interpret it all together.
The first line continues the theme of contradictions that runs through the album, and "the sewage of indecision, on which all sense of self is afloat," is a very vivid image. If "resolute in purpose its choking flow" refers to the sewage, then we're back to contradictions; other than all this, I don't see any separate meaning that can be extracted. The album is, after all, one long song; it would probably be best to interpret it all together.