So Schneider went to prison. That means he didn't got the arrangment the captain offered or did he? That would be the climax of the movie? And it would be Justine who gave him the reason to clean the dirt for a better world for his baby?
He did'nt get the arragement and was sent to a mental hospital, if I remember correctly. As for the reasons for him to get rid of the dirt, I guess Justine was part of it, as much as he was probably fed up with life. For me his actions at the end of the film just seemed logical, seeing what the character went through throughout the picture.