だいぶ - greatly? 撒く - spread? しなあ - ?
UPDATE: the context is the following. It's a scene from anime 'Your name'. The mayor is giving a speech in front of an audience. Then the focus is moved to a couple of people standing in the back among the crowd. A man says, "He's going to be reelected anyway". A woman says back to him だいぶ撒いとるしなあ. In the subtitles it is translated as "I heard he's been dishing out the pork". As far as I understand し here is used to creat a list? Like she's adding to the man's point. And なあ is just for emphasis? So "And (he's been) greatly spreading (rumors/lies?) (about himself?)