Should departmental talks be included on a CV?
As you suggest they likely have minor value, but not no value. If you include them, use a separate section. Of course, if the topics of the talks are interesting in themselves they might be useful to include, depending on the type of position you are interested it. Having done a lot of talks might be especially interesting to an undergraduate institution. Having done a lot of research talks, especially on different topics, would likely interest a more research oriented institution. 

But if your CV is solid overall you needn't worry about padding. But you have what you have and you need to present yourself in the best light possible.