A portion of a site that I maintain lists job opportunities available within an organization. The opportunities are listed on a single page with a short description which can be clicked on by the user if they desire more detail.
Here's the site, for reference: http://goo.gl/mQVyO
Question
The opportunities are fluid and change often. They are editable by human resources and change without the knowledge of the programmer (me). As the frequency of the edits/updates/removals increase, I've noticed a lot more 404 errors in my logs.
Currently, I'm redirecting to a 404 page when someone attempts to access an opportunity that no longer exists (they are accessing it from Google primarily).
Is this the best way to handle this from an SEO perspective? I'm finding that the opportunities that have been removed are taking quite a while to be removed from Google's index.