I have lived at the apartments at the corner of Hale and 9th. The smell was bad, and this location is NOT even too close.
For some reason, this facility tends to really stink (No pun intended :). I had a house in escrow for one of my clients off of Guilder Glen, another area which is not directly adjacent to the treatment facility, however the smell was still very bad.
There is a special smell disclosure which you will/would have to sign off on to purchase one of the properties which are very close-but most of the affected properties which will still will have an odor do NOT have this disclosure to sign off on.
Another important thing to remember is that the smell is by far the worst in the summer. For some reason, the heat really turns up the odor. My wife and I really hated it. Make sure you work with an agent who knows these things... hint hint....