Primarily during the summer months, there is a smell that can occur from the Dixon Landing landfill when the right combination of heat, wind direction, and one's outside proximity combine.
I have personally come across this while viewing the newer attached housing bounded by Kato Road and Warm Springs Blvd.; however, I have never personally considered it to be absolutely overpowering.
Perhaps you might consider knocking on a few doors in the neighborhood you are considering and asking for feedback regarding your concern.
However, if you feel you do not like it or if it effects your health or life somehow - then you should think about a different area.
You may consider talking to friends or residents in this area and see how they feel.
Hope this helps.