I just emailed Bill Dodd the outgoing county supervisor asking what he might know. He was active in the extension of Devlin Rd announced at the beginning of the year. I also asked him if this was part of some larger development. He's a good guy and friend so expect he'll respond.
I took a drive out there just now. I doubt it will be a the 221 Devlin Road address. That's the location of the Allied Propane business, but it's way away from any other businesses. Not a bad idea since the site features a propane tank the size of a house. The permit application shows two sites, 221 Devlin Road and on the NW corner of Devlin Road and Airport Blvd. Not a lot to do around there either, but the area is under intense development right now, so there will likely be at least one place to eat. The rest of the development consist of various wine related warehouses and businesses. It's far away from the tourist parts of Napa Valley, a popular place to put a bottling line and truck cheap wine in from the Central Valley and put "Bottled in Napa Valley" on the label.
NapaBill: I guess everyone around here know Bill Dodd. He's in my Rotary Club.