Good news! Through 
The Dutra Group, a 100+ year old dredging and marine construction company based in California, we've secured a tour of their 
San Rafael Rock Quarry, which is a major aggregate supply in the region. Photos look pretty amazing:
Since it'll need to take place during working hours - this tour will be Friday (6/24) at 11 PM. We'll coordinate carpools and other travel after all the RSVPs come in.
Limited space, as always, so e-mail me if you're interested in coming along ASAP. 
Excited,
Tim
PS: We're also working to arrange a tour of 
The Dutra Museum, a family museum detailing the history of the dredging industry in California. More details to come there.