@Johnson H. Finally made it down to the city's planning office today and got some good information. Concord requires a minimum lot size (for SFHs) of 10,000 sq. ft. Since the parcel is 1.11 acres or ~48,000 sq. ft., it may be tough to squeeze 4 separate houses + a driveway into the space. There is already existing sewer hookups, although they were unsure if it has enough capacity for 3 additional houses. I still need to call PG&E and the water district to see what they can tell me about existing utilities there. Timeframe is 3-to-6 months for full approval process, longer if the neighbors want to cause any headaches. Fees are $6,100 + $464 for each additional lot. I got a list of setback requirements and other restrictions as well.
@J. Martin - I like the way you think. I only spoke with the city about subdividing into separate parcels, but the idea of putting a bunch of townhomes in a small PUD is very intriguing. Probably a better use of the land if it can be done.
Thanks everyone for chiming in and helping out thus far. I'll keep updating as I progress. (PS: This is what makes BP awesome).