Apartment construction cost in CA Central Valley

[Ash Ram]

Hi Experts, I am looking for latest data about how much it will cost to build a 20-unit apartment complex in CA Central Valley (in/around Tracy / Modesto / Stockton) with a GC vs self-managed project with an experienced architect. Expecting about 20,000 sqft of construction (units and common areas).

1. Related info:
   1. Type:
      1. Garden-style
      2. 2-levels with mix of 2 Bed/2Bath and 1 Bed/1Bath units
      3. Mid-grade construction
   2. Site info:
      1. Flat land, no major grading work is needed
      2. Utilities are yet to be connected (the site is in a developed neighborhood with good road access and utilities at curb side)
      3. Expansive soil (known for this region)

Thanks!