Our builder has started drilling holes for all the foundation piers for the ADU. These piers will be different from the retaining wall piers, in that they won’t have half ton steel girders at their cores — just rebar and concrete. The rebar is supposed to show up this week, so right now the area sort of looks like a giant, obsessive gopher has been at work. The holes are covered with plywood; I guess that’s to keep people from stepping in accidentally (workplace safety is no joke) and to keep nature from falling in and filling the hole back up while we wait for rebar and concrete.
The Quintana-Beitzel Coprosperity Sphere 
Thank you for the pics. Your lot looks like a real construction site. I know this having grown up around them.