Today they finished drilling the last holes for what our contractor and engineer call caissons. This word choice seems odd because, according to my dictionary, a caisson is “a large watertight chamber, open at the bottom from which the water is kept out by air pressure and in which construction work may be carried out under water” — no large bodies of water here! I think that these should really be called concrete piers: i.e., “concrete columns that are formed by pouring liquid concrete into holes drilled into the ground.” The one that they finished this morning was 25 feet deep and two feet in diameter; the largest of them all. After that big one, they did the rest, the series of shallower, smaller (18 inches) ones shown in the photo. These will make sure the 2-story, gabion walls (wire cages filled with rock), which will line the west side of the house both as an architectural element and a heat shield, cannot fall even in an earthquake.
Eventually, these holes will be filled with concrete and metal posts will be attached to the top. Before that, however, the rebar cages shown below need to be lowered into the holes. For this, apparently, they need a crane. It sounds like the earliest that this can happen is Friday; so tomorrow is a day off.