Much has happened since I last updated this site. Trinity's friend John arrived to help out, we laid out some string lines to mark out where the piers should go, we finally got our building permit, my brother arrived, we started digging...
The structural engineer called for the piers to go 9' deep. I think he was playing it extremely safe because our neighborhood is known to have some expansive, clayey soils, and because a geotech report wasn't in our budget. He did tell us that we might be able to modify that if based on what we encountered as we dug. So, after a day and a half using an earth auger attached to a back hoe, we'd only managed to dig two of our 17 piers. A neighbor who is also a structural engineer stopped by and rescued us by showing us that the soil which was making the digging so difficult was viable as a bearing soil. It's a reddish soil mostly composed of sand and gravel, with redish clay mixed in. I had thought because we were still encountering clay that we didn't have any reason to amend the nine foot depth, but my neighbor explained that with such a small amount of clay, there's really no expansion and that the high amount of sand and gravel created a good bearing. So, we started digging everything to a depth of three and a half feet, and on Monday morning showed up at our structural engineer's office a little before he got to work with a ziplock back full of the redish sandy gravely clayey soil we were encountering. He checked it out, let his boss look at it, agreed, and sent us happily on our way. We still had a terrific amount of trouble with the digging, what with the auger bit getting ground down to the point of unusability, and the drive itself seizing up so that we had to finish the digging by hand. But our neighbor's intervention saved us from having to hire vastly larger and more expensive equipment.
Shorter posts and more of them on the way!