Excavation!

Buying the land, hiring the architect and getting all my permits were each big steps toward this earth sheltered home. But, digging a huge hole makes those other steps pale in comparison.  Things are now very serious. Where I once had a nice green rolling hill, I now have what appears to be some sort of ecological disaster…  Actually it looks a lot like a sand quarry.  I look forward to restoring it again as soon as possible. There is no way to turn back now, I have to push through.

 

Prep

We only had to excavate the partial basement portion, just over one third of the site.  The shape of the basement is like a half circle with a few bumps on it…  Sherri and I started the day by staking out the perimeter of the footings.  Then I had a chat with the excavators (Roe Brother Excavation).  I had invited the footings guy (Doug Dysert of Dysert Concrete) to join the conversation so that the excavation would be done according to his needs.  Since my footings are curved, he had already told me that he would rather have the excavation down to the bottom of the footings (easier to build curved forms on the ground rather than dig them out).  But now I wanted his input on how he planned to create the step footings that would transition from the full depth basement footings to the slab on grade footings and how that would affect the excavation plans…

Doug said he didn’t like engineers “sloped” step footings.  He said, “Maybe that’s how the specify it on government jobs, but that is not how we do things around here.”  He would prefer that we build the basement footings and walls first and then back-filled before working on the slab on grade footings.  I was concerned about building footings over fill and about making any changes that the inspector wouldn’t like.  Doug said I should make sure the inspector likes those footings and everyone agreed my sand would compact very nicely.  Doug also sketched me his plan for connecting the basement footings with the slab on grade footings.  The next day, I took those to the inspector, more about that in a separate post.

Anyway, back to the excavation…  Doug didn’t want a sloped excavation, but I was concerned about needing slope for the footings specified by the engineer.   We agreed that a “double over-dig” would be OK.  We would over-dig 4 ft around where the footings would go, and then step up 4 or 5 feet and then over-dig a second 4 ft out from the first.  I figured it would give the shotcrete and waterproofing people space to work and would allow me to easily excavate for sloped step footings if I needed to.   Even if it crumbles, it is essentially a 50 % slope, so it should be OK.  Doug sprayed the 4 ft offset line (curving) around my original basement footing stakes so everything was marked out.

My favorite quote of the day (paraphrased)…   “The problem with dirt is that is is all in the wrong place.  For instance, here we have some dirt where there should be a hole.  Some times you have dirt where there should be water.  An excavators job is to fix these mistakes.”  I would add to that every earth sheltered home owners fear…  “Some times there is water where there should be a hole”, fortunately, that is probably not going to be an issue for me on this sandy hill site.

 

Dick Roe (an original Roe Brother) got thinking about how to approach the dig (you don’t want to dig your self into a corner) and Marty (a Roe Son/Nephew) got busy on my drive way.  Meanwhile Sherri did the smart thing and quietly added center-line stakes well beyond the excavation area.

Lesson learned

We had made things hard on ourselves by outlining the curved project with curved offsets.  Once the excavation got started and the stakes were dug out of the hole, it got harder and harder to remember what was going on.  I couldn’t visualize it anymore and I have been staring at the plans for years, so I am sure my excavator had no chance.  The hole ended up looking somewhat like an amoeba as the excavator tried to dig just the right amount, but not too much.  It was also a challenge to deal with the growing piles of dirt around the hole

My excavator was kicking himself for not laying out the overdig with a rectilinear shape (like a trapezoid) around our curved plan.   He would have been able to stake out the overdig easily and then dig it out with much less time spent scratching his head.  Make sure to tell your excavator “the footings may be curved, but the excavation is all straight lines.”

 

The Excavation!

Here is a video of Sherri and I laying out the basement stakes and then the digger getting to work.

With the extra head scratching and time spent on my driveway, etc., they didn’t manager to finish the excavation on day 2.   They came back the following morning and took care of it.  By the second day, the excavator had decided that the site was too sandy for stepped sides and put in a slope for most of the way around (which is what I had originally asked for).  He also added a ramp to make it easier for us to get in and out of the hole. He said that if Sherri and I found it was too small, he would come back and make some final adjustments.