When Engineers Attack

NOTE: As of September 23, 2009, this post has been edited in
accordance with a court-mediated settlement. The names of the
contractor and his excavation subcontractor have been replaced with
pseudonyms.

This morning we had a big meeting with the geotechnical engineering firm (Alan Kropp and Associates) and our structural engineer (Ralph Kratz) and our contractor (Contractor A -- the one who caused all these problems) and me. Woo-hoo did we have a lot of people on site. When you get two levels of engineering involved, money starts flowing out of your hands like water flows into our basement. So if anybody reading this would like to buy something we happen to own at a price that is not at all a bargain, um, drop us a line.

Well, we started out up above, discussing the plans and the proposed engineering for the foundation. We're changing from a footing foundation, which sits on 18" wide footings all around the perimeter, to a mat slab foundation, which has a structural slab (essentially, footings that extend the entire floor) that can remain in place even if a large amount of the soil underneath it is unable to bear a load. Which means that if the basement turns to 50 percent mush in the winter, the house doesn't fall down, which is a very good thing. It's going to be 12 inches thick, with two layers of rebar in it to handle loads on both sides.

Engineers

While we were discussing slab thickness and drain fields, one of the engineers was under the house marking off the "soft spots" with pink spray paint. They are growing, and they are getting softer, which has all of us very concerned. The geotech engineers don't want anybody walking down under the house if it can be avoided, and obviously no heavy equipment. LIKE NO EFFING BOBCAT, FOR EXAMPLE.

Pink circles

With the new foundation, the permanent location of the sump has to be determined now, the sump dug and built properly, and the construction sumps decommissioned. So Contractor A (the guy who caused this mess and cost us hundreds of thousands of dollars) and the guys measured out where the sump will be and marked it on the gravel in green paint.

Where's the sump

We had an animated discussion about how deep the sump needed to be. We don't want it too deep, see, because we're not interested in pumping water out of the entire island -- all we want to do is keep the basement reasonably dry (recall that we didn't even really want a dry basement to begin with; we wanted a damp storage room for our root cellar). Also, if silt gets pumped out with the water, as has been happening, we're effectively pumping out the soil our house is sitting on, which can lead to a situation known in the field as "A Great Badness."

Sump depth

At this point, we have a lot of water flowing into our basement. The situation changes drastically in the summer, but right now it is Extreme.

Water pours in

We stood around trying to figure out how to get continuous rebar across the slab when there are these great big Jenga stacks in the way -- moving them is not an option because at this point they are sitting on the only areas of soil strong enough to hold them, not to mention that another $1200 is just not available.

Scratching chins over rebar

One of the things the engineers did today was take some core samples of the soil in the firm areas, and in the soft areas. The firm area held up nicely. Sand is that way when it's not too wet. OR HASN'T HAD A FRICKING BOBCAT DRIVEN OVER IT. Sheesh.

Core sample scar

To get a sample in the wet area, Contractor A (who had carefully tried to conceal this damage from us only a few weeks earlier) raked back the sand...

Preparing for a core sample in a soft area

Dug around in the muck to find the edge of the geotextile fabric...

Preparing for a core sample, 2

And in went the sampler.

Sampling

There's a nice firm base under there, about six inches down. But the stuff on top has the consistency of melted chocolate ice cream. Oy. That's called liquefaction, and it is not good news.

Looking at the sample

My favourite moment in the day? When the geotechnical engineer leaned over to Contractor A (who was trying to play all knowlegable and technical and coming off looking like a buffoon) and said, "You really f---ed this up." Yes, he did.

posted by ayse on 03/25/05

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