So, Turns Out, the City Knew About that Sand Beneath the Calatrava Bridge All Along
Right now I am staring at a table of Trinity River soil boring results I just received from the City of Dallas, and I am just aquiver with fascination. I see the smoke. I see the gun. But I still can't put the smoke in the gun.
Review: Last year the city's contractor was drilling a seven-foot diameter hole 90 feet down in the river bottom to hold one of the main piers for the foundation of the Margaret Hunt Hill Bridge over the Trinity. People from the U.S. Army Corps of Engineers, which has authority over the river, were watching.
All of the sudden a Vesuvius of liquefied sand comes bubbling up out of the hole; the big drilling rig starts wobbling around in quicksand; they have to halt the operation until they can get the sand stabilized. It's one of the main reasons the Corps later called off major construction on the bridge project and ordered the city to carry out a two-year $29 million study of the levee system.
Corps officials consistently have told the Observer they didn't know what kind of sand was buried in the soil beneath the bridge project. They said they didn't have the "geo-tech," which means core sample results from test borings. In a recent presentation to the city council, however, city staff told the council they had done test borings and had presented the findings to the Corps in seeking the Corps' permission to dig holes in the riverbed. I asked the city to provide me with that data, and city staff did so.
And I'm sitting here lookin' at it. And there it is, right where they drilled the seven-foot hole and the quicksand came out. It's at a point called "Bent 6" on the bridge.
I have no idea what that means. Bend me. But there it is -- a layer of sand about 25 feet down from the surface of the river bed. The sand layer varies from five- to 15-feet thick at that point. All of the other borings across the full expanse of the floodway show a similar sand layer at a similar point, which would indicate to this highly untrained, unqualified and unrecognized geologist that the sand layer extends all the way across, at least from levee to levee but probably under the levees and into Oak Cliff and downtown, at a depth of 25 feet or so.
So here's the deal. This means the city did do the geo-tech. The city says it did give the geo-tech to the Corps. The Corps did give the city the go-ahead for the project. The Corps then stopped the project and said it was shocked, shocked, when sand came out of a hole.
The geo-tech, then, is the gun. Everybody knew there was sand. The smoke is the sudden reverse of field midway into the bridge project, with everybody running around crying, "Sand! Sand! Heaven forfend, there is sand!"
But in order to put the smoke in the gun and the smoking gun in the hand of the bad guy, we still need to know who conned whom about the importance of the sand. Or were they all going to con the public and pretend the sand wasn't a problem, but somebody chickened out?
Sand, sand, every where,
And all the boards did shrink;
Sand, sand, every where
And going down the sink.
I'm becoming the ancient Marinara.