Archive for Army Corps of Engineers

On the Relative Purity of Dirt

Posted in Research, Technologies with tags , , , , , on January 24, 2010 by lexis2praxis

There’s a great deal of talk about debris found in levees along Lake Pontchartrain.

The skinny is this: Levees are made of dirt.  Prior to Katrina, the Army Corps of Engineers made some levees larger by adding additional dirt.  Back then, it is said, contractors were told to use what they call the “visual inspection” method.  This is the technical term for “eyeballing”.  Contractors were required to look at the dirt they were using to build levees and make judgment calls about how much debris was there.  If they saw debris, they were supposed to remove it.  The reason for this is that levees require a type of clay-based soil that falls within certain requirements in terms of liquid content, plasticity, and consistency.  Too much debris can break up the tensile strength of the soil.

The problem is, dump trucks carry tons of dirt to a site when building a levee.  Just eyeballing, one can’t possibly see all the chunks of concrete and bricks (or as one informant put it, “kitchen sinks and everything”) inside the dirt.  Post-Katrina requirements on levee testing revealed that debris content exceeded restrictions in these locations.  Now, all dirt must be formally tested for debris content; the Corps says it is only using trusted borrow sites (a borrow pit is where they get their dirt); and the compromised portions of levee are being replaced.

Advertisements

What is a Levee? (Part 1)

Posted in Research, Technologies with tags , , , , on November 9, 2009 by lexis2praxis

The London Avenue canal levee and floodwall

An excerpt from an academic paper (for a list of the references used, please contact me):

Levee [French levée, from Old French levee, from feminine past participle of lever, to raise; see lever.]

The primary meaning of levee, according to Merriam-Webster, is “a reception held by a person of distinction on rising from bed”.  This is a custom still practiced in Canada, where it is a general New Year’s celebration, a social affair in which people recount the past year and anticipate the next one.  The use of the term to describe a social event originates with the Levée du Soleil, the Rising of the Sun, a custom of King Louis XIV (1643-1715).  Apparently the King was in the habit of receiving male subjects in his bedchamber after waking, a custom that was then passed down to subsequent monarchs and later, heads of state and other leaders.  These gatherings were long restricted to men until recently, and now includes women and children in most cases.

The secondary meaning for levee is, perhaps, no longer secondary since Hurricane Katrina, which propelled the term into media and international conversation.  According to Merriam-Webster a levee is “an embankment for preventing flooding, a river landing place, a continuous dike or ridge (as of earth) for confining the irrigation areas of land”.  Petroski defines it as a “natural or artificial slope or wall to prevent flooding of the land behind it … often parallel to the course of a river or the coast” (Petroski 2006:7). A few people (outside of the Delta, of course) have told me that they don’t really know what a levee looks like, and can’t really imagine one.  Of course, people who live with and depend on delta engineering know all about them; in fact, the technology as well as the word entered the U.S. through the Mississippi River delta. Continue reading