Water Leveling

On my previous mission, I had an official company blog.  On this mission, I do not.  I am finding myself doing similar technical surveying techniques, so if you missed my post last year about slope surveying, here's a rehashing.

We're doing a large drainage project for the inner courtyard of the Aweil State Civil Hospital.  There are some horror stories of intense flooding in the middle of the hospital, as well as mosquito-producing lakes.  That doesn't sound like it's up to MSF's hygiene standards, so we have a large-scale intervention planned, with gutters, drains, soak-away pits, and water holding tanks.  The first step in all of this is a depth survey of the courtyard.  We're installing a 2% grade on the earth of the courtyard, through landscaping, and a 2% slope on the gutters that will line the walkways.  The 'surveying' boils down to a lot of measurement with simple math.

The infamous courtyard, pretty dry now.

The measurement happens with the construction log and I taking a clear tube about 30m long and wandering into the courtyard.  The contractor and his assistant happen to be walking through (they're on their way to the new showers they are just finalizing), so they stop and help after the first few measurements.

We fill the tube with water, then we attach one end to a stake hammered into the ground at Reference Point 1 (which happens to be a random corner we picked because it was here).  We pound a stake in the ground 30m away, and the comparing of levels is underway.  We compare many points to R1, measuring from the water level to the ground in each place, then move on to R2 for the middle of the courtyard, and finally R3.  We get a jumble of numbers that hopefully makes sense in a few hours when I have the time to sit down and type it out.

Tons of notes, a calculator and a word document is almost like having a CAD landscaping program, right?

A very sophisticated depth chart of the whole courtyard, mostly annotated by hand.

The contractor has started working on the sloping of the courtyard, and we'll bust out the water level several more times over the course of construction, to check slope measurement.  We'll also pour water on the ground and see where it runs, which is kind of more useful as a slope measurement, but sometimes it's good to be technical.