Monday, November 22, 2010

Aqueduct Theory 101

Author's Note: This post is my most viewed post on the blog.  Due to the popularity, I've created another website with a ton more information about aqueduct design, construction, and maintenance. Check it out! 

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I realize that much of what I blog about is "the volunteer experience" and yet I haven't really talked too much about what it is I actually do around here.

My life is aqueducts.

Admittedly, before Peace Corps I knew nothing about gravity-flow water systems.  I'll go out on a limb and guess that most readers don't know much either (you don't count other PCV's).

Turns out not much has changed since Roman times, including the physics.  Replace your open-channel structures with PVC tubes and you've got the basic idea.


Panama is blessed with abundant rainfall (most of the year in the Bocas region).  The water falls into your neighborhood watershed where springs feed streams, streams to rivers, and rivers to oceans.  This water is collected and distributed to provide water to a community using gravity instead of pumps.

Here's an overview of a typical gravity-flow water system in Panama.  I'll take extreme liberties in painting a picture of how easy it is to design and build your very own water system.

Intake Structure
Normally those in the community are intimately aware of where the nearest spring is to the community.  As long as that spring has good flow all year long and isn't located close to any livestock, it may be a good potential source for your gravity-flow water system.  Build a concrete box or dam to collect water into your PVC tube.  That's your intake structure.  You'll also need to do a study of the topography to determine the size of your PVC tubes and the route from the intake to the storage tank.



Storage Tank
Most likely your source (spring or stream usually) won't be enough to provide around-the-clock access to water.  After a careful study including flow, a census of the community, and the projected growth you can determine whether or not you need a storage tank to buffer the daily swings in demand.  Most of the time you design a tank to fill at night when demand is low to provide water for the community during the day.  The tank is a big concrete structure that holds about 5,000-15,000 gallons depending on the size of the community (about 250 people average).


Distribution System
Now you need to bring that water from the tank to the community.  Again, a topographical study is in order to make sure pipes are size correctly and placed in the right locations.


Each house will have a connection to a main line, just like back at home.  There will be shutoff valves for lines to do maintenance work.  We'll stand around to shoot the $#!% and watch the one guy dig the trench just like home.  It's all the same, just without pumps and heavy machinery.  Easy as pie...

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Yes, I'm being facetious.  Part of the challenge is doing it with your community, which had a whole life they were living before you ever showed up.  People will be away getting firewood or food from their fincas.  You want them to come along on the journey because that sense of ownership is the difference between an aqueduct that works and one that falls into disarray.  Then there's funding and the complexities of design and building something in the jungle and social engineering and... you get the idea.  Easy as pie.