Guatemala Water Pipeline

Engineers Without Borders USC is working with Vicampanavitz, a community of about 80 households in Nebaj, Guatemala, on a new conduction line from a spring to a primary tank. There is no pump: the line drops 172 m into a river valley and climbs back out to a tank site only 13.1 m below the spring.

Fitting the pipe to the drop.

I modeled the line in EPANET 2.2 on our team’s 95-station total station survey to choose pipe sizes and pressure classes. The survey found 11 m less drop than the satellite estimate, which left an all-2-inch line just short of the 1 m minimum pressure at the tank. The design keeps 2-inch PVC for most of the route and switches to 2½-inch for the last 841 m, which uses about 10% more PVC and leaves 2.3 m of pressure at the inlet.

3,143 m

of PVC from the spring to the tank, measured along the ground

0.8 L/s

design flow: the busiest day for a projected 615 people in 2048

8.33 m

of head loss, inside the 10.6 m of drop the survey found

245 psi

highest no-flow pressure, at the valley bottom (172 m of head)

• A pipe schedule in 160, 250, and 315 psi PVC classes: 553 six-meter lengths, ordered by pressure zone.
• Air valves, washouts, and river and road crossings placed from the survey’s high and low points.
• Checked against aged pipe, Darcy-Weisbach friction, water hammer, and sediment velocity.

Rev B design on the total station survey. Still pending a dry-season spring flow measurement and a check of the spring box water level; the line has not been built yet.