Originally posted on BGET.org

Sunday, October 5, 2008

Lessons from Poblaki

As the rising sun began to heat the streets of Mae Sot last Thursday, BGET volunteers and technicians (including American volunteers Megan, Christina, and Josh, and Thai-Karen technicians Thai, Sunti, and Em) teamed up with two folks from a Thai ram pump company to head to Poblaki, a Karen village about 6-7 hours northwest from town.

Thomas and Stefan, the folks from the ram pump company, had arrived the night before from their headquarters in Chiang Mai. Several months ago, BGET and the ram pump folks came together to install a ram pump system to deliver water from the nearby stream to the village school (if you are not familiar with ram pumps, please see the end of this post for a short description).

This system moves water from the stream to a large tank in the schoolyard. Before the installation, people had to walk nearly one kilometer down a steep path (which became very slippery during the wet season) through the jungle to reach the stream, and then carry several gallons of water back up that same path. With the system installed, families could easily walk to the school yard and use the tank's tap to withdraw the day's water.

Unfortunately, we had heard that the system was broken and water was no longer filling the tank. Those on the team with experience with the system guessed the problem lay in one or more of three possibilities: (1) the pump was not operating properly, (2) the catchment dam was clogged with mud and rocks, or (3) a pipe somewhere in the line was broken. After a brief stop at a Mae Sot hardware store to pick up a few pieces of possible replacement parts, we hit the road.

About 5 or so hours on the highway and a lunch stop just outside the Mae Moei National Park, we began to wind our way up, down, and around the mountains on mostly washed out red clay roads. Large swaths of new green rice plants interrupted the fleece-y dark green of wild jungle plants, and dramatic mountain ridges undulated far into the distance under a striking blue enamel sky.

Grey cotton clouds quickly moved into the valley, and a gentle drizzle cooled our sun-warmed skin. After about two hours on the dirt roads, we reached the last river before Poblaki. The monsoon rains had so swollen the river at one point that the bridge had been washed away. We pulled the truck over, packed up the bags and tools, and explored the banks for a shallow way across. Not finding anything promising, we asked a local the best way across, and he pointed us to a thin path a little ways up the hill.

 After a few minutes of walking in what had developed into a typical seasonal downpour, we crossed a beautiful footbridge constructed entirely of bamboo. After the bridge, we skirted acres of rice fields before arriving at a temporary shelter under the eaves of someone's house. As we waited for the storm to calm a bit, we busied ourselves with grooming -- finding the opportunistic leeches that had stuck themselves fast to our flesh and struggling to tear the slippery creatures away.

When the cacophony of rain had quieted to a dull roar, we thanked our host and began the remaining one kilometer -- all at a significant uphill grade -- to Poblaki. As we walked through town, we greeted folks sitting and chatting together under the protection of friends' and family's roof and watched chickens and dogs huddling together under the homes' raised floors. At the end of a cluster of homes, we arrived at Rose's place, our homestay for the two days. Once the sun reappeared and we had dried off a bit, we set out to inspect the ram pump.

Eight people half-slid, half-tiptoed down the hill to the stream. The Thai-Karen members of the BGET team moved confidently as though they had learned to walk on saturated jungle paths, and Thomas and Stefan admirably struggled to keep up, but the new farang BGET volunteers (i.e. Megan, Christina, and Josh) quickly fell far behind as we carefully tried to avoid (but didn't quite succeed) falling and sliding the rest of the way down the hill.

When we finally caught up to the rest of the group, we discovered that possible problem number two could have been the culprit. Rocks and silt had almost completely filled the catchment basin to divert most of the water away from the pipe. Once Thomas, Thai, Sunti, and Megan cleaned out the small basin as best we could and more water flowed into the pipe, we headed a little further downstream to inspect the pump.

As we stood around watching the ram pump folks tinker a little with the pump system, the clouds opened up a second drenching attack. With the increased flow from the unblocked catchment basin and the rainstorm, the pump quickly kicked into operation. Satisfied that we had resolved problems one and two (pump and catchment basin), we stood around and chatted about the system until the rain abated enough to make the return trip to the village a bit easier.

As we walked, we made a cursory visual check of the piping in the pump system, and since we noticed no spurting leaks, we assumed possible problem three was not a problem after all. Back in the village, we went to the school and confirmed that water flowed into the tank. Megan, Josh, and Christina spent the rest of the afternoon -- now sunny, now rainy -- performing a site survey for a future PV project for the school while the others washed and rested.

Later that evening, after a delicious Karen meal Sunti, Em, and Thai helped prepare, we learned that in fact the pump system was not working. So, after rising with the sun and the roosters at dawn, Megan, Christina, Em, Thai, and Sunti suited up in rain gear, gathered tools, and went back to check the system. As before, the rains had swept the catchment basin full of mud and debris. Once the basin was clear, the pump began to work as normal.

We returned to the village by following the delivery pipe and stooped to put our hand on the pipe to check that water was indeed flowing up. The ram pump's water hammer caused rhythmic vibrations in the delivery pipe that felt just like the heartbeat of a living thing. As we traced the pipe up to the village, we saw water glugging out of a broken end, just before the pipe crossed the road to enter the schoolyard. Turns out that problem three -- a broken pipe somewhere in the system -- was in fact our problem. The pipe had been buried under the dirt road that passed outside the schoolyard, but some rains must have washed away enough dirt to expose the pipe to animal or motor traffic.

Despite having stopped at the hardware store before leaving Mae Sot, we had not brought along enough of the required pipe size to fix the problem right away. We also suggested that the new pipe be laid inside a large pipe or piece of bamboo to protect it against future damage. Unfortunately, with most of the BGET team heading to Burma this week, we won't be able to return to Poblaki for at least three weeks, and the villagers will have to go back to the old method of fetching water.

So, what have we learned?

(1) A new design for the upstream water catchment is critical. The BGET team tossed around a few simple ideas for debris filters and a deeper catchment basin, as well more complex ideas, such as commoditizing the water with some money paying for a trained village member to clear the basin of mud and check on the pump and piping system whenever the school tank reported low or no flow.

(2) Think through all possible problems, and bring enough supplies to fix any of the problems.

NOTE: A Short Explanation of Ram Pumps

Ram pumps move water using only the potential energy of water in the form of pressure head -- no fuel and no electricity. Large flow rates falling from a low head (elevation) moves smaller flow rates up to a greater head. A drive pipe brings water from a catchment basin to the pump. A delivery pipe carries water from the pump to the desired location. Two valves in the pump and an air chamber regulate pressure oscillations (the water hammer) in the pump that force excess water from the drive pipe out of the system and move some flow uphill in the delivery pipe. As the first valve opens to release the excess water, pressure in the system decreases and water from the drive pipe enters the pump.

The entering water forces the first valve closed and compresses air in the air chamber, which rapidly builds pressure in the pump. When the pressure in the pump exceeds the pressure head of the delivery system, the pump expels water into the delivery pipe. This loss of water decreases the pressure in the pump and the first valve falls open by gravity and the cycle starts again. The second valve is a check valve to keep water from the delivery pipe from falling back into the pump when the pump pressure decreases. No photo of the ram pump will be published here to protect the proprietary rights of the company.