Pio V. Corpus WATER SYSTEM PROBLEM & RAM PUMPS

I received a comment on my previous blog post, ‘My Hometown Pio V. Corpus: POLITICS GONE WRONG’. The comment writer, presumably, is a fellow citizen in my hometown Pio V. Corpus, a kababayan. He calls me ‘Bai’ which means ‘friend’ in Bisayan dialect. His comment is in a form of question and not directly related to my blog post. He asked about the pros and cons regarding the use of ram pump to assist water distribution in my town. Here he goes:

Bai,
What would be the pros and cons of using a ram pump or a glockeman pump to assist water distribution of the manaay spring to poblacion Pio V. Corpus?

And here is my answer:

If you think installing ram pumps at the Manaay reservoir to assist water distribution to poblacion would solve the water supply shortage of the town – then, from an engineering point of view, you are wrong. But before I will tell you the how’s and why’s, here’s a little backgrounder of the Manaay reservoir.

The Manaay reservoir is surrounded by several small springs. The pictures above show one of those. The water flowing from these springs are pure; free of pollution. These springs are the main sources of drinking water. The downstream side serves as a laundry area.

The Manaay reservoir is a small concrete catchment tank built at the downstream side of Sitio Manaay spring. It collects and stores water from the spring and conveys it to the town’s water distribution system via a single 6” pipeline spanning between Manaay and Poblacion more than two kilometers in length. The spring is an abundant source of drinking water that it could supply at least three towns the size of Poblacion Pio V. Corpus. The volume of water delivered by the spring is so huge that only a fraction of the spring’s output is necessary to fill the catchment tank. The spring is situated at the forested area at the hills of Sitio Manaay about 2 kilometers south of poblacion. By virtue of its elevation, about 50 meters^{[for verification]} above sea level, the reservoir has a built-in source of potential energy more than enough for distribution. No further pumping is necessary, as gravity alone would be sufficient to do the job.

As far as I know, the reservoir and the water distribution system of Pio V. Corpus were built in the late 60s, about a generation ago. Between the 60s and the 80s, there was no issue of water distribution problem in the town. The issue started to crop up only in the early 90s and lingers onwards. Households located farthest from the source were the most affected ones: there is no water supply at all. In some households, water is only available at night when most of the households in proximity to the source are no longer using water or have closed already their faucets. As the issue of water supply lingers, the technical word ‘WATER PRESSURE’ became a household phrase. The town’s people began to blame ‘decreased water pressure’ as the root cause of the issue.

While town's people continue to blame water pressure as the culprit of the problem, little did they know that the water pressure is not the real problem at all; it is just a technical outcome of the problem. The real issue lies on Municipal Engineering or the office that manages the municipal water system. They are not doing their job, or they don’t know what to do. They just watch as the issue arises, doing nothing. They failed to tackle the following issues and scenarios:

1. That the capacity of the reservoir or catchment was, most likely, designed to supply the population in the 70s only. A further upgrade in the water system is necessary to meet the increasing demand as the population expands. The upgrade would mean replacing the existing pipeline with a bigger capacity or installing additional pipeline parallel to the existing ones to cope up with the increasing demand.
   
   Please try to check with the municipal engineering if there had been improvements being made to the water system during the period starting from the 80s onwards. These are during the terms of Mayor Avila and Mayor Amaroto. There had been reports that somewhere during their terms, there was an appropriation for the rehabilitation of the town’s water supply system.


2. That the town’s number of households is growing and so does the population. Although I don’t have exact data showing the town’s population growth but by just looking at the Google map, the area of habitation has expanded in three directions: to the north, to the west and to the south sides of the center of the town. Where do you expect these additional households get their water? They all converged to the same water pipeline built in the late 60s.


3. That the water system is getting older and becoming obsolete. Corrosion and siltation of water pipeline are inevitable. Over the years, the pipeline becomes corroded and silted, clogged up with dirt, thereby reducing the output.

As an engineer myself who grew up in town Pio V. Corpus, the only solution that I can suggest (aside from eradicating corruption in the local government) is for the municipality to build a new reservoir side by side with the existing one and a new pipeline. The new reservoir and pipeline must be built based on a feasibility study. There is no need for the old pipeline to be condemned: let it operate until it dies out. A story circulating among concerned Pio V. Corpus citizens on the Facebook has it that the municipality is planning to enter into a 50-million-peso loan with the Landbank; the purpose of which is unknown. I think building a reservoir or rehabilitating the town’s water system would be a very good justification.

Now back to the reason why a ram pump won’t work to assist the distribution of water from Manaay reservoir using the existing pipeline.

First, a ram pump, by its nature, is not designed to deliver a large amount of water. Also called an impulse pump, it is a device that uses falling water to lift a lesser amount of water to a higher elevation than the source. So, being primarily used for lifting relatively small amount of water to a higher elevation, the ram pump is not necessary in Manaay reservoir: the water source is already on the higher elevation relative to the point to be supplied. It would not be a good idea, of course, bringing the water up and then bringing it down just for the notion that it would increase the potential energy needed to deliver the water. The potential energy of the water in the reservoir is constant. It cannot be magnified by using ram pumps, as ram pumps derive energy from the potential energy coming from the reservoir. In a simple analogy, you cannot recharge a battery using its own power; some outside source must come in.

When water source is an issue, a ram pump is not a good medium for distribution; it is not efficient in terms of delivery. For a ram pump to operate, it needs at least seven times more amount of water than the amount it can pump. Meaning, if you want to deliver 1 cubic meter of water to an elevated location, you require at least 8 cubic meters of water to operate the pump - 7 cubic meters of which will be used to drive the pump and goes directly as waste.

To understand fully how a ram pump works, here’s an exerpts from Wikipedia:

• Construction and principle of operation
  

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  A hydraulic ram has only two moving parts, a spring or weight loaded "waste" valve sometimes known as the "clack" valve and a "delivery" check valve, making it cheap to build, easy to maintain, and very reliable. In addition, there is a drive pipe supplying water from an elevated source, and a delivery pipe, taking a portion of the water that comes through the drive pipe to an elevation higher than the source.


• Sequence of operation
  

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  Figure 2: Basic components of a hydraulic ram:
  1. Inlet — drive pipe
  2. Free flow at waste valve
  3. Outlet — delivery pipe
  4. Waste valve
  5. Delivery check valve
  6. Pressure vessel
  
  A simplified hydraulic ram is shown in Figure 2. Initially, the waste valve [4] is open, and the delivery valve [5] is closed. The water in the drive pipe [1] starts to flow under the force of gravity and picks up speed and kinetic energy until it forces the waste valve closed. The momentum of the water flow in the supply pipe against the now-closed waste valve causes a water hammer that raises the pressure in the pump, opens the delivery valve [5], and forces some water to flow into the delivery pipe [3]. Because this water is being forced uphill through the delivery pipe farther than it is falling downhill from the source, the flow slows; when the flow reverses, the delivery check valve closes. If all water flow has stopped, the loaded waste valve reopens against the now static head, which allows the process to begin again.
  
  
  A pressure vessel [6] containing air cushions the hydraulic pressure shock when the waste valve closes, and it also improves the pumping efficiency by allowing a more constant flow through the delivery pipe. Although, in theory, the pump could work without it, the efficiency would drop drastically and the pump would be subject to extraordinary stresses that could shorten its life considerably. One problem is that the pressurized air will gradually dissolve into the water until none remains. One solution to this problem is to have the air separated from the water by an elastic diaphragm (similar to an expansion tank); however, this solution can be problematic in developing countries where replacements are difficult to procure. Another solution is to have a mechanism such as a snifting valve that automatically inserts a small bubble of air with each pump cycle. Another solution is to insert an inner tube of a car or bicycle tire into the pressure vessel with some air in it and the valve closed. This tube is in effect the same as the diaphragm, but it is implemented with more widely available materials. The air in the tube cushions the shock of the water the same as the air in other configurations does.
  
  
  The optimum length of the drive pipe is five-to-twelve times the vertical distance between the source and the pump, or 500-to-1000 times the diameter of the delivery pipe, whichever is less. This length of drive pipe typically results in a period between pulses of one-to-two seconds. A typical efficiency is 60%, but up to 80% is possible. The drive pipe is ordinarily straight but can be curved or even wound in a spiral. The main requirement is that it be inelastic, strong, and rigid; otherwise, it would greatly diminish the efficiency.
  
  
  Some later ram designs in the UK called compound rams were designed to pump treated water using an untreated drive water source, which overcomes some of the problems of having drinking water sourced from an open stream.
  A Ram Pump in action
  


• Common operational problems
  

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  Some common operational problems are intrusion of air into the drive pipe, blockage of the intake or valves with debris, knocking due to having too little air in the pressure vessel, freezing in winter and bursting of the delivery pipe if output is blocked or pressure not relieved.