Flow Rates and Meter Readings

Putting on the Detective Hat

Weeks 4 to 6 in INTAG

FLOW MEASUREMENTS

After our introduction to the system in Limones and Villadora, we set about a fact finding mission to get a better informed picture of how the system works and the current demands the system faces. We wanted to learn how much water the people are currently using, is the systems spring supply sufficient to meet this need and for how long? and does the system have enough storage capacity to meet the peaks in demand during the day?

Without access to downloadable flow meter data as I'd become accustomed to in the UK, we needed to use our initiative to obtain the information we wanted. With stopwatch in one hand and bucket in the other we measured the flow rate at different points through the system, from the sources through to the final break pressure tank. As shown in the pictures below, we needed to use the overflow from the the "tanque de reserva" (reservoir tank) to measure the total flow entering the tank.




Now that we knew how much water was entering the system on a daily basis, the next step was to measure the consumption over a typical day. The final break pressure tank overlooks the second village of Villadora, and made the perfect spot to record the instantaneous flow rate. With this information we could get a rough idea of how much water X no. of households uses.



Farmers in the area start their days early. We wanted to capture this initial peak of the day, which meant 5am starts so that we could be measuring flow rates as dawn approached. Our measurements showed two main peaks: in the morning between 7.30am and 9.30am (0.7 l/s), and in the evening between 4.30pm and 6.30pm (0.67 l/s). The flow rate began to pick up above night-time flows as early as 6am, as we observed workers take to the fields soon after dawn. Usage was steady during the day, with flows picking up again at 3pm before the evening peak. When talking to households we learnt that soon after breakfast and after workers have left for the field, those at home begin the tasks of laundary and meal preparation, so that there is not necessarily a lunch-time peak as we might expect.

METER DATA



As part of our gathering information exercise we have been able to obtain meter reading and billing data for each of the 34 household connections dating back to 2005. This information has given us a good picture of typical consumption for this area, with monthly consumption ranging from as high as 65m3/month (=2100L/day) down to 10m3/month (330L/day). The average monthly consumption is equal to 22.3 m3/month (=733 l/day).



Following an overview census of the two villages, the average household contains 5 people. Using the population data we gathered, we've calculated an approximate consumption/day/person = 190 L/day. If you were to discount the high users in the system, the average consumption/day/person would come down to 150 L/day, which is the close to the 163 L/day/person in the UK (according to the Environment Agency).

This typical meter reading sheet shows that the a basic monthly charge of $2 is set for 25m3 consumption, which is just above the average consumption recorded. A cost of 15 centavos is charged for every m3 in addition to the basic charge. In this example, a household of 5 (2 adults and 3 children) have used 28m3 over a month period, a total price of $2.45.


Meanwhile in our home in Ibarra, for the month of August our household of 4 used 24m3, at a cost of $5.50. This price includes $3.40 for potable water and $1.70 for sewerage services.


SCHOOL'S PRESSURE PROBLEMS

The main concern in the system is the lack of water pressure at the school in Limones. The school, and its neighboring farm house, are situated on a high point in the system. During the peak usage periods the water supply up to the school's taps provides merely a trickle and in some periods no flow is delivered at all. It seems that at this point of the system, the pipe is not flowing full due to the demands downstream.

In addition, the school's meter is showing a considerable leak, of a potential magnitude of up to 500l/day.

These two issues are on the priority list to be addressed as part of the improvement works that we will be carrying out for the system.

Our next step will be to present the information we have gathered to the "Directiva de la Junta de Agua" (the water committee repsonsible for managing the system), in order to identify priority problems and the solutions that we can take to improve the operation of the system.

Day in the life of a Village Water Supply Operator

Limones y Villadora

Week 3 in INTAG

Meet Anibal Pasquel. He is the man responsible for operating and maintaining the gravity-fed water supply that serves the two villages of Limones and Villadora. In this farming community there is a total of 34 connections, which includes a school and a restaurant marked with a hotel sign. Anibal lives with his wife Maria in a wooden house that he built himself, on a plot of land where everything is grown from beans and bannanas to pineapples and cotton.

Aside from his farming commitments, Anibal is responsible for responding to any problems in the system, making syure that water is flowing and of drinkable quality. His work includes making new connections, installing meetings, organising community work teams when repair work is required or responding to a halt in flow at any time of the day.

Over the last 2 weeks we've had the privelege of spending time with Anibal and Maria to understand how the system works, where problems lie and the ideas that they and the community have for improving the system.

6 AM: OFF THE BEATEN TRACK: HILLSIDE SOURCE

Our tour of the system began with an early morning rise to make the 2 1/2 hour hike up to the system's spring source, in the hills that surround the two communities. With machete in hadn Anibal hacks his way through the evergrowing vegetation to clear our path, which includes

some very sturdy sugar cane.

9 AM: SPRING CAPTURE

There are two spring captures that feed the system. The greater of the two begins at the base of a large rock wedged into the steep slopes. Under the base of the rock, water is channeled into two concrete chambers, aligned in series, each with wire mesh filters to catch debri or sediment. A perforated capped pipe leaves the second chamber to carry water down to the communities. Three years ago, a dry summer caused an extreme reduction in flow from this source, which led to the development of a second spring further up the hillside.

The second spring collects water that has already run above from for some 8m. As a result, in our visit we observed thick sediment lining the concrete collection tank. Maria soon got to work on draining and cleaning out the tank. This second spring delivers a quarter of the 0.4 l/s that enters the system from the two sources combined. Taking this measured flow rate of 0.4 l/s, over the period of 1 day, the sources provide 34,500 l. Without taking into account storage capacity and peak demands in the system, this would be sufficient to supply 47 households using 733 l/day. This suggests that the sources are sufficient to supply the two villages with its current population - but mroe study is required to understand the sytem's storage capacity and daily usage patterns to confirm this thinking.

10 AM: PIPELINE TO THE COMMUNITIES

A path follows the route of the pipeline as it descends its way down the hillside. A flexible 1" pipe (called "mangera") is in parts suspended above ground, fixed to bamboo stakes plugged into the ground. The majority of the pipeline is buried and runds along a ridge of a the hill towards the reservoir storage tank.

11 AM: CONTROL VALVES

Along the route of the pipeline break pressure tanks ("tanque rompe presiones") are used to bring the static head back to atmospheric pressure. This reduces the pressure in the pipeline, which enables the diameter of the pipe to be kept to a minimum.

At high points along the system, valves to release air ("valvulas de aire") are positioned, whilst at low points washout valves ("valvulos de desague") are located to allow cleaning of the pipeline. In the picture above, Anibal explains that at the moment the majority of the air-release valves are manually operated, and that they require automatic valves so that he needn't have to make the trek when there is air entrained in the system.

1 PM: CHLORINATION

A chlorine batching tank sits on top of the reservoir storage tank, but has not been used for many years and the equipment has become obsolete. The reason for this seems to be due to a number of factors; one being the distance of the reservoir storage tank from Anibal's house making the frequent dosing an overbearign commitmnet, and the concern that chlorinated water was being wasted through the storage tank's washout during hte night, onto the road below.

3 PM: MINGA: COMMUNITY WORKFORCE

The line that marks Limones from Villadora is the recently upgraded main road. There are break pressure tanks located either side of the road, with a drop of some 20m between the two. SInce the roads reconstruction, the flexible "mangera" passed under the road through a drainage conduit. This low point in this part of the system has led to problems of air entrapment in the pipe. As a result, the water committee whom are responsible for manaing the water system, known as the "Directiva de la Junta de Agua", called for a "minga", to install a concrete post to elevate the pipe above the road, with the aim of removing the low point in this part of the system.

The "convocatoria" as shown by Maria above, orders all users to attend to give assistance for any repair or maintenance work required, with a penalty of $10 payable for non-attendance.

8 PM: THE SYSTEM'S LIFELINE

From our time spent with Anibal we have learnt a tremendous amount about the challenges that face a gravity-fed system, both technically and socially. We have seen firsthand Anibal's tireless work that he puts into making sure the system is working.

As I ask Anibal what inspired him to take on this role, he tells me that he's "always fascinated to learn how things work, and to get them working at their best". He jokingly tells us he doesn't have much of a technical background, but we have seen that he has the mind, the care and the attention to solve any problems that come his way. His attention to detail was demonstrated to us through his careful drawings of the system, with each house labelled by name.

At the end of a long day attending to the upkeep of the system, we are greeted by Maria who has lovingly prepared a hot nourishing soup of platano and potato grown on on their land, together with a warming soya milk. They call this valley paradise, with its abundant produce of food, and from my time here I can see why.