I Arrived in Banos at About 4 Pm

Date: December 9, 2010

EXISTING SYSTEM

Fig. 1 Tank 1, el. 2300' 3'', 570 m, 4 LB

100' 4'', 530 m, 4 LB 2.5'', 1100 m, 7 LB Cruzero, Tank 3, el. 2000' el. 2200' 200' 6'', 2050 m, 7 LB

Booster pump 260'

grade el. 1740'

~70 m well 120 m

Submersible pump

Fig. 1 shows the critical elevation diagram and distances between key points. The specific information was summarized in other documents.

NEW TANK OPTION

The assumption is that the new tank would be located near the Pedronas Crossing (Cruzero) where the lines to Tanks 1 and 3 branch from the main line. The elevation is about 260 feet above the level of the booster pump. This assumption will allow (a) distributing water to most locations below the Crossing without adding new lines; (b) independently pumping water Tanks 2 and 3. It will require adding two more pumps pumping to the elevations of 200 feet and 300 feet above the Crossing.

I estimated the relative demands by looking at the elevation of different parts of the village and counting the houses that would have to be served by Tanks 1 and 3 vs. the houses that can be served by the new tank. About 18% of houses can be served by Tank 3, 49% by Tank 1, and 33% by the new tank.

The new tank option assumes replacing the existing pumps at the well as it wouldn’t make sense to keep the high-head booster pump. Then I calculated the total power consumption, assuming 50 GPM flow to Perdonas Crossing and 50-50 split between the two tanks. The calculation is summarized in Table1:

Table 1

One pumpTank 1 Tank 3 Case 50 GPM 50 GPM 50 GPM Tot Suction head m 66 0 0 Suction head feet 216.54 0.00 0.00 Discharge Head feet 260 300 200 Losses feet -50 -50 -50 Losses psi -21.7 -21.7 -21.7 Total Discharge Head feet 427 250 150 Pump flow GPM 50 25 25 Pump efficency fraction 0.85 0.85 0.85 BHP HP 6.80 1.99 1.20 9.99 Power KW 5.07 1.49 0.89 7.45

The approximate total power consumption is about 10 HP, consistent with the previously obtained result (when evaluating savings from flow reduction). The number is quite insensitive towards the split assumption. The result gives us the approximate power consumption of pumping all the water to the higher elevation. This is the benchmark we want to compare against.

Table 2

One pumpTank 1 Tank 3 Case 50 GPM 50 GPM 50 GPM Tot Suction head m 66 0 0 Suction head feet 216.54 0.00 0.00 Discharge Head feet 260 300 200 Losses feet -50 -50 -50 Losses psi -21.7 -21.7 -21.7 Total Discharge Head feet 427 250 150 Pump flow GPM 50 12.18097 4.582367 Pump efficency fraction 0.85 0.85 0.85 BHP HP 6.80 0.97 0.22 7.99 Power KW 5.07 0.72 0.16 5.96 80.0%

Table 2 shows the calculation assuming only some of the water gests pumped to Tanks 1 and 3, according to demand. This means that one can save about 20% of power. The power cost, as is, is 3.55 kWh/1000 gal. By reducing the flow one can reduce it to 3.05 kWh/1000 gal or by about 14%. Then, by adding the new tank, one can further reduce it to 2.44 kWh/1000 gal or by additional 20%. Thus, the total savings so far are 31% (the %savings depend on the magnitude of the number).

Assuming that one can save 16% of the cost by running the pump at night, the power cost can be further reduced to 2.05 kWh/1000 gal, with the total savings of 42%.

Going back to the new tank option, the new pumps would be small, with the total cost of maybe $1,500 (scaling from quoted pump prices).

Assuming 3000 people in the village, 25 gal/person/day water demand, and 1- day supply, the new tank would have to be about 75,000 gal. The combined Tanks 1, 2, and 3 now hold only 71,550 gal. Some of the water comes from the spring. Let’s assume combined volume of Tanks 1 and 3 or 60,250 gal. Based on Apatut work, such concrete tank would cost about $39,000. The total cost of the new tank option would be about $41,000.

If we could get a design for a typical tank we may be able to build it for much less than $39,000 if we do the work using volunteer labor. Concrete is relatively cheap and Freddy is a welder and can probably help with any rebar required.