The Bessa water distribution network has 7 nodes and 8 fixed pipes. It is aimed at dimensioning, as economically as possible, the network sections and the pumping head, considering the pipeline investment costs and  energy cost of the pump, which pumps water to the reservoir. The captation water level is 30 m. The minimum head requirement at all nodes is fixed at 25 m. The set of commercially available diameters is [108.4, 156.4, 204.2, 252, 299.8, 366.2, 416.4, 466.6, 518, 619.6 milimeters]. The flow for the period of twenty years is 420.43.

The costs and pumping conditions are:
Number of pumping hours per annum = 7 300
Efficiency of the motor-pump unit= 0.75
Expected period of service for the network = 20 years
The average pumping discharge = 420.43 L/s
Power tariff is R$ 0.20/kWh
Annual rate of increase in the tariff of electrical power = 6%
Annual discount rate = 12%.

Table 1 provides the available diameters, materials, Hazen-Williams coefficients C and unitary prices for pipe investment.

TABLE
Pipeline data and costs

D (mm) Pipeline Material HW Coefficient “C” Unit Cost (R$/m)*
108.4 PVC 145    47.09
156.4 PVC 145    63.80
204.2 PVC 145    87.62
252.0 PVC 145   118.59
299.8 PVC 145   152.24
 366.2 Ductile Iron 130   317.86
 416.4 Ductile Iron 130   375.00
 466.6 Ductile Iron 130   436.23
 518.0 Ductile Iron 130   515.60
 619.6 Ductile Iron 130   640.30
*R$ – Brazilian Real (R$ 2.50 = USD 1.00 and R$ 0.24 = ZAR 1.00).

Bessa (file .inp)