Questions

1. Calculate the discharge and seepage velocities for water flowing in a pipe filled with sand, with a hydraulic conductivity of 0.02 m/day and an effective porosity of 0.25. The hydraulic gradient is 0.4. How far will the water move in one year?

2. A cylindrical column pipe, 0.3 m in diameter and 5 m long is filled with relatively homogeneous sand. If the porosity of the sand is 35% and distilled water is continuously introduced into the column, saturating the sand and establishing steady state flow conditions for which the discharge is measured to be 18.6 x 10-2 m3/day, determine:

a) The specific discharge
b) The average velocity of flow through the column

3. What is the required power to pump 55 l/s against a total dynamic head of 120 m if the pump operates at 78% efficiency?

4. A surface mine requires to pump a quantity of 2,500 litres per minute from a main sump located at the bottom of the pit to a settling pond. The vertical lift of the pipeline is 900m and the total length of the pipeline is 4000m.

Assuming the pipeline to be straight with gate valves located at 300m intervals along the pipeline, that the pipe friction factor is 0.017 determine: a) The flow rate in litres/second
b) If a flow velocity of 0.6 m /s is the design velocity in the pipeline, determine the pipe diameter.
c) Using the determined pipe diameter calculate the head loss due to friction in the pipe.
d) Determine the head loss due to a single valve and total valve head loss in the system.
e) Assuming no entry or exit losses determine the total head loss in the pipe.
f) Determine the head required by the pump
g) Determine the power added by the pump
h) If the pump has an efficiency of 85% determine the power required by the pump.
i) Select a suitable pump to undertake this task

5. Pumping occurs from a shaft bottom sump to surface via a 370m vertical pipe. Ignoring entry and exit losses, assuming a pipe friction factor of 0.02, a pipe diameter of 150mm and ignoring other losses in the pipe, if there is a flow rate of 3000 litres per minute; determine the pump head required?

6. What is the required power to pump 8000 litres/min against a total dynamic head of 250 m if the pump operates at 82% efficiency?