Extracted text: -- Water is supplied to a town through a cast iron gravity main, 0.5 m diameter and 30 km long, across an undulating ground from the headworks to the service reservoir in the town. The pipe off-take at the headworks is at RL +480 m and the maximum water level of the reservoir is at RL +370 m. The lowest ground level in the L-section of the main is at RL + 280 m at a point 15 km from the off-take. If it is desired to increase the supply to the town by 30%. (a) For what distance would you lay a duplicate pipe of the same size ? (b) What is the expected thickness of this pipe at a point 15 km away (where the RL of the centre of the pipe is 280 m) ? The water hammer pressure may be neglected as additional arrangements have been made for dissipating the same.