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5. Urban Drainage System (a) Sustainable Urban Drainage Systems (SUDS) are designed to manage quality and quantity of stormwater. Compare and contrast four techniques of SUDS in a new development of housing estate. [10 marks] (b) A new development of housing estate area as shown in Figure Q5 is drained by a number of sewers connected at manholes. For sewer 1.2 only, determine whether a concrete circular pipe with length of 250 m, slope of 0.006, diameter of 600 mm, and roughness of 0.6 mm will be sufficient to cope with the excess water due to the design storm. Use the Ministry of Health formula for a storm with a return period of 1 year and assume that the time of entry to the sewer is 3 minutes. The times of flow, catchment area, and percentage runoff are given in Table Q5. [15 marks] 5 CIVE3070 Continued on the next page X CIVE3070 Pipe 1.0 1.1 1.2 2.0 3.0 1.0 1.1 1.2 2.0 Figure Q5 for use in Question 5(b). Table Q5 for use in Question 5(b). Catchment Time of flow (min) area (km²) 0.6 0.008 0.7 0.015 - 0.012 0.5 0.004 1.5 0.010 3.0 Percentage runoff (%) 40 55 40 60 50