DESIGN OF SEWAGE DISPOSAL SYSTEM

Consider only one shaft of the building

Horizontal branches serves 53 fixture units each floor

From Table 52 of SP 35,

Size of branch pipes for 53 FU is 100 mm

Design of Stack

From table 52 of SP 35

S.No Floor DFU Cum DFU Size of Pipe in mm1 Fourth 53 53 1002 Third 53 106 1003 Second 53 159 1004 First 53 212 1005 Ground 53 265 100

Design of Vent Stack

For the total 265 DFU and total length of 17.50 m,

The size of vent stack shall be 75 mm (Reference from Table 14.4a of text book)

Design of Building Drain

From table 53 of SP 35,

The size of pipe for building drain shall be 150 mm with gradient of 1 in 50

DESIGN OF STORM WATER PIPES FOR ROOF DRAINAGE

The building is located at Coimbatore.

S.No Monthaverage rate of Rainfall in mm

2009 2010 2011 2012 20131 January 1.3 4.0 0 1.8 02 February 0 0.8 82.9 0.8 57.83 March 46.2 6.9 8.5 0.1 19.14 April 28.7 33.1 140.6 68.9 54.25 May 82.4 61.6 45.5 47.0 47.96 June 96.6 34.1 86.5 41.8 154.47 July 360.5 40.0 47.5 48.3 126.28 August 115.6 55.3 68.3 44.1 93.3

9 September 192.7 58.6 50.6 28.2 87.510 October 81.6 168.7 211.7 229.6 160.411 November 203.6 234.2 183.5 42.5 70.612 December 20.9 34.1 15.5 6.4 26.9

From table 57 of SP 35-1987, for the average rainfall of 150mm/h and for the roof area of 1650 Sqm,

Provide 20 Nos. of 150mm pipe to dispose the rain water from the roof top.