wanluQmanاِقْرَأ

Drain Page  

---

posted by adme @ 5:12pm, Tuesday 5 October 2010.

The intended contents on this page shall consist of design criteria and parameters related to surface water drainage system, as refered to the approved standards and current guidelines by professional institutions and regulatory agencies. Relevant standard drawings shall be made available on this page as reference. Contributions on materials and comments are welcome and appreciated.

 

General rule on Grades of Drain:

The grading of roadside drains should generally conform to the grade of the road which should normally be maintained at not less than 1 : 200 , however where necessary to reduce drain depths, grades may be reduced to give a minimum flow velocity of 1 m/sec. In addition, the maximum allowable velocity should be 3 m/sec for lined channels and 2.25 m/sec for grassed channels. Where the general grade is in excess of the maximum, the drain should be cascaded in 150 mm maximum steps. Based on a design n values of 0.014, the maximum and minimum allowable grades for standard block drain section are as follows;

Drain Size	Max %	Min %
9"   ( 225 mm )	7.0 ( 1 : 14 )	0.65 ( 1 : 150 )
12" ( 300 mm )	4.7	0.42 ( 1 : 250 )
15" ( 375 mm )	3.5	0.30 ( 1 : 330 )
18" ( 450 mm )	2.5	0.22 ( 1 : 450 )
24" ( 600 mm )	2.25	0.20 ( 1 : 500 )
30" ( 750 mm )	1.6	0.14 ( 1 : 700 )
36" ( 900 mm )	1.25 ( 1 : 80 )	0.11 ( 1 : 900 )

• 
• 
• 
• 
• 
• 
• 
• 
• 
•