OSD Spreadsheet Computation

This column, explain details on steps by steps of OSD spreadsheet computation.


Step 1:- Open spreadsheet.


Step 2:- Change design ARIs value.

[Refer to table 4.1 in MSMA (2000).]



Step 3:- Change Coefficient value for a, b, c and d.

[Refer to table 13.A1 in MSMA (2000).]








Step 4:- Insert tc & tcs value.

[Refer to table 14.3 for area smaller than 0.4 hectare. For area larger than 0.4 hectare, please used formula stated in chapter 14.]








Step 5:- Insert FD values for short duration.

[Refer to table 13.3 and figure 13.3 in MSMA (2000).]









Step 6:- Insert area and runoff value for impervious and pervious area.

[Refer to design chart 14.3 and design chart 14.4 in MSMA (2000) for runoff coefficients value.]








Step 7:- The PSD & SSR value will be automatically calculated for you.

[Please choose type of OSD that you want to design and select the maximum value for SSR value.]




Editor:- Dilah – 10 March 14



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