YS-INF-SWM-01

OSD DESIGN

Problem

Design an OSD tank for a 1.11 ha site located in Sepang, Selangor. The terrain is categorized as lowlying, and 90% of the site area is impervious after the development.

Solution

1. Identify the design region based on site location as per Figure 5.A1, MSMA 2.
2. Determine the permissible site discharge and site storage requirement based on the design region and terrain type, as per Table 5.A1, MSMA 2.
3. Calculate the actual site discharge and storage requirement allowed.
4. Identify the nearest major town based on the list given in Table 5.A2, MSMA 2.
5. Determine the permissible site discharge, site storage requirement and inlet flow based on the nearest major town, as per Table 5.A2, MSMA 2.
6. Calculate the actual site discharge, storage requirement allowed, as well as design inlet flow.
7. From steps 3 and 6, adopt smaller permissible site discharge and larger site storage requirement as design values.
8. Determine the inlet and outlet pipe diameter based on terrain type by using Table 5.A3, MSMA 2.
9. Determine the inlet and outlet pipe diameter based on discharge by using Table 5.A4, MSMA 2.
10. From steps 8 and 9, adopt larger inlet pipe diameter and smaller outlet pipe diameter as design values.
11. Determine the dimension of OSD tank.
12. Determine the inlet and outlet pipe diameter.