Q. Design the Drainage pipes system in reclamation areas?

In reclamation areas drainage pipes are generally laid at flatter gradients when compared with upstream stormwater pipes. The fact that nature of flow in stormwater drain is by gravity makes the downstream pipes in reclamation areas comparatively deep below ground surface. It's predominant to have outfall of drains above the tidal influence level and this accounts for the relative flatter gradient of drain pipes in reclamation area. 

Attention has to be paid to possible occurrence of differential settlement in reclamation area. For pavement design, flexible pavement is predominant to rigid pavement to cater for settlement problems. In the same way, in the design of drains flexible joints such as spigotand socket joints and movement joints in box culverts have to be provided to guard against the effect of differential settlement.