Saturday, November 05, 2005

Today (2 Nov 2005) - Reply from PUB: Drains built to allow natural drainage

Drains built to allow natural drainage

Letter from Yap Kheng Guan
Director, Drainage
Public Utilities Board (PUB)

PUB thanks Mr Jeffrey Ho Loon Poh for his letter "Drains in S'pore just do not drain", (Oct 29).

.In Singapore, we tend to experience short but heavy bursts of rain. As such, our drains are designed to handle high volumes of water efficiently.

.We agree with Mr Ho that drains should be designed, taking advantage of the natural gradient of the ground as much as possible.

.However, where the grounds are steep, such as at the Adam Road/PIE ramp mentioned by Mr Ho, a steep drain will cause the rain water to flow very rapidly which can cause flooding at the bottom of the slope during a heavy downpour.

.We have therefore designed the drains there in tiers instead, to break the flow of water so as to prevent a rush of water at the bottom.

.All drains are designed with a gradient, including the tiered drains at the Adam Road/PIE ramp.

.This allows the water to be drained naturally by gravity.

.PUB and NEA have inspected the drains at the locations mentioned by Mr Ho and found that there were natural flows of water there.

.This may not be apparent to the naked eye or in a still photo. There were some silt deposits which impeded the flow slightly but these have been removed.

.PUB is aware that there are some old drains where the gradient is too gentle and we have a programme to review and systematically upgrade these old drains.

.Similarly, these works are also being carried out by town councils for drains managed by them, such as those in common corridors and carparks.

.Stagnant water is often caused by fallen branches, rubbish, clods of earth and so on, that obstruct the flow of water.

.The public can assist by alerting NEA at 1800 225 5632 and PUB-One at 1800 284 6600 to such blockages and refrain from littering.


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