Surface Water Drainage Strategy & Flood Warning and Evacuation Plan Tilbury

Surface Water Drainage Strategy & Flood Warning and Evacuation Plan Tilbury

Southwest Environmental were instructed to undertake a Surface Water Drainage Strategy for a commercial development in the Port of Tilbury.

A few weeks after this initial instruction we were also advised to proceed with a Flood Warning and Evacuation Plan.

In both cases the key was  building up sufficient evidence in order to ascertain risks accurately, and then implement migratory measures and evacuation procedures based on those risks.

Flood Warning and Evacuation Plan

There has been historic flooding in Tilbury, and flood water can take many days to recede after an event. The flood defenses in Tilbury do provide a good level of protection but, it is important to consider over topping events.

Although the site should remain high during a flood it is thought, that workers may be isolated for a number of days. To that end a list of long life provisions was included in the Flood Warning and Evacuation Plan. Image from here.

Surface Water Drainage Strategy

The site is to be entirely covered in concrete surfaces, there is also wash water from the intended use that must be disposed of.

Surface Water and Foul Water systems were kept separate in the conceptual design, additional measures were taken to ensure that this was so, although changes to design were kept to a minimum.

The port has a complex private drainage system, and this was studied in deatil to suggest applicable options moving forward.


Surface water was disposed of to the Thames River (which runs through London) via the Open Botany Drainage Channel and Botany Sluice. Water Qaulity to the Thames was subject to new CIRIA Mitigation Indices (above).

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