S 1.14 Automatic drainage

Initiation responsibility: Project planner; agency/company management

Implementation responsibility: Construction supervisor; Head of Site/Bldg Technical Service

All areas where water can gather and accumulate, or where running water or stagnant water is discovered belatedly or not at all, and where water can cause damage, should be provided with automatic drainage and possibly with water detectors. Such areas include:

• basement,

• free spaces under false (raised) floors,

• light shafts,

• heating system.

In case of passive drainage, i.e. through floor drains leading directly into the sewerage system of the building, backflow valves are indispensable. Without such flaps, this type of drain becomes a water inlet whenever the sewage system is overloaded. After very heavy rainfall, it will, in the majority of cases, be through this system that water leaks into the basement. The operation of the backflow valves must be examined at regular intervals.

If passive drainage is not possible because the level of the sewage system is too high or because the normal hydraulic pressure is insufficient, use may be made of pumps which are automatically activated by float switches or water sensors. When such technology is used, the following points must be particularly observed:

• The pump throughput must be of sufficient size.

• The hydraulic main of the pump must be provided with a backflow valve.

• Provisions must be made against the pump being blocked by entrained objects (suction filter etc.).

• Start-up of the pump should be automatically indicated (e.g. to the janitor of the Site/Building Technical Service).

• The functioning of the pump and the switches must be regularly tested.

• The hydraulic main of the pump must not be connected to a sewage pipe run in the immediate vicinity. If such a pipe had a leak, the water would only be pumped in a circle.

Additional controls:

• Have the rooms exposed to water risks been provided with automatic drainage?