Jun 2002

Flood Exposures and Mitigation

In last month’s article, we dealt with the definitions for severe weather watches and warnings with respect to the upcoming hurricane season in the Northern Hemisphere. One peril that accompanies most severe weather conditions are flood exposures.

Realistically, if a building is in a flood prone area, there is not much that can be done to prevent flood waters from entering. However, understanding what is at risk and finding ways to limit the extent of flood damage can significantly reduce the overall property damage and interruption to production.

First we will consider what is at risk in a typical industrial facility. Then we will take a look at various ways to potentially reduce the exposure to damaging flood waters.

Risk Exposures


The height and velocity of flood waters, in addition to the amount of debris in the water, can have an effect on the overall building damage. Generally, the lighter the building construction, the greater the damage.

If the building has a basement, obviously it will be affected first. If floods cause standing water to remain outside a building for an extended period, the hydrostatic pressure on the basement walls may cause them to collapse if they are not reinforced.


Damage to contents, both product and production equipment, is the major result of flooding. Consider the following:

– Electric motors are very susceptible to damage, especially if operating when immersed. Transformers have different levels of flood damage, depending upon weather they are dry or liquid cooled. Water can contaminate the cooling oil and damage the entire unit.

– Computer equipment is very susceptible to damage from flood water. If the hardware cannot be reconditioned promptly, permanent damage may result. Paper records are usually damaged beyond repair.

– Boilers, furnaces and ovens can receive extensive damage. If water enters the units while firing or still hot, major warping or similar damage can occur. Fine silt can penetrate combustion, air and gas piping. This can be very difficult and costly to remove.

– Reciprocating machinery such as compressors, pumps and engines can be damaged by flood water but normally can be dismantled and reconditioned.

– Office areas can sustain severe damage. Gypsum walls can collapse, rugs will need to be replaced and wood furniture will swell and crack making replacement necessary.

Raw material and/or finished product can be damaged unless packaged in a watertight wrap.

Where food, drugs, tobacco, clothing or other domestic products are involved, public health officials may condemn the entire stored contents of a building

Major damage can result to outdoor process equipment such as dust collection systems, cooling towers or storage tanks. Paved roads may become impassable.

Fire protection also becomes an issue during a flood. Flood waters often carry heavy debris, which can damage flammable liquid tanks or piping and sprinkler systems. Electrical short circuits and broken gas lines are also common. Power to fire pumps, as well as the pumps themselves, may be damaged.

Business interruption can be significant depending upon the extent of down time. It must be considered how much raw material is lost, whether backup production equipment is available or whether alternate production sites are available.

Flood Mitigation

If it is determined that a building is in a flood prone area, there are some precautions that can be taken when advance warning of a flood is received.

Permanent Protection

This refers to barriers or other devices, which are permanently attached to a building. Their primary function is the elimination of openings through which water can enter a building.

Flood Doors

These are doors that may be hinged or suspended over openings, which are ready to be put in place at the first sign of flood.


Any unnecessary windows should be filled with materials similar to the wall. Display windows can be protected with movable shields.

Interior Protection

– If possible, stock or equipment susceptible to water damage can be raised off the floor.

– Fuses or circuit breakers should be clearly marked. This will aid in cutting power to the affected areas.

– Control valves for gas and/or fuel supplies should be shut off.

– It is possible to have flood waters back up through floor drains or other pluming fixtures. This can be prevented by installing shut off valves on the drain piping.

If it is determined that your plant is in a flood prone area, a Flood Emergency Response Plan (FERP) should be developed. For information on developing an FERP, and further details on Risk Exposure and Flood Mitigation, please contact us.