The following article is based on the efforts of a nine-month program to inspect, benchmark and provide advisory services in and around the flooded infrastructure of a major city where more than 237,000 inspection points were made and more than 18,000 photos were taken.
When we think of flooding —whether a minor event or a major disaster —most thoughts are directed to the obvious impact of water saturating and immersing the affected areas. Other than dealing with the catastrophic result of washed-away infrastructure, attention is usually focused on the draining, drying and disinfecting of all systems and components, small and large, in attempts to salvage and get things back to normal.
In many cases, the measure of “how long” something has been exposed to flood waters is a main factor in determining the remediation effort needed. In the case of saltwater inundation, however, this factor has little meaning. The most significant effect of saltwater flooding is not saturation, immersion or resulting organic growth, rather, it is the deposition of salt on vulnerable surfaces.
Chloride, sulfide and nitride ions of salt dissolved in sea water create chemical bonds with many surfaces. These bonds happen immediately upon wetting — resulting in a salt residue remaining long after the water is gone. One second of exposure to salt water can have the same effect as an exposure lasting an hour, a day, a week or even a month.
The residue, at a microscopic level, cannot be removed with simple rinsing or routine brushing. It requires extraordinary force or chemical neutralization. If neither is done, and the salt residue remains, the potential for latent damage will exist. Over a period of weeks, months or even years, the salt left behind will continue to corrode any susceptible, affected surface. The corrosion process will continue until the salt residue is exhausted or the corroded surface is consumed.