Environmental Engineering Reference
In-Depth Information
• Epoxy-based coatings
• Powdered epoxy coatings
• Vitreous coatings such as glass fused to steel
• Cement coatings
• Polyurethane
• Polymer modiied asphaltic membrane
• Galvanized
• Lubricant
• Asphaltic
• Vinyl ester
The following actions or conditions can enhance the life of coating systems:
• Proper surface preparation prior to coating application
• High quality of the coating (paint)
• Skilled workmanship
• Drying and aging of the coating
• Proper maintenance through periodic inspection; spot, partial, or
complete removal of old paint; and repainting as necessary
Cathodic protection
(an electrical system) is often used in preserving the
integrity and material condition of potable water storage tanks by prevent-
ing the corrosion and pitting of steel and iron surfaces in contact with water.
By passing a low-voltage current through a liquid or soil in contact with
the metal in such a manner that the external electromotive force renders
that metal structure cathodic, corrosion is transferred to auxiliary sacrifi-
cial anodic parts. Intended to corrode rather than the water storage facility
corroding, sacrificial anodes are typically made of magnesium or zinc and
must be replaced periodically as they are used up. Typically, the anodes
are suspended from the tank roof in warm climates or are submerged in
cold climates. The life of the sacrificial anode is about 10 years. Note that
cathodic protection is not a substitute for the use of a proper interior coat-
ing system.
Water Quality Monitoring at Storage Facilities
Water stored in potable water storage facilities must be routinely and prop-
erly monitored. Monitoring includes determining chlorine residual levels,
t u r b i d it y, color, coliform analysis, decimal dilution, most probable number
(MPN) analysis, and taste and odor analysis.
