National Corrugated Steel Pipe Assn.
undefinedZinc is used in a myriad of environmentally exposed products as a coating to prevent metal corrosion. Galvanized coating is used as one of several coating options for corrugated steel pipe. More interestingly, zinc is essential to life, playing an important role in biological processes of all living organisms (humans, animals and plants).
Zinc has been commonly referred to as a “healthy metal.” It is the 27th-most-abundant naturally occurring element in the Earth’s crust. As a result, natural cycling through erosion maintains consistent zinc levels in soils and water bodies. Due to its abundance, organisms have developed an essential requirement for zinc and efficiently regulate intake through water/soil and diet.
In addition, the U.S. Environmental Protection Agency (EPA) has established discharge limits for point (wastewater) and non-point (storm water) sources of zinc to protect the environment. However, EPA’s 30-year-old water quality standards for zinc seem conservative and noticeably behind other countries (Canada and European nations, for example) that have adopted the state of the science. In fact, studies have shown that zinc emissions from galvanized steel structures occur intermittently over the lifetime of the product (decades in many applications) and are generally small compared to natural sources. The American Galvanizer’s Assn. has produced a white paper that addresses the misconceptions surrounding this topic.
In humans, zinc bolsters immunity by regulating the body’s production of cells and boosts brain activity and memory via its reaction with other chemicals in the hippocampus. Every cell requires zinc to multiply; thus, zinc is vital during pregnancy. Sadly, nearly a third of the world’s population is at risk of zinc deficiency, primarily due to the lack of zinc in soil and water. Zinc deficiency causes poor fetal development and increases the severity of diarrhea, pneumonia and malaria. Children are especially vulnerable to zinc deficiency, with an estimated 450,000 dying each year as a direct result of too little zinc in their diet.
In summary, zinc, the healthy metal, plays a key role in plant, animal and human health. It is a necessary component of the environment. Zinc also is critical in protecting the infrastructure that contributes to a better quality of life for everyone. The amount of zinc emission that occurs during runoff from galvanized steel structures, culverts and buried bridges is negligible compared to the structure itself and natural occurrences. The temporary addition of zinc minimally alters the naturally occurring background zinc level, keeping it far below the criterion level established by the EPA in the Water Quality Act of 1972 and all its revisions. Hot-dip galvanized steel is ideally suited for use over even the most sensitive waterways and habitats.
The empirical sustainability data of the galvanizing process and the use of galvanized products presents an emphatic statement that the low energy requirement and zero maintenance over the life of a project make it a suitable construction material for bridges, culverts, storm drains, water quality management systems and most other infrastructure elements.
