Each year in the United States, as much as 10 billion gallons of raw sewage is thought to be released into surface water due to sanitary sewer overflows caused by blocked or broken pipes, according to the U.S. Environmental Protection Agency (EPA). A typical example was reported this summer when a two-mile stretch of beach near Marina del Rey in southern California was closed when blockage in a sewer main released about 500,000 gallons of raw sewage into a storm drain.

With more than 16,000 wastewater plants and 600,000 miles of sewers serving 190 million people, the EPA has raised concerns over the nation’s aging wastewater infrastructure, noting that many systems are reaching the end of their design lives. In order to replace existing wastewater systems and build new ones, the EPA has determined that a national investment of $390 billion will be required over the next 20 years. “We cannot ignore the arriving wave of infrastructure rehabilitation and replacement we will face over the next several decades,” the EPA’s Web site explained. “To do so would put the achievements of the last 30-40 years and our nation’s waters and public health at risk.”

The replacement of wastewater infrastructure represents a “tremendous opportunity,” according to Erica Schoenberger, professor of geography and environmental engineering at the Johns Hopkins University Whiting School of Engineering in Baltimore, Maryland. “If you are going to overhaul stuff that is about to fall apart, that is the perfect time to invest in future technologies,” Schoenberger explained in an article for Johns Hopkins Engineering Magazine.

Several examples of new technology for wastewater infrastructure were introduced at the recent Water Environment Federation’s Technical Exhibition and Conference (WEFTEC) in New Orleans. Among the new products attracting attention was a 100 percent solids, ceramic-modified polyamine epoxy liner – Series 431 Perma-Shield PL – that was developed by Tnemec specifically for steel and ductile iron pipe and fittings in severe wastewater environments.

A section of ductile iron pipe (DIP) lined with Series 431 attracted a steady influx of visitors to Tnemec’s booth, noted Caleb Parker, who is with Tnemec’s sales department. “The large pipe in the booth was a great showcase for Series 431,” Parker observed. “Many of the visitors were interested in our testing that demonstrates Series 431’s low permeation to H₂S gas and acid attack, and its resistance to abrasion and chemicals compared to older lining technology for ductile iron pipe.”

Another point of interest was the liner’s light green gloss finish, which makes visual inspections easier than black-colored coatings containing coal tar. At 90 grams per litre volatile organic compounds (VOCs), Series 431 complies with the most stringent air quality standards and has zero hazardous air pollutants (HAPs), which allows for unrestricted shop application. “The availability of this technology is well-timed in light of the EPA’s new policy to increase the sustainability of future water and wastewater infrastructure projects, which was announced at the WEFTEC show,” Parker said.

Also on display at WEFTEC was the user-friendly touch-up kit in a tube configuration that allows Series 431 to be applied using a caulking gun for small repairs and holidays. “Tnemec specifies holiday testing per NACE SP0188 at 100 to 125 volts per mil, while other DIP coating manufacturers recommend lower voltages in the 60 to 70 volts per mil range,” Parker added.

This year’s WEFTEC show, which is North America’s largest water quality event, attracted 17,515 water professionals, nearly 1,000 exhibitors and set a record with 300,000 net square feet of exhibition booth space, which exceeded the previous record set in Chicago in 2008.

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