This article was originally published in LG Magazine and the Water Journal.

Contech has released a new and superior product called Sewper Liner, which protects concrete wastewater assets from biogenic corrosion better, faster, and with less prep work and downtime than any other liner on the market.

The problems of the country’s aging water infrastructure are well known, and the costs of bringing it up to date are staggering. However, solutions that can revitalise old infrastructure to increase its lifespan or ensure a longer life for new infrastructure are a boon for local authorities looking to save money now and in the future.

Most Kiwi water engineers are familiar with Sewper Coat, a spray on liner that repairs and prevents further damage caused by biogenic corrosion in wastewater environments – from large pipes and wet wells to tanks, pump stations, and more.

Sewper Coat has been performing its job well for the past 30 years, repairing and revitalising damaged concrete. However, manufacturer Imerys saw a gap in the market for a product that can be applied to new infrastructure, preventing biogenic corrosion from the outset.

Available through Contech, the exclusive distributor for Imerys in New Zealand, Sewper Liner is a big step forward in lining technology. Contech director Derek Bilby explains:

“The big difference here is being proactive and extending the life of an asset from the start. Sewper Liner provides long-term protection and ensures that the assets we’re building today are going to perform right into the future.”

Contech business development manager Mark Kurtovich says many structures throughout the country have been affected by biogenic corrosion, and it’s very expensive to get it repaired.

“From a sustainability point of view, it’s terrible, because an awful lot of energy and product has to go into fixing it. The time to sort the problem is at construction.”

Recently, Contech demonstrated the application of Sewper Liner to an audience of wastewater engineers, who were very impressed not only with how easy the product was applied, but the lack of constraints in applying it.

They watched as a fine coating was sprayed onto a concrete surface. Unlike Sewper Coat, which goes on at 15-50mm thick, Sewper Liner is applied at a minimum of 6mm.

“The application is very controlled – there’s very little rebound (loss) when it’s being applied – as well as being very quick, making it a lot more economical,” explains Mark.

Biogenic corrosion a serious problem for asset owners when the right conditions are present; driven by temperature and humidity, acidophilic bacteria thrive in the wastewater environment and are capable of destroying up to 25mm of concrete per year.

To prevent biogenic corrosion and to repair minor damage, wastewater concrete infrastructure is typically sprayed with polymer liners, like epoxy, as a form of protection. However, the polymer’s lack of durability means, in some cases, it can fail after only a few years.

Additionally, polymer materials are expensive and hard to use as dry surfaces are required for proper bonding to occur.

“Epoxies require exacting environmental conditions regarding dew point, humidity, and concrete moisture, otherwise it will potentially fail prematurely and then allow the concrete to be exposed to biogenic corrosion.

“They also raise health and safety issues regarding working with inorganic volatile compounds and solvents in confined spaces.”

In contrast, Sewper Coat and Super Liner use a calcium aluminate mortar solution. This cementitious product induces a ‘bacterio-static effect’ which inhibits acid generation at the source. It bonds very well to moist surfaces, does not induce pin holes and provides rock solid structural rehabilitation within a few hours.

Additionally, the Sewper Liner formulation is specifically designed to achieve long-lasting protection on the dry, flat and smooth walls of new concrete assets – no prep work required.

“One of the obvious applications for this is pipes, and it can actually be applied to the mould before the pipe is cast, resulting in a lined pipe,” says Mark. “So if, for example, you’re constructing a large manhole, you can either line it in the factory or apply Sewper Liner using a spinning head which you simply pull up the manhole as it sprays the liner on.”

“If we can proactively protect these structures, quickly and easily, it’s not going to be hugely disruptive in terms of timing of the construction process, and we can really deliver superior protection over the life of that asset,” says Derek.

It is also ideal for remediating lightly damaged assets.

After being applied in a thin layer, it will harden within six hours and be at service strength in 24, says Mark. “This is an important factor in remediation works, as this means the affected pipe is only offline for a day.”

“Sewper Liner is simply a better option. It is cost-effective, easier to apply, significantly longer lasting, and a more sustainable product, all while delivering the same performance.”