Filter Ponds and Clarifier Tank at Glen Innes Water Treatment Plant Re-lined

Mainmark delivered a long-term asset preservation solution for a fresh water treatment plant at Glen Innes, New South Wales, with the rectification of linings for three filter ponds and a clarifier tank.

Glen Innes sources water from the Beardy Waters, located to the east of the town. This water is treated to meet Australian Drinking Water standards by a conventional treatment plant, constructed in 1982, managed by Glen Innes Severn Council. The treatment process involves chlorine disinfection, and provides service via approximately 90km of water main.

Lining systems break down over time as air and moisture permeate through to the substrate. This process can be measured and is commonly referred to as a material’s moisture or water vapour transfer rate (MVTR). Crucially, once a liner has been permeated, the surface adhesion is undermined and chemical reactions beneath the liner attack the substrate itself and start ageing the liner from the under-side.

To ensure the integrity of the three filter ponds and clarifier tank into the future, Mainmark applied a pure polyurea coating, creating a waterproof protective membrane to seal the concrete.

Manufactured in Australia under ISO 9001, the polyurea is certified to AS/NZS 4020- 2005 ‘Testing of products for use in contact with Drinking Water’ when exposed at area to volume ratios of 5,000mm2 /L.

Mainmark first prepared the three filter ponds and a clarifier tank by applying a specialty solution to produce a uniform surface. The surfaces were then primed with a two-part, epoxy system, designed to improve adhesion of the polyurea. This preparation process also creates outstanding water resistance, ideal for polyurea applications in permanent immersion.

The result of the project was the long-term preservation of the ponds and tanks. The drinking water-safe and chemical-resistant polyurea coating is expected to provide an effective lining for at least 20 years.

The primary project objective was to re-line the filter ponds and clarifier tank to seal and protect the existing concrete substrate. By preserving the integrity of the utility, the facility could continue to provide a minimum of 20+ years’ service to the region.

Mainmark was required to supply all materials, equipment and trained personnel to complete the work quickly and cost effectively, while causing minimal disruption to the daily operations of the water treatment plant.

Importantly, the chosen solution needed to be suitable for use with drinking water.

Work began with thorough preparation of the surfaces to be treated, which is paramount to the successful application of any concrete lining system. This included high-pressure cleaning with fresh water to totally remove the existing liner and profile the surface to remove any laitance or aggregate fines.

A fill product was then applied to the concrete substrate in order to present a uniform and aesthetically pleasing finish.

The prepared substrate was brushed with a specialty two-part epoxy priming system designed to protect concrete against corrosion and chemical attack. The system offers low viscosity (with 240 CPs), has a fast all-season cure (at temperatures as low as 0°C), and is capable of adhering strongly to damp, green and oily concrete.

Finally, the polyurea membrane was applied via a high-pressure spray process. The pure polyurea, two-component, rapid-set elastomer is engineered to provide waterproofing and a protective coating in one. The solvent free product gels in seconds to form a seamless lining with a vice-like grip to most prepared surfaces.

The polyurea coating selected by Mainmark is highly suitable for use in water treatment plants. The lining is abrasion, impact and corrosion resistant, ensuring long service life, with high chemical resistance to acids, alkali and bleach, as well as water treatment chemicals. Its high flexural strength also prevents the membrane from cracking and flaking.

Glen Innes was experiencing very cool weather at the time the work was being completed. The polyurea was one of the few products suitable for application in colder conditions, with the ability to be applied in temperatures below 0°C without requiring the product to be pre-heated.

The client was extremely pleased with the dedication and perseverance that Mainmark demonstrated in delivering the works to the highest of standards, in challenging conditions, with minimal disruption to the plant’s operations.

Glen Innes Severn Council representatives commented, “Mainmark was very professional while working on site in Glen Innes. The quality of their workmanship and products became more and more evident as the project progressed. We’re extremely happy with the end result”.