WASTEWATER and sewage contain contaminants that must be removed before the water can be converted into effluent that’s fit to be returned to the water cycle or be reclaimed for other applications, in an environmentally compliant manner. Wastewater treatment plants play an important role in this process and High-Density Polyethylene (HDPE) lined pipes from Rocla are a preferred pipe option for water treatment processes.
“Rocla’s HDPE lined pipes offer the advantages of a conventional concrete pipe as well as a plastic pipe in that it is a rigid pipe that maintains its shape under load and is inert to acid attack. The pipe joints have a degree of flexibility making them ideal for areas with soil movement or seismic activity. HDPE lined precast pipes do not rust, rot, corrode or leak, hence being a preferred solution to transport water, chemicals, and sewage.
“Due to their resistance to acids, bases, salts, dissolved solids and brine, the HDPE lined pipe offers a lifespan of between 100 years under normal conditions, making them a cost efficient and reliable solution for this critical sector of infrastructure maintenance,” commented Rocla technical executive Muhammad Bodhania.
The HDPE lining used by Rocla in South Africa uses uniformly spaced anchors and has been used for many of the large outfall sewers in this country since 1991.
Rocla says the HDPE lining offers the sewer or wastewater treatment plant owner several advantages, including:
- Its surface is smoother than concrete, and therefore a pipe with a smaller internal diameter can be used. Alternatively, the same diameter can be used at a flatter gradient.
The long-term pullout strength of the lining anchors is able to cope with a ground water pressure in excess of 10 m. If required, the HDPE lining can be welded together at the joints by applying a bead of HDPE to make the lining continuous and create a water- and gas-tight joint. - The abrasion resistance of the HDPE is greater than that of concrete.
- Rocla’s concrete pipe with a cast in HDPE lining keeps its shape and is corrosion resistant. It is the best pipe for large diameter gravity pipelines in almost any condition.
Bodhania says: “Our concrete HDPE lined pipes have been selected for sewer and wastewater projects throughout the country. We supplied 780 lengths of 1400 mm diameter Class 75D HDPE lined pipes to the Driftsands Collective Sewer Augmentation in Nelson Mandela Bay; in order to increase its capacity and we manufactured eight pipes per day for the project. We also supplied the manhole rings and cover slabs with internal HDPE liners.”
“The Polokwane Waste Water Treatment Project, an upgrade to an outdated sewage system, installed our HDPE vertical cast pipes. In total we supplied 19 km of pipe. We were selected due to the expertise of our technical support, product quality and delivery scheduling. The Rocla HDPE pipes were viewed as the best solution to waste and stormwater plant projects, a big feather in our cap,” commented Bodhania.
Rocla offers various reinforced concrete pipe ranges for sewer reticulation purposes, these are supplied either with an HDPE lining; or with a sacrificial layer; or with Xypex BIO-SCAN C500 (300mm – 600mm diameter pipes).
“Customers can be confronted with many challenges when planning to develop a new, or upgrade an existing sewage, water treatment or stormwater facility. Challenges such as a realignment of an existing pipe route, installation of new manhole access points, dense rock, deep trenches and delivery difficulties. Our technical team has a reputation for innovative solutions to overcome these issues, and it is a reputation we are proud of,” says Bodhania.