One of the biggest recent trends in sewer installations has been the move from concrete pipes and maintenance structures to those made from ultra-strong polypropylene.
Not only are such systems lighter, cheaper and faster to lay, but innovative technologies mean they last just as long or even longer than those made from concrete.
“Concrete has always been the conventional material for sewer maintenance structures poured in situ,” said Iplex Senior Sales Engineer Don Tasevski, a well-known industry figure for 35 years.
“But increasingly, engineers have been recognising that heavy-duty plastic alternatives are affordable, reliable and long-lasting so they make more sense.”
Another significant advantage they hold is their ability to meet the environmental, technical and economic demands of water authorities for water-tight, corrosion proof, stable and durable systems.
In recent years, Sydney Water, SA Water, Unity Water in Queensland, MRWA and many others have chosen Iplex EZIpit, an industry-leading polypropylene inspection and maintenance structure for buried gravity sewer applications.
Its three components — base, single wall corrugated riser and cover for either trafficable or non-trafficable areas — are easy to install, lightweight and connect seamlessly with the company’s range of PVC and PP sewer pipes.
“You simply cut the riser to the correct length, and you’re done,” Tasevski said. “It can be fitted in under an hour whereas, with concrete, the process can take several days and leaving an open excavation.”
Saving time and money
Such a time saving was one of the reasons that Hall Contracting turned to the EZIpit when constructing the 39 business units at Beerwah Industrial Park, a 30-minute drive south west of the Sunshine Coast in Queensland.
Using concrete would have meant leaving the maintenance holes open for an extended period, complicating the project and requiring skilled concreters to build the benching in the base.
The EZIpit, by contrast, eliminated the waiting time and the dangers associated with leaving such deep excavations open overnight.
“The concrete manhole would have taken four days to complete,” Project Manager Richard Hooper noted. “The EZIpit was literally done in an hour. We will be installing these pits in our projects wherever we can.”
EZIpit also has a high resistance to sulphuric acid corrosion, surface wear and abrasion, while its flat base makes it easy to position in the trench. In fact, the design of the channel eliminates the need for a vertical fall across the base and its smooth surfaces provide a superior hydraulic flow performance to concrete.
“Engineers love the fact it doesn’t need much of a gradient, which means they don’t have to dig down as far and you save a considerable amount of time,” Tasevski said. “Concrete usually requires a fall.”
It’s the only sewer maintenance structure with fully integrated swivel sockets in the base. They rotate up to 7.5 degrees in any direction, permitting adjustments in the trench allowing narrower trench alignments as well as reduced excavation.
Watertight and strong
The flexible riser copes with ground movement and traffic loads without cracking and remains completely watertight to depths of six metres. Unlike concrete, it is also resistant to tree root intrusion, a common and expensive maintenance problem for sewers.
EZIpit is available in three sizes:
- DN425 maintenance shafts
- DN600 maintenance chambers
- DN1000 maintenance holes
The first two provide access for cleaning and inspection equipment such as CCTV cameras, and jet nozzles, while the third is big enough to allow safe entry by qualified and approved personnel.
“It’s a premium product and gaining a lot of traction in the market because engineers know it makes long-term surveying and upkeep easy, and they can completely rely on its performance,” Tasevski said.
“It also makes a big difference that our sales team are engineers so they can quickly understand the specific needs of every customer.”