Problem solving is something that Wavin has been doing for decades. Our innovations in technology are solutions to challenges faced by our customers, our communities and our municipalities. So, when we observed how frost damage from extreme winter weather caused pavements to swell and crack, sinking the manholes, we knew how to mitigate the problem.
After the Winter, when snow and ice have melted, it's time to investigate how much damage father Winter has done to our streets. Asphalt pavements have a tendency to expand and contract with extreme weather. In wintertime, but also in the summer. And the same goes for the ground underneath. In extremely cold weather, when water gets into the ground beneath the pavement, it can freeze into ice which, in turn, will lift the road’s surface. When this happens, we begin to see potholes, pavement cracks and sewer manholes sinking below street level. A process that is called frostheaving, perfectly explained in this video.
Although some of this asphalt erosion does, in fact, settle down after the thaw, most of it causes moderate-to-severe road damage. A reversed problem occurs when the road settles over time. The road surface slowly lowers, while the inflexible systems underneath roads, stay where they are. In both situations this results in costly recurrent repairs. Municipalities bear the financial burden of road maintenance and repair, while the city dwellers must suffer the cost of damage to their cars (from street cracks and potholes) and the inconvenience of traffic congestion and delays (from road construction).
Picture by Michael Gil
No more bumps in the road with corrugated shafts
As the saying goes, “The road to hell is paved with good intentions.” In this case, “hell” is a bumpy, crack-filled asphalt road. And, unfortunately, good intentions are not enough. But Wavin has figured out how to smooth away our winter woes. The corrugated shaft pipes that we use in our manholes and inspection chambers are structured so that the width, depth and angle of the pipe’s valleys (or notches) accommodate the soil conditions – allowing the soil to get in the free spaces at standard compaction conditions and with different backfill soils. It’s a very “contractor-friendly” structure: a correctly installed, durable inspection chamber – achieved in the quickest possible way! Here are some of the key advantages to using corrugated shaft pipes:
- They allow us to obtain a durable and indestructible riser/ground system
- They overcome the buoyancy of manhole/inspection chamber at high groundwater levels
- They provide wide support for side connections to the shaft, in the form of “in situ” fittings
- They respond flexibly to dynamic ground behaviour (i.e. its upheaval and settlement) and thereby provide a variable height for the manhole/inspection chamber, depending on:
- ground settlement in an excavation over the period of its consolidation after work execution,
- periodic ground volume changes due to freezing and defrosting of ground water
- and unexpected force distribution (eg. in mining operation areas).
Breakthrough sewer technology
A corrugated shaft pipe is nothing without its “missing link” – the manhole and/or inspection chamber. Did you know that Wavin produced the World’s First industrial manufactured plastic manholes and chambers? Corrugated shaft pipes are utilised for both manholes, the systems used for real man-access (>800mm), as well as for our smaller inspection chambers (315-600mm). Since Wavin Tegra manholes are approximately 90% lighter than the cumbersome concrete manholes, they are much easier to handle and install. Additionally, a nearly step-less height adjustment can be made to the corrugated shaft pipe, to adapt either the manhole or inspection chamber to the required installation depth. The advanced design of the rib structure and shape of the Wavin Tegra’s cone gives the required strength and stability against heavy traffic load. Wavin's manholes and inspection chambers are a contractor’s dream: easy to install, easy to access, versatile and flexible. And above all – durable. An ideal solution for public sewer systems.
So when it comes to smoothing out the bumps in the road, our corrugated plastic shaft pipes, manholes and inspection chambers will withstand whatever weather challenge Mother Nature throws our way. And as for the municipalites and their citizens: the end of winter will no longer mean the beginning of the road construction season. It will simply mean the beginning of yet another beautiful season – Spring.
For more information on our piping systems and manholes/inspection chambers, please contact your local Wavin office.