Waikato District Council identified a failing wastewater manhole with structural damage that was in urgent need of replacement. As the damage to the concrete manhole was caused by the elevated Hydrogen Sulphide gases present within the wastewater network, a non-concrete solution had to be found.
The condition of the manhole made it a high risk of failure and therefore a high priority replacement was needed. As this manhole discharges up to 30L/s of wastewater (approximately 85% of Raglan’s wastewater) and its proximity to the Raglan Harbour, significant planning was required to mitigate any general or environmental risks this project could pose.
This planning process determined that the best solution was going to be a Smartstream PE Manhole created as a replica of the existing deteriorated concrete one.
The Smartstream PE Manhole was selected for this project due to many whole-of-life benefits such as:
- Polyethylene does not suffer from internal and external gas attacks (H2S protection).
- Ease of retrofitting into an existing network which allowed essential utilities to remain in service.
- Elimination of root intrusion and ground water ingress through PE welded joints.
- The prefabricated design delivers significant time and cost savings during installation.
- Durable and light weight, reducing transport and handling costs.
- Along with hydraulic benefits the spherical base allows multiple inlets to be attached at any angle between 45° and 315°, with allowance of varying and specific grades.
- As it is Polyethylene and prefabricated, there are no delays waiting for epoxy to cure.
The Smartstream PE Manhole was the first of its type to be installed within the Waikato District network. The smooth and successful installation of this PE manhole has highlighted the benefits and importance of selecting the right product for any particular application.