GRP Manhole for Trunk Sewer Upgrade – Case Study

Clover GRP Manhole Solution

In 2015, Clover Pipelines’ GRP Manhole solution was selected by Gosford City Council for a critical DN1100 Trunk sewer main replacement. The team was chosen due to our flexibility in developing customised solutions for specific projects, and the innovative design and long-term durability of the GRP manhole product.

The job required problem-solving, not just product supply.

For this particular project in Woy Woy, New South Wales, our team designed a lean and cost-effective solution with specialised functionality to meet site-specific criteria.


Solution highlights

  • We designed three custom GRP manholes to suit a new DN1100 GRP gravity sewer main.
  • A DN1500 GRP access riser with fully benched and deflected chamber and access platform with multipart riser to allow for staged installation.
  • Flanged rising main connection and anti-buoyancy considerations incorporated into shaft design.
  • Laminated inlet and outlets were designed to match the existing reinforced concrete sewer main diameter.
  • Superlit GRP coupling system with full face EPDM seal for guaranteed seal integrity.
  • Long life, corrosion resistant material does not require sealing or protective coating enabling for faster implementation and low-fuss maintenance.

With lightweight design features and integrated lifting points for reduced installation time, the GRP solution perfectly accommodated the challenging deadlines of the Gosford Council project. It also helped minimise a range of general ongoing costs and difficulties associated with the sewer upgrade.

Built from resilient and corrosion–resistant materials, the GRP manhole requires minimal ongoing maintenance. Additionally, considered design eliminates the need for welding, ensuring the product is simple and far more efficient to install. The Gosford project provides another great example of Clover’s problem-solving capability, and our flexible approach to developing custom products with site-specific functionality.