Fibreglass Future – GRP Maintenance Structures on Large Gravity Sewers

Abstract

Maintenance structures (or “manholes”) play an essential role in helping keep sewerage systems running. They enable the owner of the sewer to access, inspect and maintain a sewer throughout its asset life. Over the past 10 years, Melbourne water retailer Yarra Valley Water has embraced the use of glass-reinforced plastic (GRP) maintenance structures on its larger branch and main sewers. These differ from conventional concrete manholes in terms of how they are constructed, maintained, and operated safely. This paper explores the use of GRP manholes through the lens of Yarra Valley Water’s Lockerbie Main Sewer Project, constructed by Ventia-Jaydo Joint Venture. The paper explores the key points of difference and considerations for designers, manufacturers, contractors, and asset owners when considering GRP manholes in the design of a sewer system.