Use of fibreglass (or glass-reinforced plastic, GRP) is becoming more widespread in wastewater conveyance. Particularly in the case of GRP submersible pump stations, there is potential to provide significant benefits in corrosion resistance, reduced construction times, less extensive and safer site works and overall project cost savings. By fabricating the structures in a factory environment and delivering near-complete units to site, “plugand-play” installations are not just a pipe dream.
This paper provides two case studies of GRP pump stations in sewer networks within Marlborough. In one, a GRP pump station has replaced an existing concrete pump station conveying corrosive winery wastewater. It provided the secondary benefits of requiring a simple, yet seismically-resilient, foundation and delivery to meet a tight commissioning deadline based on the grape harvest. The project was completed early and under-budget. In the other, preliminary design of an upgrade to the Picton sewerage system had proposed reinforced concrete structures built-in situ for the pump stations. Subsequently, with confirmed reduced flows, and accounting for post-earthquake learnings from Christchurch, the design was re-visited. This generated a radical solution, incorporating GRP pump stations. A triple pump station at the terminal site has been replaced with three individual GRP units within the same footprint as the originally-proposed concrete structure. At another, the site footprint has been much reduced, providing less visual impact and disruption to neighbours. Capital savings of over $1Million have been estimated, while reducing the construction programme by months.