A tunnel project in Sydney had issues with a submersible pump not providing the required head. The issue was caused by using a 2" line for a 4" discharge pump and running the line up the tunnel wall by 15 metres and 150 metres horizontally to reach the fish tank.

Running 4" lines was not possible with the setup that they have at the site. We recommended rerouting the line following the incline of the tunnel to reach the fish tank.

When a smaller discharge pipe is used, pump capacity and efficiency are compromised. The pump struggles to push its rated flow rate through the pipe and the increased friction creates back pressure. Despite the ideal choice being 4" lines, a 2" line worked after rerouting. This enabled them to continue using the existing pump onsite, saving on the expenses of purchasing and installing a new pump.