Haslin Constructions


The Nepean Tunnel

Sector Water + Wastewater
Completion 2019
Location Pheasant’s Nest, NSW
Client Water NSW
Value $1.2m

This intricate project entailed the Design and Construction of a complex water inlet structure at the mouth of the Nepean Tunnel in Pheasant’s Nest. Lynchpin of the Upper Nepean Scheme, the 7km Nepean Tunnel is a vital link in Sydney’s water supply chain.

The works – completed in a challenging geographical footprint – saw Haslin completing significant structural concreting works atop the existing century-old tunnel, strengthening its roof and fully encapsulating the original headwall. This was followed by delicate rock removal and trimming up of the tunnel entrance in preparation for the gate installation. The Haslin-designed gate is a one-of-a-kind, 4.5 tonne, vertical dual lift / undershot gate capable of withstanding 100 year flood events.

Haslin also undertook significant metalworks; installation of new gratings, balustrades, access ladders and steel members. To ensure remote functionality, Haslin reconfigured the existing wiring, allowing both on-site control and integration with  WaterNSW’s SCADA infrastructure.