• Client: Shared Services Procurement and EDD
• Value: $15.6M
• Completion date: February 2016

Overview

The Molonglo Link Bridge and associated trunk sewer project is located approximately within the new residential development area of the Molonglo Valley. The bridge carries a new trunk gravity sewer across the river and links into the existing main to the Lower Molonglo Sewage Treatment Works. The bridge is also used for pedestrian and cycleway access.

The project represents a construction high point in the history of Woden Contractors. Built in partnership with Civil Bridge & Wharf (CBW), the 243m bridge is the longest ever built in the ACT, and at 30m above the Molonglo River, posed the significant engineering challenges of incrementally launched construction and environmental management in a sensitive area.

The associated 2,992m of trunk sewer, at depths up to 5.5m and ranging in diameters from 300mm to 600mm, was all laid to a minimum grade of 0.4%. It was required to be constructed each side of the bridge separately, as an early project milestone, with the infill section across the structure being attached to the bridge just before each 35m section of box girder was launched. The need to vary from the traditional approach of commencing at the low point of a sewer and laying towards the upstream direction posed significant survey and construction control issues in achieving the flat grades and tolerances required by the client.