Newcomen Street is supported by a combination of old brick and stone masonry retaining walls, the earliest of which dates from around 1840. The existing masonry retaining walls were damaged by a severe storm that occurred in June 2007. In addition, it has been found that the walls do not comply with current Australian Standards.

The project involves the construction of a new mass gravity retaining wall formed with interlocking jet-grouted columns of soil. This new mass gravity retaining wall is to relieve all earth pressure and surcharge live loads from the existing masonry retaining walls.

Outlined below are the major items completed by Haslin:

• Design and installation of a propping / scaffolding system to complete the jet grouting works
• Demolition of a portion of the existing brick fence and wall
• Design and construct a jet grouting system behind the retaining wall in Newcomen Street
• Earthworks necessary for construction of jet grouting and retaining wall remediation, including management of contaminated material
• Supply and place anchor bolts including wale beams, plates etc in the existing wall
• Construction of approx 200m of new reinforced concrete retaining wall sections including footings, walls, face brickwork and render
• Re-pointing of sandstone block work and brickwork
• Construct new road pavement including stone kerb, concrete gutter, islands, base, sub base, asphalt, bollards, line marking etc
• Removal, storage and re-instatement of 7 date palm trees

Project issues/challenges:

• Management of contaminated material
• Performing works in heritage environment (some existing works onsite date back to the 1840’s so Haslin has worked closely with the heritage officer during construction)
• Difficult access issues (very narrow, small site and working at heights)