Mill Edge Lane Development

Client: Milledge (TAS) Pty Ltd
Architect: LXN Architecture
Builder: Fairbrother
Structural & Civil Engineer: Collective Consulting
Key Personnel: Alan Leake (Principal Structural Engineer), Darren Bosveld (Structural Draftsman)
Construction Date: 2018
Value: $8 million

Three-Story Commercial Office in Launceston's Industrial Heritage Precinct

Milledge (TAS) Pty Ltd engaged Collective to provide civil and structural engineering services for the Milledge Lane Development, a three-story commercial office building on the outskirts of Launceston's Central Business District. The architectural design pays homage to Launceston's industrial heritage, situated near notable landmarks including the former gasworks, gasometer, and Boag's Brewery.

The area is characterised by soft river estuary soils, presenting significant geotechnical challenges for foundation design. The project required bored pile foundations extending approximately 10 metres into soft rock to support a brittle masonry façade on unstable soils. Collective provided feasibility studies, structural concept designs, detailed designs, and construction administration throughout the project lifecycle.

Engineering Challenges

• Soft Soil Foundations: The river estuary soils required bored pile foundations extending 10 metres into soft rock to support the brittle masonry façade. Ground floor utilised stiffened void-form slab-on-grade construction while first and second floors employed in-situ reinforced concrete beams and Bondek slabs with corbelled edge beams supporting façade brickwork.
• Cantilever Beam Defects: During construction, removal of formwork revealed inadequate compaction near large steel reinforcements, resulting in significant honeycombing and voids in cantilever beams. This required immediate engineering assessment and remediation.
• Fire Safety Requirements: Precast concrete walls functioned as firewalls, requiring careful detailing to maintain structural and fire-rated performance.
• Underground Services Coordination: Civil engineering design integrated with ongoing Cimitiere Street upgrades, requiring meticulous coordination of underground services within this historical industrial precinct.
• Geotechnical Supervision: Bored piers required supervision by geotechnical engineers and monitoring by Collective's design team, with pre-pour inspections ensuring compliance with reinforcement and structural design intent.

Structural and Civil Solutions

The structural design incorporated bored pile foundations, in-situ reinforced concrete beams, Bondek suspended slabs, and precast concrete firewall elements. The ground floor slab-on-grade provided economical foundation support while upper levels achieved open-plan commercial functionality.

Civil works included detailed design and documentation for the new parking facility and coordination with Cimitiere Street infrastructure upgrades. This required careful integration of underground services within the historically significant industrial precinct.

Defect Rectification and Engineering Response

The discovery of honeycombing and voids in cantilever beams triggered an immediate engineering response. Collective collaborated with Fairbrother, the principal contractor, to conduct concrete scanning and assess the integrity of concrete surrounding cantilevered beams. The majority of the structure was found sound, with limited areas requiring remediation.

Rectification measures included:

• Drilling bleed holes and applying regrouting techniques
• Specialised bonding agents and repair mortars ensuring overall structural integrity
• Comprehensive testing and investigations with transparent client communication

All remediation was performed with the client fully informed, demonstrating Collective's commitment to defect identification, transparent communication, and collaborative problem-solving regardless of complexity.

Commitment to Quality and Collaboration

Collective's operational methodology prioritises collaboration and proactive defect management. While most projects progress smoothly, construction complexities occasionally produce defects. Collective's system of checks and balances, alongside thorough inspection processes, enables prompt defect identification and resolution through contractor partnership.

This project exemplifies Collective's commitment to ensuring all engineering components meet National Construction Code standards and established design principles, safeguarding public safety and delivering high-quality, fit-for-purpose outcomes. The minor rectifications undertaken, while potentially concerning, exemplify the human element in construction with proactive and collaborative approaches achieving better outcomes than neglecting defect disclosure.

Key Outcomes

• Three-story commercial office successfully completed in Launceston's industrial heritage precinct.
• Bored pile foundation system overcoming soft river estuary soil challenges.
• Proactive defect identification and collaborative rectification preserving structural integrity.
• Transparent client communication throughout construction defect resolution process.
• Integration of modern commercial building with historical industrial context.
• Demonstration of engineering commitment to quality assurance and public safety.