Project Overview:
PCA Ground Engineering was engaged by Hutchinson Builders to design and construct a foundation and slope stability system for a challenging beachfront site at 71 Seaview Terrace, Sunshine Beach. The steeply sloped block, located beside Noosa National Park and accessible only via a narrow private laneway, posed multiple constraints. Traditional CFA and screw piling methods were deemed unviable due to the site’s soft dune sand, weathered rock profile, and restricted access. PCA developed a hybrid solution using grout-injected micropiles and a custom-engineered GroutShore™ wall system—delivering structural support, earth retention, and slope stability with minimal impact on the environment and community.
Challenges
- Limited access via narrow private laneway
- Environmental constraints from adjacent Noosa National Park
- Steep slope with complex geotechnical conditions
- Deep dune sand overlying highly weathered rock
- Original design requiring large equipment unsuitable for the site
Innovative Solution
PCA implemented a tailored system that included:
- Grout-injected micropiles for structural and slope support
- High-pressure grout columns integrated with steel verticals
- A 4m-tall GroutShore™ wall dividing the site into three levels
- Load-bearing propped cantilever design constructed pre-excavation
- Use of lightweight equipment with minimal site disruption
- Temporary support during construction that transitions into the permanent retention solution
The GroutShore™ & Micropile Advantage
This project introduced a new approach to propped cantilever contiguous walls by using high-pressure grout injection and micropiles, allowing construction on geotechnically sensitive, restricted-access sites. Advantages included:
- Minimal vibration and environmental impact
- Reduced site traffic—no need for large concrete or steel deliveries
- Pre-excavation installation reduced construction risk
- Compliance with local council and environmental guidelines
- Successful installation in a densely built-up area
Outcome
- Project delivered safely and on schedule
- Enabled development on a highly restricted site
- Provided a permanent, code-compliant earth retention solution
- Set a new precedent for urban slope stability engineering using innovative micropile systems