Papamoa Interchange Menard CAPs, Tauranga, New Zealand Ground Improvement
Client: Tauranga City Council
Engineer: CMW Geoscience
General Contractor: HEB Construction Limited
Construction Period: July 2024 – December 2025
Ground Improvement: 9,000 lm CAP columns
Project Overview
The Papamoa Interchange Project is a key infrastructure upgrade in Tauranga, designed to improve traffic flow and connectivity across the Tauranga Eastern Link (TEL). The project involves the construction of a 34.2‑meter span, 5‑lane bridge over the TEL carriageway, supported by 900 mm diameter concrete stems and 9‑meter high mechanically stabilized earth (MSE) retaining walls at each abutment.
North of the overbridge, Sands Avenue and Te Okuroa Drive are being extended over undulating dune terrain, requiring significant cut and fill earthworks. Given the challenging ground conditions, specialized ground improvement methods were essential to ensure safety, performance, and resilience.
Ground Conditions
Site investigations revealed a complex geotechnical profile, including::
• Predominantly granular sands from Holocene‑aged dunes and fluvial deposits
• Interbedded silts and organic silt layers at varying depths
• Fibrous peat and soft organic silts in low‑lying areas across the southern portion of the site
These soft soils posed risks of liquefaction, settlement, and slope instability during seismic events, making deep ground improvement a critical component of the design.
Ground Improvement Solution
To ensure long‑term stability and compliance with the NZTA Bridge Manual, Menard Oceania implemented a deep ground improvement solution beneath the bridge abutments and road embankments:
• To ensure long‑term stability and compliance with the NZTA Bridge Manual, Menard Oceania implemented a deep ground improvement solution beneath the bridge abutments and road embankments:
• Installed on 1.8 m triangular spacing
• Total of 9,000 m of CAP columns completed in 2024 to increase soil bearing capacity and enhance the performance of the embankments.
This approach mitigates liquefaction settlements and improves global stability under the DCLS seismic event.
Post‑installation Cone Penetration Testing (CPT) verified that the ground improvement met all design criteria, ensuring a safe and durable foundation for the new interchange.
Project Benefits
• Seismic resilience: Reduced liquefaction and settlement risks
• Enhanced stability: Strengthened foundations for bridge abutments and embankments
• Efficient construction: Allowed safe progression of major earthworks over soft ground
• Long‑term connectivity: Supports Tauranga’s growing transport network with a durable solution
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