Metrosports — Jet Grouting Under Live Structure

The Christchurch Metrosports facility — a major aquatics and indoor sports complex — required specialist ground improvement to address ground conditions that emerged during construction. The challenge was exceptional: works needed to be carried out beneath and immediately adjacent to a partially completed structure, with zero tolerance for structural disturbance or column installation deviation.

GSI was engaged by CPB and Aurecon to design and deliver 107 jet grout columns to 15 m depth. The jet grouting approach was selected for its ability to create high-strength, controlled-diameter soilcrete columns through the varied Christchurch alluvial soils. The team surveyed the existing structure beforehand and established trigger points to detect any movement during works. Quality assurance included daily mud balance testing of the grout mix, core sampling, and cross-hole shear wave velocity testing of completed columns.

All 107 jet grout columns were successfully installed to specification, providing the ground improvement required to support the completed Metrosports structure. The project was delivered without structural incidents, within programme, and to the full satisfaction of CPB and Aurecon.

Metrosports has become a reference case for specialist jet grouting in Christchurch and across New Zealand — demonstrating the precision required when ground improvement must be delivered beneath partially completed structures in post-earthquake urban environments.