Ground engineering excellence

BPC Geotech Engineer Andrew Hills presented to the Young Geotechnical Professionals Conference in Adelaide about the complex temporary works that our team has undertaken on the Bothamley Park trunk sewer upgrade in Porirua. The annual conference is an initiative of the New Zealand Geotechnical Society and the Australian Geomechanics Society.

Andrew described the challenging conditions on the site, an infilled gully with geological complexities including a perched groundwater regime and variable rockhead depth across the excavation footprint. Other constraints included a sensitive sewer line and temporary mud pond located at the top of the batter, restricting traditional methods like sheet piling or benching.

A bored pile wall and observational monitoring system including piezometers was successfully implemented on site during construction using alert and alarm level thresholds, traditional survey, and regular visual checks. Andrew highlighted both the technical aspects of the design and construction process, as well as the importance of adaptive monitoring and intervention strategies in addressing unforeseen challenges during infrastructure projects.