Client name: Van Vugt Brothers Limited

Duration: April 2014 – June 2014

Location: Piako Road, Hamilton, New Zealand 

Coffey’s geotechnical investigation analysis determined the most cost effective foundation design solution to reduce the risk of failure and ensure the long term viability of the structure.

Designing foundations for effluent tank in challenging soil conditions   

Our client needed to assess foundation construction design requirements to support a 3.5 million litre capacity effluent tank to support their building consent application.

Testing and logging of the subsoil revealed challenging soil conditions consisting of soft peat to 1.7m below ground level. This was underlain by a narrow clay layer and then sand. Groundwater was encountered below the clay layer, adding to the project’s complexity. Additional liquefaction analysis assessed the suitability of the foundation design in response to an extreme event. Should any undermining of the deeper subsoils occur this could lead to different rates of settlement, leading to structural failure.

Analysis of geotechnical data and tank design parameters

We analysed the geotechnical data in combination with the tank design parameters. This showed the ground conditions would be susceptible to settlement under heavy loads, and a detailed engineering design was required.

We gave our client a range of design options using different methodologies to ensure they could make an informed selection.

Throughout the course of the foundation construction, we provided inspections and advice to ensure design specifications were met and consent would be granted.

Achieving Building Consent with cost-effective perimeter foundation design

A perimeter foundation design to support the areas of maximum loading was determined to be the best solution. Existing peat was removed and replaced with compacted brown rock to limit the amount of earthworks reduce overall costs.

Following the acceptance of the building consent, we provided construction inspections to deliver a Producer Statement certifying the construction works.