CMW Geosciences was engaged to carry out the geotechnical assessment and design for a pump station on the eastern bank of the Whakatāne River in an area of high seismicity, soft soils, a shallow groundwater table and liquefaction risk.
The client, Whakatāne District Council, was concerned about the effect excavation at the site would have on seepage rates in flood events through the stopbank of the river.
Our Involvement
Our team carried out an assessment of the site’s geotechnical investigation data. This assessment found that ground improvement would be required to mitigate the liquefaction and lateral spread hazards impacting the pump station.
The following ground improvement options were proposed:
- Stone columns
- Rammed Aggregate Piers
- Lattice grid structure (DSM or CFA piles)
Our team also carried out an assessment of the potential for increased seepage and piping caused by potential excavations and flooding on site.
What we achieved
Based on the sustainability principles and local knowledge of the efficacy of stone columns, Rammed Aggregate Piers were selected as the most appropriate option to progress through to detailed design.
Following this project, our CMW Geosciences team carried out similar assessments on behalf of Whakatāne District Council (WDC) for the Ferry Road, Buddle Street and McAlister Street pump stations, and Tarawa Creek pump station for Opotiki District Council.
We have used these projects to develop a strong relationship with both the client (Whakatāne District Council) and civil engineer WMC Consulting.