Previously this central Wellington site was occupied by a service station. Now a new 12 storey commercial building is being constructed and will be home to BNZ at 1 Whitmore Street.
The new building is a large, waterfront, modern structure with an innovative design. It is a building at the forefront of the Harbour and will be a key building on the Wellington Skyline. The new building will have a 5 Green Star rating.
ENGEO has provided geotechnical and environmental services for this 12 storey base isolated structure. An approximately one-storey basement has been formed to accommodate the base isolation system below ground level.
Our involvement with 1 Whitmore Street included due diligence support, geotechnical and environmental ground investigations and geotechnical design for the basement excavations and building design, dewatering assessment and environmental monitoring.
ENGEO also represented Newcrest’s interests in overviewing the soil remediation of the former service station by the former leaseholders. Soil contamination was present in areas of the site and required remediation. By excavating out the impacted soil and removing impacted groundwater, a contaminated site in the heart of Wellington, has been rehabilitated and the site repurposed for commercial land use.
Early consultation and open responsive communication with key stakeholders was key to achieving a successful outcome for this project.
The new building structure is founded on 28 x 1.5 m diameter bored piles to a maximum depth of around 60m below ground level. Extensive construction observation and monitoring to ensure that adjacent buildings and infrastructure assets were not impacted during construction. Foundation works were completed on time and as per the program and design without compromising on Health and Safety and quality of work.
The project also involved the excavation of several thousand tonnes of petroleum hydrocarbon impacted soil and disposal off-site. ENGEO completed a waste classification assessment to reduce the amount of spoil being disposed of as contaminated waste. Although this ultimately saved our client money, it also diverted clean soil to be re-used as cover material or to an alternative licensed landfill.
ENGEO completed the site monitoring and management of the contamination remedial works and ensured the works were completed in a manner which minimised the effects of nuisance caused by dust and odour as well as ensuring environmental effects to groundwater and the nearby harbour environment were acceptable.
ENGEO managed stakeholder relationships by offering a large and experienced project team and being available whenever required. The remedial earthworks were due to commence during March 2020, however various challenges arose due to the Covid-19 lockdown during that year. The project was able to progress with multiple project meetings held over video conference during the lockdown and consent applications progressed in this time.
Our environmental team provided oversight of the remedial works and completed a groundwater assessment and dewatering monitoring work. Our team, who are all keen on the outdoors and water pursuits, were fully aware of the cultural and societal importance of water and the need to protect the Harbour from contamination during the works. Working with the appointed dewatering sub-contractors, we assisted in establishing a dewatering design that would include sufficient filtration and settlement at the site to meet the GWRC requirements and not to have a significant effect on the water it was discharged into. The dewatering is almost complete (at the time of writing) and to date there have been no exceedances or complaints from the regulator or public. Significant consultation was held with Greater Wellington Regional Council regarding the proposed dewatering methodologies and potential environmental effects in order to ensure the environment was protected, the adopted dewatering plan was supported by GWRC and the dewatering process ran smoothly.
An in-depth understanding of the ground, seismic performance and our practical approach allowed us to come up with a robust design that met and exceeded the requirements and achieved one of the most resilient buildings on Wellington’s Waterfront.
Lincoln Fraser, a Director of Newcrest, stated in March 2021 that “he was very happy with the service he had received from ENGEO and that the project had gone very well,” saying he “appreciated our efforts and availability in overcoming the challenging ground and land contamination issues’.