Australian National Botanic Gardens

Canberra ACT


The Australian National Botanical Gardens (ANBG) constructed the new Ian Potter Conservatory Building during 2021 and 2022. The new conservatory building required the excavation of approximately three stories for basement works in deep colluvial soil, on the side slopes of Black Mountain, above Canberra City. The setting for investigation and construction was particularly sensitive, being Australia’s national botanical gardens facility.


D&N has worked closely with the ANBG for investigations during 2017 and 2018. D&N carried out the geotechnical investigation and design recommendations for the works. Subsequently, the contractor for the works, Project Coordination Pty Ltd commissioned D&N in 2021 for construction stage assistance, to manage challenging ground conditions and dewatering concerns. D&N further assisted Project Coordination with temporary works design for construction stage works, including crane lifts and dewatering.


Significant wet seasons occurred between the time of investigation and the time of construction. As a result, considerable groundwater inflows into the excavation works were encountered once the basement excavations were opened. D&N assisted Project Coordination with consideration of the latent conditions, and further designed and oversaw the installation of seepage cutoff works. Following the cutoff works, inflows into the works reduced significantly and works resumed with minimal delays.

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