Ground Investigation In The Sydney CBD — A More Sustainable Model For The Future

Below Sydney’s central business district (CBD) lies a complex network of transport and service tunnels competing for space with building basements and confined by changes in topography. Although the geological setting is well understood and documented, potentially millions of dollars are spent each year on new ground investigations. Why?

Over the last 50 years, NSW Government departments have spent millions of dollars on substantial engineering and geotechnical site investigations within the Sydney CBD and are estimated to have drilled thousands of boreholes.

The majority of existing geotechnical information was collected by government departments and geotechnical consultancies and stored in libraries or archived. Over time this data may become misplaced or in many cases disposed of. There are many government departments and consultancies that preserve data in systematic electronic GIS type databases. Indeed, if the basic information was attributed (e.g. grid coordinates, borehole No., Department, and Project No. etc.) the stored data could be assessed quickly to determine if any data is located within a project area by interrogating a central GIS database (or GIS web service) and therefore retrieved from the relevant storage achieve or geotechnical consultant at minimal cost. The NSW Government is planning on making it mandatory to apply for permits to drill, but also to record information from any borehole that encounters groundwater or potentially water bearing rocks. Permits and recording of boreholes is also the case within mining and mineral exploration in NSW. It is therefore envisaged that much of the geotechnical investigation data produced across the Sydney CBD could be centrally stored in a GIS database. A data model based on the British Geological Survey – National Geoscience Data Centre model is proposed to more efficiently store large amounts of geotechnical data. Access to this information could then be provided through a secure, GIS-based Internet web portal. In many cases, planning for new projects could rely heavily on accessing existing data through this single point-of-truth database and over time, new geotechnical models could be added to further develop an evolving 3-D geological model of the Sydney CBD and other key locations.