An independent costing report on underground cabling for the HumeLink project has shown significant discrepancies in Transgrid’s costings which have caused calls for a reassessment ASAP. Yass Valley Council were pursuing the option of under-grounding the works, however, faced pushback due to costing reasons but the new report has found under-grounding would be cheaper long term. In the report by Amplitude, they said the main concerns with the original report are in the costing of the HVDC underground cables.



“Comparing the cost per kilometre presented by GHD for the HVDC underground options with our own estimates and other benchmarks…it is clear that even within the range of accuracy and considering current market cost pressures, the cost per kilometre used by GHD is excessive,” said the report.



“Amplitude’s estimates of the two options presented, based on our own estimates of HVDC converter station costs and bottom up of long distance HVDC underground cable cost and installation in Australia, has resulted in multiples (when compared to the latest reported cost of the HumeLink AC over head line project) of 1.5 times the cost of the 2A-1 AC overhead line option and 1.37 time the cost of the escalated 1C-new AC overhead line option.”



The report took issue with the projects referenced in Transgrid’s estimate, EuroAsia and Harmony Link, and believed it blew up the price estimate. “EuroAsia….is a predominantly subsea cable project, with only 23 km of the 1,208 km cable route using underground cables. The impact on cost of supply and installation is significant for shorter lengths, resulting in very high costs per kilometre,” the report wrote.



“Harmony link, similarly, this is also predominately subsea cable, with only 40 km of the overall 330 km long cable route being underground cable. For the above reasons, it is expected that using these two projects as a cost reference would necessarily result in a much higher cost per kilometre for land cables than would be expected for circa 680 km of underground land cable.”



The HumeLink Alliance and HumeLink Action Groups have said if Transgrid was truly committed to working with the community, it must reapply the regulatory investment test for transmission (RIT-T). There are also calls for Transgrid to halt any further investments in equipment procurement, contract signings, or land acquisitions while the feasibility of under-grounding was subject to a select committee inquiry.

Jack Murray