Work to upgrade Esk St has restarted after the discovery of contaminated material last year.
Progress in Esk St stopped in December when bone and other artefacts discovered by heritage experts unexpectedly changed colour, triggering testing.
Invercargill City Council infrastructure group manager Erin Moogan said low levels of cyanide and a mix of heavy metals were detected, but they did not pose a risk to public health.
The work restarted following extensive testing by environmental scientists and the granting of resource consent for soil disturbance and off-site disposal for material, she said.
"We can now fully recommence works subject to several conditions which relate to how we deal with the earthworks.
"I am thrilled we have been able to recommence so swiftly and that the delay has been shorter than expected, with teams moving quickly to get works back on track."
The council would review the programme to ensure the impact of the delay was minimised, Ms Moogan said.
The work is part of an upgrade of inner-city streets to create a more attractive city centre, starting with Esk and Don Sts.
The Esk St work is expected to be completed by November.
