The towering yellow rig, which has been sited on the Camp St side of the the Village Green for nearly a week, was connected to work being done on the new wastewater pumping station beside the Queenstown Recreation Ground.
Queenstown Lakes District Council communications spokesman Jack Barlow said it was part of "exploratory work''.
"[It is] to help us get ready for a major upgrade to the Recreation Ground wastewater pumping station and rising main [wastewater pipeline] through the Queenstown town centre."
The Mountain Scene reported in November the new pump would provide emergency storage, extra pumping capacity and a new rising main, or pipeline, for wastewater across town.
Drilling beside the Village Green was expected to finish last night, Mr Barlow said.
The upgrade project was set to start on March 16 and would take about nine months to complete.
