A drilling rig near the base of the Pukaki Dam and a digger working nearby have had some people perplexed about what the dam's owner, Meridian Energy Ltd, is doing.
The rig can only be seen by looking down off the side of SH8 or from viewing areas off the highway.
Meridian Energy said the work related to the Pukaki Dam structural safety evaluation project.
The investigation was being carried out to confirm the engineering characteristics of the dam foundation, shoulder and core materials matched those from the construction records.
The investigations consisted of trenching downstream to expose and sample the dam foundation materials and drilling to sample and test dam shoulder and core materials.
The project was a part of Meridian's overall dam safety assurance programme.
''We have completed these studies on the Aviemore and Waitaki dams and are now working on Pukaki Dam,'' Meridian said.
The purpose of the Pukaki project was to review the design, construction and performance of the dam against Meridian's current level of understanding of hazards - floods, earthquakes or other loads - to confirm the dam fully met present dam safety criteria.
''There are no identified dam safety deficiencies with Pukaki Dam.
"The structural safety reviews are part of a best practice dam safety assurance programme ... which Meridian undertakes as a responsible dam owner,'' the company said.
Site works started on October 23 and are expected to be completed before the end of this month.
