How do you refurbish a power station while keeping it fully operational, and keeping everyone in the team – and local wildlife – safe?
These are just some of the challenges the two project managers – yes, this project needed two! – overcame in this complex and multi-faceted project by Meridian Energy, which is one of three finalists of the PMI New Zealand 2017 Psoda Project of the Year award. The winner of which will be announced on 21 September at this year’s PMINZ Conference.
In this third of our three-part series on the finalists of the Psoda Project of the Year award, we look at Meridian Energy’s Waitaki Hydro Power Station Refurbishment project.
Waitaki power station is Meridian Energy’s oldest power station and the last station in the Waitaki River chain of power stations. The original power house and dam were constructed between 1928 and 1935 as a Makework project during the Great Depression. While there had been enhancements to the generator electronic protection and fire suppression systems, both had reached the end of their life and needed to be replaced.
The Waitaki Hydro Power Station Refurbishment project was a $40 million project to ensure the power station kept functioning. It included earthquake strengthening, upgrading the protection systems on the six working generating units and reinstating the site’s seventh generation unit that was decommissioned in 1998. It also included erosion, seismic and flood protection work on the site, as well as making access to the site safer.
This project was unusual in that there were two project managers involved – one for the mechanical and electrical works and one for the site refurbishment works.
There were a number of challenges associated with delivering this project:
- The power station was fully operational during the site refurbishment work. All project site works needed to be scheduled around generation requirements, hydrology and resource consent conditions. It also had to work with Transpower upgrades to substation and transmission lines that was happening at the same time.
- Limited ability to control water spillage. The Waitaki dam is a weir dam, so any excess water spills over the top. Spilling generally occurs between November and May each year so all site work in the river below the dam needed to be scheduled to avoid this spill period.
- If all the generating units at Waitaki trip, there is a risk that the Waitaki River stops flowing. To mitigate this risk there are two sluice gates available that open to maintain the river flow. During the project, work was required to be done on the sluices gates. When working on the gates, water was deliberately spilled over the dam to ensure there was no risk of stopping river flow.
- Special environmental considerations over and above normal water contamination risks. This included the annual elver (baby eels) trapping season, involving the elvers being trapped below the dam and released upstream and the discovery of a protected black billed gull colony nesting on the sluice pier, which was one of the work sites. Site works on the sluice pier was delayed until the birds had left the nesting area. The birds have since returned to the site.
- Access to some parts of the work site was very restricted and this was a key design consideration communicated clearly to design consultants and contractors. When the site was originally built, there was little consideration as to how various aspects of the site would be safely maintained. Various means of access were deployed in order to provide safe access for people, plant and equipment. This included negotiating access over a privately owned (and very steep) farm track, the use of a helicopter, jet boats, work from suspended platforms installed by specialist abseiling teams, a temporary tower crane and the use of numerous other mobile cranes and elevated work platforms. Equipment was also selected so that there was no chance of coming into contact with the high voltage (220kV) transmission lines which spanned across the tailrace from the powerhouse to the switchyard.
The project has delivered tangible benefits. It has reduced a significant number of known failure risks and has made sure that the Waitaki power station can continue to safely and reliably generate power for the foreseeable future. It has also enabled 15MW of additional generating capacity.
Why it was selected as a finalist
The Waitaki Hydro Power Station Refurbishment project was selected as a finalist for the 2017 Psoda Project of the Year award because it was a complex and multi-faceted project delivered in an environmentally sensitive way. It used well developed methodologies and worked hard to deliver the promised business outcomes.
One of the highlights from the sponsor’s letter was the statement that the project had improved on its original business goals.
The judges agreed this entry managed complexity in the project well, including that it was an operational power station. In addition, this project also scored well with respect to delivering well within budget, managing site safety and stakeholder management. External stakeholders included Transpower, ECANs, NZTA and the Waitaki Regional Council, as well as local landowners.