Hydro helps Fiji reach renewable goals

It may be surprising to learn that Fiji is considered an early pioneer in hydropower development, having created a long-term strategy in the early 1970s for using this renewable energy source across its main island of Viti Levu. At that time, the Fiji Electricity Authority (FEA) identified four major hydropower projects, with the last project – Nadarivatu – on track for completion this year.

An important upstream augmentation of Nadarivatu, the Qaliwana renewable energy project, was also recently proposed. Once completed, the Qaliwana project is expected to provide Nadarivatu with critical storage capacity and increased operational flexibility to further meet the island’s electricity needs.

In the meantime, the Nadarivatu project has faced and overcome a variety of design and construction challenges, namely project delivery standards, access and financing, which may serve as lessons learned for future projects in Fiji and similar countries. The FEA worked with engineering firm MWH Global to address those challenges and help ensure the Nadarivatu project will be completed on time and on budget. In fact, over the last two years, MWH has also helped the FEA relook at the original long-term strategy and identify the ‘what’s next’ projects.

Fiji’s renewable background

Fiji is a remote island in the South Pacific with roughly 850,000 residents. Traditionally, the country has relied on high cost, imported diesel for power generation. However, the FEA, which was established in 1966 under the Electricity Act, recently revised its mission to ‘provide 90% of the country’s energy from renewable energy sources’. A wealth of new policies and projects have since been implemented or proposed (including Nadarivatu and Qaliwana) to help the country achieve this goal and more adequately address the electricity needs of its growing population.

Hydropower is just one of many renewable energy sources available in Fiji. Other sources include wind energy, geothermal, biomass from sugar cane waste and biodiesel from coconut oil. While the 83MW Monasavu/Wailoa hydro scheme is the largest, currently providing half of the country’s power, both the Nadarivatu and the Qaliwana projects are expected to provide an additional combined 61MW of power - enough to meet an additional 20% of the island’s electricity needs.

Nadarivatu

MWH has been involved in the Nadarivatu project since 2002 when the FEA retained the company to provide initial feasibility studies and geotechnical investigations. This involved undertaking a detailed review of the 1970s feasibility studies and identifying the procurement strategy and initial risk assessments for the project.

The resulting scheme was fast tracked, with site investigations, detailed design and advanced works contracts occurring concurrently, with the main construction beginning in 2009. MWH was hired on as the project’s owner engineer, with Sinohydro Corporation of China in charge of executing the construction of the project under an engineer-procure-construct (EPC) contract. Together, the project team embarked on a 36-month construction schedule, which is set to be completed in April 2012. The US$150M project has employed at its peak 465 workers, 150 of whom are local to Fiji.

The Nadarivatu project consists of a 42MW power station with two vertical pelton turbines, providing 103GWh of electricity annually. The project also includes:

• A 30m high concrete gravity dam, including three radial gates and two sluice gates.

• Two kilometers of tunnels, including intake structures and screens.

• A 1.5km long, 2.2m diameter buried steel penstock pipeline.

• A 132kV, 5km long transmission line connecting to the existing Fiji transmission system through a switching station

Challenges and solutions

Throughout the duration of the Nadarivatu project, the project team developed sound solutions to overcome the challenges associated with project access, financing and delivery.

Access

The initial risk assessment concluded that access and transportation would be the most challenging problems to overcome, mainly because of the site’s remote location in the central highlands of Viti Levu – an area known for its steep and rugged terrain.

Prior to the start of construction, significant transportation upgrades were required to reach the project site. These included upgrading (widening and draining) approximately 40km of existing unsealed access roads, which ran from the main international airport and port city prior to reaching the closest town of Tavua. The road from Tavua, which also sees an elevation gain of 900m, was one of the biggest access upgrades, which included both widening and improving the road.

An additional 15km of new roads were built within the project site. This included a ‘zig-zag’ road formation, requiring some equipment deliveries to be reversed down mid-way by transport operators over a length of 500m. Regular maintenance to the gravel roads was also required due to heavy rainfall and tropical conditions. The roads were designed and overseen by MWH, using a specialist earthworks company from New Zealand to facilitate completion.

The remote nature of many power projects, including Nadarivatu, includes complex terrain and long travel times between power stations. There are also numerous times a year where sites cannot be accessed because of tropical weather conditions, increasing the risk of plant outages. With a low system capacity and a complex electricity system, operating between the various schemes and energy sources is inherently challenging. With these limitations, losing communication or control of any individual project would be a significant blow to the energy grid. As a result, the Nadarivatu project was designed to be remotely controlled from the National Control Centre near Lautoka City, which is located about 120km (by road) from the plant. This is to prevent a loss of power should an issue occur and affect the entire island’s power capacity, potentially causing blackouts at major tourist areas. Remote access also allows the plant to be more efficiently managed, and it enabled the project to become a reality despite its remote location.

Financing

Finding ways to finance Nadarivatu posed additional challenges. Since the development of the Monavasu hydro scheme in the 1980s, the FEA has utilised independent power producers (IPP) to provide the capital investment to augment its renewable energy program. IPP’s involve a partnership between private companies and the FEA to provide upfront capital for projects. Once the projects are completed, power is sold back to the FEA over a fixed-term contract at an agreed upon price.

While the Nadarivatu project originated as an IPP, the FEA also sought funding via the World Bank. The World Bank advised on an open international tender, which required that the project be constructed according to the engineer-procure-construct (EPC) project delivery mechanism, which is a delivery method similar to the design-build delivery system that’s often used in the US. FEA retained MWH to prepare the revised ‘EPC base design’ and to prepare the bidding documents based on the World Bank’s standards. However, due to some ongoing political and financial uncertainty, the World Bank decided to withdraw its financing, leaving the project to be funded through a balance of FEA capital, commercial loans and an additional loan from the Chinese Development Bank, which was arranged by Sinohydro.

Project delivery standards

While financing didn’t materialise from the World Bank, the project still proceeded under an EPC contract. EPC has proven a hard model to successfully implement for this project, primarily because it required that the design delivery be executed by the contractor, Sinohydro, who typically only performs procurement and construction. The international team also struggled to develop designs based on western standards; however, this was overcome by MWH taking on the role of owner’s engineer, representing the FEA and providing technical due diligence across the project, including design. MWH had six full-time engineers on site, in addition to 20 FEA engineers and technicians. MWH was responsible for managing the budget and schedule, upsizing the team and supervisory responsibilities to ensure the quality assurance, health, safety and project standards were met. The on-site team was also supported by a design review team of MWH engineers in New Zealand, who offered extensive design review and guidance.

Environmental benefits

While there were challenges, the scope and location of the Nadarivatu project is naturally conducive to limited environmental and community impacts. Although Vitu Levu is home to most of the island nation’s residents, communities are sparsely populated. In fact, the closest downstream population centre to the Nadarivatu project is located 18km from the dam, which means it will generally experience little impact from changes in river levels. Areas of vegetation will experience high re-growth thanks to the tropical environment. With the small impoundment area, the site’s footprint is also relatively small. In addition, small hydropower development like Nadarivatu is also responsible for bringing power to communities for the first time. This includes the Buya Buya, a village near the powerhouse site that had no power or road access prior to project construction.

The project team and FEA are committed to protecting the natural environment and nearby populations. A detailed environmental impact assessment conducted during the early stages of the project led to an environmental approval plan that outlines all environmental risks and mitigation measures. As a result, the team worked to address and resolve all potential health and safety issues, including managing the worker’s camp for proper water supply, health and hygiene, and extensive monitoring, reporting, evaluation and review.

Looking forward

The Qaliwana renewable energy project is an upstream augmentation to Nadarivatu. Qaliwana is expected to increase Nadarivatu’s storage capacity, providing an additional 40GWh of energy while also enabling it to have better operational flexibility.

The Qaliwana project consists of:

• A 60m high concrete arch gravity dam and associated spillway, gates, intake tower, sluice tower and sluice channels.

• 2.3km of tunnel and portal structures, surge shaft, penstock bridge and penstock.

• A 19MW submerged power station and reservoir outlet, discharging 400m upstream of the current Nadarivatu project.

MWH began revising the Qaliwana renewable energy project in 2009 after the initial feasibility study, conducted jointly with Hadarivatu, which was conducted in 2003. Since 2009, MWH prepared full construction contract documents for the project, which will likely be delivered under what’s referred to as a build-own-operate-transfer (BOOT) contract. A BOOT contract is unique in that the funding and operations are the prime responsibility of the contractor. Contract negotiations are currently underway, with the project expected to begin this year.

In addition to the Nadarivatu and Qaliwana projects, there are a number of other hydro projects on the horizon that will help Fiji reach its renewable energy goals. These include:

• Raising the Wainisavulevu weir that feeds the existing 6MW Wainikasou power station, which will increase both its head and storage capacity.

• Developing a new project on the Ba river downstream of the Nadarivatu project.

• Developing a new hydropower scheme downstream of the existing 83MW Wailoa power station.

• Conducting new feasibility studies for the Navua river.

In total, these planned projects will add more than 25% additional energy generation from hydropower to the country’s energy grid.

While much work remains to be done in Fiji, the country has progressed markedly from its initial plans in the 1970s. With the continued progress on both the Nadarivatu project and expected Qaliwana upgrade, combined with the use of biomass to produce thermal energy, Fiji will soon be even closer to its renewable energy goals and to providing its citizens with access to increased clean energy that they and the rest of the world can feel good about.

Greg Brown is construction manager at MWH Global, based in New Zealand. He specialises in the design and project management of hydropower facilities, including on-site construction management of the Nadarivatu project. He can be reached at Greg.Brown@mwhglobal.com.