APA Group recently completed expansions of the Goldfields Gas Pipeline, in Western Australia, and its Carpentaria Gas Pipeline, in Queensland. The expansions involved the construction of compressor stations which included 4.5 MW Solar Centaur C50 compressor packages, control rooms, workshops, accommodation, piping systems and onsite power generation.

Goldfields expansion

The compression stations constructed at Wyloo West and Ned’s Creek on the Goldfields Gas Pipeline added an additional 20 per cent to the capacity of the 1,380 km pipeline, taking the pipeline’s nominal capacity to approximately 150 TJ/d.

The Wyloo West expansion project was approved by the APA Group board in November 2007 and reached practical completion in May 2009. The Ned’s Creek project was approved in December 2007 and reached practical completion in July 2009.

The projects were conceived as part of an ongoing plan for the development of capacity in the Goldfields Gas Pipeline in order to serve the growing demand from the mining industry in the nearby Pilbara and Goldfields regions of Western Australia.

In addition to the Solar Centaur C50 gas turbine compressor package, specific equipment and materials were supplied and installed for each of the Wyloo West and Ned’s Creek compressor stations. These included:

* Station filtration and coalescing; * Gas aftercooler; * Utility valve skid; * Fuel gas skid; * Station pipework; * Valves; * Two gas engine alternators; * Control room, workshop, accommodation, battery charger and oil store structures; * Site electrical, controls, instrumentation, protection systems, and SCADA; * Compressed air, water reticulation, oily water and lube oil distribution systems; and, * Additional communications equipment.

Carpentaria expansion

APA installed a new compressor station at the Davenport Downs scraper station site to increase the pipeline capacity to 116 TJ/d to meet the demand for new contracts. The Carpentaria Gas Pipeline capacity is to be progressively increased by the installation of additional compressor stations in the future at scraper station sites along the pipeline.

APA said that the original compression requirements evolved from the Ballera to Mt Isa Pipeline Gas Compression Study, completed in August 1997. The study examined the feasibility of multiple 1 MW units versus 4 MW units at each compressor site to progressively increase the pipeline’s capacity to 175 TJ/d.

Further, Carpentaria Gas Pipeline capacity assessments concluded that to meet future predicted loads, the existing Morney Tank Compressor Station would require restaging to achieve the forecast duty points used for the Davenport Downs compressor unit selection.

The scope of works for the 4.5 MW Solar Centaur C50 Davenport Downs Compressor Station included supporting infrastructure consistent with existing compressor stations including a control room, workshop, accommodation, piping systems and onsite power generation.

The scope of equipment and materials supplied and installed for the compressor station included:

* One Solar Centaur C50 gas turbine compressor package and associated auxiliary equipment; * Station filtration and automated dump system; * Gas aftercooler; * Unit valve skid; * Fuel gas skid; * Station pipework; * Valves; * Two gas engine alternators; * Control room, workshop with electrical and installation room, accommodation modifications, battery room, gas engine alternator shelter, fuel gas skid shelter, oil store shelter/structure; * Site electrical, controls, instrumentation, protection systems, communications and SCADA; * Compressed air system; * Water reticulation, oily water and lube oil distribution systems; * Demolition of the existing scraper station remote terminal unit and associated solar panels including the installation of additional solar panels and transfer of all scraper station I/O to the compressor station control system; * Modifications to the existing scraper station kicker piping to allow the pipeline to be pigged whilst the compressor is in operation; and, * Fencing, lighting and security.

Enerflex worked with the APA projects team to complete the project, supporting APA with construction management, offsite fabrication and site construction activities for the compressor set and associated equipment. The project began in February 2008 and was completed in June 2009.

APA and Enerflex had a team of approximately 40–50 employees working on and offsite. Overall, more than 150 workers had input during the life of the project including engineers, managers, administration, civil/mechanical/electrical trades, site supervision, stores, procurement and logistics and quality control.

Challenges

Both the Goldfields and Carpentaria pipelines are situated in extremely remote locations, presenting significant challenges to the construction of the compressor stations.

The remote location of the projects meant that not only the facilities associated with the compressor stations needed to be constructed, but also utilities such as electricity, water and accommodation onsite.

On the Goldfields Gas Pipeline project, equipment transported by road from Perth had to travel almost 2,000 km. In addition, the construction period continued over the summer months, with site temperatures near 50 degrees Celsius, and also coincided with the cyclone season.

The construction of the Davenport Downs Compressor Station on the Carpentaria pipeline also posed several challenges, with construction occurring at an extremely remote site in an area of Queensland that is prone to flooding in the wet season.

Accessibility to the site was a major part of the project management process with over 250 km of dirt roads to maintain throughout the life of the project. Flooding due to the inclement weather between January and March 2009 meant that a high level of co-ordination and communication was required between the APA and Enerflex teams. The delivery of equipment, fuel and general stores to the site was an ongoing challenge throughout these periods. Onsite, a culture of resourcefulness was encouraged, and using the tools and materials on hand. Fabrication and pre-assembly of equipment was completed offsite as much as possible.

“The Davenport Homestead provided much assistance with machinery, equipment, fuel, materials and accommodation during the project,” said Peter Bowd, APA Manager Major Projects, Queensland. Safety

Across all compressor station projects APA’s focus on safety was paramount. Construction risk assessments were held for each project and the necessary controls were implemented to ensure all risk was as low as reasonably practical.

To maximise onsite safety and ensure regulatory compliance, the Wyloo West and Ned’s Creek compressor stations were constructed under a Safety Management Plan (SMP) developed and approved by the Department of Mines and Petroleum and Goldfields Gas Transmission (GGT).

The SMP forms part of the Goldfields compressor project construction safety case, which defines the minimum health and safety standards and requirements for construction of the project. The construction safety case described the co-regulatory regime that applies to all managers, personnel and visitors working in connection with the Ned’s Creek and Wyloo sites.

When constructing the Wyloo West Compressor Station on the Goldfields Gas Pipeline, the closest towns were a 2–3.5 hour drive away, being Paraburdoo and Karratha. Similarly, the closest towns to the Ned’s Creek Compressor Station were 3.5 hours in either direction (Newman or Meekatharra). Hence, it was critical that APA’s construction safety cases for all three projects incorporated site specific measures to manage the risks of isolation and detailed how the project interfaced with key stakeholders such as nearby mines sites, emergency services and the Royal Flying Doctor Service. This proved exceptionally successful in achieving zero lost time injuries, despite 178 contractors and employees working a combined total of 155,000 man hours across the three projects.

The remote location of the Carpentaria project and vehicle access issues also posed a safety risk, with over 250 km of unsealed roads and a total of 350 km between the site and the nearest town. Because of the long distance to the nearest medical facility, precautions were taken with a Safety Critical Box and extra medical provisions kept onsite.

To increase safety, checks and approvals were required prior to mobilising plant, equipment, Enerflex personnel and subcontractors. It was made sure that any existing health conditions or medications of employees were reviewed during the mobilisation process. Regular communication with the Royal Flying Doctor Service was maintained throughout the duration of the project.

APA placed a strong focus on heat stress and hydration during hot weather, providing a water chiller during the hotter months and heat relief breaks for employees.

In addition, emergency position-indicating radio beacons, emergency water and fuel, and satellite phones were carried in each vehicle, and a strict travel management policy was implemented.

Environment

The Carpentaria Gas Pipeline’s Davenport Downs Compressor Station site was located near known bilby habitats and, as such, extra precautions were needed within the construction easement to ensure minimal disruption in this fragile environment.

The construction of the compressor stations on both pipelines were undertaken according to a strict environmental reporting regime.

The construction of the facility had to occur within a confined area on the Miscellaneous Transport Infrastructure Corridor under the approved Environmental Management Plan and Bilby Management Plan. Neil Weatherly, HELM Manager for APA Queensland said “The management plans were authorised following lengthy negotiations with stakeholders such as landowners, federal, state and local governments, environmental experts and native title claimants.”

At the Davenport Downs campsite, the treatment of waste products from the construction campsite required an innovative solution. A mobile waste treatment plant housed in a purpose built transport container fed a subsurface irrigation system situated 200 m upstream from the camp. The system which proved easy to maintain, coped efficiently for the 40 person camp and required minimal rehabilitation when removed.

Storage of fuel at the site used to power generators and machinery required additional approval to maintain supplies during periods when road were cut. Roads and access to the site especially through water courses were constantly monitored to ensure minimal disruption to the fragile embankments.

Expanding pipelines throughout Australia

The successful completion of the compressor stations on the Goldfields Gas Pipeline and Carpentaria Gas Pipeline will serve to further enhance APA’s service to the remote Western Australian and Queensland regions.

APA is focused on enhancing its portfolio of gas infrastructure assets throughout Australia. The company is Australia’s largest transporter of natural gas in terms of pipeline length, capacity and volume.

APA Managing Director Mick McCormack said “By virtue of the size of our portfolio, and its proximity to gas supply and markets, we have many development and growth opportunities before us.

“In the east we have projects underway like the northern expansion on the Victorian Transmission System, and increasing the winter capacity on the Moomba to Sydney Pipeline,” he said.

“In the west APA is proceeding with initial engineering studies to expand its facilities at the Moondarra Underground Gas Storage Facility, located 350 km north of Perth in Western Australia. This facility recently played a crucial role in the security of gas supplies to Western Australia during the recent Varanus Island incident.

“The strength of APA is that we’re connected to the Australian economy’s growing demand for clean gas energy so there is a raft of opportunities in front of us across the country that, combined with our existing business, will ensure the continued success of the APA Group.”