Corrosion Control Engineering
Corrosion Control Engineering supplied an automatically controlled cathodic protection (CP) system for the pipeline, consisting of a potential controlled rectifier in conjunction with an anode groundbed of mixed metal oxide coated titanium anodes in calcined coke backfill.
A single permanent CP installation was installed approximately mid-way along the pipeline at the only site on the pipeline route with shallow soil conditions suitable for a groundbed installation. The site also provided access to the power supply through the construction of a stepdown transformer.
As the pipeline route is close to HV power lines in some areas, a low frequency induction (LFI) study was required in the early stages of the project to determine the possible impact. The study revealed two points where fault currents on the HV power lines had the potential to result in induced voltage levels along the pipeline in excess of the allowable limits nominated in AS 4853.
As a result, the necessary LFI mitigation was implemented through the installation of earthing along the affected pipeline sections. The pipeline was designated as AS 4853 Category B, which requires that contact points with the pipeline be secure. The only appurtenances along the pipeline were CP test points which were placed within lockable test point boxes.
To reduce the effects of this earthing on the cathodic protection system, the earthing systems were de-coupled via solid state type polarisation cell devices.
Four Wheel Drive Hire
Four Wheel Drive Hire Service, a specialist 4WD vehicle rental company, played an important role in the construction of the SESA Gas Pipeline in the supply of vehicles to Nacap, the pipeline construction contractor.
With a fleet of over 800 purpose-built vehicles, Four Wheel Drive Hire Service had the experience, capability and flexibility to supply vehicles to suit any 4WD needs. The company supplied 14 Landcruiser Dual Cabs (a 100 series Landcruiser Wagon cut down to make a Dual Cab Ute), 21 Landcruiser Traybacks, three 100 series Landcruiser Wagons and a Landcruiser Troop Carrier fitted out as an Ambulance for the project. The majority of these vehicles were delivered and collected direct from site by Four Wheel Drive Hire Service’s operations team.
A site visit was conducted in early April by Ed Burrows, Four Wheel Drive Hire Service’s Southern Region Sales Executive. Mr Burrows, who was responsible for coordinating the project’s transport needs, used the visit to examine the progress of pipeline construction and gain a better understanding of Nacap’s specific requirements for the project.
Four Wheel Drive Hire Service’s ongoing relationship with Nacap once again proved a successful partnership and is a testament to the value of close contact between supplier and client.
Ecos
Ecos Consulting formed a key part of Origin Energy’s project team, and were primarily responsible for environment, heritage and regulatory approvals for the SESA pipeline.
Ecos joined the project team early on and immediately assisted with refining the pipeline route. Route selection faced a unique challenge from the start. The location of the offtake valve for the pipeline had been selected several years earlier, when maps and the latest aerial photos showed cleared paddocks for most of the way to Ladbroke Grove. However, when it came to selecting a route on the ground, it was found that the majority of the Victorian section was now covered in bluegum plantations – most of which had grown to well over head-high.
The reasonably direct pipeline route originally proposed had to be amended to zig-zag along plantation firebreaks in order to minimise impacts on forestry operations. Further complications arose due to the narrow width of many of the firebreaks which were bordered by strips of the last remaining native vegetation in the area (including threatened species).
As the pipeline was located half in Victoria and half in South Australia, the approval process was significantly more involved than would typically be expected for a 45 km pipeline. Crossing the two jurisdictions meant two separate approval processes. Despite the complexity of working across two States, Ecos and the project team secured the required approvals in rapid time, with the approval of both South Australian and Victorian government agencies. This was critical, given the small window of opportunity for construction prior to winter.
The overall environmental outcome of the project was excellent – during construction, no environmental incidents were reported, nearly all of the native vegetation along the route was able to be retained and habitats of threatened species (such as the Growling Grass Frog or Red-Tailed Black Cockatoo) along the route were not damaged.
The rapid approvals and excellent environmental outcomes can be attributed to a number of factors, including:
- Regular contact with government agencies.
- Early development of a GIS with aerial photographs. The GIS ran on MapInfo’s free ProViewer software, which allowed it to be readily distributed to the project team for use in route planning and risk assessments. It also enabled the GIS to be easily loaded onto laptops for presentation to government agencies and other stakeholders.
- Thorough and early environmental review of the route by Ecos and its sub-consultants, allowing issues to be identified early and addressed (for example, by realignment).
- Rigorous heritage and ecology review of all realignments throughout the planning process.
- Ecos’ on-ground role as Origin’s representative during construction, which helped Nacap to ensure commitments made during planning were understood and followed through.
- Use of an arborist to lop tree limbs before clear and grade, which allowed many trees to be retained on or next to the easement, and minimised visual evidence of construction.
- Green tagging of sensitive areas before clear and grade, based on a clear and concise line list of environmental requirements in the Construction Environmental Management Plan.
- A strong commitment to achieving the best practicable environmental outcomes from everyone involved, from Origin through to Nacap.
Lester Franks
Lester Franks was engaged by Nacap to provide survey services for pipeline construction. Their involvement included the construction and post-construction phases of the SESA pipeline, having a technician on site conducting both setting out and as constructed surveys.
The Lester Franks technician, who was present while the pipe was being laid in the ground, recorded the location of welds and various other features of the pipeline. In order to carry out this task, a combination of GPS and software, including the EDDICT data capture system and construction management system was used.
Malcolm Lester, Managing Director at Lester Franks, said that the fact that only one person was required on site to carry out this work is a feature in itself. The capability of the software used is such that staff – and thus costs – required for pipeline surveys is significantly reduced.
The technician and the equipment used on the project were sourced from Lester Franks’ new Adelaide office. Last year, when Lester Franks bought the existing business of Adelaide surveying firm, Todd Alexander, it gave them access to resources so they could participate in future major projects.
Since completing the surveying work for the SESA project, Lester Franks has commenced work on a new gas pipeline being built in Townsville to Queensland Nickel’s Yabulu refinery.
Lester Franks Survey & Geographic commenced operations in 1964 and has grown from its surveying roots to become a specialist provider of services in the fields of land and hydrographic surveying, spatial information systems, industrial metrology, strategic and statutory planning, photogrammetry and, more recently, 3D laser scanning.
Denso
Denso Australia provided the field joint coating for the SESA project. The project utilised Denso’s S43/R23 butyl tape system, comprising Denso Butyl Primer, Denso S43 innerwrap and Denso R23 outerwrap. These products chemically amalgamated to provide seamless protective coating along the pipe with the added advantage of excellent adhesion, resistance to cathodic disbondment, and ease of application and impact resistance. Denso also provided training to Nacap personnel on the use of their products.