In June 2010 the Peru LNG Pipeline commenced transporting gas from the Camisea gas fields to the southern coastal region of Peru for export at a new LNG Plant, constructed at Pampa Melchorita. Originating in Chiquintirca in the Andes Mountains, east of Ayacucho, the pipeline also crosses through 22 districts: nine in Ayacucho, four in Huancavelica, eight in Ica and one in Lima.
The 34 inch diameter pipeline system includes mainline valves, pig receiver/launcher facilities, a pressure control station, meter station, fibre optic cable and a SCADA system. The system traverses approximately 308 km of rugged mountain terrain with numerous river crossings, and approximately 100 km of coastal desert plain.
The Peru LNG Pipeline right-of-way follows a route parallel to the Transportada de Gas del Peru (TGP) Pipeline for half of its route, deviating where improved routing was accessible and where engineering, physical, environmental or archaeological conditions restricted the ability to remain in the TGP corridor.
The biggest area of deviation occurs at kilometre point (KP) 240 to KP 340, where the pipeline deviates approximately 10 km south of the existing line. This deviation avoids a rugged descent from a mountainous ridge, the narrow and sensitive Pisco River valley and the six crossings of the Pisco River that the existing TGP Pipeline encountered.
The world’s highest pipeline
The pipeline route begins 2,700 m above sea level near the Chiquintirca community, in the province of La Mar in the highlands of Ayacucho. From there the pipeline route winds through the Andean mountains descending and climbing the mountain range until reaching an altitude of over 4,901 m above sea level at KP 161, earning it a place in the Guinness World Records as the highest pipeline in the world.
From the starting point in Chiquintirca, the first 50 km of the highland segment are characterised by abundant steep slopes ranging between 25 and 45 degrees, requiring the participation of a team of specialists qualified in pipeline installation at high altitudes and steep slopes. The area in general is very remote with limited access and scarce road infrastructure.
The next 250 km of the route are dominated by undulating highland plateaux, reaching altitudes between 2,700 and 4,300 m.
In many areas the route follows the Los Libertadores Highway, while the final 108km run parallel to the South Pan-American Highway, along the Peruvian coast, up to the natural gas liquefaction plant.
The pipeline crosses various microclimates, from very humid and rainy areas as in Chiquintirca, Ayacucho, to cold, snow and ice-covered landscape in the high Sierra, and the arid and dry deserts on the coast.
Since pipeline construction began, project workers have been focused on minimising impact to the local environment. This has included erosion control work carried out before clearing and grading key sections of the pipeline spread to minimise the possible effects of erosion.
A challenging route
Gulf Interstate Engineering (GIE) Company provided basic design services on the project including assessment of the route selection and constructability analysis.
To ensure the route was technically feasible and environmentally safe, GIE bought in specialists to identify a route with the least environmental impact. With selected specialists, GIE evaluated routes based on areas of the Andes that were more geotechnically stable, and decreased the number of steep gradients and river crossings required for the project.
GIE engaged the services of subcontractors to provide satellite imagery and perform control surveys, geotechnical investigations, hydrological investigations, and topographic surveys.
From this, GIE developed reports detailing design recommendations for all river crossings; a report providing assessment of the entire route, including identification of any seismic areas crossed by the pipeline system; and, additional field surveys to complement existing survey data.
During construction, the project was divided into two work fronts: a western front, which began at the natural gas liquefaction plant, and the second front near the other end of the pipeline in the Chiquintirca area.
Due to the conditions of the route through the Andes Mountain Range, a comprehensive logistics plan was decisive for the project’s success.
Sixteen temporary camps were installed along the route with a capacity to house over 500 workers each. At the project’s peak, approximately ten camps operated simultaneously, housing approximately
2,500 workers. In addition to the workers housed at the camps, another 2,000 from the local communities joined the workforce, giving the pipeline project a head count of approximately 4,500 people.
The local workforce covered most of the labour required by the project from inception. In particular, the extensive geotechnical and erosion control programme implemented required intensive hiring of labour from the neighbouring agrarian communities.
The transportation of pipe along the route, from the receiving point at Pisco Port on the coast, also posed a logistical challenge. In order to facilitate the haulage of pipe and other materials to their final destination, hundreds of kilometres of existing infrastructure of local roads were upgraded and approximately 100 km of new access routes were built. This allowed a total of approximately 35,000 sections of pipe to be efficiently and safely transported.
Working on narrow mountain crests
The pipeline follows an undulating route, winding along narrow mountain ridges through the Andes Mountains with near-inaccessible locations and terrain conditions. These conditions are considered the toughest in the world when engineering and constructing a pipeline project of this sort.
The installation of the pipeline on steep slopes posed another major challenge. As GIE notes “Slope instability is one of the most serious concerns in constructing a pipeline in this area.”
In the eastern front, a 600 m section with a 48 degree slope was encountered, immediately followed by another section of 900 m with a 30 degree slope.
GIE noted that innovative technology was implemented to monitor movement on the ground. “A specialised fibre-optic cable is buried beside the pipeline to measure strain and movement. This system can alert the operator and perhaps prevent a landslide.”
Along its route, the pipeline crossed small drainages and canals and over 38rivers of various sizes, which required special construction designs aimed at preserving the environment. The 700 m wide and over 5 m deep Pisco River was one of the major challenges that was successfully resolved.
Reflecting on the project, Peru LNG Pipeline Project Director David Chapman said “Peru LNG overcame many challenges in some of the toughest terrain on earth to install the world’s highest gas pipeline. All this was done while meeting the most rigorous standards in technical, safety, social and environmental areas.”
