Due to orographic conditions of the locations and of the very special characteristics of the area, the execution of the portion of the 20-inch Atacama Gas Pipeline for a total length of kms 597, entailed the most serious difficulties of all the Project.

The main data of the Project, successfully overcome by Bonatti in consortium with local partners, could be resumed as for:

• Andes Mountains and Atacama Desert crossings, the latter know to be the driest desert in the world and with temperatures below -20°C;
• Pipeline construction activities (in the bordering region between Chile/Argentina) at an height over 5.200 m. above sea level, which makes it as the highest pipeline ever built in the world;

The execution of the C1 portion began on November 15, 1997 and was completed on February 15, 1999. On June 1, 1998 the A3 portion was began and completed on March 7, 1999. The 2 spreads were completed in 15 and 9 months respectively.

Main technical data are:

• Pipeline 20-inch, API 5L-X70, Wall Thickness 0.288”, 0.375” and 0.415”;
• Route length: kms 597 (spreads C1, A3);
• Twenty (20) line valves, Type MLV, ten (10) of these valves are regulated by Scada system which is fed by electrical power thermal generators using the gas sourced from the same pipelines, the rest of the valves are manually operated;
• Three (3) Scaper Traps were installed. Two of them are dual and were placed in Calama and Salar de Olaroz towns, and the third one is a reception trap installed in Mejillones.

For the execution of the activities related the C1 Spread, an average of 500 direct workers have been employed, being 90% of them local, while for A3 spread manpower was composed of 350 workers, being 95% local. Special excavation equipment was used in rocky areas like: 110 tons trenching machines, backhoes with high capacity for extensive excavation and padding machines, rock crusher machines and padding machines.

The Atacama Desert is a region rich in archeological treasures, for that reason special construction procedures have been adopted in order to preserve the discoveries from any damage.