The Camisea Pipeline Transport System [“Sistema de Transporte por Ductos”] consists of two parallel pipelines, one of which carries natural gas (NG) over a distance of 730 km, and the other which carries liquid natural gas (LNG) over a distance of 560 km, starting in the Amazon basin in Malvinas (Cusco). The LNG pipeline ends in Playa Lobería (ICA) and the NG pipeline ends at the City Gate located in Lurín (Lima).
In terms of complexity, the geographic, geological, and climate-related characteristics of the rain-forest, mountain, and coastal regions through which the pipeline passes set it apart from the rest of the world’s pipelines. The highest point in the area is 4,860 meters above mean sea level in its mountain portion in the Peruvian Andes.
The first 200 km, which pose the greatest operational challenges, are characterized by residual soils, slopes steeper than 45°, and rainfall of more than 6,000 mm per year — in addition to the logistical difficulties presented by the lack of vehicular access for the transport of personnel, materials, and equipment, such that maintenance work must be done by helicopter.
The purpose of this article is to illustrate the diversity of geotechnical scenarios in this geographical area, and to discuss the early identification of risks through the management and control cycle for geotechnical threats, which consists of the following stages:
• The Threat Identification System: This stage includes the continuous monitoring of the right-of-way in order to detect geotechnical problems, which are triggered primarily by rainfall.
• Risk assessment: This stage involves the use of a geotechnical risk matrix that was developed in accordance with the so-called “Safety Ratio” [“Relación de Seguridad”], which assimilates the parameters for the calculation of the Safety Factor used in slope stability analysis, thereby making it possible to establish the various risk levels.
• Structure design: Depending on the risk level, the corresponding engineering tasks are developed and prioritized in order to determine the designs, through the use of geotechnical engineering processes such as subsurface exploration, laboratory tests, mathematical modeling, and instrumentation.
• Implementation of the structures: The geotechnical stabilization structures are built during the dry season, i.e., from April to October of each year.
• Monitoring and surveillance: Once the stabilization structures have been built and the dry season has ended, continuous monitoring is performed during the rainy season (November to April), through ongoing inspections, topographic monitoring, and instrumentation at sensitive sites, using inclinometers, piezometers, and strain gauges.
Thanks to these working techniques and control measures, as implemented in an area with special topographic and climate-related characteristics, it has been possible to achieve a dramatic reduction in the geotechnical risks to which the Camisea transport system is exposed.