Many pipelines are built in regions affected by harsh environmental conditions where changes in soil texture between winter and summer increase the likelihood of risks. Pipeline routes also cross the mountains that are characterized by steep slopes and unstable soils as in the Andes and along the coastal range of Brazil. In other cases, these pipelines are laid in remote areas with significant seismic activity or exposure to permafrost. Depending on weather conditions and location, visual inspection is difficult or even impossible and therefore remote sensing solutions for pipes offer significant advantages over conventional inspection techniques. Optical fibers can help solve these challenges. Optical fiber based geotechnical and structural monitoring use distributed measurement of strain and temperature thanks to the sensitivity of Brillouin scattering to mechanical and thermal stresses. The analysis of scattering combined with a time domain technique allows the measurement of strain and temperature profiles. Temperature measurement is carried out to control soil erosion or dune migration through event quantification and spatial location. Direct measurement of strain in the soil also improves the detection of environmental hazards. As an example the technology can pinpoint the early signs of landslide. In some cases, pipe actual deformation must be monitored such as in case of active tectonic fault crossing. Pipe deformation monitoring operation is achieved by the measurement of distributed strain along fiber sensors attached to the structure. This paper comprehensively reviews over 10 years of continuous development from technology qualification and validation to its implementation in real cases as well as its successful continuous operation. Case studies present pipeline monitoring in Arctic and Siberian environment as well as in the Andes. They illustrate how the technology is used and demonstrate proof of early detection and location of events such as erosion, landslide, subsidence and pipe deformation.

Establishing pipeline failure frequencies enables designers and operators to make informed decisions on the allocation of resources to address different threats. Normally, this would involve the selection and timing of inspection, monitoring and protection activities. Typically, failure frequencies are defined based on the collection of historical statistics. This is difficult for geohazards due to the comparatively low incident rate compared to other hazards, however the consequences tend to be catastrophic. As a result, significant uncertainties are attached to predicted failure frequencies for geohazards. Two principal areas of uncertainty cover the occurrence and nature of loading events and whether the pipeline will survive the loading. This paper addresses both of these key aspects. The occurrence and nature of loading can be determined from the examination of in-line inspection records through different terrains. The pipeline survival rate is based on the efficient execution of multiple analysis runs within a finite element code where the distributions of the key input variables are defined to cover either observed or potential variation in the field. These include landslide size, orientation, movement and soil stiffness values as well as considerations of tensile fracture limits. The calculation of the probability of pipeline failure due to landslide loading is illustrated using a case study.

TGN operates a system of 9,000 kilometers, with a long stretch traveling next to the foothills. Although it is clear now that this path may not be the best choice, it was defined for access convenience parallel to a national highway back in 1960, when erosion was not an important issue. Whenever a pipeline crossing is located at a place where a river experiences a break in its slope, development of meanders poses a significant threat to its integrity. The interaction between a rigid structure and a changing environment sets the scenario of a problem that needs constant attention. Thus, meanders become the main cause that leads to the implementation of expensive remediation works. In the following paragraphs, a method of evaluating meanders is presented based on concepts of channel stability regarding river curvature, width, slope and flows. This is complemented with real cases in which theoretical aspects are matched with actual crossings, its construction characteristics and the evolution of meanders with time. Long term performance of typical solutions such as soil movement channeling, bank protections, jetties and pipeline lowering are compared. Finally the inverse problem is addressed in which guidelines for the design of a new crossing are listed.

Hydrocarbon pipelines are exposed to hazards from natural processes, which may affect their integrity and trigger processes that have consequences on the environment. Among the natural hazards are the effects of the earthquakes, the neotectonic activity, the volcanism, the weathering of soils and rocks, the landslides, the flows or avalanches of mud or debris, the processes related to sediment transport such as the erosion, the scour by streams, the floods and the sloughing due to rains. Those processes are sometimes related to each other, e.g. the earthquakes can produce slides, or movement of geological faults, or soil liquefaction; the rain can trigger landslides and can cause avalanches and mudslides or debris flow; the volcanic eruptions can originate landslides and avalanches, or pyroclastic flows. Human activities can also induce or accelerate “natural” processes that affect the integrity of the pipelines. The strength and stiffness of the pipelines allow them to tolerate the effects of natural hazards for some period of time. The amount of time depends on the strength and deformability, the stress state, the age, the conditions of installation and operation of the pipelines and their geometric arrangement with regard to the hazardous processes. In the programs for pipeline integrity management, the risk is defined as a function that relates the probability of the pipeline rupture and the consequences of the failure. However, some people define risk as the summation of the indicators of probability and consequences, such as a RAM matrix. Others define the risk as the product of the probability of failure times the cost of the consequences, while the overall function used to evaluate the rupture probability of a pipeline facing hazards considered in the ASME b31.8 S standard includes all the elements involved in the failure process. In that standard, for the specific analysis of natural hazards, it is proposed that the function is separated in the two following principal elements: the probability of occurrence of the threatening process (hazard) and the pipeline’s capacity to tolerate it. In this paper a general function is proposed, which is the product of the probability of occurrence of the threatening process, the vulnerability of the pipeline (expressed as the fraction of the potential damage the pipe can undergo), and the consequences of the pipeline failure (represented in the summation of the costs of the spilled product, its collection, the pipeline repair and the damages made by the rupture).

The present paper presents the analysis, carried out by the Ocensa pipeline, against a case of longitudinal or axial landslide to the pipeline in the KM 35 + 690, starting from the identification by inertial tool, the geotechnical characterization and the analysis of Soil-pipe interaction, excavation and stress relief and the techniques used to mitigate the effects of sliding on the pipe.

Unmanned aerial vehicles (UAV), also known as drones, have become a very reliable and convenient tool to many engineering applications. Pipeline corridors are often exposed to geotechnical risk that may interrupt proper service. The risk sources vary, and range from steep hills to many site conditions such as ancient landslides, changes on phreatic water level, creeping soils, or geomorphological changes on the environment. Knowing and understanding the level of risk is highly dependent on identifying any geotechnical hazard in due time, before it materializes. Pipeline corridors are measured in kilometers, and the area that may adversely affect the corridor can vary from a few meters to several hundred on each side of the corridor. This paper presents an application of UAV based digital photogrammetry to evaluate and monitor the hazard and evolution of the site PK 469 OCENSA km 149 ODC. The site is maintained by Oleoducto Central S.A. (OCENSA), and the paper describes the different geotechnical studies and works carried out to maintain uninterrupted service of the pipeline. The paper includes technical information supporting the processing and characteristics of the photogrammetry based evaluation and monitoring method, to highlight the efficiency and accuracy of the proposed method.

The OCENSA pipeline crosses the Valley of the Magdalena river flood on its way to the Caribbean Sea, the area of the valley is commonly inundated during the rainy season on shallow waters that remain flooded swamps. These swamps soils are composed by extremely soft peat with thicknesses greater than 15 meters. In June 2016 started the construction of a highway with an embankment of 6 meters in height which was more than 30 meters away from the OCENSA 30” pipeline, Due to the high compressibility of peat, to construct the road the soil is subjected to a process of consolidation and the height of the embankment was corrected adding more material. In July 29 2016 occurs a failure by load capacity on the ground under the embankment and as a result of this fault a lateral displacement of the adjacent soil producing a horizontal displacement in the pipeline of more than 50 cm. This document shows results from the affectation to the pipe and the measures taken to correct the situation.

Oil pipelines and gas pipelines usually go through geotechnically unstable areas for different reasons. These can go from situations related to the engineering stage (trace), to environmental and social aspects during the construction process. Due to these aspects, the ducts go through geotechnically undesirable areas. Usually, the geotechnical instabilities, according to the kind of movement, are low speed (cm/year), medium (m/year) and very quick processes that generate movements of tens to hundreds of meters per day. Most of Mass Removal Phenomenon (MRF) are triggered by rain and/or earthquakes and are translated into land movements which at the same time involve, occasionally, important deformations in pipelines or its breaking, depending on the movement speed and the possibility of making works before the pipeline breaking. To get to know the pipeline tensional state from the beginning of the pipeline operation, in this unstable zones, is an essential task, which depends on the early identification of the said land movements and the possibility to do measurements on the pipelines using tools such as In-line inspection running (ILI) or the installation of strain gauges. This situation makes the task of monitoring in unstable zones a vital one. The current paper is based on a breaking pipeline case due to soil movement, “monitored by inclinometers”, with the purpose to show the importance of a geotechnical and mechanical instrumentation that offers useful results. The instrumentation allows to model the interaction soil-pipeline to accomplish relevant tasks, that avoid the pipeline breaking and at the same time allow to stablish deformation thresholds of soil or pipeline, which will become early warnings to avoid breakings. Furthermore, the soil and pipeline’s deformation thresholds are documented, based on a system transport by pipelines (STP) breaking cases, to stablish threat classifications to a specific pipeline. The called instrument reading in real time implies: detection, measurement and data broadcasting that allows the user to have daily records of the movements or required associated variables, with no need to depend on other communication systems that might be inexistent in some areas. This paper also shows the development and operation of a monitoring station that includes: inclinometers, piezometers, strain gauges and rain gauges, among others. These broadcast their data to a server that the user has access to, from any place with a Wi-Fi network, here the user will be able to display information from each one of the instruments, emphasizing the measured variables or magnitudes (displacement, water level, micro strain mm/day) into graphics. The station has a limitation over battery length of 6 months, when it’s problematic to install a recharge solar cell system.

The Camisea’s Pipeline Transportation System (PTS) in Peru, owned by Transportadora de Gas del Perú (TgP) and operated by Compañía Operadora de Gas del Amazonas (COGA), stars in the Amazon rainforest, crosses the Andes Mountain (4850masl) and descends finally towards the coast of the Pacific. The PTS has more than 10 years of operation and it has two pipelines: one transports Natural Gas (NG) and the other Natural Gas Liquids (NGL) pipelines. The NG pipeline has a length of 864km including a Loop pipeline of 135km. The NGL pipeline has a length of 557km. Because of particular physiographic conditions of each geographic sector that cross the right-of-way (ROW), the integrity of the PTS acquires a level of significant susceptibility to the occurrence of geohazard, which are the product of natural erosive processes and mass movements. In the coast sector, one of the most representative processes of geotechnical instability is the soil or debris flow (mass movements of soils). The occurrence of this type of flow has a greater incidence in the torrential creek, which generate transport of large volumes of sediments during rainy seasons. The flow has destructive effects and therefore, it is necessary to analyze the geomorphological, geological and hydrological aspects of the main creek and rivers that crosses the ROW with the objective of maintaining the integrity of the pipelines. In Peru, the flows are associated and known as Huayco or Huaico. As an additional component, it is highlight that the Peruvian coast is located within the area of interaction between the South American Continental Plate and the Nazca Plate, where there is evidence of seismic activity with different magnitude that influence on the occurrence of geo-dynamic processes with certain periods of frequency that could change the terrane’s morphology. The current article describes technical aspects of identification, intervention, monitoring, and geotechnical control in sub-fluvial crossings with levels of potential damage to the geohazard defined as huayco in the integrity management program of PTS. This activity include 63 main sub-fluvial crosses, approximately 30% are of the seasonal flow regime, located in the coast zone; at the same time, these are tributary to main rivers of constant flow as is the case of the Pisco, Cañete and Mala rivers. In this paper, it is place a special emphasis on the fourth crossing of the Huáncano creek, because it is a place of potential impact in the occurrence of soil flows. Within the annual geotechnical maintenance of the sub-fluvial crosses, in the part of the Peruvian coast, for the operation of the PTS of TgP, bed and banks protection some works are implemented, such as: Check dams, re-channeling, levees and stone riprap (Stone armour). Likewise, a program of evaluation and technical inspection is develop: it includes the analysis of the expected levels of undermining and performance condition of the existing works, which allow defining the geotechnical intervention in a term according to the identified risk level. All in all framed within a process of permanent geotechnical monitoring of the right of way. Finally, it is highlighted that to date the application of the process described above has been continued, which has facilitated the development and continuous assessment of the risk condition by huaycos in the PTS of TgP. This program has maintained an operation with an acceptable level of risk in the areas of interest and avoiding problems and consequences of great impact to communities, the environment and the operation of the system.

An analysis was performed of the charts that are traditionally employed in the determination of the separation of geotechnical protective structures on rights-of-way, such as cut-offs and trench barriers. An analysis was performed for the specific study area, with information from the existing weather and rainfall stations, which made it possible to characterize more accurately the rainfall figure required for curve fitting. Furthermore, knowledge of the soils in the area made it possible to classify them in terms of erodability. This classification was used to establish curves that better reflect the actual conditions of the soils of the rights-of-way. A conceptual analysis was performed of the need for the implementation of these structures in order to control erosion along the rights-of-way. This analysis made it possible to propose changes in the materials specification, in order to optimize costs during construction. As a supplement to the study of the protective structures for the rights-of-way, the dimensions of the trench for the installation of the pipelines was analyzed. This analysis included a comparison of the actual construction dimensions of the trench against the dimensions recommended by international standards and the ones contained in the international literature. Certain Colombian projects that supplement the analysis are also cited. The foregoing findings were used in the preparation of certain recommendations regarding the reduction of the dimensions of the trench for certain specific technical, social, and environmental conditions. Last, based on the analyses that were performed, the study proposes certain changes in the operator’s current standards, primarily regarding items such as cut-offs, trench barriers, and the dimensions of the trench. These changes will lead to a reduction in the construction costs of the geotechnical protective structures for hydrocarbon-pipeline rights-of-way. These items are typical, because the pipelines in question are located predominantly on foothill plains.

The OPASC and the OSPAR are 10″ and 30″ pipelines, respectively, which interconnect the State of Santa Catarina and Paraná, crossing the Serra do Mar, in southern Brazil. In 2003, after conducting slope stabilization works on a point of geotechnical activity, vibrating string gauges were installed to monitor the stress in these pipelines, in addition to geotechnical instruments installed to monitor the slope. These gauges were installed in seven sections, with 3 instruments per section, along a span of 180 meters. Although the geotechnical instrumentation has shown no evidence of movement in the slope, the gauges recorded an increase in stress values in some of the sections within three months from the time of installation, however, they remained stable in their values for the next ten years. In 2013, blind hole tests were performed to determine the stresses in these sections and to verify the proper function of the gauges. The combination of these two measurement techniques, vibrating string gauges and blind hole tests, allowed for the determination of the stress state in sections, over time. From there, equivalent stress could be determined and compared with allowable stresses defined in standards. After the completion of the blind hole test and subsequent backfill, stress rose again at the same rate, returning to the level reached after the initial installation of the strain gauges. To reduce the stress level additional excavations have been made to relieve the stress on the pipeline, followed by backfilling performed in a controlled manner in order for the soil to properly compact, which reduced the stress value over the pipes. The graphs depicting variation over time of stress showed a significant reduction in the level of stress after the backfill. The main conclusions are listed as follows: a) the evolution of stress observed by the extensometers was primarily caused by pipeline settling; b) the vibrating string gauges are functioning properly and provide reliable readings even after ten years of service; c) the blind hole testing performed in conjunction with monitoring by vibrating string gauges can provide approximate values of the full stress state; d) after stress relief, backfilling of the trench must be carried out by compacting the soil beneath the pipe in order to reduce bending stresses due to the weight of the soil; e) backfilling of the trench, when not properly performed, can cause compressive stress in bending, reaching 390 mPa over the next few months.

Long range, distributed fiber optic sensing systems have been an available tool for more than a decade to monitor pipeline subsidence integrity challenges. Effective deployment scenarios are an important decision to be factored into the selection of this monitoring equipment and typologies relative to specific project needs. In an effort to analyze the effectiveness of various fiber optic deployment conditions, a controlled field experiment was conducted. Within this field experiment, a variety of distributed fiber optic sensors and point sensors were deployed in predefined positions. These positions relative to the pipeline were selected to support a range of deployment needs including new construction or retrofitting of existing pipelines. A 16-inch diameter by 60-meter long epoxy coated pipeline that was capable of being pressurized to mimic operating conditions was utilized. This test pipe was installed in a typical trench setting. Conventional point gauges were installed at key locations on the pipeline. Fiber optic sensor cables were installed at key locations providing 14 alternative scenarios in terms of sensitivity, accuracy, and cost. After construction of the test pipeline, real time continuous monitoring via the array of conventional and fiber optic sensors commenced. A deep trench was excavated adjacent and parallel to the central portion of the pipeline which began to induce subsidence in the test pipeline. Continued monitoring of the various sensors produced real time visualization of the evolving subsidence. A comparison of the reaction of the sensors is compiled to provide an intelligent selection criteria for integrity managers in terms of accuracy, deployment, and costs for pipeline subsidence monitoring projects. In addition, further analysis of this sensor data should provide more insight into pipeline/soil interaction models and behaviors.

Technological advances have improved pipeline capacity to accommodate large ground deformation associated with earthquakes, floods, landslides, tunneling, deep excavations, mining, and subsidence. The fabrication of polyvinyl chloride (PVC) piping, for example, can be modified by expanding PVC pipe stock to approximately twice its original diameter, thus causing PVC molecular chains to realign in the circumferential direction. This process yields biaxially oriented polyvinyl chloride (PVCO) pipe with increased circumferential strength, reduced pipe wall thickness, and enhanced cross-sectional flexibility. This paper reports on experiments performed at the Cornell University Large-Scale Lifelines Testing Facility characterizing PVCO pipeline performance in response to large ground deformation. The evaluation was performed on 150-mm (6-in.)-diameter PVCO pipelines with bell-and-spigot joints. The testing procedure included determination of fundamental PVCO material properties, axial joint tension and compression tests, four-point bending tests, and a full-scale fault rupture simulation. The test results show the performance of segmental PVCO pipelines under large ground deformation is strongly influenced by the axial pullout and compressive load capacity of the joints, as well as their ability to accommodate deflection and joint rotation. The PVCO pipeline performance is quantified in terms of its capacity to accommodate horizontal ground strain, and compared with a statistical characterization of lateral ground strains caused by soil liquefaction during the Canterbury earthquake sequence in New Zealand.

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.

One of the major concerns for pipeline operators is to efficiently monitor the events happening over the pipeline corridor, or right-of-way (ROW). Monitoring of the ROW is an important part of ensuring the safe and efficient transportation of oil and gas. Events occurring within this zone require rapid assessment and, if necessary, mitigation. These events could be physical intrusions such as encroachment from growing settlements, impact of vegetation, pipeline leakage or geo-environmental hazards. Analysis of satellite imagery can provide an efficient and low cost solution to access and quantify change across the ROW. Examining these events over a periodic interval requires implementation of specific methods that can support the on-going monitoring and decision making practices. In this context, satellite remote sensing images can provide a low cost and efficient solution for monitoring the physical and environmental impacts over the ROW of pipeline system. This paper reports on the development of a methodological approach for environmental change analysis using high resolution satellite images that can help decision making in pipeline systems. Analysis results and maps produced during this work provide an insight into landcover change over the study area and expected to support in on-going pipeline management practices. Two methods, Vegetation index differencing and post classification comparison have been implemented to identify change areas in the Taranaki region of the North Island of New Zealand. Vegetation index differencing with NDVI shows increase or decrease of overall vegetation within the study area. Special focus was given on large area increase and decrease with area threshold value above 0.2 hectare. Detailed analysis of change was conducted with post classification comparison method that uses land cover classification results of year 2010 and 2013. An overall change of 10% has been observed throughout the study area with large area change of approximately 5%. Results obtained from post classification comparison method were further analyzed with 6 focus areas and compared with the existing soil data and rainfall data. The methods adopted during this study are expected to provide a base for environmental change analysis in similar pipeline corridors to support decision making.

The principle of redundancy in the analysis of pipeline integrity has taken on particular significance in recent years, thanks to the integration and relating of information obtained from various sources, which include, smart pig runs, visual right-of-way inspections and monitoring of the land and the pipeline. This document contains information related to the monitoring and analysis prior to emergency actions taken in the case study presented, located in northeast Colombia, where the effects of mining activity and excess rain during the winter period of 2010–2011 combined. The integrity information available with regard to background, visual right-of-way inspection, threat and risk assessments, direct monitoring of the pipeline and the analysis of deformation by bending, which Ecopetrol’s Office of Vice-president for Transportation and Logistics (VIT) made at the site, was taken into account. In addition, it includes a description of the interrelationship of such information, the findings in the activities conducted during the attention to the site, for the purpose of identifying the evidence related to external loads exerted by the land in the soil-pipeline interaction, which made it possible to better determine the proposed plan of action. The redundancy in the analysis of this information makes it possible to more accurately determine the root cause of the problem, the interaction between the phenomenon (external load - geotechnical event) and the pipeline, by which attention was directed in the field and action plans were obtained that better mitigate the threat and guarantee more safe and reliable operation.

With regard to hydrocarbon transmission lines, the analysis of susceptibility to external corrosion constitutes a fundamental tool in formulating management plans for the purpose of mitigating such threat by establishing protection barriers that are appropriate for the environmental characteristics identified. This document presents a perspective from the management of the Weather-related and Outside Force Threat as a contribution to the determination of the corrosivity index for the electrolyte by relating the lithological units of soils with their potential for generating electrochemical oxidation-reduction processes that can lead to the corrosion of buried pipelines.

Extreme meteorological events associated with climate change are a real issue and have important impact over the economy of infrastructure sector, including highways, hydrocarbon transport by pipelines, mines, etc., because saturation of soils by water can produce landslides and it could produce the fracture of pipelines or other kind of tangible assets. For example, an assessment of historical geotechnical failures in Ecopetrol (Colombian Oil Company) vs. extreme meteorological events shows that during La Niña (extreme rainfall period) geotechnical failures are three times greater. This work shows a method to identify places of risk by extreme meteorological events, mainly La Niña phenomenon, with focus in most probably alteration of rainfall. Our results illustrate the hot spots where there is a high probability of slight excess (120–160% of average rainfall) and high excess (>160%) of average rainfall. The results were intersected in a GIS with pipelines and mass movement risk maps to identify the places of high risk along Santander region.

The OCENSA pipeline system crosses a wide range of geological zones, finding different stability problems. Those problems related with landslides are stabilized with different kinds of geotechnical works within the pipeline maintenance programs, but sometimes these problems reach big dimensions making very difficult to stabilize them, so mitigation techniques are necessary in order to guarantee the pipe integrity. A mitigation technique using EPS (Expanded Poly-Styrene) blocks is being used in the OCENSA pipeline system (Colombia) in order to reduce the buried pipe response due to soil displacements during landslide events and in creeping slopes. OCENSA is the first operator in Latin America using this technique. Prior to the use of this technique, numerical modeling studies were done with the support of SOLSIN S.A.S. These studies were focused on determining the viability and effectiveness of the proposed technique. The purpose of the EPS blocks is to constitute a low-density fill with very low Young modulus reducing the soil-pipeline interaction forces. These blocks are located near the landslide limits in both, the stable and un-stable zones in order to reduce the stiffness of the materials around the pipe. These blocks allow the pipe to move beyond the landslide limits, reducing the bending strains. The extension of the EPS backfill is determined by means of the geotechnical investigation of the place in study and using the in-line inspection tools data to determine the length of the pipe affected by the soil movement. In this paper, three case studies are presented in which the proposed mitigation technique effectiveness was proved. In this part, data analyses coming from the in line inspection program was done. The inertial tool data showed that the EPS blocks had a significant effect on the pipe response, reducing the total strains compared with those obtained with a normal backfill. This technique can be used to reduce the frequency of the strain-relief excavations in unstable slopes. That means a cost reduction in the pipe maintenance activities and a more efficient integrity management program.

When a buried pipeline is exposed in the middle of a river, the need of a mitigation action immediately arises. Lowering the pipeline by natural flexion is sometimes chosen after competing in magnitude, complexity and cost with other alternatives such as river bank and bed erosion control protections. Although simple in its conceptual design, its implementation requires taking into consideration several factors that can affect its successful outcome in terms of the final position of the pipeline and the remediation measures needed to restore the terrain and environment to its original situation. Five different field cases are presented: Río Colorado, Río Santa María, Río Negro and Río Suquía, all of them located at northern Argentina, and a fifth one placed at the Patagonian desert. For each of them references are made regarding the following issues: reasons for the selection of this option, in or out of service movement operation, depth of burial, design of the lowering curve based on pipe allowable tensions, topographic reference system, ditch design, drainage and stabilization, need for river diversion, lowering equipment, ditch interceptors design, ditch filling and soil compaction procedure, and ROW remediation. Finally, a set of recommendations are included as a way to share this experience and provide a guideline for future works.