Pipeline Risk & Pipeline Pollution Risk Assessment

LandTech has developed and demonstrated an integrated system in order to assess on a routine base failure and pollution risk along the path of a planned or existing pipeline. This powerful, easy to use tool (which is designed specifically for each case history considering the peculiarities of each individual pipeline) allows end users to prepare comprehensive Risk Assessment models for their pipeline systems. This will help determine where potential exposures exist and how to minimize the potential for failures where the risk is greatest to public safety and environmentally sensitive areas.

For each pipeline segment various factors (such as local geology, probability of seismic motion, corrosion index, leak impact factor etc.) are scored and based on the score and the impact of a potential failure a value is assigned. As a result we can determine which segments are at higher risk, and determine what actions, if any, can be taken to reduce the risk. With this methodology we focus our time, effort and money in areas where the environment and public is most at risk.

The principal methodologies followed, stem out from well approved and adopted methods in the construction of seismic scenarios of earthquake prone cities and the prediction throughout numerical modeling of the movement of pollutant in the Earth’s crust.

Obviously, a pipeline due to it’s considerable length, passes throughout a great variety of geological formations and it is characterized by a rather non-uniform and complicated failure risk distribution along its length.

If one wants to define the pollution risk due to failure, has to think of the following two components: a) the failure risk of the pipeline components and b) the degree of presence o pollutant prone geological formations at the point of failure.

Local effects such as: active faults crossing the line, slope stability problems, fall of overhanging rocks, man maid accidents etc.

Distant effects: as those we characterize the strong ground motion at the foundation site due to earthquake activity. It is also possible that the prevailing geological conditions along certain paths of the line to result in a strong amplification of the seismic motion (site effects) and cause considerable strain deformation along the axis of the pipeline.

As r as the oil pollution it’s self is concerned, obviously this is determined by the characteristics and the distribution of pollutant prone geological formations at the point of failure and the presence of environmentally sensitive natural and man make objects (lakes, forests, streams, rivers, villages, etc.).

Site investigation for new pipelines

LandTech offers also detailed geophysical site investigations along the route of a planned pipeline.

The majority of our work in this field is during the early planning stages for dredging and pipeline installation projects.

It is essential, if dredging is envisaged, that the client and consultant can accurately estimate the cost of dredging. This cost can increase dramatically if the material to be removed is hard to dredge. For example if the seabed consists of sediments such as silts and sands the dredging cost is likely to be only 10% of the cost of removing rock.

The following important information to the design engineers can be obtained by LandTech’s geophysical investigators.

For pipeline river crossing the following info can also be provided.

Pipeline pollution scenarios (LandTech’s methodology)

Assessment of failure risk

This part of the project focuses on the subject of recognizing those sections of the pipeline which possess the highest probability of failure. This failure, as previously mentioned, can be either the effect of local geotechnical factors or the effect from distant earthquake activity.

In situ risks

The principal local factors which can cause the failure of a pipeline are the following:

The methodology which will be followed to determine the above mentioned factors will be the development of a GIS based system gathering all the existing information from air photos to geological, geotechnical, hydrogeological and seismotectonic maps. This data base will be used to define those parts of the line’s route which require special in situ geological or geophysical investigations or additional non-destructive tests.

Seismic risk

In earthquake prone areas, the failure of the pipeline due to strong seismic ground motion is the main factor which should be taken into account. Due to the importance of this factor we describe the corresponding phases which will be adopted to define the seismic risk.

In the past several years, there has been a significant increase in the understanding of the physical parameters that affect the amplitude, spectral and temporal characteristics of strong ground motions experienced during earthquakes. In 1985, the destructive Michoacán, Mexico earthquake and the Hansin Kobe 1996 earthquake made seismologists and earthquake engineers all over the world realize how important the effects of surface geology are.

In many cases, it has been shown that even simplified geological models can be used for the synthesis of the expected strong ground motion which compares relatively well with the observed pattern of damages. LandTech follows the following methodology to construct seismic scenarios along the pipeline route:

As a result of the previously presented analytical investigations of the various factors controlling the expected site response behavior along the route of the pipe line will be the identification of its parts possessing the greatest failure risk. These results will be given in the form of either a probability of exceeded of strong motion along the route of the pipeline in various time intervals (10,50,100 years) or in the form of failure risk taking into consideration the mechanical characteristics of the various parts of the pipeline. The final conclusion of this stage of the project will be the characterization of the various sections of the pipeline by their Failure Risk Index (FRI) as follows:

Assessment of Pollution Index

One of the principal factors which control the severity of pollution caused by the sudden failure or leakage of an oil pipeline, is the distribution of pollutant prone geological formations at the vicinity of the failed section.

By using the already developed GIS based data base, all the geological formations along the foundation route, will be characterized according to their pollution potential in a more or less qualitative matter.

This characterization will span from meaningless pollution potential (e.g. clays) characterized by a Pollution Index (PI) of I to extremely pollutant prone formations (e.g. sands and gravels) characterized by a pollution index of IV. During the assessment of the pollution index, special environmental factors (e.g. lakes, streams, national wild parks, etc.) will be taken into consideration.

The next stage will be to compare failure and pollution risk indexes all along the route of the pipeline and assess the Total Pollution Index, (TPI) taking into consideration both the failure risk and the potential of the prevailing geological formations to transport the oil spill and spread the pollution. The characterization of the sites by their total pollution index, will be based on the following table:

Total Pollution Index

Sections, along the pipeline, characterized by high values of total pollution index (1&2) will be given particular consideration and will be the subject of assessing various pollution scenarios and non-destructive tests.

Construction of pollution scenarios

An invaluable tool in the effort to mitigate pollution along oil pipelines, will certainly be the beforehand knowledge of those parts of the line characterized by the highest failure risk and the possible mechanisms (scenarios) of the movement of the pollutants within the surrounding the pipe pollutant prone geological formations.

The proposed methodology will permit the examination of various pollution scenarios employing a specifically designed Pollution Assessment Scenario Software Shell (P.A.S.S).

The general structure of P.A.S.S. system is designed in a user friendly way to ensure that even non computer experts could use it and test various pollution scenarios. In order to understand the operation and use of the above system, we will describe an example of a fictitious pollution scenario.

Let’s suppose that an earthquake of magnitude 6.8 occurs at a certain distance from the route of the pipeline. The system will automatically display those sections of the line possessing the highest probability of being seriously affected. It will also alarm along those parts which possess the highest pollution risk. The user of the system, could then cause an artificial leakage (pollution scenario) of the pollutant fluid (heavy oil) and follow in a graphical presentation it’s spreading within the surrounding pollutant prone geological formations. It will even warn on the expected time of affecting nearby streams or lakes.

Obviously the systematic evaluation of various types of scenarios will permit to prepare various measures to be taken immediately without delay in cases of real pipeline failures.