Modelling the geological factors in pipe failure for better infrastructure management

Lead Research Organisation: NERC British Geological Survey
Department Name: Environmental Modelling

Abstract

Water companies manage extensive networks of clean and waste water pipes. Sometimes these pipes fail catastrophically, resulting in; loss of supply to properties, public highway closures and potentially long-term inconvenience to business and the general public. Pipes also frequently suffer leakage resulting in loss of pressure, increased demands on water treatment works (increasing carbon emissions) and water-related ground instability for example. The potential for pipe failure is, to some extent, controlled by ground conditions, in particular soil corrosion and stresses resulting from ground movement. This project is concerned with understanding the relationship between ground conditions and pipe failure so that we can attempt to predict where pipes are more likely to fail. The project will focus on the Yorkshire Water region and will take advantage of their pipe failure database. Locations where pipe failure has occurred will be analysed against data on ground stability, terrain and soil corrosivity sourced from the British Geological Survey. A conceptual model of pipe failure and a map showing predicted failure rate will be developed. The results of this project are anticipated to improve the ability of Yorkshire Water to plan their asset investment strategies for repair and maintenance. This will allow them to target investment to pipes that are most susceptible to fail, and thus use customer's money more efficiently. It will also reduce the frequency of catastrophic pipe failures, long-term leakage and reduce diffuse pollution caused by leaking sewerage pipes and infiltration of groundwater into pipes (causing combined sewers to overflow). Whilst this project is specifically concerned with the Yorkshire Water region, the results and/or methodology tested during this project are anticipated to be transferable to other water companies.

Publications


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Description The aim of the project was to develop a spatial model that provides information on the environmental, topographical and geohazard factors that contribute to pipe failures within the Yorkshire Water (YW) region.

Previous methods of assessing how soil conditions contribute to pipe failure have generally not considered additional interacting factors, particularly how parent material and landscape influences the flow of water through the soil. Initially, models were developed to predict the expected number of bursts per unit area in the clean water pipe network. Further environmental (factors) e.g. road type (A, B or C road), topography (e.g. elevation, slope) and geohazard (eg soil corrosivity, ground movements) information were added to this null model.

Outputs from the model include the significant factors causing pipe failure in the Yorkshire Water region, and maps of model residual showing where the model under or over-predicts the density of pipe failures.

Both of these outputs can be used to inform the development of resilience in the pipe network, thus reducing leakages. Information regarding the significant model covariates can be examined in conjunction with maps of those environmental or geo-hazard properties (e.g. shrink swell) so that improved engineering solutions may be adopted in those areas. Maps of model residuals can be used to identify other factors not included within the model that may contribute towards higher than expected pipe failures (e.g. water source).
Exploitation Route We were awarded a second grant from NERC to refine the model and consider how the model may be applied to other regions. This grant brings in additional water company involvement from Scottish Water and Welsh Water.
Sectors Agriculture, Food and Drink,Environment,Other
 
Description The model developed in this project yielded a prioritised list of factors that are associated with (clean water) pipe failure in the Yorkshire Water (YW) region. Maps are available showing where these factors occur. YW will benefit from the model outputs as it will inform their future asset management strategies, which in turn will enable them to make more proactive maintenance decisions. In addition to the positive impact on YW, the methodology also has potential to be adopted by other water utilities in respect to clean and waste water as well as those organisations including National Grid and energy utilities that own and maintain both surface and sub-surface pipelines. YW provided the following statement: The impact for Yorkshire Water will be an improved understanding of how the geological, geohazard and other factors impact our infrastructure assets. We can use this information to assess whether different pipe materials or sizes are impacted differently. This could help us improve design standards for different pipe materials (eg plastic, ferrous, concrete). The model can also be used as a screening tool to identify regions where additional factors not related to model covariates are causing high incidences of pipe failure. There is the possibility that the outputs could be included within the infrastructure deterioration models that are used for future investment planning. We will invest approximately £300m on the renovation and rehabilitation of infrastructure assets. Although an exact figure is difficult to establish, some of this investment will be related to pipes that have failed due to external influences upon them.
First Year Of Impact 2016
Sector Environment
 
Description Environmental Risks to Infrastructure Innovation Programme
Amount £35,814 (GBP)
Funding ID NE/N013026/1 
Organisation Natural Environment Research Council (NERC) 
Sector Public
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 01/2016 
End 06/2016
 
Title New model to predict pipe failure 
Description A model was developed to provide information on the environmental, topographical and geohazard factors that contribute to pipe failures within the Yorkshire Water (YW) region. Outputs from the model include the significant factors causing pipe failure in the Yorkshire Water region, and maps of model residual showing where the model under or over-predicts the density of pipe failures. The outputs can be used to inform the development of resilience in the pipe network, thus reducing leakage. Maps of model residuals can be used to identify other factors not included within the model that may contribute towards higher than expected pipe failures (e.g. water source). 
Type Of Material Computer model/algorithm 
Provided To Others? No  
Impact Significant interest from Yorkshire Water. Work is ongoing to refine model 
 
Description Expert elicitation meeting 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Industry/Business
Results and Impact Four members of the British Geological Survey and 6 members of Yorkshire Water met to discuss the factors affecting pipe failure. The workshop resulted in a prioritised list of environmental factors that might cause pipe failure. Experiences of pipe failure in the Yorkshire Region was discussed.
Year(s) Of Engagement Activity 2015
 
Description Research meeting discussion of results and debrief 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Industry/Business
Results and Impact Two members of BGS and four members of YW staff discussed the results of the pipe failure project and the potential impact of those results on predicting pipe failure in the Yorkshire Water region. Yorkshire Water were very engaged and interested in the results gained and further work was discussed.
Year(s) Of Engagement Activity 2016