The influence of soil on the impacts of burst water mains on infrastructure and society: A mixed methods investigation

Society relies on infrastructure, but colocation and interdependencies make infrastructure systems vulnerable to cascading failures. This study investigated cross-infrastructure and societal impacts of burst water mains, with the hypotheses that (1) burst main-triggered cross-infrastructure failures are more common in sandy soils and (2) mixed-methods approaches are more beneficial than pure data analysis for understanding the wide-ranging impacts of these events. When water mains in sandy soils burst, pressurised water can create sub-surface voids and abrasive slurries, contributing to further infrastructure failures. To investigate the role of soil in hosting cascading infrastructure failures, maps of soil sand content for England and Wales were created. Analysis of the infrastructure impacts arising from burst mains combined; (1) spatio-temporal clustering and analysis of infrastructure failure data, (2) meta-analysis of web-based media reports of burst mains impacting on other networks, and (3) workshop discussions and structured interviews with infrastructure industry experts. The workshop, interviews and media reports produced a greater depth of information on the infrastructure and societal impacts of cascading failures than the spatio-temporal data analysis. Cross infrastructure impacts were most common on roads, built structures and gas pipes, and occurred at a higher rate in soils with very high sand contents.