Scottish and Southern Energy (SSE) Distribution Management Programme North (DMPN) Flood Resilience Framework
Waterman were appointed as consultants by Scottish and Southern Energy (SSE) Distribution Major Projects (North) (DMPN) to undertake a Flood Resilience study. The aim of the year-long study was to determine the potential impact of flooding on at-risk critical electrical substations and to develop options to improve the flood resilience to a level that would be acceptable to SSE, Ofgem and the government.
The summer of 2007 highlighted that a number of electricity substations across the UK could be at risk of flooding. Whilst the floodwaters themselves caused extensive damage, it was the subsequent loss of critical infrastructure that proved the biggest problem, causing major social and financial upheaval in affected areas. This prompted a review of flooding resilience for primary and high voltage substations and the establishment of steps required to mitigate current and future flood risk.
SSE have some 435 Primary (Distribution) substations in their Scotland North area, 22 of which were deemed by Waterman to be critical due to the risk of flooding and potential disruption to customers’ supply, and therefore required further investigation.
Waterman’s scope was to carry out further investigation into the potential flood risk, impact of flooding and protection of the 22 critical substations, in accordance with guidance laid out in the Energy Networks Association Technical Report ETR 138.
The substation sites varied in size from those serving fewer than 500 customers in rural locations, to those serving over 30,000 customers in urban areas. The sites were located throughout the North of Scotland, from Shetland, to the Kintyre Peninsula; from the Isle of Lewis to Aberdeen.
Waterman adopted a systematic approach to assessing the flood risk and protection requirements for each substation. The flood risk to each site was considered from all sources, including fluvial, pluvial, coastal, groundwater, drainage and infrastructure failure. The initial phase of the study involved carrying out consultations with SEPA and local authorities to obtain flood records and to establishing whether sites were protected by existing flood prevention schemes. Site visits were carried out and topographical surveys were procured for each site to enable hydraulic modelling and flood risk assessments to be undertaken. As a result, the most appropriate flood protection was identified for each site.
The study, which was managed by the Hydrology team in Waterman’s Edinburgh office, concluded that 20 of the 22 substations required some mitigation, ranging from the installation of flood defence walls and bunding, to drainage improvements and sealing of building entrances.