London Underground Comprehensive Review of Flood Risk (LUCRFR)

Transcription

1 London Underground Comprehensive Review of Flood Risk (LUCRFR) Nick Bean Mott MacDonald Anthony Fernihough London Underground Ian Uttley London Underground 23 rd February 2016

2 LUCRFR To undertake a comprehensive review of all sources of flood risk to all of London Underground s Vulnerable Assets.

3 LUCRFR Flood An overflow / accumulation / sudden release of water that submerges LU assets that are not normally submerged, or flows over LU assets causing dampening with the potential to result in disruption to LU operations, significant asset damage / reputational effects and / or safety risk to passengers, employees and / or the general public. Vulnerable Asset (VA) An asset which will cease to function as intended if inundated with flood water and, by ceasing to function as intended, will have an adverse effect on the ability of London Underground to run a normal service. Risk Risk is a consideration of the likelihood of an adverse event occurring together with the consequences that might result. The frequency of the flood event (e.g. burst water main causing LU asset inundation) is multiplied by the consequences of the flood event (impact on station and running lines in both safety and business terms) to produce an average annual risk exposure.

4 Background to the project Between Flood Mitigation Project (FMP) assessed the network for flood risk, but only considered safety risk, and did not assess pluvial flooding. June 2012 a water main burst ruptured 150m from the Old Ford Vent shaft. 3million litres of water inundated the tunnel flooding the Central line for 26 hours.

5 Risk Based Approach to Managing Floods Safety Certificate and Authorisation under The Railways and Other Guided Transport Systems (Safety) Regulations (ROGS) that the residual (post mitigation) safety risk from flooding must always remain As Low as Reasonably Practical (ALARP). Standard of Protection is 1:200 years (plus relevant climate change)

6 LUCRFR - Process Since 2001 improvements to modelling and GIS techniques. A more precise methodology of modelling and GIS recording, has led to a reduced cost Quantification of the magnitude of flood Quantified Risk Assessment Recommendations for mitigation measures

7 Sources of Flooding Risk to LU Natural Flooding Tidal and Fluvial Surface Water (Pluvial) Ground Water Flooding Canal and Reservoir Flooding Man Made Flooding Sewer Flooding Burst Water Mains

8 Flood Hazard Analysis Tidal / Fluvial (Out of Bank / Overtopping) Tidal / Fluvial Breach Pluvial Surface Water (and Sewers) Groundwater Burst Water Mains

9 Flood Hazard Analysis Flood outlines used for assessment and review Sources EA, LLFA, BGS

10 Quantified Risk Assessment Flood risk sources used Pluvial having a RP of 1 in 200 years Water main bursts Direct connection from 3 rd party sewer 80 sites have high volume of water inflow with an annual (safety and business) risk value of >= 15K/year (Highest value 462K/year) Total annualised flood risk approximately 6.1M

11 Flood Risk WebGIS Portal Key output from the review Shows Potential Points of Water Entry Flood Hazard information Automatic production of flood hazard mapping Functionality to search specific flood risk and LU asset

12 Conclusions 80 sites are at high levels of Risk 74 sites are at significant levels of Risk Total Annualised Risk approximately 6.1M Ongoing review of sites and a programme to address the High Risk sites with Site Specific mitigation. Ongoing detailed assessment of lower priority sites and assets