Drainage Challenges The need for LoDEG Owen Davies Sustainability Engineer Environmental Services & Highways 21st November 2011

Introduction

What is London at risk from? Coastal Fluvial Pluvial Groundwater Reservoir Sewer Human EA LA TW TW (generally)

Pluvial Flooding Hampshire 2000 Boscastle 2004 Leeds 2007 Cumbria 2009 Bournemouth 2011 “There has been an instance of serious Surface water flooding every month in the UK since June 2007”

Groundwater Flooding Water table rising No industry Natural Spring lines/resurgence points Peckham spring Geology Clay

Worked Example

Lambeth Pluvial Risk (1:100+CC)

Historical Rivers

Historical Flooding

Sewer Network

So what is the Problem? 1:15 design standard too low for a modern city? Combined sewer Has it encouraged a “Three Monkey” approach?

Anything else? Loss of front gardens? Did we ever need grass verges? Traffic calming? Enforcement? Efficiencies? Design?

Nothing else then? “I am informed that the flooding has been the same for the past eight to ten years in times of sudden and heavy rainfall. If you have any suggestions to offer as to dealing with the trouble I shall presume to hear from you in due course“ Mr Fitzmaurice, LCC to Borough Engineer 29th August 1911

What we Know (Lambeth) Not a case of if but when 49,813 properties at risk (3-10cm) = 37% of the entire housing in Lambeth. Insurance cost at 2007 prices of £1.2bn Does not include asset or EP costs (Roads £83m) The areas at risk from Surface/ground Water flooding The areas Lambeth controls/influences

What we Know (Lambeth) Cont… 19% or 22,976 increase in housing stock 9.8m/l a day increase in potable water use 159m/l a day increase in sewage (not including surface water) Population growth to exceed 300k

Who can we blame? Thames Water? TfL? Housing? Education? Environment Agency? Defra? Victorians? Planners? History?

Challenges Understanding pluvial flooding Understanding Groundwater Understanding resources Understanding infrastructure & Assets Understanding responsibilities Understanding funding Understanding ownership

What do we understand? Pfra’s SWMP’s Hazard mapping CDA’s Assets

Solutions SUD’s Green Infrastructure (GI) Blue Corridors Design Maintenance Enforcement LoDEG

LoDEG 19 Boroughs responded + TfL & London Councils 60% response rate Q1 100% in favour of LoDEG Q2 90% in favour of meeting quarterly Q5 100% in favour of training

Areas of concern Resource/Funding = 25% Asset = 15% SUD’s = 15% SAB = 8% Communications = 8% Flood Risk Plans = 7% Water companies = 2%

What will - is happening First Full Meeting 30th November 2011 2 Seats on TAG Coastal & Fluvial Committee Representation on ATDA Representation on LoTAMB Seeking acceptance to LoTAG 8th December 2011

Conclusion We are all in this together We cant control when it will happen We can control it’s affects and influence

Owen Davies Sustainability Engineer Environmental Services & Highways odavies@lambeth.gov.uk 07850 22 33 09