Engineering Consultants & Chartered Building Surveyors - - PowerPoint PPT Presentation

www.richardjackson.uk.co m

• Building Surveying
• Insurance Surveying
• Project Management
• Expert Witness
• Structural Engineering
• Civil Engineering
• Pre-planning & Flood Risk
• Geotechnical Engineering

Engineering Consultants & Chartered Building Surveyors www.rj.uk.com

We Welco come me

Mart rtin n Do Doughty ghty, , Di Dire rector tor Richard Jackson Limited

www.rj.uk.com

Pl Planning anning for Flood

• d Risk

k Management anagement

• History
• Current Policy – Sequential and Exception tests
• How potential solutions translate into planning

requirements

www.rj.uk.com

History tory of Flood

• d Management

anagement

• Parish based maintenance of drainage infrastructure
• Break up of water industry post 1974 worsened the

situation interested parties include

– Environment Agency – Highways Authorities – Sewer Authorities – Lead Local Flood Authorities – Internal Drainage Boards – Local Authorities – Land Owners

• Little joined up thinking and silo approach

www.rj.uk.com

History tory of Flood

• d Management

anagement

• Hard engineering systems installed over time

Advantage tages: s: – Self cleansing – reduces maintenance – Improved public health Disadvanta dvantages: – Limited capacity – Out of sight out of mind

www.rj.uk.com

History tory of Flood

• d Management

anagement

• PPG 25
• Michael Pitt review after flooding in 2007 made a number of

recommendations

• PPS25 and then NPPF
• Flood and Water Act:

Reduce flood risk Improve flood risk management Risk based approach on Reservoirs Encourage use of Sustainable Urban Drainage Systems Enhance water quality Improve water management in drought Financial changes www.rj.uk.com

Cur urrent ent Flood

• d Risk

k Management anagement Po Policy cy

National Planning Policy Framework And Planning Practice Guidance These require a two stage approach

– The sequential test – The exception test

Local Policy

• Shoreline Management Plans
• Catchment Flood Management Plan
• Local Plan
• LLFA Standing Advice
• Strategic Flood Risk Assessments
• Surface water management plans

www.rj.uk.com

The he Seq eque uential ntial Tes est

NPPF Section 10 Meeting the challenge of climate change flooding and coastal change Para 101 “The aim of the sequential test is to steer new development to areas with

the lowest probability of flooding. Developments should not be allocated

• r permitted if there are reasonably available sites appropriate for the

proposed development in areas with a lower probability of flooding. The Strategic Flood Risk Assessment will provide the basis for applying this

• test. A sequential approach should be used in areas known to be at risk

from any form of flooding.”

www.rj.uk.com

The he Seq eque uential ntial Tes est

Flooding – understanding your risk

www.rj.uk.com

Sour urces ces of Fl Floodin ding

www.rj.uk.com

In Intern rnal l Floo

• odi

ding ng

• Not a planning issue

www.rj.uk.com

Extern rnal al In Infra rastructure structure

• Water Mains
• Adopted
• Private
• Sewers
• Foul water
• Surface water
• Private systems

Private, adopted or highways

www.rj.uk.com

Exte ternal rnal In Infrastructure rastructure

• How to assess risk currently difficult
• Lead Local flood Authority – County Councils
• Sewers are generally designed for 1 in 1 or, 1 in 30 year events
• Water Companies maintain a list of assets that have flooded
• Planning policy requires new developments to respond to 1 in 100

year event with climate change

www.rj.uk.com

Sur urface face Wa Wate ter Flooding

• ding - Pr

Prec ecipitati pitation

• n
• Flood routeing and threshold design
• Design for Exceedance

www.rj.uk.com

Fluvi vial al Floo

• oding

ing - Rivers rs

• Fluvial
• Rivers
• Streams
• Ditches
• Causes
• High flow/lack of

capacity

• Blockage

www.rj.uk.com

How to assess ss Fluvi vial al Risk

• What zone are you shown to

be in on Environment Agency mapping

• Review strategic flood risk

assessment

• Is there a source near your

site

• What is the landform like
• Is there a culvert that may

cause a blockage

• If a main river ask

Environment Agency

• If a water course ask Local

Authority

www.rj.uk.com

Ti Tidal Floo

• od

d Risk

• What zone are you shown to

be in on Environment Agency mapping

• What does the strategic

flood risk assessment say

• How far is the sea/estuary
• Is there any defence or

barrier – is it high enough

• If so ask how this is

managed and maintained

• What is the policy in the

Shoreline Management Plan for the area

www.rj.uk.com

Gro roun und d Water

• Not currently mapped by

anybody although suitable geology is

• Environment Agency and

Local Authority may be aware if there is a history

• The Environment Agency

are gathering information about this risk

• Is your building in an

area that could retain water e.g. low depression

www.rj.uk.com

Reservo rvoirs rs & Ca Canals

• Often hold water above

ground level

• Environment Agency

mapping available

• Risk of flooding associated

with failure

• Monitored under Reservoirs

Act currently

www.rj.uk.com

Seq eque uential ntial Tes est

• There is no fixed way to apply the sequential test
• It could be district/borough wide
• Smaller regeneration areas can be ring fenced
• Marketing areas can be defined
• Exception sites for affordable housing

www.rj.uk.com

Excepti ception

• n Tes

est

www.rj.uk.com

Excepti ception

• n Tes

est

NPPF para 102

• It must be demonstrated that the development provides

wider sustainability benefits to the community that

• utweigh flood risk, informed by a strategic flood risk

assessment where one has been prepared; and

• A site specific risk assessment must demonstrate that the

development will be safe for its lifetime taking account of the vulnerability of its users, without increasing flood risk elsewhere, and where possible will reduce flood risk

• verall.

www.rj.uk.com

Excepti ception

• n Tes

est t – Pa Part t 1

• Responds to the Local Development Plan
• Provides housing where there is a 5 year land supply

deficit

• Provides needed facilities

www.rj.uk.com

Excepti ception

• n Tes

est t – Pa Part t 2

Safe for its lifetime

– 100 years unless limited life proposed – Finished floor levels – Flood resistance and resilience

www.rj.uk.com

Excepti ception

• n Tes

est t – Pa Part t 2

Taking account vulnerability of its users

– Safe access and egress – Evacuation in events (Emergency Planners)

Without increasing flood risk elsewhere

– Consume your own smoke – Match existing surface water run off rate (SUDS)

Where possible reduce flood risk overall

– Brownfield sites reduce run off by using SUDS

www.rj.uk.com

How poten ential tial so solutions tions translate slate into plann nning ing req equire ireme ments nts

Building Safe

– Raise floor levels – Structural integrity – Flood resistance, barriers, valves land raising – Flood resilience, suitable construction and less vulnerable use on lower floors

People Safe

– Access and egress during design flood events – Warnings and evacuation if appropriate – Refuge for defence failures and extreme events

www.rj.uk.com

How poten ential tial so solutions tions translate slate into plann nning ing req equire ireme ments nts

Two main types

– How the development form responds to the risks of flood and any residual risks – How the development reduces risks on and off site

www.rj.uk.com

How poten ential tial so solutions tions translate slate into plann nning ing req equire ireme ments nts

• Reduction of surface water run off rate – SUDS
• Opportunities to reduce existing flooding by returning

brown field sites to pre-development condition

www.rj.uk.com

The he cha hallenges llenges th that at rem emain ain

• Adoption

– Planning policy and adoption are out of step - Still

– Maintenance who pays for SUDS maintenance

• Strategic defence improvements on the shoreline
• Upstream impounding schemes to protect existing urban areas of risk
• Retrofit water reuse systems
• Garden paving enforcement
• Retrofit SUDS to existing built

environment

www.rj.uk.com