7344 – White Cart Flood Prevention

Scheme Contract 1 – Flood Storage Areas

• 1,710 residential properties at risk

• 40 businesses at risk

• 20 significant floods in last 100 years

• Last significant flood in 1990

• Events in January 2005 and October

2008 were close to flooding property

• Flood damages estimated >£100M

Project Scope

• Contract 1 comprises the construction of:

• 3 earth embankment dams

• 2 road bridges

• 275m flood defence walls

• Extensive environmental works

• Contract awarded to Carillion plc

• Starting date February 2008

• Planned completion in winter 2010

• 1,710 residential properties at risk

• 40 business at risk

• 20 significant floods in last 100

years

• Last significant flood in 1990

• Events in January 2005 and

October 2008 were close to

flooding property

• Flood damages >£100M

Spillway Crest

Vortex flow control

Screen

Screen

Culvert

Embankment dam

Typical cross section

Spillway protection –

articulated concrete mattress

Vortex flow control

Environmental mitigation

• Wetlands constructed at all sites

• Culverts designed for fish and mammal passage

• Extensive tree and shrub planting

• Replacement hedgerows

• Artificial badger sett

• Artificial Sand Martin bank

• Re-meandering of straightened channel

• Bird and bat boxes

Protecting the environment

Culverts – boulders

and baffles for fish

passage

Searching for bats

Otter survey in progress

Site issues – Kirkland Bridge

• Access to Mains Farm to be maintained at all times

• Early completion of flood defence walls required

• Large flows in the White Cart Water

• Sandmartins

• Tame deer

An uninvited visitor is

sent to get a yellow

vest and hard hat

Nesting Sandmartins in

face of excavation

Kirkland Bridge – habitat creation

Kirkland Bridge – October 2009

Borrow

pit Wetlands

Already the future benefit is clear?

• Numerous badger setts to be avoided

• Artificial sett to be created

• Service diversions and protection

• Overhead sewer

• Close to residential properties

• Very ‘flashy’ river

Site issues – Kittoch Bridge

Kittoch Bridge – habitat creation

Kittoch Bridge – October 2009

Borrow

pit

Wetlands

Site Issues – Blackhouse

• High voltage overhead power lines

• Right of way to be maintained

• Poor access from main transport routes

• Access to Blackhouse Farm to be maintained during

bridge construction

• Impacts on existing wetland to be minimised

• Imported fill for embankment construction

• Ground improvement required

Blackhouse – June 2009

Blackhouse – October 2009

Wetlands

Facts and figures

• Combined storage volume

• Peak flow reduction

• Flow controls

• Maximum dam height

• Earthworks

• Wetlands

– 2.6M cubic metres

– circa 45%

– 5 Hydrobrakes

– 15 metres

– 175,000 cubic metres

– 90,000 square metres