How Does Benefit Cost Analysis Help Make Decisions About Flood Management

Environmental analysis

Environmental impacts of proposed options

Option / Key Positive Impacts / Key Negative Impacts
Do nothing /

Significant increase in flood risk and damage/disruption to people, property, ecology and cultural heritage.

Do minimum /

Increase in flood risk and damage/disruption to people, property, ecology and cultural heritage.

Option 3: Low Wall /

Improved flood protection to Uckfield town centre
short construction period with no modification to existing channel
opportunity to enhance vegetation around Kennet House and in the car park area through vegetation plantings
installation of an interceptor pit on the new surface water outfall

Removal of several trees and vegetation around Kennet House, which may impact on nesting birds if undertaken from March – August.
Minor clearance of vegetation in bypass channel, which may impact on nesting birds if undertaken from March – August.
Temporary impact on local community, traffic and transport from construction activities

Option 4: High Wall /

Potential tree loss/damage in LNR and in back gardens of properties along Olives Meadows and associated potential impact on bat habitat
Potential impact to one Tree Preservation Order (TPOs)
Potential impact associated with proposed riverside walk and river crossings leading from Somerfield car park towards Hemstead Mill and south of High St bridge
Loss of visual amenity through construction of visually intrusive walls on northern and southern banks of the river
Potential for impact to the grounds of two listed buildings, Bridge Cottage and Uckfield Mill which may trigger Listed Building Consent.
Increased flood risk to one listed building, Uckfield Mill

Option 5: Wall & downstream Channel /

Improved flood protection to Uckfield town centre
Scope for access improvements and the development of additional riverside walks potentially with disabled access
Potential to enhance fish passage through the bypass channel
Enhanced flood protection of one listed building, Bridge Cottage
opportunity to enhance Local Nature Reserve through tree plantings etc

Potential tree loss/damage in LNR and in back gardens of properties along Olives Meadows and associated potential impact on bat habitat and breeding birds (March – August inclusive).
Potential damage to LNR through excavation and construction impacts
Permanent loss of industrial/commercial properties downstream of High St Bridge
Potential impact to one TPO
Potential impact associated with proposed riverside walk and river crossings leading from Somerfield car park towards Hempstead Mill and south of High St bridge
Loss of visual amenity through construction of visually intrusive walls on northern and southern banks of the river
loss of mature trees and bankside vegetation
Potential for impact to the curtilage of two listed buildings, Bridge Cottage and Uckfield Mill which may trigger Listed Building Consent.
Increased flood risk to one listed building, Uckfield Mill

Option 6: Upstream Storage /

Improved flood protection to wider area of Uckfield town centre
Provision of additional informal recreation opportunities in the community such as walking, fishing, boating
Potential for positive impact to upstream and downstream environment dependant on flooding regime

Potential tree loss through construction of water retaining structure and associated potential impact on bat habitat
Permanent and temporary damage to terrestrial ecology/agricultural land use during flood storage
Impact on landscape values and visual amenity
Potential archaeological impact, i.e. one SM, ASAs and recorded archaeological sites.
Potential negative impact to upstream and downstream environment dependant on flooding regime;
Potential for degradation of downstream river habitat due to reduction in scale of flood events

LNR: Local Nature Reserve

TPO: Tree Preservation Order

SM: Scheduled Monument

ASA: Archaeologically Sensitive Area