Barton on Sea

How do the strategies compare?

• First impressions?

• Which elements can you identify?

Hard Engineering• Mixture of wooden groynes and Rock

armour groynes.• Why – largely historical

Rock revetment • Replaces wooden revetment backed

by infill• Protects the toe of the slopes• Adds weight to the seawards side of

the slope system

History - outline• 1930s protection from timber groynes• Halted during war• 1964 to 1968 – Cliff toe protection – Timber revetment, rock revetment – timber and rock groynes = successful

• 1965 to 1968 Sheet pile cut off wall with drainage

• 1971 Replacement of timber with rock armour groynes

• 1996 Cliff drainage system replaced

Successful Revetment

Costs

• 1971 • Replacement with 90 000 tonnes

rock armour• Carboniferous limestone from Mendip

Hills• 1.5km coast• Each stone 2 to 6 tonnes• Provides toe protection and toe

weight

Success?

Overall role of holding the line successfulWithin the slope system collapses in 1975, 1993 and 2016.Sheet piling added in 65 to 68 with drainage, pore pressure overturned

Geology within system still allows percolation and so loads Charma bedsBoreholes in 2016 to 2017 to collect data

Ineffective Piling

Geology• Upper layers – Plateau gravels

• Upper, middle and lower Barton Clays – 3 layers

• Charma bed – water bearing sandy, silty clays.

• Area closed post 2016 upper slip

• FUTURE • 18 boreholes will

be drilled• 10 at cliff top• 8 in the under-cliff• 20m to 35 m deep

to collect data

• Aim – to better understand the sub-surface movement.

• http://www.southampton.ac.uk/~imw/barteros.htm

What about Naish cliff – West Barton

Naish • Holiday development which can be moved back

from edge c.f. substantial 1930s development in E. Barton

• TOO Expensive – groyne, toe protection, drainage c.f. a lack of permanent development

• 1993 – compromise solution suggested – 3 strongpoints would 1) diffuse erosion, 2) mainatain beach structure, 3) won’t damage geology SSSI, 4) improve recreational value.

• NOT IMPLETMENTED – suggestion that tension cracking and aerial erosion will continue until face resolves angle of repose.