North Beach Swanage Landslip – Cliff Stability Report Summary
August 2013
Local Councils and other organisations including the Coastguard, Environment
Agency, Swanage Coastal Change Forum and Living with a Changing Coast project
are working together to assist the landowners who were affected by the landslides at
Swanage North Beach during last winter. Although the areas affected are the
responsibility of the individual landowners, to help minimise cost and disruption,
Purbeck District Council would support a co-ordinated approach to any clearing-up
and stabilisation work. We are committed to helping with the clear-up, which will
require all of the landowners to play a full part in the process and to contribute to the
costs of necessary work. The co-ordinating organisations are open to discussion to
identify ways to reduce the costs (please see August newsletter for details of 11
October drop-in session).
The landslip zone includes protected areas (Sites of Special Scientific Interest and
Areas of Outstanding Natural Beauty) so relevant authorities will need to be
consulted and planning permission may be required prior to any work being carried
out.
Survey findings
To gain a better understanding of the current condition of the cliffs, the Environment
Agency granted Purbeck District Council emergency funding to commission a full cliff
stability survey and investigation of safety measures. The report is now available on
line at www.dorsetforyou.com/coastprotection/purbeck. The purpose of this leaflet is
to provide a summary of the findings and recommendations to help landowners
understand the risks in each area.
The site inspection identified 12 locations where recent cliff falls and landslips were
evident. To the south of the North Beach (to the left of Groyne 6 up to mid-way
between Groynes 8 and 9) there is evidence of relatively small cliff falls, debris falls
and debris slides which have either come to rest on beach huts, on the promenade
or behind makeshift retaining walls. In the central and northern areas, from
Burlington Chine up to Sheps Hollow (to the left of Groyne 12 up to Groyne 15),
larger landslips and mudslides are evident which, in some instances, involve
reactivation of previous cliff falls and landslips. The impact of these events has been
to overwhelm the promenade and upper beach with up to 1.5m deep debris and to
expose the upper cliffs which will be prone to further cliff falls and landslips.
The cliff falls and landslips were caused by the cumulative effect of a very wet
summer and winter in 2012/13 which raised ground water to exceptional levels in the
cliffs. Other factors that will have contributed to the problems in the longer term
include the effects of development and uncontrolled drainage on the cliffs, and
coastal erosion in the undefended areas by wave action from the sea.
Report Recommendations
Purbeck District Council with all stakeholders will help to co-ordinate a strategy for
managing cliff instability at North Beach in the long term and integrate it with the
shoreline management policy. The sites are shown on the enclosed map and further
details on each site can be found in the full report.
Site 1: A small cliff fall occurred impacting a private beach hut development. Cliff
protection measures should be installed to protect the development from future
events.
Sites 2-4: A cliff fall and debris slide run-out poses a substantial risk to a single row
of 30 timber beach huts and the promenade. A makeshift barrier erected above the
beach huts is close to failure. Cliff protection measures and a rock catch fence
should be installed to protect the beach huts, the occupants and the public using the
promenade.
Sites 5-6: Small cliff falls occurred which pose a significant risk to public. Cliff
protection measures should be installed to prevent cliff fall impact on the promenade.
Site 7: A shallow landslide affects mostly private land but outward displacement of
the block wall above the promenade poses a hazard to residents and the public. The
site should be stabilised and repaired.
Site 8: Cliff falls and landslip debris are resting on the beach huts. The debris should
be removed in a safe, controlled manner and cliff protection measures installed to
protect the beach huts and occupants from possible repeat events.
Sites 8-11: By virtue of their scale and impact on private development and shoreline
infrastructure, the cliff falls, debris slides and mudslides in this area pose an
unacceptable risk to the public in the short and long term. Urgent action is needed to
clear landslide debris from the upper beach and promenade and install structural
support and protection to the promenade to prevent run-out of debris onto the beach.
An Emergency Government Grant via the Environment Agency is helping to fund
clearing this section.
Site 12: There is a risk to the public of rock fall and debris slides along this section
and the public should be advised to keep off and stay a safe distance away from the
cliffs.
Further information can be found in the full report which is available on line at
www.dorsetforyou.com/coastprotection/purbeck. A paper copy of the report can be
obtained from Purbeck District Council at a cost of £5.00 to cover the cost of printing
and postage.
Enquiries regarding the report to Mike Goater, District Engineer, Purbeck District
Council, email: [email protected] or ‘phone 01929 557271 (Tuesday
to Thursday).