Background Information

Why are these works required?

Due to significant ground movement and slope instability, the Green Seafront comprising Sandpit Field, Weather Station Field, and the ‘Spa’ beach hut area requires essential work to stabilise the land.

Ground movement in this location has been evident for a number of years with extensive ground stabilisation works being completed by the Council at the Recreation Ground in 2013/14. 

Following this, and further to receipt of a number of geotechnical reports and advice, in 2020 the Council commenced active monitoring of the extent and nature of this ground movement on  the Green Seafront.   This was achieved through the insertion of a number of bore holes  many metres deep to enable monthly monitoring of inclinometer and ground water levels to establish precisely the nature and extent of the ground movement. Monitoring results from 2020 to date have demonstrated substantial ground movement across the Green Seafront. This is in addition to defects to structures above ground such as stone walls and pathways that are visibly showing signs of stress and movement. 

In 2022 the Council engaged professional geotechnical advice to provide a Ground Stabilisation Feasibility study to assess the potential geotechnical solutions available to stabilise the ground. These remedial options set out a range of interventions that could be used, more likely in tandem, and included soil nails/anchorages, full reconstruction of existing walls as gravity walls or embedded retaining walls, slope regarding and granular replacement.

In 2023 the Council engaged further professional advice to identify defects across the Green Seafront and develop a risk register to enable determination of the rate of deterioration of assets in these locations.  These defects include:

Retaining walls with vertical and/or horizontal cracking, bulging or bowing, partial failure in bearing/overturning etc.; 

• Hummocky areas where surface distress was identified in grassed areas and footways; 
• Tension cracking forming in oversteep vegetated slopes; 
• Footway and stairway distress in the form of tension cracking, structural cracking, pavement settlement and heave;
• Dilapidated surface drainage and retaining wall weepholes, blocked or semi-blocked by debris and siltation.

Regular risk inspections have been completed since that time most recently in February 2025 and the Council is now monitoring 46 defects. As a result of these and other risk inspections many interventions have been made by the Council which include:

• Removal of a tarmac pathway approximately 30m in length 
• Installation of heras fencing on a retaining stone wall showing stress and cracking;
• Installation of an exclusion zone of circa 25m in length along a section of stone wall as a result of lateral movement.
• Resurfacing of a tarmac pathway due to deterioration due to ground movement
• Removal of benches and installation of ‘barriers’ created from railway sleepers to prevent access to specific risk locations,
• Installation of safety signage warning of uneven and shearing ground;
• Reinstatement/replacement of stone blocks due to overturning as a result of ground movement.
• ‘Fencing off’ specific locations to prevent public access as a result of unstable walls and other landscape features.

Access restrictions at Walrond Road, March 2025

 Professional advice has indicated that over time there will be an increasing risk of significant and sudden ground movement.  To give precise timescales or calculate the risk of this occurring at any given moment is not possible as this depends on a wide range of factors. What is evident however are the negative impacts of the ground movement that can be seen now, and which will continue and increase in their impact upon the use of these spaces.   These negative impacts therefore also include increasing risks of increased dereliction and costs associated with temporary/emergency works.

Evidence of the ground movement is visible if you visit the areas concerned – which show large areas of uneven ground and significant cracks in both retaining walls and in the footpaths. The Spa public conveniences and surrounding paths were closed to the public in 2018 due to ground movement. Swanage Town Council are now monitoring over 44 'defects'.

Whilst it is not possible to determine when a significant ground movement may occur, as this depends on a wide range of factors, there are consequences of inaction, e.g. risks of increased dereliction and costs of temporary/emergency works. Therefore, the essential stabilisation works are currently scheduled for 2026/2027 and there may be an opportunity - as presented in the Swanage Seafront Masterplan - to significantly enhance these areas, whilst retaining them as a premier events field and key green space. This would ultimately be dependent upon funding.