Emergency Stabilisation and Retaining Wall Reconstruction at Chywoone Hill, Penzance

Introduction

Jointline was appointed to undertake the emergency stabilisation and reconstruction of a failed retaining wall at Chywoone Hill in Penzance. The collapse resulted in the immediate closure of a key access route due to the risk of further landslip, creating a significant 13-mile diversion and considerable disruption for residents and road users.

Commissioned by Trinity Claims on behalf of the landowner, the project required a technically robust and safety-critical solution. Beyond the engineering challenge, the scheme was delivered within a highly sensitive environment, where public concern was elevated and confidence in the process had been affected by previous delays and contractor withdrawal.

Jointline’s approach combined geotechnical stabilisation, structural reconstruction, rigorous safety management, and a strong emphasis on transparent communication and community collaboration.

The Challenge

The primary challenge was the instability of the embankment following the retaining wall collapse. The failure had compromised the structural integrity of the slope, creating an ongoing risk of further ground movement and potential landslide onto the carriageway.

To mitigate this risk, the road was closed in full. While necessary from a safety perspective, the closure placed a significant burden on the local community, requiring a 13-mile diversion and impacting daily travel, local businesses, and emergency access routes.

Compounding the situation, a previously appointed contractor had vacated the site before completing the works. This contributed to:

• Reduced public confidence in project delivery
• Heightened frustration within the community
• Increased scrutiny of all subsequent activities

Local sentiment, particularly across community groups and social media, reflected consistent concerns around:

• Lack of clear and accessible information
• Limited visibility of progress
• Uncertainty regarding the duration and necessity of the closure

From a technical standpoint, the scheme required a complete reconstruction of the retaining structure, including:

• Stabilisation of the failed slope
• Construction of a reinforced retaining wall capable of resisting lateral earth pressures
• Integration of effective drainage to prevent water build-up and hydrostatic loading
• Reinstatement of the highway infrastructure

The solution also needed to respect the local environment, incorporating a traditional locally sourced granite finish to maintain visual continuity with the surrounding area

All works had to be delivered safely within a constrained footprint, with strict control measures in place to protect both operatives and the public.

The Solution

Jointline delivered a comprehensive and integrated solution, combining detailed engineering methodology with a proactive and transparent approach to stakeholder engagement.

Engineering and Ground Stabilisation

The works commenced with a detailed site assessment and controlled excavation of the failed material. Given the instability of the slope, excavation was carefully sequenced and supported by an engineered slope stabilisation strategy.

A key element of the stabilisation works was the installation of soil nails (pinning) to secure the embankment and prevent further movement during construction. A total of 86 steel pins were installed into the slope, drilled and grouted to designed depths to provide immediate and long-term stabilisation. This pinning system acted to reinforce the ground mass, increasing shear resistance and ensuring a safe working environment for subsequent construction activities.

Following stabilisation, the retaining structure was constructed using a reinforced concrete system designed to withstand long-term loading conditions. The construction methodology included:

• Formation of a stable foundation following excavation and pinning
• Installation of a reinforced retaining wall with a fully integrated rebar system
• Incorporation of a comprehensive drainage design, including weep holes and free-draining backfill, to relieve hydrostatic pressure
• Construction of a traditional granite facing wall, mechanically tied back to the structural wall for durability and visual integration

The embankment was then reinstated using engineered fill materials, finished with topsoil and seeding to encourage natural regeneration.

Safety and Risk Management

Safety remained the primary driver throughout the project. The decision to maintain the road closure was based on the ongoing risk of further landslip, particularly during the early phases of excavation and stabilisation.

Jointline implemented a comprehensive safety regime, including:

• Detailed risk assessments and method statements (RAMS)
• Controlled excavation supported by pinned stabilisation
• Continuous monitoring of slope behaviour and structural performance
• Clearly defined exclusion zones and controlled site access
• Daily coordination and safety briefings for all personnel

The integration of the pinning system was critical in reducing immediate ground risk, allowing works to proceed in a controlled and safe manner.

Community Engagement and Communication Strategy

Recognising the importance of restoring public confidence, Jointline prioritised early engagement with the community.

A public meeting was held prior to mobilisation, providing residents with:

• A clear explanation of the failure mechanism and associated risks
• Insight into the stabilisation process, including the use of pinning to secure the slope
• Justification for the continued road closure on safety grounds
• An open forum to ask questions and raise concerns

To maintain transparency throughout the project, Jointline developed a dedicated project website, providing regular updates, programme information, and direct contact details for the project team.

QR codes were displayed on site signage and shared via local social media channels, ensuring residents could easily access up-to-date information at any time.

Jointline worked closely with Cornwall Council Councillor Thalia Marrington, who supported the communication strategy and helped disseminate accurate and timely updates within the community.

Councillor Thalia Marrington commented:
"Clear communication was essential on this project, and Jointline demonstrated a strong commitment to keeping residents informed. Their willingness to engage directly with the community helped to address concerns and build confidence as the works progressed."

The Benefits

Structural Integrity and Long-Term Resilience

The completed retaining wall provides a robust and durable solution, designed to stabilise the embankment and prevent future failure. The integration of soil nailing, reinforced wall construction, and effective drainage significantly reduces the risk of future instability.

The reinstated highway restores full access along Chywoone Hill, removing the need for the extended diversion and improving connectivity for residents and local services.

The project was completed ahead of programme, allowing the road to reopen earlier than anticipated and reducing overall disruption.

Community Trust and Social Value

A defining success of the project was the transformation of community sentiment. Through consistent communication, visible progress, and respectful engagement, Jointline rebuilt trust and developed a positive relationship with local residents.

Community support became a notable aspect of the project, with residents regularly providing refreshments to the workforce and expressing appreciation for the team’s efforts.

One particularly significant moment occurred when the team temporarily made the site safe and reopened the road to allow the funeral cortege of Doreen Sutton to pass through without undertaking the diversion. This ensured that family and attendees could travel along Chywoone Hill during an important and sensitive occasion, demonstrating a strong commitment to community values and respect for local circumstances.

At the formal reopening, Doreen’s husband, Jeff Sutton, carried out the ribbon cutting. He reflected that the structure would be remembered as “Doreen’s Wall”, creating a lasting and meaningful connection between the project and the community.

Community Investment and Legacy

To mark completion, Jointline hosted a community event at a local church, thanking residents for their support throughout the works.

As part of its social value commitments, Jointline:

• Donated food and drink to the local community food bank
• Provided financial support to the Penlee Lifeboat (RNLI), supporting vital lifesaving services

These contributions reinforced Jointline’s commitment to delivering projects that provide lasting benefits beyond the immediate scope of works.

Leadership and Collaborative Delivery

The project was delivered in close collaboration with Trinity Claims, ensuring alignment between technical delivery and client requirements.

Jointline’s Managing Director, Gary Massey, maintained a visible presence throughout, attending both the initial public meeting and the completion event to engage directly with residents.

Gary Massey commented, "This project required not only technical expertise but also a strong commitment to safety and community engagement. By working closely with residents and stakeholders, we were able to deliver a solution that restores both the infrastructure and confidence in its long-term stability."